drm/panfrost: Add SYSTEM_TIMESTAMP and SYSTEM_TIMESTAMP_FREQUENCY parameters

Expose system timestamp and frequency supported by the GPU.

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.

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

v3:
- Move panfrost_cycle_counter_get and panfrost_cycle_counter_put to
  panfrost_ioctl_query_timestamp
- Handle possible overflow in panfrost_timestamp_read

Signed-off-by: Mary Guillemard <mary.guillemard@collabora.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240819080224.24914-2-mary.guillemard@collabora.com

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
index fd8e44992184f..f19f918e2330e 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
@@ -380,6 +380,18 @@ unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev)
 	return ((u64)hi << 32) | lo;
 }
 
+unsigned long long panfrost_timestamp_read(struct panfrost_device *pfdev)
+{
+	u32 hi, lo;
+
+	do {
+		hi = gpu_read(pfdev, GPU_TIMESTAMP_HI);
+		lo = gpu_read(pfdev, GPU_TIMESTAMP_LO);
+	} while (hi != gpu_read(pfdev, GPU_TIMESTAMP_HI));
+
+	return ((u64)hi << 32) | lo;
+}
+
 static u64 panfrost_get_core_mask(struct panfrost_device *pfdev)
 {
 	u64 core_mask;