drm/etnaviv: add etnaviv cooling device

Each Vivante GPU contains a clock divider which can divide the GPU clock
by 2^n, which can lower the power dissipation from the GPU.  It has been
suggested that the GC600 on Dove is responsible for 20-30% of the power
dissipation from the SoC, so lowering the GPU clock rate provides a way
to throttle the power dissiptation, and reduce the temperature when the
SoC gets hot.

This patch hooks the Etnaviv driver into the kernel's thermal management
to allow the GPUs to be throttled when necessary, allowing a reduction in
GPU clock rate from /1 to /64 in power of 2 steps.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
index 1c0606ea7d5e..6a1e68eec24c 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
@@ -97,6 +97,7 @@ struct etnaviv_cmdbuf;
 
 struct etnaviv_gpu {
 	struct drm_device *drm;
+	struct thermal_cooling_device *cooling;
 	struct device *dev;
 	struct mutex lock;
 	struct etnaviv_chip_identity identity;
@@ -150,6 +151,7 @@ struct etnaviv_gpu {
 	u32 hangcheck_fence;
 	u32 hangcheck_dma_addr;
 	struct work_struct recover_work;
+	unsigned int freq_scale;
 };
 
 static inline void gpu_write(struct etnaviv_gpu *gpu, u32 reg, u32 data)