drm/etnaviv: implement cooling support for new GPU cores

GPU cores with the DYNAMIC_FREQUENCY_SCALING feature bit set expect the
platform to provide the clock scaling and ignore any requests to use the
internal FSCALE divider. Writes to this register still work, but don't
have any effect on the GPU clock frequency.

Save the initial core and shader clock frequency and ask the platform
to provide a slower clock when cooling is requested.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gpu.c

@@ -412,13 +412,19 @@ static void etnaviv_gpu_load_clock(struct etnaviv_gpu *gpu, u32 clock)
 
 static void etnaviv_gpu_update_clock(struct etnaviv_gpu *gpu)
 {
-	unsigned int fscale = 1 << (6 - gpu->freq_scale);
-	u32 clock;
-
-	clock = VIVS_HI_CLOCK_CONTROL_DISABLE_DEBUG_REGISTERS |
-		VIVS_HI_CLOCK_CONTROL_FSCALE_VAL(fscale);
+	if (gpu->identity.minor_features2 &
+	    chipMinorFeatures2_DYNAMIC_FREQUENCY_SCALING) {
+		clk_set_rate(gpu->clk_core,
+			     gpu->base_rate_core >> gpu->freq_scale);
+		clk_set_rate(gpu->clk_shader,
+			     gpu->base_rate_shader >> gpu->freq_scale);
+	} else {
+		unsigned int fscale = 1 << (6 - gpu->freq_scale);
+		u32 clock = VIVS_HI_CLOCK_CONTROL_DISABLE_DEBUG_REGISTERS |
+			    VIVS_HI_CLOCK_CONTROL_FSCALE_VAL(fscale);
 
-	etnaviv_gpu_load_clock(gpu, clock);
+		etnaviv_gpu_load_clock(gpu, clock);
+	}
 }
 
 static int etnaviv_hw_reset(struct etnaviv_gpu *gpu)
@@ -1742,11 +1748,13 @@ static int etnaviv_gpu_platform_probe(struct platform_device *pdev)
 	DBG("clk_core: %p", gpu->clk_core);
 	if (IS_ERR(gpu->clk_core))
 		gpu->clk_core = NULL;
+	gpu->base_rate_core = clk_get_rate(gpu->clk_core);
 
 	gpu->clk_shader = devm_clk_get(&pdev->dev, "shader");
 	DBG("clk_shader: %p", gpu->clk_shader);
 	if (IS_ERR(gpu->clk_shader))
 		gpu->clk_shader = NULL;
+	gpu->base_rate_shader = clk_get_rate(gpu->clk_shader);
 
 	/* TODO: figure out max mapped size */
 	dev_set_drvdata(dev, gpu);

drivers/gpu/drm/etnaviv/etnaviv_gpu.h

@@ -152,6 +152,8 @@ struct etnaviv_gpu {
 	u32 hangcheck_dma_addr;
 	struct work_struct recover_work;
 	unsigned int freq_scale;
+	unsigned long base_rate_core;
+	unsigned long base_rate_shader;
 };
 
 static inline void gpu_write(struct etnaviv_gpu *gpu, u32 reg, u32 data)