drm: Move sysfb drivers into separate subdirectory

The ofdrm and simpledrm drivers are special as they operate on
externally provided framebuffers. Move them into their own sub-
directory. Will let them share common code.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250401094056.32904-5-tzimmermann@suse.de

4 files changed, 2521 insertions, 0 deletions

diff --git a/drivers/gpu/drm/sysfb/Kconfig b/drivers/gpu/drm/sysfb/Kconfig
new file mode 100644
index 000000000000..9eafc06b7192
--- /dev/null
+++ b/drivers/gpu/drm/sysfb/Kconfig
@@ -0,0 +1,38 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "Drivers for system framebuffers"
+	depends on DRM
+
+config DRM_OFDRM
+	tristate "Open Firmware display driver"
+	depends on DRM && MMU && OF && (PPC || COMPILE_TEST)
+	select APERTURE_HELPERS
+	select DRM_CLIENT_SELECTION
+	select DRM_GEM_SHMEM_HELPER
+	select DRM_KMS_HELPER
+	help
+	  DRM driver for Open Firmware framebuffers.
+
+	  This driver assumes that the display hardware has been initialized
+	  by the Open Firmware before the kernel boots. Scanout buffer, size,
+	  and display format must be provided via device tree.
+
+config DRM_SIMPLEDRM
+	tristate "Simple framebuffer driver"
+	depends on DRM && MMU
+	select APERTURE_HELPERS
+	select DRM_CLIENT_SELECTION
+	select DRM_GEM_SHMEM_HELPER
+	select DRM_KMS_HELPER
+	help
+	  DRM driver for simple platform-provided framebuffers.
+
+	  This driver assumes that the display hardware has been initialized
+	  by the firmware or bootloader before the kernel boots. Scanout
+	  buffer, size, and display format must be provided via device tree,
+	  UEFI, VESA, etc.
+
+	  On x86 BIOS or UEFI systems, you should also select SYSFB_SIMPLEFB
+	  to use UEFI and VESA framebuffers.
+
+endmenu
diff --git a/drivers/gpu/drm/sysfb/Makefile b/drivers/gpu/drm/sysfb/Makefile
new file mode 100644
index 000000000000..f6c03629accb
--- /dev/null
+++ b/drivers/gpu/drm/sysfb/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_DRM_OFDRM)		+= ofdrm.o
+obj-$(CONFIG_DRM_SIMPLEDRM)	+= simpledrm.o
diff --git a/drivers/gpu/drm/sysfb/ofdrm.c b/drivers/gpu/drm/sysfb/ofdrm.c
new file mode 100644
index 000000000000..7d5beaf6a42c
--- /dev/null
+++ b/drivers/gpu/drm/sysfb/ofdrm.c
@@ -0,0 +1,1407 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/aperture.h>
+#include <linux/of_address.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+
+#include <drm/clients/drm_client_setup.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fbdev_shmem.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_probe_helper.h>
+
+#define DRIVER_NAME	"ofdrm"
+#define DRIVER_DESC	"DRM driver for OF platform devices"
+#define DRIVER_MAJOR	1
+#define DRIVER_MINOR	0
+
+#define PCI_VENDOR_ID_ATI_R520	0x7100
+#define PCI_VENDOR_ID_ATI_R600	0x9400
+
+#define OFDRM_GAMMA_LUT_SIZE	256
+
+/* Definitions used by the Avivo palette  */
+#define AVIVO_DC_LUT_RW_SELECT                  0x6480
+#define AVIVO_DC_LUT_RW_MODE                    0x6484
+#define AVIVO_DC_LUT_RW_INDEX                   0x6488
+#define AVIVO_DC_LUT_SEQ_COLOR                  0x648c
+#define AVIVO_DC_LUT_PWL_DATA                   0x6490
+#define AVIVO_DC_LUT_30_COLOR                   0x6494
+#define AVIVO_DC_LUT_READ_PIPE_SELECT           0x6498
+#define AVIVO_DC_LUT_WRITE_EN_MASK              0x649c
+#define AVIVO_DC_LUT_AUTOFILL                   0x64a0
+#define AVIVO_DC_LUTA_CONTROL                   0x64c0
+#define AVIVO_DC_LUTA_BLACK_OFFSET_BLUE         0x64c4
+#define AVIVO_DC_LUTA_BLACK_OFFSET_GREEN        0x64c8
+#define AVIVO_DC_LUTA_BLACK_OFFSET_RED          0x64cc
+#define AVIVO_DC_LUTA_WHITE_OFFSET_BLUE         0x64d0
+#define AVIVO_DC_LUTA_WHITE_OFFSET_GREEN        0x64d4
+#define AVIVO_DC_LUTA_WHITE_OFFSET_RED          0x64d8
+#define AVIVO_DC_LUTB_CONTROL                   0x6cc0
+#define AVIVO_DC_LUTB_BLACK_OFFSET_BLUE         0x6cc4
+#define AVIVO_DC_LUTB_BLACK_OFFSET_GREEN        0x6cc8
+#define AVIVO_DC_LUTB_BLACK_OFFSET_RED          0x6ccc
+#define AVIVO_DC_LUTB_WHITE_OFFSET_BLUE         0x6cd0
+#define AVIVO_DC_LUTB_WHITE_OFFSET_GREEN        0x6cd4
+#define AVIVO_DC_LUTB_WHITE_OFFSET_RED          0x6cd8
+
+enum ofdrm_model {
+	OFDRM_MODEL_UNKNOWN,
+	OFDRM_MODEL_MACH64, /* ATI Mach64 */
+	OFDRM_MODEL_RAGE128, /* ATI Rage128 */
+	OFDRM_MODEL_RAGE_M3A, /* ATI Rage Mobility M3 Head A */
+	OFDRM_MODEL_RAGE_M3B, /* ATI Rage Mobility M3 Head B */
+	OFDRM_MODEL_RADEON, /* ATI Radeon */
+	OFDRM_MODEL_GXT2000, /* IBM GXT2000 */
+	OFDRM_MODEL_AVIVO, /* ATI R5xx */
+	OFDRM_MODEL_QEMU, /* QEMU VGA */
+};
+
+/*
+ * Helpers for display nodes
+ */
+
+static int display_get_validated_int(struct drm_device *dev, const char *name, uint32_t value)
+{
+	if (value > INT_MAX) {
+		drm_err(dev, "invalid framebuffer %s of %u\n", name, value);
+		return -EINVAL;
+	}
+	return (int)value;
+}
+
+static int display_get_validated_int0(struct drm_device *dev, const char *name, uint32_t value)
+{
+	if (!value) {
+		drm_err(dev, "invalid framebuffer %s of %u\n", name, value);
+		return -EINVAL;
+	}
+	return display_get_validated_int(dev, name, value);
+}
+
+static const struct drm_format_info *display_get_validated_format(struct drm_device *dev,
+								  u32 depth, bool big_endian)
+{
+	const struct drm_format_info *info;
+	u32 format;
+
+	switch (depth) {
+	case 8:
+		format = drm_mode_legacy_fb_format(8, 8);
+		break;
+	case 15:
+	case 16:
+		format = drm_mode_legacy_fb_format(16, depth);
+		break;
+	case 32:
+		format = drm_mode_legacy_fb_format(32, 24);
+		break;
+	default:
+		drm_err(dev, "unsupported framebuffer depth %u\n", depth);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/*
+	 * DRM formats assume little-endian byte order. Update the format
+	 * if the scanout buffer uses big-endian ordering.
+	 */
+	if (big_endian) {
+		switch (format) {
+		case DRM_FORMAT_XRGB8888:
+			format = DRM_FORMAT_BGRX8888;
+			break;
+		case DRM_FORMAT_ARGB8888:
+			format = DRM_FORMAT_BGRA8888;
+			break;
+		case DRM_FORMAT_RGB565:
+			format = DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN;
+			break;
+		case DRM_FORMAT_XRGB1555:
+			format = DRM_FORMAT_XRGB1555 | DRM_FORMAT_BIG_ENDIAN;
+			break;
+		default:
+			break;
+		}
+	}
+
+	info = drm_format_info(format);
+	if (!info) {
+		drm_err(dev, "cannot find framebuffer format for depth %u\n", depth);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return info;
+}
+
+static int display_read_u32_of(struct drm_device *dev, struct device_node *of_node,
+			       const char *name, u32 *value)
+{
+	int ret = of_property_read_u32(of_node, name, value);
+
+	if (ret)
+		drm_err(dev, "cannot parse framebuffer %s: error %d\n", name, ret);
+	return ret;
+}
+
+static bool display_get_big_endian_of(struct drm_device *dev, struct device_node *of_node)
+{
+	bool big_endian;
+
+#ifdef __BIG_ENDIAN
+	big_endian = !of_property_read_bool(of_node, "little-endian");
+#else
+	big_endian = of_property_read_bool(of_node, "big-endian");
+#endif
+
+	return big_endian;
+}
+
+static int display_get_width_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 width;
+	int ret = display_read_u32_of(dev, of_node, "width", &width);
+
+	if (ret)
+		return ret;
+	return display_get_validated_int0(dev, "width", width);
+}
+
+static int display_get_height_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 height;
+	int ret = display_read_u32_of(dev, of_node, "height", &height);
+
+	if (ret)
+		return ret;
+	return display_get_validated_int0(dev, "height", height);
+}
+
+static int display_get_depth_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 depth;
+	int ret = display_read_u32_of(dev, of_node, "depth", &depth);
+
+	if (ret)
+		return ret;
+	return display_get_validated_int0(dev, "depth", depth);
+}
+
+static int display_get_linebytes_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 linebytes;
+	int ret = display_read_u32_of(dev, of_node, "linebytes", &linebytes);
+
+	if (ret)
+		return ret;
+	return display_get_validated_int(dev, "linebytes", linebytes);
+}
+
+static u64 display_get_address_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 address;
+	int ret;
+
+	/*
+	 * Not all devices provide an address property, it's not
+	 * a bug if this fails. The driver will try to find the
+	 * framebuffer base address from the device's memory regions.
