feat(drm): Implement classes to read drm subsystem

Signed-off-by: Juerg Ritter <[email protected]>

sysfs/class_drm_amdgpu_test.go

@@ -46,6 +46,16 @@ func TestClassDRMCardAMDGPUStats(t *testing.T) {
 			PowerDPMForcePerformanceLevel: "manual",
 			UniqueID:                      "0123456789abcdef",
 		},
+		{
+			Name:                  "card1",
+			GPUBusyPercent:        0,
+			MemoryGTTSize:         0,
+			MemoryGTTUsed:         0,
+			MemoryVisibleVRAMSize: 0,
+			MemoryVisibleVRAMUsed: 0,
+			MemoryVRAMSize:        0,
+			MemoryVRAMUsed:        0,
+		},
 	}
 
 	if !reflect.DeepEqual(classDRMCardStats, drmTest) {

sysfs/class_drm_card.go

@@ -0,0 +1,128 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build linux
+// +build linux
+
+package sysfs
+
+import (
+	"fmt"
+	"path/filepath"
+
+	"github.com/prometheus/procfs/internal/util"
+)
+
+const drmClassPath = "class/drm"
+
+// DrmCard contains info from files in /sys/class/drm for a
+// single DRM Card device.
+type DrmCard struct {
+	Name   string
+	Driver string
+	Ports  map[string]DrmCardPort
+}
+
+// DrmCardPort contains info from files in
+// /sys/class/drm/<Card>/<Card>-<Name>
+// for a single port of one DrmCard device.
+type DrmCardPort struct {
+	Name    string
+	Status  string
+	Dpms    string
+	Enabled string
+}
+
+// DrmCardClass is a collection of every Card device in
+// /sys/class/drm.
+//
+// The map keys are the names of the InfiniBand devices.
+type DrmCardClass map[string]DrmCard
+
+// DrmCardClass returns infos for all Drm devices read from
+// /sys/class/drm.
+func (fs FS) DrmCardClass() (DrmCardClass, error) {
+
+	cards, err := filepath.Glob(fs.sys.Path("class/drm/card[0-9]"))
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to list DRM card ports at %q: %w", cards, err)
+	}
+
+	drmCardClass := make(DrmCardClass, len(cards))
+	for _, c := range cards {
+		card, err := fs.parseDrmCard(filepath.Base(c))
+		if err != nil {
+			return nil, err
+		}
+
+		drmCardClass[card.Name] = *card
+	}
+
+	return drmCardClass, nil
+}
+
+// Parse one DrmCard.
+func (fs FS) parseDrmCard(name string) (*DrmCard, error) {
+	path := fs.sys.Path(drmClassPath, name)
+	card := DrmCard{Name: name}
+
+	// Read the kernel module of the card
+	cardDriverPath, err := filepath.EvalSymlinks(filepath.Join(path, "device/driver"))
+	if err != nil {
+		return nil, fmt.Errorf("failed to read driver: %w", err)
+	}
+	card.Driver = filepath.Base(cardDriverPath)
+
+	portsPath, err := filepath.Glob(filepath.Join(path, filepath.Base(path)+"-*-*"))
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to list DRM card ports at %q: %w", portsPath, err)
+	}
+
+	card.Ports = make(map[string]DrmCardPort, len(portsPath))
+	for _, d := range portsPath {
+		port, err := parseDrmCardPort(d)
+		if err != nil {
+			return nil, err
+		}
+
+		card.Ports[port.Name] = *port
+	}
+
+	return &card, nil
+}
+
+func parseDrmCardPort(port string) (*DrmCardPort, error) {
+	portStatus, err := util.SysReadFile(filepath.Join(port, "status"))
+	if err != nil {
+		return nil, err
+	}
+
+	drmCardPort := DrmCardPort{Name: filepath.Base(port), Status: portStatus}
+
+	portDpms, err := util.SysReadFile(filepath.Join(port, "dpms"))
+	if err != nil {
+		return nil, err
+	}
+
+	drmCardPort.Dpms = portDpms
+
+	portEnabled, err := util.SysReadFile(filepath.Join(port, "enabled"))
+	if err != nil {
+		return nil, err
+	}
+	drmCardPort.Enabled = portEnabled
+
+	return &drmCardPort, nil
+}

sysfs/class_drm_card_test.go

@@ -0,0 +1,65 @@
+// Copyright 2021 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build linux
+// +build linux
+
+package sysfs
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestClassDRMCard(t *testing.T) {
+	fs, err := NewFS(sysTestFixtures)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := fs.DrmCardClass()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want := DrmCardClass{
+		"card0": DrmCard{
+			Name:   "card0",
+			Driver: "amdgpu",
+			Ports:  map[string]DrmCardPort{},
+		},
+		"card1": DrmCard{
+			Name:   "card1",
+			Driver: "i915",
+			Ports: map[string]DrmCardPort{
+				"card1-DP-1": {
+					Name:    "card1-DP-1",
+					Dpms:    "Off",
+					Enabled: "disabled",
+					Status:  "disconnected",
+				},
+				"card1-DP-5": {
+					Name:    "card1-DP-5",
+					Dpms:    "On",
+					Enabled: "enabled",
+					Status:  "connected",
+				},
+			},
+		},
+	}
+
+	if diff := cmp.Diff(want, got); diff != "" {
+		t.Fatalf("unexpected DrmCard class (-want +got):\n%s", diff)
+	}
+}