drm/panthor: Add DEV_QUERY_TIMESTAMP_INFO dev query

Expose timestamp information supported by the GPU with a new device
query.

Mali uses an external timer as GPU system time. On ARM, this is wired to
the generic arch timer so we wire cntfrq_el0 as device frequency.

This new uAPI will be used in Mesa to implement timestamp queries and
VK_KHR_calibrated_timestamps.

Since this extends the uAPI and because userland needs a way to advertise
those features conditionally, this also bumps the driver minor version.

v2:
- Rewrote to use GPU timestamp register
- Added timestamp_offset to drm_panthor_timestamp_info
- Add missing include for arch_timer_get_cntfrq
- Rework commit message

v3:
- Add panthor_gpu_read_64bit_counter
- Change panthor_gpu_read_timestamp to use
  panthor_gpu_read_64bit_counter

v4:
- Fix multiple typos in uAPI documentation
- Mention behavior when the timestamp frequency is unknown
- Use u64 instead of unsigned long long
  for panthor_gpu_read_timestamp
- Apply r-b from Mihail

Signed-off-by: Mary Guillemard <mary.guillemard@collabora.com>
Reviewed-by: Mihail Atanassov <mihail.atanassov@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240830080349.24736-2-mary.guillemard@collabora.com

1 files changed, 42 insertions, 1 deletions

diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
index b5e7b919f241..444e3bb1cfb5 100644
--- a/drivers/gpu/drm/panthor/panthor_drv.c
+++ b/drivers/gpu/drm/panthor/panthor_drv.c
@@ -3,6 +3,10 @@
 /* Copyright 2019 Linaro, Ltd., Rob Herring <robh@kernel.org> */
 /* Copyright 2019 Collabora ltd. */
 
+#ifdef CONFIG_ARM_ARCH_TIMER
+#include <asm/arch_timer.h>
+#endif
+
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
@@ -164,6 +168,7 @@ panthor_get_uobj_array(const struct drm_panthor_obj_array *in, u32 min_stride,
 	_Generic(_obj_name, \
 		 PANTHOR_UOBJ_DECL(struct drm_panthor_gpu_info, tiler_present), \
 		 PANTHOR_UOBJ_DECL(struct drm_panthor_csif_info, pad), \
+		 PANTHOR_UOBJ_DECL(struct drm_panthor_timestamp_info, current_timestamp), \
 		 PANTHOR_UOBJ_DECL(struct drm_panthor_sync_op, timeline_value), \
 		 PANTHOR_UOBJ_DECL(struct drm_panthor_queue_submit, syncs), \
 		 PANTHOR_UOBJ_DECL(struct drm_panthor_queue_create, ringbuf_size), \
@@ -750,10 +755,33 @@ static void panthor_submit_ctx_cleanup(struct panthor_submit_ctx *ctx,
 	kvfree(ctx->jobs);
 }
 
+static int panthor_query_timestamp_info(struct panthor_device *ptdev,
+					struct drm_panthor_timestamp_info *arg)
+{
+	int ret;
+
+	ret = pm_runtime_resume_and_get(ptdev->base.dev);
+	if (ret)
+		return ret;
+
+#ifdef CONFIG_ARM_ARCH_TIMER
+	arg->timestamp_frequency = arch_timer_get_cntfrq();
+#else
+	arg->timestamp_frequency = 0;
+#endif
+	arg->current_timestamp = panthor_gpu_read_timestamp(ptdev);
+	arg->timestamp_offset = panthor_gpu_read_timestamp_offset(ptdev);
+
+	pm_runtime_put(ptdev->base.dev);
+	return 0;
+}
+
 static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct drm_file *file)
 {
 	struct panthor_device *ptdev = container_of(ddev, struct panthor_device, base);
 	struct drm_panthor_dev_query *args = data;
+	struct drm_panthor_timestamp_info timestamp_info;
+	int ret;
 
 	if (!args->pointer) {
 		switch (args->type) {
@@ -765,6 +793,10 @@ static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct d
 			args->size = sizeof(ptdev->csif_info);
 			return 0;
 
+		case DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO:
+			args->size = sizeof(timestamp_info);
+			return 0;
+
 		default:
 			return -EINVAL;
 		}
@@ -777,6 +809,14 @@ static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct d
 	case DRM_PANTHOR_DEV_QUERY_CSIF_INFO:
 		return PANTHOR_UOBJ_SET(args->pointer, args->size, ptdev->csif_info);
 
+	case DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO:
+		ret = panthor_query_timestamp_info(ptdev, &timestamp_info);
+
+		if (ret)
+			return ret;
+
+		return PANTHOR_UOBJ_SET(args->pointer, args->size, timestamp_info);
+
 	default:
 		return -EINVAL;
 	}
@@ -1372,6 +1412,7 @@ static void panthor_debugfs_init(struct drm_minor *minor)
 /*
  * PanCSF driver version:
  * - 1.0 - initial interface
+ * - 1.1 - adds DEV_QUERY_TIMESTAMP_INFO query
  */
 static const struct drm_driver panthor_drm_driver = {
 	.driver_features = DRIVER_RENDER | DRIVER_GEM | DRIVER_SYNCOBJ |
@@ -1385,7 +1426,7 @@ static const struct drm_driver panthor_drm_driver = {
 	.desc = "Panthor DRM driver",
 	.date = "20230801",
 	.major = 1,
-	.minor = 0,
+	.minor = 1,
 
 	.gem_create_object = panthor_gem_create_object,
 	.gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table,