+	 */
+	ret = of_property_read_u32(of_node, "address", &address);
+	if (ret)
+		return OF_BAD_ADDR;
+
+	return address;
+}
+
+static bool is_avivo(u32 vendor, u32 device)
+{
+	/* This will match most R5xx */
+	return (vendor == PCI_VENDOR_ID_ATI) &&
+	       ((device >= PCI_VENDOR_ID_ATI_R520 && device < 0x7800) ||
+		(PCI_VENDOR_ID_ATI_R600 >= 0x9400));
+}
+
+static enum ofdrm_model display_get_model_of(struct drm_device *dev, struct device_node *of_node)
+{
+	enum ofdrm_model model = OFDRM_MODEL_UNKNOWN;
+
+	if (of_node_name_prefix(of_node, "ATY,Rage128")) {
+		model = OFDRM_MODEL_RAGE128;
+	} else if (of_node_name_prefix(of_node, "ATY,RageM3pA") ||
+		   of_node_name_prefix(of_node, "ATY,RageM3p12A")) {
+		model = OFDRM_MODEL_RAGE_M3A;
+	} else if (of_node_name_prefix(of_node, "ATY,RageM3pB")) {
+		model = OFDRM_MODEL_RAGE_M3B;
+	} else if (of_node_name_prefix(of_node, "ATY,Rage6")) {
+		model = OFDRM_MODEL_RADEON;
+	} else if (of_node_name_prefix(of_node, "ATY,")) {
+		return OFDRM_MODEL_MACH64;
+	} else if (of_device_is_compatible(of_node, "pci1014,b7") ||
+		   of_device_is_compatible(of_node, "pci1014,21c")) {
+		model = OFDRM_MODEL_GXT2000;
+	} else if (of_node_name_prefix(of_node, "vga,Display-")) {
+		struct device_node *of_parent;
+		const __be32 *vendor_p, *device_p;
+
+		/* Look for AVIVO initialized by SLOF */
+		of_parent = of_get_parent(of_node);
+		vendor_p = of_get_property(of_parent, "vendor-id", NULL);
+		device_p = of_get_property(of_parent, "device-id", NULL);
+		if (vendor_p && device_p) {
+			u32 vendor = be32_to_cpup(vendor_p);
+			u32 device = be32_to_cpup(device_p);
+
+			if (is_avivo(vendor, device))
+				model = OFDRM_MODEL_AVIVO;
+		}
+		of_node_put(of_parent);
+	} else if (of_device_is_compatible(of_node, "qemu,std-vga")) {
+		model = OFDRM_MODEL_QEMU;
+	}
+
+	return model;
+}
+
+/*
+ * Open Firmware display device
+ */
+
+struct ofdrm_device;
+
+struct ofdrm_device_funcs {
+	void __iomem *(*cmap_ioremap)(struct ofdrm_device *odev,
+				      struct device_node *of_node,
+				      u64 fb_bas);
+	void (*cmap_write)(struct ofdrm_device *odev, unsigned char index,
+			   unsigned char r, unsigned char g, unsigned char b);
+};
+
+struct ofdrm_device {
+	struct drm_device dev;
+
+	const struct ofdrm_device_funcs *funcs;
+
+	/* firmware-buffer settings */
+	struct iosys_map screen_base;
+	struct drm_display_mode mode;
+	const struct drm_format_info *format;
+	unsigned int pitch;
+
+	/* colormap */
+	void __iomem *cmap_base;
+
+	/* modesetting */
+	uint32_t formats[8];
+	struct drm_plane primary_plane;
+	struct drm_crtc crtc;
+	struct drm_encoder encoder;
+	struct drm_connector connector;
+};
+
+static struct ofdrm_device *ofdrm_device_of_dev(struct drm_device *dev)
+{
+	return container_of(dev, struct ofdrm_device, dev);
+}
+
+/*
+ * Hardware
+ */
+
+#if defined(CONFIG_PCI)
+static struct pci_dev *display_get_pci_dev_of(struct drm_device *dev, struct device_node *of_node)
+{
+	const __be32 *vendor_p, *device_p;
+	u32 vendor, device;
+	struct pci_dev *pcidev;
+
+	vendor_p = of_get_property(of_node, "vendor-id", NULL);
+	if (!vendor_p)
+		return ERR_PTR(-ENODEV);
+	vendor = be32_to_cpup(vendor_p);
+
+	device_p = of_get_property(of_node, "device-id", NULL);
+	if (!device_p)
+		return ERR_PTR(-ENODEV);
+	device = be32_to_cpup(device_p);
+
+	pcidev = pci_get_device(vendor, device, NULL);
+	if (!pcidev)
+		return ERR_PTR(-ENODEV);
+
+	return pcidev;
+}
+
+static void ofdrm_pci_release(void *data)
+{
+	struct pci_dev *pcidev = data;
+
+	pci_disable_device(pcidev);
+}
+
+static int ofdrm_device_init_pci(struct ofdrm_device *odev)
+{
+	struct drm_device *dev = &odev->dev;
+	struct platform_device *pdev = to_platform_device(dev->dev);
+	struct device_node *of_node = pdev->dev.of_node;
+	struct pci_dev *pcidev;
+	int ret;
+
+	/*
+	 * Never use pcim_ or other managed helpers on the returned PCI
+	 * device. Otherwise, probing the native driver will fail for
+	 * resource conflicts. PCI-device management has to be tied to
+	 * the lifetime of the platform device until the native driver
+	 * takes over.
+	 */
+	pcidev = display_get_pci_dev_of(dev, of_node);
+	if (IS_ERR(pcidev))
+		return 0; /* no PCI device found; ignore the error */
+
+	ret = pci_enable_device(pcidev);
+	if (ret) {
+		drm_err(dev, "pci_enable_device(%s) failed: %d\n",
+			dev_name(&pcidev->dev), ret);
+		return ret;
+	}
+	ret = devm_add_action_or_reset(&pdev->dev, ofdrm_pci_release, pcidev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+#else
+static int ofdrm_device_init_pci(struct ofdrm_device *odev)
+{
+	return 0;
+}
+#endif
+
+/*
+ *  OF display settings
+ */
+
+static struct resource *ofdrm_find_fb_resource(struct ofdrm_device *odev,
+					       struct resource *fb_res)
+{
+	struct platform_device *pdev = to_platform_device(odev->dev.dev);
+	struct resource *res, *max_res = NULL;
+	u32 i;
+
+	for (i = 0; pdev->num_resources; ++i) {
+		res = platform_get_resource(pdev, IORESOURCE_MEM, i);
+		if (!res)
+			break; /* all resources processed */
+		if (resource_size(res) < resource_size(fb_res))
+			continue; /* resource too small */
+		if (fb_res->start && resource_contains(res, fb_res))
+			return res; /* resource contains framebuffer */
+		if (!max_res || resource_size(res) > resource_size(max_res))
+			max_res = res; /* store largest resource as fallback */
+	}
+
+	return max_res;
+}
+
+/*
+ * Colormap / Palette
+ */
+
+static void __iomem *get_cmap_address_of(struct ofdrm_device *odev, struct device_node *of_node,
+					 int bar_no, unsigned long offset, unsigned long size)
+{
+	struct drm_device *dev = &odev->dev;
+	const __be32 *addr_p;
+	u64 max_size, address;
+	unsigned int flags;
+	void __iomem *mem;
+
+	addr_p = of_get_pci_address(of_node, bar_no, &max_size, &flags);
+	if (!addr_p)
+		addr_p = of_get_address(of_node, bar_no, &max_size, &flags);
+	if (!addr_p)
+		return IOMEM_ERR_PTR(-ENODEV);
+
+	if ((flags & (IORESOURCE_IO | IORESOURCE_MEM)) == 0)
+		return IOMEM_ERR_PTR(-ENODEV);
+
+	if ((offset + size) >= max_size)
+		return IOMEM_ERR_PTR(-ENODEV);
+
+	address = of_translate_address(of_node, addr_p);
+	if (address == OF_BAD_ADDR)
+		return IOMEM_ERR_PTR(-ENODEV);
+
+	mem = devm_ioremap(dev->dev, address + offset, size);
+	if (!mem)
+		return IOMEM_ERR_PTR(-ENOMEM);
+
+	return mem;
+}
+
+static void __iomem *ofdrm_mach64_cmap_ioremap(struct ofdrm_device *odev,
+					       struct device_node *of_node,
+					       u64 fb_base)
+{
+	struct drm_device *dev = &odev->dev;
+	u64 address;
+	void __iomem *cmap_base;
+
+	address = fb_base & 0xff000000ul;
+	address += 0x7ff000;
+
+	cmap_base = devm_ioremap(dev->dev, address, 0x1000);
+	if (!cmap_base)
+		return IOMEM_ERR_PTR(-ENOMEM);
+
+	return cmap_base;
+}
+
+static void ofdrm_mach64_cmap_write(struct ofdrm_device *odev, unsigned char index,
+				    unsigned char r, unsigned char g, unsigned char b)
+{
+	void __iomem *addr = odev->cmap_base + 0xcc0;
+	void __iomem *data = odev->cmap_base + 0xcc0 + 1;
+
+	writeb(index, addr);
+	writeb(r, data);
+	writeb(g, data);
+	writeb(b, data);
+}
+
+static void __iomem *ofdrm_rage128_cmap_ioremap(struct ofdrm_device *odev,
+						struct device_node *of_node,
+						u64 fb_base)
+{
+	return get_cmap_address_of(odev, of_node, 2, 0, 0x1fff);
+}
+
+static void ofdrm_rage128_cmap_write(struct ofdrm_device *odev, unsigned char index,
+				     unsigned char r, unsigned char g, unsigned char b)
+{
+	void __iomem *addr = odev->cmap_base + 0xb0;
+	void __iomem *data = odev->cmap_base + 0xb4;
+	u32 color = (r << 16) | (g << 8) | b;
+
+	writeb(index, addr);
+	writel(color, data);
+}
+
+static void __iomem *ofdrm_rage_m3a_cmap_ioremap(struct ofdrm_device *odev,
+						 struct device_node *of_node,
+						 u64 fb_base)
+{
+	return get_cmap_address_of(odev, of_node, 2, 0, 0x1fff);
+}
+
+static void ofdrm_rage_m3a_cmap_write(struct ofdrm_device *odev, unsigned char index,
+				      unsigned char r, unsigned char g, unsigned char b)
+{
+	void __iomem *dac_ctl = odev->cmap_base + 0x58;
+	void __iomem *addr = odev->cmap_base + 0xb0;
+	void __iomem *data = odev->cmap_base + 0xb4;
+	u32 color = (r << 16) | (g << 8) | b;
+	u32 val;
+
+	/* Clear PALETTE_ACCESS_CNTL in DAC_CNTL */
+	val = readl(dac_ctl);
+	val &= ~0x20;
+	writel(val, dac_ctl);
+
+	/* Set color at palette index */
+	writeb(index, addr);
+	writel(color, data);
+}
+
+static void __iomem *ofdrm_rage_m3b_cmap_ioremap(struct ofdrm_device *odev,
