irqchip: Renesas INTC External IRQ pin driver

This patch adds a driver for external IRQ pins connected
to the INTC block on recent SoCs from Renesas.

The INTC hardware block usually contains a rather wide
range of features ranging from external IRQ pin handling
to legacy interrupt controller support. On older SoCs
the INTC is used as a general purpose interrupt controller
both for external IRQ pins and on-chip devices.

On more recent ARM based SoCs with Cortex-A9 the main
interrupt controller is the GIC, but IRQ trigger setup
still need to happen in the INTC hardware block.

This driver implements the glue code needed to configure
IRQ trigger and also handle mask/unmask and demux of
external IRQ pins hooked up from the INTC to the GIC.

Tested on sh73a0 and r8a7779. The hardware varies quite
a bit with SoC model, for instance register width and
bitfield widths vary wildly. The driver requires one GIC
SPI per external IRQ pin to operate.  Each driver instance
will handle up to 8 external IRQ pins.

The SoCs using this driver are currently mainly used
together with regular platform devices so this driver
allows configuration via platform data to support things
like static interrupt base address. DT support will
be added incrementally in the not so distant future.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

3 files changed, 469 insertions, 0 deletions

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index a350969e5efe..0f5f1c3825bc 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -25,6 +25,10 @@ config ARM_VIC_NR
 	  The maximum number of VICs available in the system, for
 	  power management.
 
