drm/msm/a6xx: Add devfreq support for a6xx

Implement routines to estimate GPU busy time and fetching the
current frequency for the polling interval. This is required by
the devfreq framework which recommends a frequency change if needed.
The driver code then tries to set this new frequency on the GPU by
sending an Out Of Band(OOB) request to the GMU.

Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/adreno/a6xx_gmu.c

@@ -61,8 +61,10 @@ static bool a6xx_gmu_gx_is_on(struct a6xx_gmu *gmu)
 		A6XX_GMU_SPTPRAC_PWR_CLK_STATUS_GX_HM_CLK_OFF));
 }
 
-static int a6xx_gmu_set_freq(struct a6xx_gmu *gmu, int index)
+static void __a6xx_gmu_set_freq(struct a6xx_gmu *gmu, int index)
 {
+	int ret;
+
 	gmu_write(gmu, REG_A6XX_GMU_DCVS_ACK_OPTION, 0);
 
 	gmu_write(gmu, REG_A6XX_GMU_DCVS_PERF_SETTING,
@@ -78,7 +80,37 @@ static int a6xx_gmu_set_freq(struct a6xx_gmu *gmu, int index)
 	a6xx_gmu_set_oob(gmu, GMU_OOB_DCVS_SET);
 	a6xx_gmu_clear_oob(gmu, GMU_OOB_DCVS_SET);
 
-	return gmu_read(gmu, REG_A6XX_GMU_DCVS_RETURN);
+	ret = gmu_read(gmu, REG_A6XX_GMU_DCVS_RETURN);
+	if (ret)
+		dev_err(gmu->dev, "GMU set GPU frequency error: %d\n", ret);
+
+	gmu->freq = gmu->gpu_freqs[index];
+}
+
+void a6xx_gmu_set_freq(struct msm_gpu *gpu, unsigned long freq)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct a6xx_gmu *gmu = &a6xx_gpu->gmu;
+	u32 perf_index = 0;
+
+	if (freq == gmu->freq)
+		return;
+
+	for (perf_index = 0; perf_index < gmu->nr_gpu_freqs - 1; perf_index++)
+		if (freq == gmu->gpu_freqs[perf_index])
+			break;
+
+	__a6xx_gmu_set_freq(gmu, perf_index);
+}
+
+unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct a6xx_gmu *gmu = &a6xx_gpu->gmu;
+
+	return  gmu->freq;
 }
 
 static bool a6xx_gmu_check_idle_level(struct a6xx_gmu *gmu)
@@ -637,7 +669,7 @@ int a6xx_gmu_reset(struct a6xx_gpu *a6xx_gpu)
 		ret = a6xx_hfi_start(gmu, GMU_COLD_BOOT);
 
 	/* Set the GPU back to the highest power frequency */
-	a6xx_gmu_set_freq(gmu, gmu->nr_gpu_freqs - 1);
+	__a6xx_gmu_set_freq(gmu, gmu->nr_gpu_freqs - 1);
 
 out:
 	if (ret)
@@ -676,7 +708,7 @@ int a6xx_gmu_resume(struct a6xx_gpu *a6xx_gpu)
 	ret = a6xx_hfi_start(gmu, status);
 
 	/* Set the GPU to the highest power frequency */
-	a6xx_gmu_set_freq(gmu, gmu->nr_gpu_freqs - 1);
+	__a6xx_gmu_set_freq(gmu, gmu->nr_gpu_freqs - 1);
 
 out:
 	/* Make sure to turn off the boot OOB request on error */

drivers/gpu/drm/msm/adreno/a6xx_gmu.h

@@ -74,6 +74,8 @@ struct a6xx_gmu {
 	unsigned long gmu_freqs[4];
 	u32 cx_arc_votes[4];
 
+	unsigned long freq;
+
 	struct a6xx_hfi_queue queues[2];
 
 	struct tasklet_struct hfi_tasklet;

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -7,6 +7,8 @@
 #include "a6xx_gpu.h"
 #include "a6xx_gmu.xml.h"
 
+#include <linux/devfreq.h>
+
 static inline bool _a6xx_check_idle(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
@@ -682,6 +684,8 @@ static int a6xx_pm_resume(struct msm_gpu *gpu)
 
 	gpu->needs_hw_init = true;
 
+	msm_gpu_resume_devfreq(gpu);
+
 	return ret;
 }
 
@@ -690,6 +694,8 @@ static int a6xx_pm_suspend(struct msm_gpu *gpu)
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 
+	devfreq_suspend_device(gpu->devfreq.devfreq);
+
 	/*
 	 * Make sure the GMU is idle before continuing (because some transitions
 	 * may use VBIF
@@ -753,6 +759,24 @@ static void a6xx_destroy(struct msm_gpu *gpu)
 	kfree(a6xx_gpu);
 }
 
+static unsigned long a6xx_gpu_busy(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	u64 busy_cycles;
+	unsigned long busy_time;
+
+	busy_cycles = gmu_read64(&a6xx_gpu->gmu,
+			REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_L,
+			REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_H);
+
+	busy_time = ((busy_cycles - gpu->devfreq.busy_cycles) * 10) / 192;
+
+	gpu->devfreq.busy_cycles = busy_cycles;
+
+	return busy_time;
+}
+
 static const struct adreno_gpu_funcs funcs = {
 	.base = {
 		.get_param = adreno_get_param,
@@ -768,6 +792,9 @@ static const struct adreno_gpu_funcs funcs = {
 #if defined(CONFIG_DEBUG_FS) || defined(CONFIG_DEV_COREDUMP)
 		.show = a6xx_show,
 #endif
+		.gpu_busy = a6xx_gpu_busy,
+		.gpu_get_freq = a6xx_gmu_get_freq,
+		.gpu_set_freq = a6xx_gmu_set_freq,
 	},
 	.get_timestamp = a6xx_get_timestamp,
 };

drivers/gpu/drm/msm/adreno/a6xx_gpu.h

@@ -56,5 +56,6 @@ void a6xx_gmu_clear_oob(struct a6xx_gmu *gmu, enum a6xx_gmu_oob_state state);
 
 int a6xx_gmu_probe(struct a6xx_gpu *a6xx_gpu, struct device_node *node);
 void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu);
-
+void a6xx_gmu_set_freq(struct msm_gpu *gpu, unsigned long freq);
+unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu);
 #endif /* __A6XX_GPU_H__ */