+						 struct device_node *of_node,
+						 u64 fb_base)
+{
+	return get_cmap_address_of(odev, of_node, 2, 0, 0x1fff);
+}
+
+static void ofdrm_rage_m3b_cmap_write(struct ofdrm_device *odev, unsigned char index,
+				      unsigned char r, unsigned char g, unsigned char b)
+{
+	void __iomem *dac_ctl = odev->cmap_base + 0x58;
+	void __iomem *addr = odev->cmap_base + 0xb0;
+	void __iomem *data = odev->cmap_base + 0xb4;
+	u32 color = (r << 16) | (g << 8) | b;
+	u32 val;
+
+	/* Set PALETTE_ACCESS_CNTL in DAC_CNTL */
+	val = readl(dac_ctl);
+	val |= 0x20;
+	writel(val, dac_ctl);
+
+	/* Set color at palette index */
+	writeb(index, addr);
+	writel(color, data);
+}
+
+static void __iomem *ofdrm_radeon_cmap_ioremap(struct ofdrm_device *odev,
+					       struct device_node *of_node,
+					       u64 fb_base)
+{
+	return get_cmap_address_of(odev, of_node, 1, 0, 0x1fff);
+}
+
+static void __iomem *ofdrm_gxt2000_cmap_ioremap(struct ofdrm_device *odev,
+						struct device_node *of_node,
+						u64 fb_base)
+{
+	return get_cmap_address_of(odev, of_node, 0, 0x6000, 0x1000);
+}
+
+static void ofdrm_gxt2000_cmap_write(struct ofdrm_device *odev, unsigned char index,
+				     unsigned char r, unsigned char g, unsigned char b)
+{
+	void __iomem *data = ((unsigned int __iomem *)odev->cmap_base) + index;
+	u32 color = (r << 16) | (g << 8) | b;
+
+	writel(color, data);
+}
+
+static void __iomem *ofdrm_avivo_cmap_ioremap(struct ofdrm_device *odev,
+					      struct device_node *of_node,
+					      u64 fb_base)
+{
+	struct device_node *of_parent;
+	void __iomem *cmap_base;
+
+	of_parent = of_get_parent(of_node);
+	cmap_base = get_cmap_address_of(odev, of_parent, 0, 0, 0x10000);
+	of_node_put(of_parent);
+
+	return cmap_base;
+}
+
+static void ofdrm_avivo_cmap_write(struct ofdrm_device *odev, unsigned char index,
+				   unsigned char r, unsigned char g, unsigned char b)
+{
+	void __iomem *lutsel = odev->cmap_base + AVIVO_DC_LUT_RW_SELECT;
+	void __iomem *addr = odev->cmap_base + AVIVO_DC_LUT_RW_INDEX;
+	void __iomem *data = odev->cmap_base + AVIVO_DC_LUT_30_COLOR;
+	u32 color = (r << 22) | (g << 12) | (b << 2);
+
+	/* Write to both LUTs for now */
+
+	writel(1, lutsel);
+	writeb(index, addr);
+	writel(color, data);
+
+	writel(0, lutsel);
+	writeb(index, addr);
+	writel(color, data);
+}
+
+static void __iomem *ofdrm_qemu_cmap_ioremap(struct ofdrm_device *odev,
+					     struct device_node *of_node,
+					     u64 fb_base)
+{
+	static const __be32 io_of_addr[3] = {
+		cpu_to_be32(0x01000000),
+		cpu_to_be32(0x00),
+		cpu_to_be32(0x00),
+	};
+
+	struct drm_device *dev = &odev->dev;
+	u64 address;
+	void __iomem *cmap_base;
+
+	address = of_translate_address(of_node, io_of_addr);
+	if (address == OF_BAD_ADDR)
+		return IOMEM_ERR_PTR(-ENODEV);
+
+	cmap_base = devm_ioremap(dev->dev, address + 0x3c8, 2);
+	if (!cmap_base)
+		return IOMEM_ERR_PTR(-ENOMEM);
+
+	return cmap_base;
+}
+
+static void ofdrm_qemu_cmap_write(struct ofdrm_device *odev, unsigned char index,
+				  unsigned char r, unsigned char g, unsigned char b)
+{
+	void __iomem *addr = odev->cmap_base;
+	void __iomem *data = odev->cmap_base + 1;
+
+	writeb(index, addr);
+	writeb(r, data);
+	writeb(g, data);
+	writeb(b, data);
+}
+
+static void ofdrm_device_set_gamma_linear(struct ofdrm_device *odev,
+					  const struct drm_format_info *format)
+{
+	struct drm_device *dev = &odev->dev;
+	int i;
+
+	switch (format->format) {
+	case DRM_FORMAT_RGB565:
+	case DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN:
+		/* Use better interpolation, to take 32 values from 0 to 255 */
+		for (i = 0; i < OFDRM_GAMMA_LUT_SIZE / 8; i++) {
+			unsigned char r = i * 8 + i / 4;
+			unsigned char g = i * 4 + i / 16;
+			unsigned char b = i * 8 + i / 4;
+
+			odev->funcs->cmap_write(odev, i, r, g, b);
+		}
+		/* Green has one more bit, so add padding with 0 for red and blue. */
+		for (i = OFDRM_GAMMA_LUT_SIZE / 8; i < OFDRM_GAMMA_LUT_SIZE / 4; i++) {
+			unsigned char r = 0;
+			unsigned char g = i * 4 + i / 16;
+			unsigned char b = 0;
+
+			odev->funcs->cmap_write(odev, i, r, g, b);
+		}
+		break;
+	case DRM_FORMAT_XRGB8888:
+	case DRM_FORMAT_BGRX8888:
+		for (i = 0; i < OFDRM_GAMMA_LUT_SIZE; i++)
+			odev->funcs->cmap_write(odev, i, i, i, i);
+		break;
+	default:
+		drm_warn_once(dev, "Unsupported format %p4cc for gamma correction\n",
+			      &format->format);
+		break;
+	}
+}
+
+static void ofdrm_device_set_gamma(struct ofdrm_device *odev,
+				   const struct drm_format_info *format,
+				   struct drm_color_lut *lut)
+{
+	struct drm_device *dev = &odev->dev;
+	int i;
+
+	switch (format->format) {
+	case DRM_FORMAT_RGB565:
+	case DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN:
+		/* Use better interpolation, to take 32 values from lut[0] to lut[255] */
+		for (i = 0; i < OFDRM_GAMMA_LUT_SIZE / 8; i++) {
+			unsigned char r = lut[i * 8 + i / 4].red >> 8;
+			unsigned char g = lut[i * 4 + i / 16].green >> 8;
+			unsigned char b = lut[i * 8 + i / 4].blue >> 8;
+
+			odev->funcs->cmap_write(odev, i, r, g, b);
+		}
+		/* Green has one more bit, so add padding with 0 for red and blue. */
+		for (i = OFDRM_GAMMA_LUT_SIZE / 8; i < OFDRM_GAMMA_LUT_SIZE / 4; i++) {
+			unsigned char r = 0;
+			unsigned char g = lut[i * 4 + i / 16].green >> 8;
+			unsigned char b = 0;
+
+			odev->funcs->cmap_write(odev, i, r, g, b);
+		}
+		break;
+	case DRM_FORMAT_XRGB8888:
+	case DRM_FORMAT_BGRX8888:
+		for (i = 0; i < OFDRM_GAMMA_LUT_SIZE; i++) {
+			unsigned char r = lut[i].red >> 8;
+			unsigned char g = lut[i].green >> 8;
+			unsigned char b = lut[i].blue >> 8;
+
+			odev->funcs->cmap_write(odev, i, r, g, b);
+		}
+		break;
+	default:
+		drm_warn_once(dev, "Unsupported format %p4cc for gamma correction\n",
+			      &format->format);
+		break;
+	}
+}
+
+/*
+ * Modesetting
+ */
+
+struct ofdrm_crtc_state {
+	struct drm_crtc_state base;
+
+	/* Primary-plane format; required for color mgmt. */
+	const struct drm_format_info *format;
+};
+
+static struct ofdrm_crtc_state *to_ofdrm_crtc_state(struct drm_crtc_state *base)
+{
+	return container_of(base, struct ofdrm_crtc_state, base);
+}
+
+static void ofdrm_crtc_state_destroy(struct ofdrm_crtc_state *ofdrm_crtc_state)
+{
+	__drm_atomic_helper_crtc_destroy_state(&ofdrm_crtc_state->base);
+	kfree(ofdrm_crtc_state);
+}
+
+static const uint64_t ofdrm_primary_plane_format_modifiers[] = {
+	DRM_FORMAT_MOD_LINEAR,
+	DRM_FORMAT_MOD_INVALID
+};
+
+static int ofdrm_primary_plane_helper_atomic_check(struct drm_plane *plane,
+						   struct drm_atomic_state *new_state)
+{
+	struct drm_device *dev = plane->dev;
+	struct ofdrm_device *odev = ofdrm_device_of_dev(dev);
+	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(new_state, plane);
+	struct drm_shadow_plane_state *new_shadow_plane_state =
+		to_drm_shadow_plane_state(new_plane_state);
+	struct drm_framebuffer *new_fb = new_plane_state->fb;
+	struct drm_crtc *new_crtc = new_plane_state->crtc;
+	struct drm_crtc_state *new_crtc_state = NULL;
+	struct ofdrm_crtc_state *new_ofdrm_crtc_state;
+	int ret;
+
+	if (new_crtc)
+		new_crtc_state = drm_atomic_get_new_crtc_state(new_state, new_plane_state->crtc);
+
+	ret = drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
+						  DRM_PLANE_NO_SCALING,
+						  DRM_PLANE_NO_SCALING,
+						  false, false);
+	if (ret)
+		return ret;
+	else if (!new_plane_state->visible)
+		return 0;
+
+	if (new_fb->format != odev->format) {
+		void *buf;
+
+		/* format conversion necessary; reserve buffer */
+		buf = drm_format_conv_state_reserve(&new_shadow_plane_state->fmtcnv_state,
+						    odev->pitch, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+	}
+
+	new_crtc_state = drm_atomic_get_new_crtc_state(new_state, new_plane_state->crtc);
+
+	new_ofdrm_crtc_state = to_ofdrm_crtc_state(new_crtc_state);
+	new_ofdrm_crtc_state->format = new_fb->format;
+
+	return 0;
+}
+
+static void ofdrm_primary_plane_helper_atomic_update(struct drm_plane *plane,
+						     struct drm_atomic_state *state)
+{
+	struct drm_device *dev = plane->dev;
+	struct ofdrm_device *odev = ofdrm_device_of_dev(dev);
+	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
+	struct drm_framebuffer *fb = plane_state->fb;
+	unsigned int dst_pitch = odev->pitch;
+	const struct drm_format_info *dst_format = odev->format;
+	struct drm_atomic_helper_damage_iter iter;
+	struct drm_rect damage;
+	int ret, idx;