+config RENESAS_INTC_IRQPIN
+	bool
+	select IRQ_DOMAIN
+
 config VERSATILE_FPGA_IRQ
 	bool
 	select IRQ_DOMAIN
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 98e3b87bdf1b..1aaa4073ab60 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -8,4 +8,5 @@ obj-$(CONFIG_ARCH_SUNXI)		+= irq-sunxi.o
 obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o
 obj-$(CONFIG_ARM_GIC)			+= irq-gic.o
 obj-$(CONFIG_ARM_VIC)			+= irq-vic.o
+obj-$(CONFIG_RENESAS_INTC_IRQPIN)	+= irq-renesas-intc-irqpin.o
 obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
diff --git a/drivers/irqchip/irq-renesas-intc-irqpin.c b/drivers/irqchip/irq-renesas-intc-irqpin.c
new file mode 100644
index 000000000000..1e5058a56517
--- /dev/null
+++ b/drivers/irqchip/irq-renesas-intc-irqpin.c
@@ -0,0 +1,464 @@
+/*
+ * Renesas INTC External IRQ Pin Driver
+ *
+ *  Copyright (C) 2013 Magnus Damm
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/platform_data/irq-renesas-intc-irqpin.h>
+
+#define INTC_IRQPIN_MAX 8 /* maximum 8 interrupts per driver instance */
+
+#define INTC_IRQPIN_REG_SENSE 0 /* ICRn */
+#define INTC_IRQPIN_REG_PRIO 1 /* INTPRInn */
+#define INTC_IRQPIN_REG_SOURCE 2 /* INTREQnn */
+#define INTC_IRQPIN_REG_MASK 3 /* INTMSKnn */
+#define INTC_IRQPIN_REG_CLEAR 4 /* INTMSKCLRnn */
+#define INTC_IRQPIN_REG_NR 5
+
+/* INTC external IRQ PIN hardware register access:
+ *
+ * SENSE is read-write 32-bit with 2-bits or 4-bits per IRQ (*)
+ * PRIO is read-write 32-bit with 4-bits per IRQ (**)
+ * SOURCE is read-only 32-bit or 8-bit with 1-bit per IRQ (***)
+ * MASK is write-only 32-bit or 8-bit with 1-bit per IRQ (***)
+ * CLEAR is write-only 32-bit or 8-bit with 1-bit per IRQ (***)
+ *
+ * (*) May be accessed by more than one driver instance - lock needed
+ * (**) Read-modify-write access by one driver instance - lock needed
+ * (***) Accessed by one driver instance only - no locking needed
+ */
+
+struct intc_irqpin_iomem {
+	void __iomem *iomem;
+	unsigned long (*read)(void __iomem *iomem);
+	void (*write)(void __iomem *iomem, unsigned long data);
+	int width;
+};  
+
+struct intc_irqpin_irq {
+	int hw_irq;
+	int irq;
+	struct intc_irqpin_priv *p;
+};  
+
+struct intc_irqpin_priv {
+	struct intc_irqpin_iomem iomem[INTC_IRQPIN_REG_NR];
+	struct intc_irqpin_irq irq[INTC_IRQPIN_MAX];
+	struct renesas_intc_irqpin_config config;
+	unsigned int number_of_irqs;
+	struct platform_device *pdev;
+	struct irq_chip irq_chip;
+	struct irq_domain *irq_domain;
+};
+
+static unsigned long intc_irqpin_read32(void __iomem *iomem)
+{
+	return ioread32(iomem);
+}
+
+static unsigned long intc_irqpin_read8(void __iomem *iomem)
+{
+	return ioread8(iomem);
+}
+
+static void intc_irqpin_write32(void __iomem *iomem, unsigned long data)
+{
+	iowrite32(data, iomem);
+}
+
+static void intc_irqpin_write8(void __iomem *iomem, unsigned long data)
+{
+	iowrite8(data, iomem);
+}
+
+static inline unsigned long intc_irqpin_read(struct intc_irqpin_priv *p,
+					     int reg)
+{
+	struct intc_irqpin_iomem *i = &p->iomem[reg];
+	return i->read(i->iomem);
+}
+
+static inline void intc_irqpin_write(struct intc_irqpin_priv *p,
+				     int reg, unsigned long data)
+{
+	struct intc_irqpin_iomem *i = &p->iomem[reg];
+	i->write(i->iomem, data);
+}
+
