drm/amd/amdgpu: Add a GPU_LOAD entry to sysfs (v3)

This adds what should be a stable interface to read GPU
load from userspace.

(v2): Fix comments and name of file per recommendations.
(v3): Add chapter to amdgpu.rst as well.

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Acked-by: Slava Abramov <slava.abramov@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index 113edffb5960..fdb399821915 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -918,6 +918,36 @@ fail:
         return -EINVAL;
 }
 
+/**
+ * DOC: busy_percent
+ *
+ * The amdgpu driver provides a sysfs API for reading how busy the GPU
+ * is as a percentage.  The file gpu_busy_percent is used for this.
+ * The SMU firmware computes a percentage of load based on the
+ * aggregate activity level in the IP cores.
+ */
+static ssize_t amdgpu_get_busy_percent(struct device *dev,
+                struct device_attribute *attr,
+                char *buf)
+{
+        struct drm_device *ddev = dev_get_drvdata(dev);
+        struct amdgpu_device *adev = ddev->dev_private;
+        int r, value, size = sizeof(value);
+
+        /* sanity check PP is enabled */
+        if (!(adev->powerplay.pp_funcs &&
+              adev->powerplay.pp_funcs->read_sensor))
+                return -EINVAL;
+
+        /* read the IP busy sensor */
+        r = amdgpu_dpm_read_sensor(adev, AMDGPU_PP_SENSOR_GPU_LOAD,
+                                   (void *)&value, &size);
+        if (r)
+                return r;
+
+        return snprintf(buf, PAGE_SIZE, "%d\n", value);
+}
+
 static DEVICE_ATTR(power_dpm_state, S_IRUGO | S_IWUSR, amdgpu_get_dpm_state, amdgpu_set_dpm_state);
 static DEVICE_ATTR(power_dpm_force_performance_level, S_IRUGO | S_IWUSR,
                    amdgpu_get_dpm_forced_performance_level,
@@ -951,6 +981,8 @@ static DEVICE_ATTR(pp_power_profile_mode, S_IRUGO | S_IWUSR,
 static DEVICE_ATTR(pp_od_clk_voltage, S_IRUGO | S_IWUSR,
                 amdgpu_get_pp_od_clk_voltage,
                 amdgpu_set_pp_od_clk_voltage);
+static DEVICE_ATTR(gpu_busy_percent, S_IRUGO,
+                amdgpu_get_busy_percent, NULL);
 
 static ssize_t amdgpu_hwmon_show_temp(struct device *dev,
                                       struct device_attribute *attr,
@@ -1854,6 +1886,13 @@ int amdgpu_pm_sysfs_init(struct amdgpu_device *adev)
                                 "pp_od_clk_voltage\n");
                 return ret;
         }
+        ret = device_create_file(adev->dev,
+                        &dev_attr_gpu_busy_percent);
+        if (ret) {
+                DRM_ERROR("failed to create device file "
+                                "gpu_busy_level\n");
+                return ret;
+        }
         ret = amdgpu_debugfs_pm_init(adev);
         if (ret) {
                 DRM_ERROR("Failed to register debugfs file for dpm!\n");
@@ -1889,6 +1928,7 @@ void amdgpu_pm_sysfs_fini(struct amdgpu_device *adev)
                         &dev_attr_pp_power_profile_mode);
         device_remove_file(adev->dev,
                         &dev_attr_pp_od_clk_voltage);
+        device_remove_file(adev->dev, &dev_attr_gpu_busy_percent);
 }
 
 void amdgpu_pm_compute_clocks(struct amdgpu_device *adev)