+
+	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
+	if (ret)
+		return;
+
+	if (!drm_dev_enter(dev, &idx))
+		goto out_drm_gem_fb_end_cpu_access;
+
+	drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
+	drm_atomic_for_each_plane_damage(&iter, &damage) {
+		struct iosys_map dst = odev->screen_base;
+		struct drm_rect dst_clip = plane_state->dst;
+
+		if (!drm_rect_intersect(&dst_clip, &damage))
+			continue;
+
+		iosys_map_incr(&dst, drm_fb_clip_offset(dst_pitch, dst_format, &dst_clip));
+		drm_fb_blit(&dst, &dst_pitch, dst_format->format, shadow_plane_state->data, fb,
+			    &damage, &shadow_plane_state->fmtcnv_state);
+	}
+
+	drm_dev_exit(idx);
+out_drm_gem_fb_end_cpu_access:
+	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
+}
+
+static void ofdrm_primary_plane_helper_atomic_disable(struct drm_plane *plane,
+						      struct drm_atomic_state *state)
+{
+	struct drm_device *dev = plane->dev;
+	struct ofdrm_device *odev = ofdrm_device_of_dev(dev);
+	struct iosys_map dst = odev->screen_base;
+	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+	void __iomem *dst_vmap = dst.vaddr_iomem; /* TODO: Use mapping abstraction */
+	unsigned int dst_pitch = odev->pitch;
+	const struct drm_format_info *dst_format = odev->format;
+	struct drm_rect dst_clip;
+	unsigned long lines, linepixels, i;
+	int idx;
+
+	drm_rect_init(&dst_clip,
+		      plane_state->src_x >> 16, plane_state->src_y >> 16,
+		      plane_state->src_w >> 16, plane_state->src_h >> 16);
+
+	lines = drm_rect_height(&dst_clip);
+	linepixels = drm_rect_width(&dst_clip);
+
+	if (!drm_dev_enter(dev, &idx))
+		return;
+
+	/* Clear buffer to black if disabled */
+	dst_vmap += drm_fb_clip_offset(dst_pitch, dst_format, &dst_clip);
+	for (i = 0; i < lines; ++i) {
+		memset_io(dst_vmap, 0, linepixels * dst_format->cpp[0]);
+		dst_vmap += dst_pitch;
+	}
+
+	drm_dev_exit(idx);
+}
+
+static const struct drm_plane_helper_funcs ofdrm_primary_plane_helper_funcs = {
+	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
+	.atomic_check = ofdrm_primary_plane_helper_atomic_check,
+	.atomic_update = ofdrm_primary_plane_helper_atomic_update,
+	.atomic_disable = ofdrm_primary_plane_helper_atomic_disable,
+};
+
+static const struct drm_plane_funcs ofdrm_primary_plane_funcs = {
+	.update_plane = drm_atomic_helper_update_plane,
+	.disable_plane = drm_atomic_helper_disable_plane,
+	.destroy = drm_plane_cleanup,
+	DRM_GEM_SHADOW_PLANE_FUNCS,
+};
+
+static enum drm_mode_status ofdrm_crtc_helper_mode_valid(struct drm_crtc *crtc,
+							 const struct drm_display_mode *mode)
+{
+	struct ofdrm_device *odev = ofdrm_device_of_dev(crtc->dev);
+
+	return drm_crtc_helper_mode_valid_fixed(crtc, mode, &odev->mode);
+}
+
+static int ofdrm_crtc_helper_atomic_check(struct drm_crtc *crtc,
+					  struct drm_atomic_state *new_state)
+{
+	static const size_t gamma_lut_length = OFDRM_GAMMA_LUT_SIZE * sizeof(struct drm_color_lut);
+
+	struct drm_device *dev = crtc->dev;
+	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(new_state, crtc);
+	int ret;
+
+	if (!new_crtc_state->enable)
+		return 0;
+
+	ret = drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
+	if (ret)
+		return ret;
+
+	if (new_crtc_state->color_mgmt_changed) {
+		struct drm_property_blob *gamma_lut = new_crtc_state->gamma_lut;
+
+		if (gamma_lut && (gamma_lut->length != gamma_lut_length)) {
+			drm_dbg(dev, "Incorrect gamma_lut length %zu\n", gamma_lut->length);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static void ofdrm_crtc_helper_atomic_flush(struct drm_crtc *crtc, struct drm_atomic_state *state)
+{
+	struct ofdrm_device *odev = ofdrm_device_of_dev(crtc->dev);
+	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
+	struct ofdrm_crtc_state *ofdrm_crtc_state = to_ofdrm_crtc_state(crtc_state);
+
+	if (crtc_state->enable && crtc_state->color_mgmt_changed) {
+		const struct drm_format_info *format = ofdrm_crtc_state->format;
+
+		if (crtc_state->gamma_lut)
+			ofdrm_device_set_gamma(odev, format, crtc_state->gamma_lut->data);
+		else
+			ofdrm_device_set_gamma_linear(odev, format);
+	}
+}
+
+/*
+ * The CRTC is always enabled. Screen updates are performed by
+ * the primary plane's atomic_update function. Disabling clears
+ * the screen in the primary plane's atomic_disable function.
+ */
+static const struct drm_crtc_helper_funcs ofdrm_crtc_helper_funcs = {
+	.mode_valid = ofdrm_crtc_helper_mode_valid,
+	.atomic_check = ofdrm_crtc_helper_atomic_check,
+	.atomic_flush = ofdrm_crtc_helper_atomic_flush,
+};
+
+static void ofdrm_crtc_reset(struct drm_crtc *crtc)
+{
+	struct ofdrm_crtc_state *ofdrm_crtc_state =
+		kzalloc(sizeof(*ofdrm_crtc_state), GFP_KERNEL);
+
+	if (crtc->state)
+		ofdrm_crtc_state_destroy(to_ofdrm_crtc_state(crtc->state));
+
+	if (ofdrm_crtc_state)
+		__drm_atomic_helper_crtc_reset(crtc, &ofdrm_crtc_state->base);
+	else
+		__drm_atomic_helper_crtc_reset(crtc, NULL);
+}
+
+static struct drm_crtc_state *ofdrm_crtc_atomic_duplicate_state(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_crtc_state *crtc_state = crtc->state;
+	struct ofdrm_crtc_state *new_ofdrm_crtc_state;
+	struct ofdrm_crtc_state *ofdrm_crtc_state;
+
+	if (drm_WARN_ON(dev, !crtc_state))
+		return NULL;
+
+	new_ofdrm_crtc_state = kzalloc(sizeof(*new_ofdrm_crtc_state), GFP_KERNEL);
+	if (!new_ofdrm_crtc_state)
+		return NULL;
+
+	ofdrm_crtc_state = to_ofdrm_crtc_state(crtc_state);
+
+	__drm_atomic_helper_crtc_duplicate_state(crtc, &new_ofdrm_crtc_state->base);
+	new_ofdrm_crtc_state->format = ofdrm_crtc_state->format;
+
+	return &new_ofdrm_crtc_state->base;
+}
+
+static void ofdrm_crtc_atomic_destroy_state(struct drm_crtc *crtc,
+					    struct drm_crtc_state *crtc_state)
+{
+	ofdrm_crtc_state_destroy(to_ofdrm_crtc_state(crtc_state));
+}
+
+static const struct drm_crtc_funcs ofdrm_crtc_funcs = {
+	.reset = ofdrm_crtc_reset,
+	.destroy = drm_crtc_cleanup,
+	.set_config = drm_atomic_helper_set_config,
+	.page_flip = drm_atomic_helper_page_flip,
+	.atomic_duplicate_state = ofdrm_crtc_atomic_duplicate_state,
+	.atomic_destroy_state = ofdrm_crtc_atomic_destroy_state,
+};
+
+static const struct drm_encoder_funcs ofdrm_encoder_funcs = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static int ofdrm_connector_helper_get_modes(struct drm_connector *connector)
+{
+	struct ofdrm_device *odev = ofdrm_device_of_dev(connector->dev);
+
+	return drm_connector_helper_get_modes_fixed(connector, &odev->mode);
+}
+
+static const struct drm_connector_helper_funcs ofdrm_connector_helper_funcs = {
+	.get_modes = ofdrm_connector_helper_get_modes,
+};
+
+static const struct drm_connector_funcs ofdrm_connector_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static const struct drm_mode_config_funcs ofdrm_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+/*
+ * Init / Cleanup
+ */
+
+static const struct ofdrm_device_funcs ofdrm_unknown_device_funcs = {
+};
+
+static const struct ofdrm_device_funcs ofdrm_mach64_device_funcs = {
+	.cmap_ioremap = ofdrm_mach64_cmap_ioremap,
+	.cmap_write = ofdrm_mach64_cmap_write,
+};
+
+static const struct ofdrm_device_funcs ofdrm_rage128_device_funcs = {
+	.cmap_ioremap = ofdrm_rage128_cmap_ioremap,
+	.cmap_write = ofdrm_rage128_cmap_write,
+};
+
+static const struct ofdrm_device_funcs ofdrm_rage_m3a_device_funcs = {
+	.cmap_ioremap = ofdrm_rage_m3a_cmap_ioremap,
+	.cmap_write = ofdrm_rage_m3a_cmap_write,
+};
+
+static const struct ofdrm_device_funcs ofdrm_rage_m3b_device_funcs = {
+	.cmap_ioremap = ofdrm_rage_m3b_cmap_ioremap,
+	.cmap_write = ofdrm_rage_m3b_cmap_write,
+};
+
+static const struct ofdrm_device_funcs ofdrm_radeon_device_funcs = {
+	.cmap_ioremap = ofdrm_radeon_cmap_ioremap,
+	.cmap_write = ofdrm_rage128_cmap_write, /* same as Rage128 */
+};
+
+static const struct ofdrm_device_funcs ofdrm_gxt2000_device_funcs = {
+	.cmap_ioremap = ofdrm_gxt2000_cmap_ioremap,
+	.cmap_write = ofdrm_gxt2000_cmap_write,
+};
+
+static const struct ofdrm_device_funcs ofdrm_avivo_device_funcs = {
+	.cmap_ioremap = ofdrm_avivo_cmap_ioremap,
+	.cmap_write = ofdrm_avivo_cmap_write,
+};
+
+static const struct ofdrm_device_funcs ofdrm_qemu_device_funcs = {
+	.cmap_ioremap = ofdrm_qemu_cmap_ioremap,
+	.cmap_write = ofdrm_qemu_cmap_write,
+};
+
+static struct drm_display_mode ofdrm_mode(unsigned int width, unsigned int height)
+{
+	/*
+	 * Assume a monitor resolution of 96 dpi to
+	 * get a somewhat reasonable screen size.