+static inline unsigned long intc_irqpin_hwirq_mask(struct intc_irqpin_priv *p,
+						   int reg, int hw_irq)
+{
+	return BIT((p->iomem[reg].width - 1) - hw_irq);
+}
+
+static inline void intc_irqpin_irq_write_hwirq(struct intc_irqpin_priv *p,
+					       int reg, int hw_irq)
+{
+	intc_irqpin_write(p, reg, intc_irqpin_hwirq_mask(p, reg, hw_irq));
+}
+
+static DEFINE_RAW_SPINLOCK(intc_irqpin_lock); /* only used by slow path */
+
+static void intc_irqpin_read_modify_write(struct intc_irqpin_priv *p,
+					  int reg, int shift,
+					  int width, int value)
+{
+	unsigned long flags;
+	unsigned long tmp;
+
+	raw_spin_lock_irqsave(&intc_irqpin_lock, flags);
+
+	tmp = intc_irqpin_read(p, reg);
+	tmp &= ~(((1 << width) - 1) << shift);
+	tmp |= value << shift;
+	intc_irqpin_write(p, reg, tmp);
+
+	raw_spin_unlock_irqrestore(&intc_irqpin_lock, flags);
+}
+
+static void intc_irqpin_mask_unmask_prio(struct intc_irqpin_priv *p,
+					 int irq, int do_mask)
+{
+	int bitfield_width = 4; /* PRIO assumed to have fixed bitfield width */
+	int shift = (7 - irq) * bitfield_width; /* PRIO assumed to be 32-bit */
+
+	intc_irqpin_read_modify_write(p, INTC_IRQPIN_REG_PRIO,
+				      shift, bitfield_width,
+				      do_mask ? 0 : (1 << bitfield_width) - 1);
+}
+
+static int intc_irqpin_set_sense(struct intc_irqpin_priv *p, int irq, int value)
+{
+	int bitfield_width = p->config.sense_bitfield_width;
+	int shift = (7 - irq) * bitfield_width; /* SENSE assumed to be 32-bit */
+
+	dev_dbg(&p->pdev->dev, "sense irq = %d, mode = %d\n", irq, value);
+
+	if (value >= (1 << bitfield_width))
+		return -EINVAL;
+
+	intc_irqpin_read_modify_write(p, INTC_IRQPIN_REG_SENSE, shift,
+				      bitfield_width, value);
+	return 0;
+}
+
+static void intc_irqpin_dbg(struct intc_irqpin_irq *i, char *str)
+{
+	dev_dbg(&i->p->pdev->dev, "%s (%d:%d:%d)\n",
+		str, i->irq, i->hw_irq,
+		irq_find_mapping(i->p->irq_domain, i->hw_irq));
+}
+
+static void intc_irqpin_irq_enable(struct irq_data *d)
+{
+	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
+	int hw_irq = irqd_to_hwirq(d);
+
+	intc_irqpin_dbg(&p->irq[hw_irq], "enable");
+	intc_irqpin_irq_write_hwirq(p, INTC_IRQPIN_REG_CLEAR, hw_irq);
+}
+
+static void intc_irqpin_irq_disable(struct irq_data *d)
+{
+	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
+	int hw_irq = irqd_to_hwirq(d);
+
+	intc_irqpin_dbg(&p->irq[hw_irq], "disable");
+	intc_irqpin_irq_write_hwirq(p, INTC_IRQPIN_REG_MASK, hw_irq);
+}
+
+static void intc_irqpin_irq_enable_force(struct irq_data *d)
+{
+	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
+	int irq = p->irq[irqd_to_hwirq(d)].irq;
+
+	intc_irqpin_irq_enable(d);
+	irq_get_chip(irq)->irq_unmask(irq_get_irq_data(irq));
+}
+
+static void intc_irqpin_irq_disable_force(struct irq_data *d)
+{
+	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
+	int irq = p->irq[irqd_to_hwirq(d)].irq;
+
+	irq_get_chip(irq)->irq_mask(irq_get_irq_data(irq));
+	intc_irqpin_irq_disable(d);
+}
+
+#define INTC_IRQ_SENSE_VALID 0x10
+#define INTC_IRQ_SENSE(x) (x + INTC_IRQ_SENSE_VALID)
+
+static unsigned char intc_irqpin_sense[IRQ_TYPE_SENSE_MASK + 1] = {
+	[IRQ_TYPE_EDGE_FALLING] = INTC_IRQ_SENSE(0x00),
+	[IRQ_TYPE_EDGE_RISING] = INTC_IRQ_SENSE(0x01),
+	[IRQ_TYPE_LEVEL_LOW] = INTC_IRQ_SENSE(0x02),
