drm/amdgpu: Add sysfs file for PCIe usage v5

Add a sysfs file that reports the number of bytes transmitted and
received in the last second. This can be used to approximate the PCIe
bandwidth usage over the last second.

v2: Clarify use of mps as estimation of bandwidth
v3: Don't make the file on APUs
v4: Early exit for APUs in the read function, change output to
    display "packets-received packets-sent mps"
v5: fix missing header for si (Alex)

Signed-off-by: Kent Russell <kent.russell@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index 6896dec97fc7..b38c06f0196e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -990,6 +990,31 @@ static ssize_t amdgpu_get_busy_percent(struct device *dev,
         return snprintf(buf, PAGE_SIZE, "%d\n", value);
 }
 
+/**
+ * DOC: pcie_bw
+ *
+ * The amdgpu driver provides a sysfs API for estimating how much data
+ * has been received and sent by the GPU in the last second through PCIe.
+ * The file pcie_bw is used for this.
+ * The Perf counters count the number of received and sent messages and return
+ * those values, as well as the maximum payload size of a PCIe packet (mps).
+ * Note that it is not possible to easily and quickly obtain the size of each
+ * packet transmitted, so we output the max payload size (mps) to allow for
+ * quick estimation of the PCIe bandwidth usage
+ */
+static ssize_t amdgpu_get_pcie_bw(struct device *dev,
+                struct device_attribute *attr,
+                char *buf)
+{
+        struct drm_device *ddev = dev_get_drvdata(dev);
+        struct amdgpu_device *adev = ddev->dev_private;
+        uint64_t count0, count1;
+
+        amdgpu_asic_get_pcie_usage(adev, &count0, &count1);
+        return snprintf(buf, PAGE_SIZE, "%llu %llu %i\n",
+                        count0, count1, pcie_get_mps(adev->pdev));
+}
+
 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,
@@ -1025,6 +1050,7 @@ static DEVICE_ATTR(pp_od_clk_voltage, S_IRUGO | S_IWUSR,
                 amdgpu_set_pp_od_clk_voltage);
 static DEVICE_ATTR(gpu_busy_percent, S_IRUGO,
                 amdgpu_get_busy_percent, NULL);
+static DEVICE_ATTR(pcie_bw, S_IRUGO, amdgpu_get_pcie_bw, NULL);
 
 static ssize_t amdgpu_hwmon_show_temp(struct device *dev,
                                       struct device_attribute *attr,
@@ -2108,6 +2134,14 @@ int amdgpu_pm_sysfs_init(struct amdgpu_device *adev)
                                 "gpu_busy_level\n");
                 return ret;
         }
+        /* PCIe Perf counters won't work on APU nodes */
+        if (adev->flags & !AMD_IS_APU) {
+                ret = device_create_file(adev->dev, &dev_attr_pcie_bw);
+                if (ret) {
+                        DRM_ERROR("failed to create device file pcie_bw\n");
+                        return ret;
+                }
+        }
         ret = amdgpu_debugfs_pm_init(adev);
         if (ret) {
                 DRM_ERROR("Failed to register debugfs file for dpm!\n");
@@ -2147,6 +2181,8 @@ void amdgpu_pm_sysfs_fini(struct amdgpu_device *adev)
                 device_remove_file(adev->dev,
                                 &dev_attr_pp_od_clk_voltage);
         device_remove_file(adev->dev, &dev_attr_gpu_busy_percent);
+        if (adev->flags & !AMD_IS_APU)
+                device_remove_file(adev->dev, &dev_attr_pcie_bw);
 }
 
 void amdgpu_pm_compute_clocks(struct amdgpu_device *adev)