+	 */
+	const struct drm_display_mode mode = {
+		DRM_MODE_INIT(60, width, height,
+			      DRM_MODE_RES_MM(width, 96ul),
+			      DRM_MODE_RES_MM(height, 96ul))
+	};
+
+	return mode;
+}
+
+static struct ofdrm_device *ofdrm_device_create(struct drm_driver *drv,
+						struct platform_device *pdev)
+{
+	struct device_node *of_node = pdev->dev.of_node;
+	struct ofdrm_device *odev;
+	struct drm_device *dev;
+	enum ofdrm_model model;
+	bool big_endian;
+	int width, height, depth, linebytes;
+	const struct drm_format_info *format;
+	u64 address;
+	resource_size_t fb_size, fb_base, fb_pgbase, fb_pgsize;
+	struct resource *res, *mem;
+	void __iomem *screen_base;
+	struct drm_plane *primary_plane;
+	struct drm_crtc *crtc;
+	struct drm_encoder *encoder;
+	struct drm_connector *connector;
+	unsigned long max_width, max_height;
+	size_t nformats;
+	int ret;
+
+	odev = devm_drm_dev_alloc(&pdev->dev, drv, struct ofdrm_device, dev);
+	if (IS_ERR(odev))
+		return ERR_CAST(odev);
+	dev = &odev->dev;
+	platform_set_drvdata(pdev, dev);
+
+	ret = ofdrm_device_init_pci(odev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	/*
+	 * OF display-node settings
+	 */
+
+	model = display_get_model_of(dev, of_node);
+	drm_dbg(dev, "detected model %d\n", model);
+
+	switch (model) {
+	case OFDRM_MODEL_UNKNOWN:
+		odev->funcs = &ofdrm_unknown_device_funcs;
+		break;
+	case OFDRM_MODEL_MACH64:
+		odev->funcs = &ofdrm_mach64_device_funcs;
+		break;
+	case OFDRM_MODEL_RAGE128:
+		odev->funcs = &ofdrm_rage128_device_funcs;
+		break;
+	case OFDRM_MODEL_RAGE_M3A:
+		odev->funcs = &ofdrm_rage_m3a_device_funcs;
+		break;
+	case OFDRM_MODEL_RAGE_M3B:
+		odev->funcs = &ofdrm_rage_m3b_device_funcs;
+		break;
+	case OFDRM_MODEL_RADEON:
+		odev->funcs = &ofdrm_radeon_device_funcs;
+		break;
+	case OFDRM_MODEL_GXT2000:
+		odev->funcs = &ofdrm_gxt2000_device_funcs;
+		break;
+	case OFDRM_MODEL_AVIVO:
+		odev->funcs = &ofdrm_avivo_device_funcs;
+		break;
+	case OFDRM_MODEL_QEMU:
+		odev->funcs = &ofdrm_qemu_device_funcs;
+		break;
+	}
+
+	big_endian = display_get_big_endian_of(dev, of_node);
+
+	width = display_get_width_of(dev, of_node);
+	if (width < 0)
+		return ERR_PTR(width);
+	height = display_get_height_of(dev, of_node);
+	if (height < 0)
+		return ERR_PTR(height);
+	depth = display_get_depth_of(dev, of_node);
+	if (depth < 0)
+		return ERR_PTR(depth);
+	linebytes = display_get_linebytes_of(dev, of_node);
+	if (linebytes < 0)
+		return ERR_PTR(linebytes);
+
+	format = display_get_validated_format(dev, depth, big_endian);
+	if (IS_ERR(format))
+		return ERR_CAST(format);
+	if (!linebytes) {
+		linebytes = drm_format_info_min_pitch(format, 0, width);
+		if (drm_WARN_ON(dev, !linebytes))
+			return ERR_PTR(-EINVAL);
+	}
+
+	fb_size = linebytes * height;
+
+	/*
+	 * Try to figure out the address of the framebuffer. Unfortunately, Open
+	 * Firmware doesn't provide a standard way to do so. All we can do is a
+	 * dodgy heuristic that happens to work in practice.
+	 *
+	 * On most machines, the "address" property contains what we need, though
+	 * not on Matrox cards found in IBM machines. What appears to give good
+	 * results is to go through the PCI ranges and pick one that encloses the
+	 * "address" property. If none match, we pick the largest.
+	 */
+	address = display_get_address_of(dev, of_node);
+	if (address != OF_BAD_ADDR) {
+		struct resource fb_res = DEFINE_RES_MEM(address, fb_size);
+
+		res = ofdrm_find_fb_resource(odev, &fb_res);
+		if (!res)
+			return ERR_PTR(-EINVAL);
+		if (resource_contains(res, &fb_res))
+			fb_base = address;
+		else
+			fb_base = res->start;
+	} else {
+		struct resource fb_res = DEFINE_RES_MEM(0u, fb_size);
+
+		res = ofdrm_find_fb_resource(odev, &fb_res);
+		if (!res)
+			return ERR_PTR(-EINVAL);
+		fb_base = res->start;
+	}
+
+	/*
+	 * I/O resources
+	 */
+
+	fb_pgbase = round_down(fb_base, PAGE_SIZE);
+	fb_pgsize = fb_base - fb_pgbase + round_up(fb_size, PAGE_SIZE);
+
+	ret = devm_aperture_acquire_for_platform_device(pdev, fb_pgbase, fb_pgsize);
+	if (ret) {
+		drm_err(dev, "could not acquire memory range %pr: error %d\n", &res, ret);
+		return ERR_PTR(ret);
+	}
+
+	mem = devm_request_mem_region(&pdev->dev, fb_pgbase, fb_pgsize, drv->name);
+	if (!mem) {
+		drm_warn(dev, "could not acquire memory region %pr\n", &res);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	screen_base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
+	if (!screen_base)
+		return ERR_PTR(-ENOMEM);
+
+	if (odev->funcs->cmap_ioremap) {
+		void __iomem *cmap_base = odev->funcs->cmap_ioremap(odev, of_node, fb_base);
+
+		if (IS_ERR(cmap_base)) {
+			/* Don't fail; continue without colormap */
+			drm_warn(dev, "could not find colormap: error %ld\n", PTR_ERR(cmap_base));
+		} else {
+			odev->cmap_base = cmap_base;
+		}
+	}
+
+	/*
+	 * Firmware framebuffer
+	 */
+
+	iosys_map_set_vaddr_iomem(&odev->screen_base, screen_base);
+	odev->mode = ofdrm_mode(width, height);
+	odev->format = format;
+	odev->pitch = linebytes;
+
+	drm_dbg(dev, "display mode={" DRM_MODE_FMT "}\n", DRM_MODE_ARG(&odev->mode));
+	drm_dbg(dev, "framebuffer format=%p4cc, size=%dx%d, linebytes=%d byte\n",
+		&format->format, width, height, linebytes);
+
+	/*
+	 * Mode-setting pipeline
+	 */
+
+	ret = drmm_mode_config_init(dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	max_width = max_t(unsigned long, width, DRM_SHADOW_PLANE_MAX_WIDTH);
+	max_height = max_t(unsigned long, height, DRM_SHADOW_PLANE_MAX_HEIGHT);
+
+	dev->mode_config.min_width = width;
+	dev->mode_config.max_width = max_width;
+	dev->mode_config.min_height = height;
+	dev->mode_config.max_height = max_height;
+	dev->mode_config.funcs = &ofdrm_mode_config_funcs;
+	dev->mode_config.preferred_depth = format->depth;
+	dev->mode_config.quirk_addfb_prefer_host_byte_order = true;
+
+	/* Primary plane */
+
+	nformats = drm_fb_build_fourcc_list(dev, &format->format, 1,
+					    odev->formats, ARRAY_SIZE(odev->formats));
+
+	primary_plane = &odev->primary_plane;
+	ret = drm_universal_plane_init(dev, primary_plane, 0, &ofdrm_primary_plane_funcs,
+				       odev->formats, nformats,
+				       ofdrm_primary_plane_format_modifiers,
+				       DRM_PLANE_TYPE_PRIMARY, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+	drm_plane_helper_add(primary_plane, &ofdrm_primary_plane_helper_funcs);
+	drm_plane_enable_fb_damage_clips(primary_plane);
+
+	/* CRTC */
+
+	crtc = &odev->crtc;
+	ret = drm_crtc_init_with_planes(dev, crtc, primary_plane, NULL,
+					&ofdrm_crtc_funcs, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+	drm_crtc_helper_add(crtc, &ofdrm_crtc_helper_funcs);
+
+	if (odev->cmap_base) {
+		drm_mode_crtc_set_gamma_size(crtc, OFDRM_GAMMA_LUT_SIZE);
+		drm_crtc_enable_color_mgmt(crtc, 0, false, OFDRM_GAMMA_LUT_SIZE);
+	}
+
+	/* Encoder */
+
+	encoder = &odev->encoder;
+	ret = drm_encoder_init(dev, encoder, &ofdrm_encoder_funcs, DRM_MODE_ENCODER_NONE, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+	encoder->possible_crtcs = drm_crtc_mask(crtc);
+
+	/* Connector */
+
+	connector = &odev->connector;
+	ret = drm_connector_init(dev, connector, &ofdrm_connector_funcs,
+				 DRM_MODE_CONNECTOR_Unknown);
+	if (ret)
+		return ERR_PTR(ret);
+	drm_connector_helper_add(connector, &ofdrm_connector_helper_funcs);
+	drm_connector_set_panel_orientation_with_quirk(connector,
+						       DRM_MODE_PANEL_ORIENTATION_UNKNOWN,
+						       width, height);
+
+	ret = drm_connector_attach_encoder(connector, encoder);
+	if (ret)
+		return ERR_PTR(ret);
+
+	drm_mode_config_reset(dev);
+
+	return odev;
+}
+
+/*
+ * DRM driver
+ */
+
+DEFINE_DRM_GEM_FOPS(ofdrm_fops);
+
+static struct drm_driver ofdrm_driver = {
+	DRM_GEM_SHMEM_DRIVER_OPS,
+	DRM_FBDEV_SHMEM_DRIVER_OPS,
+	.name			= DRIVER_NAME,
+	.desc			= DRIVER_DESC,
+	.major			= DRIVER_MAJOR,
+	.minor			= DRIVER_MINOR,
+	.driver_features	= DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
+	.fops			= &ofdrm_fops,
+};
+
+/*
+ * Platform driver
+ */
+
+static int ofdrm_probe(struct platform_device *pdev)
+{
+	struct ofdrm_device *odev;
+	struct drm_device *dev;
+	int ret;
+
+	odev = ofdrm_device_create(&ofdrm_driver, pdev);
+	if (IS_ERR(odev))
+		return PTR_ERR(odev);
+	dev = &odev->dev;
+
+	ret = drm_dev_register(dev, 0);
+	if (ret)
+		return ret;
+
+	drm_client_setup(dev, odev->format);
+
+	return 0;
+}
+
+static void ofdrm_remove(struct platform_device *pdev)
+{
+	struct drm_device *dev = platform_get_drvdata(pdev);
+
+	drm_dev_unplug(dev);
+}
+
+static const struct of_device_id ofdrm_of_match_display[] = {
+	{ .compatible = "display", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ofdrm_of_match_display);
+
+static struct platform_driver ofdrm_platform_driver = {
+	.driver = {
+		.name = "of-display",
+		.of_match_table = ofdrm_of_match_display,
+	},
+	.probe = ofdrm_probe,
+	.remove = ofdrm_remove,
+};
+
+module_platform_driver(ofdrm_platform_driver);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
diff --git a/drivers/gpu/drm/sysfb/simpledrm.c b/drivers/gpu/drm/sysfb/simpledrm.c
new file mode 100644
index 000000000000..d949713f5ff6
--- /dev/null
+++ b/drivers/gpu/drm/sysfb/simpledrm.c
@@ -0,0 +1,1072 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/aperture.h>
+#include <linux/clk.h>
+#include <linux/of_clk.h>
+#include <linux/minmax.h>
+#include <linux/of_address.h>