+	[IRQ_TYPE_LEVEL_HIGH] = INTC_IRQ_SENSE(0x03),
+	[IRQ_TYPE_EDGE_BOTH] = INTC_IRQ_SENSE(0x04),
+};
+
+static int intc_irqpin_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	unsigned char value = intc_irqpin_sense[type & IRQ_TYPE_SENSE_MASK];
+	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
+
+	if (!(value & INTC_IRQ_SENSE_VALID))
+		return -EINVAL;
+
+	return intc_irqpin_set_sense(p, irqd_to_hwirq(d),
+				     value ^ INTC_IRQ_SENSE_VALID);
+}
+
+static irqreturn_t intc_irqpin_irq_handler(int irq, void *dev_id)
+{
+	struct intc_irqpin_irq *i = dev_id;
+	struct intc_irqpin_priv *p = i->p;
+	unsigned long bit;
+
+	intc_irqpin_dbg(i, "demux1");
+	bit = intc_irqpin_hwirq_mask(p, INTC_IRQPIN_REG_SOURCE, i->hw_irq);
+
+	if (intc_irqpin_read(p, INTC_IRQPIN_REG_SOURCE) & bit) {
+		intc_irqpin_write(p, INTC_IRQPIN_REG_SOURCE, ~bit);
+		intc_irqpin_dbg(i, "demux2");
+		generic_handle_irq(irq_find_mapping(p->irq_domain, i->hw_irq));
+		return IRQ_HANDLED;
+	}
+	return IRQ_NONE;
+}
+
+static int intc_irqpin_irq_domain_map(struct irq_domain *h, unsigned int virq,
+				      irq_hw_number_t hw)
+{
+	struct intc_irqpin_priv *p = h->host_data;
+
+	intc_irqpin_dbg(&p->irq[hw], "map");
+	irq_set_chip_data(virq, h->host_data);
+	irq_set_chip_and_handler(virq, &p->irq_chip, handle_level_irq);
+	set_irq_flags(virq, IRQF_VALID); /* kill me now */
+	return 0;
+}
+
+static struct irq_domain_ops intc_irqpin_irq_domain_ops = {
+	.map	= intc_irqpin_irq_domain_map,
+};
+
+static int intc_irqpin_probe(struct platform_device *pdev)
+{
+	struct renesas_intc_irqpin_config *pdata = pdev->dev.platform_data;
+	struct intc_irqpin_priv *p;
+	struct intc_irqpin_iomem *i;
+	struct resource *io[INTC_IRQPIN_REG_NR];
+	struct resource *irq;
+	struct irq_chip *irq_chip;
+	void (*enable_fn)(struct irq_data *d);
+	void (*disable_fn)(struct irq_data *d);
+	const char *name = dev_name(&pdev->dev);
+	int ret;
+	int k;
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p) {
+		dev_err(&pdev->dev, "failed to allocate driver data\n");
+		ret = -ENOMEM;
+		goto err0;
+	}
+
+	/* deal with driver instance configuration */
+	if (pdata)
+		memcpy(&p->config, pdata, sizeof(*pdata));
+	if (!p->config.sense_bitfield_width)
+		p->config.sense_bitfield_width = 4; /* default to 4 bits */
+
+	p->pdev = pdev;
+	platform_set_drvdata(pdev, p);
+
+	/* get hold of manadatory IOMEM */
+	for (k = 0; k < INTC_IRQPIN_REG_NR; k++) {
+		io[k] = platform_get_resource(pdev, IORESOURCE_MEM, k);
+		if (!io[k]) {
+			dev_err(&pdev->dev, "not enough IOMEM resources\n");
+			ret = -EINVAL;
+			goto err1;
+		}
+	}
+
+	/* allow any number of IRQs between 1 and INTC_IRQPIN_MAX */
+	for (k = 0; k < INTC_IRQPIN_MAX; k++) {
+		irq = platform_get_resource(pdev, IORESOURCE_IRQ, k);
+		if (!irq)
+			break;
+
+		p->irq[k].hw_irq = k;
+		p->irq[k].p = p;
+		p->irq[k].irq = irq->start;
+	}
+
+	p->number_of_irqs = k;
+	if (p->number_of_irqs < 1) {
+		dev_err(&pdev->dev, "not enough IRQ resources\n");
+		ret = -EINVAL;
+		goto err1;
+	}
+
+	/* ioremap IOMEM and setup read/write callbacks */
+	for (k = 0; k < INTC_IRQPIN_REG_NR; k++) {
+		i = &p->iomem[k];
+
+		switch (resource_size(io[k])) {
+		case 1:
+			i->width = 8;
+			i->read = intc_irqpin_read8;
+			i->write = intc_irqpin_write8;