+#include <linux/platform_data/simplefb.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/clients/drm_client_setup.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fbdev_shmem.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_panic.h>
+#include <drm/drm_probe_helper.h>
+
+#define DRIVER_NAME	"simpledrm"
+#define DRIVER_DESC	"DRM driver for simple-framebuffer platform devices"
+#define DRIVER_MAJOR	1
+#define DRIVER_MINOR	0
+
+/*
+ * Helpers for simplefb
+ */
+
+static int
+simplefb_get_validated_int(struct drm_device *dev, const char *name,
+			   uint32_t value)
+{
+	if (value > INT_MAX) {
+		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
+			name, value);
+		return -EINVAL;
+	}
+	return (int)value;
+}
+
+static int
+simplefb_get_validated_int0(struct drm_device *dev, const char *name,
+			    uint32_t value)
+{
+	if (!value) {
+		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
+			name, value);
+		return -EINVAL;
+	}
+	return simplefb_get_validated_int(dev, name, value);
+}
+
+static const struct drm_format_info *
+simplefb_get_validated_format(struct drm_device *dev, const char *format_name)
+{
+	static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
+	const struct simplefb_format *fmt = formats;
+	const struct simplefb_format *end = fmt + ARRAY_SIZE(formats);
+	const struct drm_format_info *info;
+
+	if (!format_name) {
+		drm_err(dev, "simplefb: missing framebuffer format\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	while (fmt < end) {
+		if (!strcmp(format_name, fmt->name)) {
+			info = drm_format_info(fmt->fourcc);
+			if (!info)
+				return ERR_PTR(-EINVAL);
+			return info;
+		}
+		++fmt;
+	}
+
+	drm_err(dev, "simplefb: unknown framebuffer format %s\n",
+		format_name);
+
+	return ERR_PTR(-EINVAL);
+}
+
+static int
+simplefb_get_width_pd(struct drm_device *dev,
+		      const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_int0(dev, "width", pd->width);
+}
+
+static int
+simplefb_get_height_pd(struct drm_device *dev,
+		       const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_int0(dev, "height", pd->height);
+}
+
+static int
+simplefb_get_stride_pd(struct drm_device *dev,
+		       const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_int(dev, "stride", pd->stride);
+}
+
+static const struct drm_format_info *
+simplefb_get_format_pd(struct drm_device *dev,
+		       const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_format(dev, pd->format);
+}
+
+static int
+simplefb_read_u32_of(struct drm_device *dev, struct device_node *of_node,
+		     const char *name, u32 *value)
+{
+	int ret = of_property_read_u32(of_node, name, value);
+
+	if (ret)
+		drm_err(dev, "simplefb: cannot parse framebuffer %s: error %d\n",
+			name, ret);
+	return ret;
+}
+
+static int
+simplefb_read_string_of(struct drm_device *dev, struct device_node *of_node,
+			const char *name, const char **value)
+{
+	int ret = of_property_read_string(of_node, name, value);
+
+	if (ret)
+		drm_err(dev, "simplefb: cannot parse framebuffer %s: error %d\n",
+			name, ret);
+	return ret;
+}
+
+static int
+simplefb_get_width_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 width;
+	int ret = simplefb_read_u32_of(dev, of_node, "width", &width);
+
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int0(dev, "width", width);
+}
+
+static int
+simplefb_get_height_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 height;
+	int ret = simplefb_read_u32_of(dev, of_node, "height", &height);
+
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int0(dev, "height", height);
+}
+
+static int
+simplefb_get_stride_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 stride;
+	int ret = simplefb_read_u32_of(dev, of_node, "stride", &stride);
+
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int(dev, "stride", stride);
+}
+
+static const struct drm_format_info *
+simplefb_get_format_of(struct drm_device *dev, struct device_node *of_node)
+{
+	const char *format;
+	int ret = simplefb_read_string_of(dev, of_node, "format", &format);
+
+	if (ret)
+		return ERR_PTR(ret);
+	return simplefb_get_validated_format(dev, format);
+}
+
+static struct resource *
+simplefb_get_memory_of(struct drm_device *dev, struct device_node *of_node)
+{
+	struct device_node *np;
+	struct resource *res;
+	int err;
+
+	np = of_parse_phandle(of_node, "memory-region", 0);
+	if (!np)
+		return NULL;
+
+	res = devm_kzalloc(dev->dev, sizeof(*res), GFP_KERNEL);
+	if (!res)
+		return ERR_PTR(-ENOMEM);
+
+	err = of_address_to_resource(np, 0, res);
+	if (err)
+		return ERR_PTR(err);
+
+	if (of_property_present(of_node, "reg"))
+		drm_warn(dev, "preferring \"memory-region\" over \"reg\" property\n");
+
+	return res;
+}
+
+/*
+ * Simple Framebuffer device
+ */
+
+struct simpledrm_device {
+	struct drm_device dev;
+
+	/* clocks */
+#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
+	unsigned int clk_count;
+	struct clk **clks;
+#endif
+	/* regulators */
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+	unsigned int regulator_count;
+	struct regulator **regulators;
+#endif
+	/* power-domains */
+#if defined CONFIG_OF && defined CONFIG_PM_GENERIC_DOMAINS
+	int pwr_dom_count;
+	struct device **pwr_dom_devs;
+	struct device_link **pwr_dom_links;
+#endif
+
+	/* simplefb settings */
+	struct drm_display_mode mode;
+	const struct drm_format_info *format;
+	unsigned int pitch;
+
+	/* memory management */
+	struct iosys_map screen_base;
+
+	/* modesetting */
+	uint32_t formats[8];
+	struct drm_plane primary_plane;
+	struct drm_crtc crtc;
+	struct drm_encoder encoder;
+	struct drm_connector connector;
+};
+
+static struct simpledrm_device *simpledrm_device_of_dev(struct drm_device *dev)
+{
+	return container_of(dev, struct simpledrm_device, dev);
+}
+
+/*
+ * Hardware
+ */
+
+#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
+/*
+ * Clock handling code.
+ *
+ * Here we handle the clocks property of our "simple-framebuffer" dt node.
+ * This is necessary so that we can make sure that any clocks needed by
+ * the display engine that the bootloader set up for us (and for which it
+ * provided a simplefb dt node), stay up, for the life of the simplefb
+ * driver.
+ *
+ * When the driver unloads, we cleanly disable, and then release the clocks.
+ *
+ * We only complain about errors here, no action is taken as the most likely
+ * error can only happen due to a mismatch between the bootloader which set
+ * up simplefb, and the clock definitions in the device tree. Chances are
+ * that there are no adverse effects, and if there are, a clean teardown of
+ * the fb probe will not help us much either. So just complain and carry on,
+ * and hope that the user actually gets a working fb at the end of things.
+ */
+
+static void simpledrm_device_release_clocks(void *res)
+{
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(res);
+	unsigned int i;
+
+	for (i = 0; i < sdev->clk_count; ++i) {
+		if (sdev->clks[i]) {
+			clk_disable_unprepare(sdev->clks[i]);
+			clk_put(sdev->clks[i]);
+		}
+	}
+}
+
+static int simpledrm_device_init_clocks(struct simpledrm_device *sdev)
+{
+	struct drm_device *dev = &sdev->dev;
+	struct platform_device *pdev = to_platform_device(dev->dev);
+	struct device_node *of_node = pdev->dev.of_node;
+	struct clk *clock;
+	unsigned int i;
+	int ret;
+
+	if (dev_get_platdata(&pdev->dev) || !of_node)
+		return 0;
+
+	sdev->clk_count = of_clk_get_parent_count(of_node);
+	if (!sdev->clk_count)
+		return 0;
+
+	sdev->clks = drmm_kzalloc(dev, sdev->clk_count * sizeof(sdev->clks[0]),
+				  GFP_KERNEL);
+	if (!sdev->clks)
+		return -ENOMEM;
+
+	for (i = 0; i < sdev->clk_count; ++i) {
+		clock = of_clk_get(of_node, i);
+		if (IS_ERR(clock)) {
+			ret = PTR_ERR(clock);
+			if (ret == -EPROBE_DEFER)
+				goto err;
+			drm_err(dev, "clock %u not found: %d\n", i, ret);
+			continue;
+		}
+		ret = clk_prepare_enable(clock);
+		if (ret) {
+			drm_err(dev, "failed to enable clock %u: %d\n",
+				i, ret);
+			clk_put(clock);
+			continue;
+		}
+		sdev->clks[i] = clock;
+	}
+
+	return devm_add_action_or_reset(&pdev->dev,
+					simpledrm_device_release_clocks,
+					sdev);
+
+err:
+	while (i) {
+		--i;
+		if (sdev->clks[i]) {
+			clk_disable_unprepare(sdev->clks[i]);
+			clk_put(sdev->clks[i]);
+		}
+	}
+	return ret;
+}
+#else
+static int simpledrm_device_init_clocks(struct simpledrm_device *sdev)
+{
+	return 0;
+}
+#endif
+
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+
+#define SUPPLY_SUFFIX "-supply"
+
+/*
+ * Regulator handling code.
+ *
+ * Here we handle the num-supplies and vin*-supply properties of our
+ * "simple-framebuffer" dt node. This is necessary so that we can make sure
+ * that any regulators needed by the display hardware that the bootloader
+ * set up for us (and for which it provided a simplefb dt node), stay up,
+ * for the life of the simplefb driver.
+ *
+ * When the driver unloads, we cleanly disable, and then release the
+ * regulators.
+ *
+ * We only complain about errors here, no action is taken as the most likely
+ * error can only happen due to a mismatch between the bootloader which set
+ * up simplefb, and the regulator definitions in the device tree. Chances are
+ * that there are no adverse effects, and if there are, a clean teardown of
+ * the fb probe will not help us much either. So just complain and carry on,
+ * and hope that the user actually gets a working fb at the end of things.