+			break;
+		case 4:
+			i->width = 32;
+			i->read = intc_irqpin_read32;
+			i->write = intc_irqpin_write32;
+			break;
+		default:
+			dev_err(&pdev->dev, "IOMEM size mismatch\n");
+			ret = -EINVAL;
+			goto err2;
+		}
+
+		i->iomem = ioremap_nocache(io[k]->start, resource_size(io[k]));
+		if (!i->iomem) {
+			dev_err(&pdev->dev, "failed to remap IOMEM\n");
+			ret = -ENXIO;
+			goto err2;
+		}
+	}
+
+	/* mask all interrupts using priority */
+	for (k = 0; k < p->number_of_irqs; k++)
+		intc_irqpin_mask_unmask_prio(p, k, 1);
+
+	/* use more severe masking method if requested */
+	if (p->config.control_parent) {
+		enable_fn = intc_irqpin_irq_enable_force;
+		disable_fn = intc_irqpin_irq_disable_force;
+	} else {
+		enable_fn = intc_irqpin_irq_enable;
+		disable_fn = intc_irqpin_irq_disable;
+	}
+
+	irq_chip = &p->irq_chip;
+	irq_chip->name = name;
+	irq_chip->irq_mask = disable_fn;
+	irq_chip->irq_unmask = enable_fn;
+	irq_chip->irq_enable = enable_fn;
+	irq_chip->irq_disable = disable_fn;
+	irq_chip->irq_set_type = intc_irqpin_irq_set_type;
+	irq_chip->flags	= IRQCHIP_SKIP_SET_WAKE;
+
+	p->irq_domain = irq_domain_add_simple(pdev->dev.of_node,
+					      p->number_of_irqs,
+					      p->config.irq_base,
+					      &intc_irqpin_irq_domain_ops, p);
+	if (!p->irq_domain) {
+		ret = -ENXIO;
+		dev_err(&pdev->dev, "cannot initialize irq domain\n");
+		goto err2;
+	}
+
+	/* request and set priority on interrupts one by one */
+	for (k = 0; k < p->number_of_irqs; k++) {
+		if (request_irq(p->irq[k].irq, intc_irqpin_irq_handler,
+				0, name, &p->irq[k])) {
+			dev_err(&pdev->dev, "failed to request low IRQ\n");
+			ret = -ENOENT;
+			goto err3;
+		}
+		intc_irqpin_mask_unmask_prio(p, k, 0);
+	}
+
+	dev_info(&pdev->dev, "driving %d irqs\n", p->number_of_irqs);
+
+	/* warn in case of mismatch if irq base is specified */
+	if (p->config.irq_base) {
+		k = irq_find_mapping(p->irq_domain, 0);
+		if (p->config.irq_base != k)
+			dev_warn(&pdev->dev, "irq base mismatch (%d/%d)\n",
+				 p->config.irq_base, k);
+	}
+	
+	return 0;
+
+err3:
+	for (; k >= 0; k--)
+		free_irq(p->irq[k - 1].irq, &p->irq[k - 1]);
+
+	irq_domain_remove(p->irq_domain);
+err2:
+	for (k = 0; k < INTC_IRQPIN_REG_NR; k++)
+		iounmap(p->iomem[k].iomem);
+err1:
+	kfree(p);
+err0:
+	return ret;
+}
+
+static int intc_irqpin_remove(struct platform_device *pdev)
+{
+	struct intc_irqpin_priv *p = platform_get_drvdata(pdev);
+	int k;
+
+	for (k = 0; k < p->number_of_irqs; k++)
+		free_irq(p->irq[k].irq, &p->irq[k]);
+
+	irq_domain_remove(p->irq_domain);
+
+	for (k = 0; k < INTC_IRQPIN_REG_NR; k++)
+		iounmap(p->iomem[k].iomem);
+
+	kfree(p);
+	return 0;
+}
+
+static struct platform_driver intc_irqpin_device_driver = {
+	.probe		= intc_irqpin_probe,
+	.remove		= intc_irqpin_remove,
+	.driver		= {
+		.name	= "renesas_intc_irqpin",
+	}
+};
+
+static int __init intc_irqpin_init(void)
+{
+	return platform_driver_register(&intc_irqpin_device_driver);
+}
+postcore_initcall(intc_irqpin_init);
+
+static void __exit intc_irqpin_exit(void)
+{
+	platform_driver_unregister(&intc_irqpin_device_driver);
+}
+module_exit(intc_irqpin_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("Renesas INTC External IRQ Pin Driver");
+MODULE_LICENSE("GPL v2");