+ */
+
+static void simpledrm_device_release_regulators(void *res)
+{
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(res);
+	unsigned int i;
+
+	for (i = 0; i < sdev->regulator_count; ++i) {
+		if (sdev->regulators[i]) {
+			regulator_disable(sdev->regulators[i]);
+			regulator_put(sdev->regulators[i]);
+		}
+	}
+}
+
+static int simpledrm_device_init_regulators(struct simpledrm_device *sdev)
+{
+	struct drm_device *dev = &sdev->dev;
+	struct platform_device *pdev = to_platform_device(dev->dev);
+	struct device_node *of_node = pdev->dev.of_node;
+	struct property *prop;
+	struct regulator *regulator;
+	const char *p;
+	unsigned int count = 0, i = 0;
+	int ret;
+
+	if (dev_get_platdata(&pdev->dev) || !of_node)
+		return 0;
+
+	/* Count the number of regulator supplies */
+	for_each_property_of_node(of_node, prop) {
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (p && p != prop->name)
+			++count;
+	}
+
+	if (!count)
+		return 0;
+
+	sdev->regulators = drmm_kzalloc(dev,
+					count * sizeof(sdev->regulators[0]),
+					GFP_KERNEL);
+	if (!sdev->regulators)
+		return -ENOMEM;
+
+	for_each_property_of_node(of_node, prop) {
+		char name[32]; /* 32 is max size of property name */
+		size_t len;
+
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (!p || p == prop->name)
+			continue;
+		len = strlen(prop->name) - strlen(SUPPLY_SUFFIX) + 1;
+		strscpy(name, prop->name, min(sizeof(name), len));
+
+		regulator = regulator_get_optional(&pdev->dev, name);
+		if (IS_ERR(regulator)) {
+			ret = PTR_ERR(regulator);
+			if (ret == -EPROBE_DEFER)
+				goto err;
+			drm_err(dev, "regulator %s not found: %d\n",
+				name, ret);
+			continue;
+		}
+
+		ret = regulator_enable(regulator);
+		if (ret) {
+			drm_err(dev, "failed to enable regulator %u: %d\n",
+				i, ret);
+			regulator_put(regulator);
+			continue;
+		}
+
+		sdev->regulators[i++] = regulator;
+	}
+	sdev->regulator_count = i;
+
+	return devm_add_action_or_reset(&pdev->dev,
+					simpledrm_device_release_regulators,
+					sdev);
+
+err:
+	while (i) {
+		--i;
+		if (sdev->regulators[i]) {
+			regulator_disable(sdev->regulators[i]);
+			regulator_put(sdev->regulators[i]);
+		}
+	}
+	return ret;
+}
+#else
+static int simpledrm_device_init_regulators(struct simpledrm_device *sdev)
+{
+	return 0;
+}
+#endif
+
+#if defined CONFIG_OF && defined CONFIG_PM_GENERIC_DOMAINS
+/*
+ * Generic power domain handling code.
+ *
+ * Here we handle the power-domains properties of our "simple-framebuffer"
+ * dt node. This is only necessary if there is more than one power-domain.
+ * A single power-domains is handled automatically by the driver core. Multiple
+ * power-domains have to be handled by drivers since the driver core can't know
+ * the correct power sequencing. Power sequencing is not an issue for simpledrm
+ * since the bootloader has put the power domains already in the correct state.
+ * simpledrm has only to ensure they remain active for its lifetime.
+ *
+ * When the driver unloads, we detach from the power-domains.
+ *
+ * We only complain about errors here, no action is taken as the most likely
+ * error can only happen due to a mismatch between the bootloader which set
+ * up the "simple-framebuffer" dt node, and the PM domain providers in the
+ * device tree. Chances are that there are no adverse effects, and if there are,
+ * a clean teardown of the fb probe will not help us much either. So just
+ * complain and carry on, and hope that the user actually gets a working fb at
+ * the end of things.
+ */
+static void simpledrm_device_detach_genpd(void *res)
+{
+	int i;
+	struct simpledrm_device *sdev = res;
+
+	if (sdev->pwr_dom_count <= 1)
+		return;
+
+	for (i = sdev->pwr_dom_count - 1; i >= 0; i--) {
+		if (sdev->pwr_dom_links[i])
+			device_link_del(sdev->pwr_dom_links[i]);
+		if (!IS_ERR_OR_NULL(sdev->pwr_dom_devs[i]))
+			dev_pm_domain_detach(sdev->pwr_dom_devs[i], true);
+	}
+}
+
+static int simpledrm_device_attach_genpd(struct simpledrm_device *sdev)
+{
+	struct device *dev = sdev->dev.dev;
+	int i;
+
+	sdev->pwr_dom_count = of_count_phandle_with_args(dev->of_node, "power-domains",
+							 "#power-domain-cells");
+	/*
+	 * Single power-domain devices are handled by driver core nothing to do
+	 * here. The same for device nodes without "power-domains" property.
+	 */
+	if (sdev->pwr_dom_count <= 1)
+		return 0;
+
+	sdev->pwr_dom_devs = devm_kcalloc(dev, sdev->pwr_dom_count,
+					       sizeof(*sdev->pwr_dom_devs),
+					       GFP_KERNEL);
+	if (!sdev->pwr_dom_devs)
+		return -ENOMEM;
+
+	sdev->pwr_dom_links = devm_kcalloc(dev, sdev->pwr_dom_count,
+						sizeof(*sdev->pwr_dom_links),
+						GFP_KERNEL);
+	if (!sdev->pwr_dom_links)
+		return -ENOMEM;
+
+	for (i = 0; i < sdev->pwr_dom_count; i++) {
+		sdev->pwr_dom_devs[i] = dev_pm_domain_attach_by_id(dev, i);
+		if (IS_ERR(sdev->pwr_dom_devs[i])) {
+			int ret = PTR_ERR(sdev->pwr_dom_devs[i]);
+			if (ret == -EPROBE_DEFER) {
+				simpledrm_device_detach_genpd(sdev);
+				return ret;
+			}
+			drm_warn(&sdev->dev,
+				 "pm_domain_attach_by_id(%u) failed: %d\n", i, ret);
+			continue;
+		}
+
+		sdev->pwr_dom_links[i] = device_link_add(dev,
+							 sdev->pwr_dom_devs[i],
+							 DL_FLAG_STATELESS |
+							 DL_FLAG_PM_RUNTIME |
+							 DL_FLAG_RPM_ACTIVE);
+		if (!sdev->pwr_dom_links[i])
+			drm_warn(&sdev->dev, "failed to link power-domain %d\n", i);
+	}
+
+	return devm_add_action_or_reset(dev, simpledrm_device_detach_genpd, sdev);
+}
+#else
+static int simpledrm_device_attach_genpd(struct simpledrm_device *sdev)
+{
+	return 0;
+}
+#endif
+
+/*
+ * Modesetting
+ */
+
+static const uint64_t simpledrm_primary_plane_format_modifiers[] = {
+	DRM_FORMAT_MOD_LINEAR,
+	DRM_FORMAT_MOD_INVALID
+};
+
+static int simpledrm_primary_plane_helper_atomic_check(struct drm_plane *plane,
+						       struct drm_atomic_state *state)
+{
+	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, plane);
+	struct drm_shadow_plane_state *new_shadow_plane_state =
+		to_drm_shadow_plane_state(new_plane_state);
+	struct drm_framebuffer *new_fb = new_plane_state->fb;
+	struct drm_crtc *new_crtc = new_plane_state->crtc;
+	struct drm_crtc_state *new_crtc_state = NULL;
+	struct drm_device *dev = plane->dev;
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(dev);
+	int ret;
+
+	if (new_crtc)
+		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
+
+	ret = drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
+						  DRM_PLANE_NO_SCALING,
+						  DRM_PLANE_NO_SCALING,
+						  false, false);
+	if (ret)
+		return ret;
+	else if (!new_plane_state->visible)
+		return 0;
+
+	if (new_fb->format != sdev->format) {
+		void *buf;
+
+		/* format conversion necessary; reserve buffer */
+		buf = drm_format_conv_state_reserve(&new_shadow_plane_state->fmtcnv_state,
+						    sdev->pitch, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void simpledrm_primary_plane_helper_atomic_update(struct drm_plane *plane,
+							 struct drm_atomic_state *state)
+{
+	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
+	struct drm_framebuffer *fb = plane_state->fb;
+	struct drm_device *dev = plane->dev;
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(dev);
+	struct drm_atomic_helper_damage_iter iter;
+	struct drm_rect damage;
+	int ret, idx;
+
+	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
+	if (ret)
+		return;
+
+	if (!drm_dev_enter(dev, &idx))
+		goto out_drm_gem_fb_end_cpu_access;
+
+	drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
+	drm_atomic_for_each_plane_damage(&iter, &damage) {
+		struct drm_rect dst_clip = plane_state->dst;
+		struct iosys_map dst = sdev->screen_base;
+
+		if (!drm_rect_intersect(&dst_clip, &damage))
+			continue;
+
+		iosys_map_incr(&dst, drm_fb_clip_offset(sdev->pitch, sdev->format, &dst_clip));
+		drm_fb_blit(&dst, &sdev->pitch, sdev->format->format, shadow_plane_state->data,
+			    fb, &damage, &shadow_plane_state->fmtcnv_state);
+	}
+
+	drm_dev_exit(idx);
+out_drm_gem_fb_end_cpu_access:
+	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
+}
+
+static void simpledrm_primary_plane_helper_atomic_disable(struct drm_plane *plane,
+							  struct drm_atomic_state *state)
+{
+	struct drm_device *dev = plane->dev;
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(dev);
+	int idx;
+
+	if (!drm_dev_enter(dev, &idx))
+		return;
+
+	/* Clear screen to black if disabled */
+	iosys_map_memset(&sdev->screen_base, 0, 0, sdev->pitch * sdev->mode.vdisplay);
+
+	drm_dev_exit(idx);
+}
+
+static int simpledrm_primary_plane_helper_get_scanout_buffer(struct drm_plane *plane,
+							     struct drm_scanout_buffer *sb)
+{
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(plane->dev);
+
+	sb->width = sdev->mode.hdisplay;
+	sb->height = sdev->mode.vdisplay;
+	sb->format = sdev->format;
+	sb->pitch[0] = sdev->pitch;
+	sb->map[0] = sdev->screen_base;
+
+	return 0;
+}
+
+static const struct drm_plane_helper_funcs simpledrm_primary_plane_helper_funcs = {
+	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
+	.atomic_check = simpledrm_primary_plane_helper_atomic_check,
+	.atomic_update = simpledrm_primary_plane_helper_atomic_update,
+	.atomic_disable = simpledrm_primary_plane_helper_atomic_disable,
+	.get_scanout_buffer = simpledrm_primary_plane_helper_get_scanout_buffer,
+};
+
+static const struct drm_plane_funcs simpledrm_primary_plane_funcs = {
+	.update_plane = drm_atomic_helper_update_plane,
+	.disable_plane = drm_atomic_helper_disable_plane,
+	.destroy = drm_plane_cleanup,
+	DRM_GEM_SHADOW_PLANE_FUNCS,
+};
+
+static enum drm_mode_status simpledrm_crtc_helper_mode_valid(struct drm_crtc *crtc,
+							     const struct drm_display_mode *mode)
+{
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(crtc->dev);
+
+	return drm_crtc_helper_mode_valid_fixed(crtc, mode, &sdev->mode);
+}
+
+/*
+ * The CRTC is always enabled. Screen updates are performed by
+ * the primary plane's atomic_update function. Disabling clears
+ * the screen in the primary plane's atomic_disable function.
+ */
+static const struct drm_crtc_helper_funcs simpledrm_crtc_helper_funcs = {
+	.mode_valid = simpledrm_crtc_helper_mode_valid,
+	.atomic_check = drm_crtc_helper_atomic_check,
+};
+
+static const struct drm_crtc_funcs simpledrm_crtc_funcs = {
+	.reset = drm_atomic_helper_crtc_reset,
+	.destroy = drm_crtc_cleanup,
+	.set_config = drm_atomic_helper_set_config,
+	.page_flip = drm_atomic_helper_page_flip,
+	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+};
+
+static const struct drm_encoder_funcs simpledrm_encoder_funcs = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static int simpledrm_connector_helper_get_modes(struct drm_connector *connector)
+{
+	struct simpledrm_device *sdev = simpledrm_device_of_dev(connector->dev);
+
+	return drm_connector_helper_get_modes_fixed(connector, &sdev->mode);
+}
+
+static const struct drm_connector_helper_funcs simpledrm_connector_helper_funcs = {
+	.get_modes = simpledrm_connector_helper_get_modes,
+};
+
+static const struct drm_connector_funcs simpledrm_connector_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static const struct drm_mode_config_funcs simpledrm_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+/*
+ * Init / Cleanup
+ */
+
+static struct drm_display_mode simpledrm_mode(unsigned int width,
+					      unsigned int height,
+					      unsigned int width_mm,
+					      unsigned int height_mm)
+{
+	const struct drm_display_mode mode = {
+		DRM_MODE_INIT(60, width, height, width_mm, height_mm)
+	};
+
+	return mode;
+}
+
+static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
+							struct platform_device *pdev)
+{
+	const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
+	struct device_node *of_node = pdev->dev.of_node;
+	struct simpledrm_device *sdev;
+	struct drm_device *dev;
+	int width, height, stride;
+	int width_mm = 0, height_mm = 0;
+	struct device_node *panel_node;
+	const struct drm_format_info *format;
+	struct resource *res, *mem = NULL;
+	struct drm_plane *primary_plane;
+	struct drm_crtc *crtc;
+	struct drm_encoder *encoder;
+	struct drm_connector *connector;
+	unsigned long max_width, max_height;
+	size_t nformats;
+	int ret;
+
+	sdev = devm_drm_dev_alloc(&pdev->dev, drv, struct simpledrm_device, dev);
+	if (IS_ERR(sdev))
+		return ERR_CAST(sdev);
+	dev = &sdev->dev;
+	platform_set_drvdata(pdev, sdev);
+
+	/*
+	 * Hardware settings
+	 */
+
+	ret = simpledrm_device_init_clocks(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+	ret = simpledrm_device_init_regulators(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+	ret = simpledrm_device_attach_genpd(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (pd) {
+		width = simplefb_get_width_pd(dev, pd);
+		if (width < 0)
+			return ERR_PTR(width);
+		height = simplefb_get_height_pd(dev, pd);
+		if (height < 0)
+			return ERR_PTR(height);
+		stride = simplefb_get_stride_pd(dev, pd);
+		if (stride < 0)
+			return ERR_PTR(stride);
+		format = simplefb_get_format_pd(dev, pd);
+		if (IS_ERR(format))
+			return ERR_CAST(format);
+	} else if (of_node) {
+		width = simplefb_get_width_of(dev, of_node);
+		if (width < 0)
+			return ERR_PTR(width);
+		height = simplefb_get_height_of(dev, of_node);
+		if (height < 0)
+			return ERR_PTR(height);
+		stride = simplefb_get_stride_of(dev, of_node);
+		if (stride < 0)
+			return ERR_PTR(stride);
+		format = simplefb_get_format_of(dev, of_node);
+		if (IS_ERR(format))
+			return ERR_CAST(format);
+		mem = simplefb_get_memory_of(dev, of_node);
+		if (IS_ERR(mem))
+			return ERR_CAST(mem);
+		panel_node = of_parse_phandle(of_node, "panel", 0);
+		if (panel_node) {
+			simplefb_read_u32_of(dev, panel_node, "width-mm", &width_mm);
+			simplefb_read_u32_of(dev, panel_node, "height-mm", &height_mm);
+			of_node_put(panel_node);
+		}
+	} else {
+		drm_err(dev, "no simplefb configuration found\n");
+		return ERR_PTR(-ENODEV);
+	}
+	if (!stride) {
+		stride = drm_format_info_min_pitch(format, 0, width);
+		if (drm_WARN_ON(dev, !stride))
+			return ERR_PTR(-EINVAL);
+	}
+
+	/*
+	 * Assume a monitor resolution of 96 dpi if physical dimensions
+	 * are not specified to get a somewhat reasonable screen size.
+	 */
+	if (!width_mm)
+		width_mm = DRM_MODE_RES_MM(width, 96ul);
+	if (!height_mm)
+		height_mm = DRM_MODE_RES_MM(height, 96ul);
+
+	sdev->mode = simpledrm_mode(width, height, width_mm, height_mm);
+	sdev->format = format;
+	sdev->pitch = stride;
+
+	drm_dbg(dev, "display mode={" DRM_MODE_FMT "}\n", DRM_MODE_ARG(&sdev->mode));
+	drm_dbg(dev, "framebuffer format=%p4cc, size=%dx%d, stride=%d byte\n",
+		&format->format, width, height, stride);
+
+	/*
+	 * Memory management
+	 */
+
+	if (mem) {
+		void *screen_base;
+
+		ret = devm_aperture_acquire_for_platform_device(pdev, mem->start,
+								resource_size(mem));
+		if (ret) {
+			drm_err(dev, "could not acquire memory range %pr: %d\n", mem, ret);
+			return ERR_PTR(ret);
+		}
+
+		drm_dbg(dev, "using system memory framebuffer at %pr\n", mem);
+
+		screen_base = devm_memremap(dev->dev, mem->start, resource_size(mem), MEMREMAP_WC);
+		if (IS_ERR(screen_base))
+			return screen_base;
+
+		iosys_map_set_vaddr(&sdev->screen_base, screen_base);
+	} else {
+		void __iomem *screen_base;
+
+		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+		if (!res)
+			return ERR_PTR(-EINVAL);
+
+		ret = devm_aperture_acquire_for_platform_device(pdev, res->start,
+								resource_size(res));
+		if (ret) {
+			drm_err(dev, "could not acquire memory range %pr: %d\n", res, ret);
+			return ERR_PTR(ret);
+		}
+
+		drm_dbg(dev, "using I/O memory framebuffer at %pr\n", res);
+
+		mem = devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
+					      drv->name);
+		if (!mem) {
+			/*
+			 * We cannot make this fatal. Sometimes this comes from magic
+			 * spaces our resource handlers simply don't know about. Use
+			 * the I/O-memory resource as-is and try to map that instead.
+			 */
+			drm_warn(dev, "could not acquire memory region %pr\n", res);
+			mem = res;
+		}
+
+		screen_base = devm_ioremap_wc(&pdev->dev, mem->start, resource_size(mem));
+		if (!screen_base)
+			return ERR_PTR(-ENOMEM);
+
+		iosys_map_set_vaddr_iomem(&sdev->screen_base, screen_base);
+	}
+
+	/*
+	 * Modesetting
+	 */
+
+	ret = drmm_mode_config_init(dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	max_width = max_t(unsigned long, width, DRM_SHADOW_PLANE_MAX_WIDTH);
+	max_height = max_t(unsigned long, height, DRM_SHADOW_PLANE_MAX_HEIGHT);
+
+	dev->mode_config.min_width = width;
+	dev->mode_config.max_width = max_width;
+	dev->mode_config.min_height = height;
+	dev->mode_config.max_height = max_height;
+	dev->mode_config.preferred_depth = format->depth;
+	dev->mode_config.funcs = &simpledrm_mode_config_funcs;
+
+	/* Primary plane */
+
+	nformats = drm_fb_build_fourcc_list(dev, &format->format, 1,
+					    sdev->formats, ARRAY_SIZE(sdev->formats));
+
+	primary_plane = &sdev->primary_plane;
+	ret = drm_universal_plane_init(dev, primary_plane, 0, &simpledrm_primary_plane_funcs,
+				       sdev->formats, nformats,
+				       simpledrm_primary_plane_format_modifiers,
+				       DRM_PLANE_TYPE_PRIMARY, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+	drm_plane_helper_add(primary_plane, &simpledrm_primary_plane_helper_funcs);
+	drm_plane_enable_fb_damage_clips(primary_plane);
+
+	/* CRTC */
+
+	crtc = &sdev->crtc;
+	ret = drm_crtc_init_with_planes(dev, crtc, primary_plane, NULL,
+					&simpledrm_crtc_funcs, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+	drm_crtc_helper_add(crtc, &simpledrm_crtc_helper_funcs);
+
+	/* Encoder */
+
+	encoder = &sdev->encoder;
+	ret = drm_encoder_init(dev, encoder, &simpledrm_encoder_funcs,
+			       DRM_MODE_ENCODER_NONE, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+	encoder->possible_crtcs = drm_crtc_mask(crtc);
+
+	/* Connector */
+
+	connector = &sdev->connector;
+	ret = drm_connector_init(dev, connector, &simpledrm_connector_funcs,
+				 DRM_MODE_CONNECTOR_Unknown);
+	if (ret)
+		return ERR_PTR(ret);
+	drm_connector_helper_add(connector, &simpledrm_connector_helper_funcs);
+	drm_connector_set_panel_orientation_with_quirk(connector,
+						       DRM_MODE_PANEL_ORIENTATION_UNKNOWN,
+						       width, height);
+
+	ret = drm_connector_attach_encoder(connector, encoder);
+	if (ret)
+		return ERR_PTR(ret);
+
+	drm_mode_config_reset(dev);
+
+	return sdev;
+}
+
+/*
+ * DRM driver
+ */
+
+DEFINE_DRM_GEM_FOPS(simpledrm_fops);
+
+static struct drm_driver simpledrm_driver = {
+	DRM_GEM_SHMEM_DRIVER_OPS,
+	DRM_FBDEV_SHMEM_DRIVER_OPS,
+	.name			= DRIVER_NAME,
+	.desc			= DRIVER_DESC,
+	.major			= DRIVER_MAJOR,
+	.minor			= DRIVER_MINOR,
+	.driver_features	= DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
+	.fops			= &simpledrm_fops,
+};
+
+/*
+ * Platform driver
+ */
+
+static int simpledrm_probe(struct platform_device *pdev)
+{
+	struct simpledrm_device *sdev;
+	struct drm_device *dev;
+	int ret;
+
+	sdev = simpledrm_device_create(&simpledrm_driver, pdev);
+	if (IS_ERR(sdev))
+		return PTR_ERR(sdev);
+	dev = &sdev->dev;
+
+	ret = drm_dev_register(dev, 0);
+	if (ret)
+		return ret;
+
+	drm_client_setup(dev, sdev->format);
+
+	return 0;
+}
+
+static void simpledrm_remove(struct platform_device *pdev)
+{
+	struct simpledrm_device *sdev = platform_get_drvdata(pdev);
+	struct drm_device *dev = &sdev->dev;
+
+	drm_dev_unplug(dev);
+}
+
+static const struct of_device_id simpledrm_of_match_table[] = {
+	{ .compatible = "simple-framebuffer", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, simpledrm_of_match_table);
+
+static struct platform_driver simpledrm_platform_driver = {
+	.driver = {
+		.name = "simple-framebuffer", /* connect to sysfb */
+		.of_match_table = simpledrm_of_match_table,
+	},
+	.probe = simpledrm_probe,
+	.remove = simpledrm_remove,
+};
+
+module_platform_driver(simpledrm_platform_driver);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL v2");