1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2013 Red Hat
4 * Author: Rob Clark <robdclark@gmail.com>
5 */
6
7/* For profiling, userspace can:
8 *
9 * tail -f /sys/kernel/debug/dri/<minor>/gpu
10 *
11 * This will enable performance counters/profiling to track the busy time
12 * and any gpu specific performance counters that are supported.
13 */
14
15#ifdef CONFIG_DEBUG_FS
16
17#include <linux/debugfs.h>
18#include <linux/uaccess.h>
19
20#include <drm/drm_file.h>
21
22#include "msm_drv.h"
23#include "msm_gpu.h"
24
25struct msm_perf_state {
26 struct drm_device *dev;
27
28 bool open;
29 int cnt;
30 struct mutex read_lock;
31
32 char buf[256];
33 int buftot, bufpos;
34
35 unsigned long next_jiffies;
36};
37
38#define SAMPLE_TIME (HZ/4)
39
40/* wait for next sample time: */
41static int wait_sample(struct msm_perf_state *perf)
42{
43 unsigned long start_jiffies = jiffies;
44
45 if (time_after(perf->next_jiffies, start_jiffies)) {
46 unsigned long remaining_jiffies =
47 perf->next_jiffies - start_jiffies;
48 int ret = schedule_timeout_interruptible(timeout: remaining_jiffies);
49 if (ret > 0) {
50 /* interrupted */
51 return -ERESTARTSYS;
52 }
53 }
54 perf->next_jiffies += SAMPLE_TIME;
55 return 0;
56}
57
58static int refill_buf(struct msm_perf_state *perf)
59{
60 struct msm_drm_private *priv = perf->dev->dev_private;
61 struct msm_gpu *gpu = priv->gpu;
62 char *ptr = perf->buf;
63 int rem = sizeof(perf->buf);
64 int i, n;
65
66 if ((perf->cnt++ % 32) == 0) {
67 /* Header line: */
68 n = snprintf(buf: ptr, size: rem, fmt: "%%BUSY");
69 ptr += n;
70 rem -= n;
71
72 for (i = 0; i < gpu->num_perfcntrs; i++) {
73 const struct msm_gpu_perfcntr *perfcntr = &gpu->perfcntrs[i];
74 n = snprintf(buf: ptr, size: rem, fmt: "\t%s", perfcntr->name);
75 ptr += n;
76 rem -= n;
77 }
78 } else {
79 /* Sample line: */
80 uint32_t activetime = 0, totaltime = 0;
81 uint32_t cntrs[5];
82 uint32_t val;
83 int ret;
84
85 /* sleep until next sample time: */
86 ret = wait_sample(perf);
87 if (ret)
88 return ret;
89
90 ret = msm_gpu_perfcntr_sample(gpu, activetime: &activetime, totaltime: &totaltime,
91 ARRAY_SIZE(cntrs), cntrs);
92 if (ret < 0)
93 return ret;
94
95 val = totaltime ? 1000 * activetime / totaltime : 0;
96 n = snprintf(buf: ptr, size: rem, fmt: "%3d.%d%%", val / 10, val % 10);
97 ptr += n;
98 rem -= n;
99
100 for (i = 0; i < ret; i++) {
101 /* cycle counters (I think).. convert to MHz.. */
102 val = cntrs[i] / 10000;
103 n = snprintf(buf: ptr, size: rem, fmt: "\t%5d.%02d",
104 val / 100, val % 100);
105 ptr += n;
106 rem -= n;
107 }
108 }
109
110 n = snprintf(buf: ptr, size: rem, fmt: "\n");
111 ptr += n;
112 rem -= n;
113
114 perf->bufpos = 0;
115 perf->buftot = ptr - perf->buf;
116
117 return 0;
118}
119
120static ssize_t perf_read(struct file *file, char __user *buf,
121 size_t sz, loff_t *ppos)
122{
123 struct msm_perf_state *perf = file->private_data;
124 int n = 0, ret = 0;
125
126 mutex_lock(&perf->read_lock);
127
128 if (perf->bufpos >= perf->buftot) {
129 ret = refill_buf(perf);
130 if (ret)
131 goto out;
132 }
133
134 n = min((int)sz, perf->buftot - perf->bufpos);
135 if (copy_to_user(to: buf, from: &perf->buf[perf->bufpos], n)) {
136 ret = -EFAULT;
137 goto out;
138 }
139
140 perf->bufpos += n;
141 *ppos += n;
142
143out:
144 mutex_unlock(lock: &perf->read_lock);
145 if (ret)
146 return ret;
147 return n;
148}
149
150static int perf_open(struct inode *inode, struct file *file)
151{
152 struct msm_perf_state *perf = inode->i_private;
153 struct drm_device *dev = perf->dev;
154 struct msm_drm_private *priv = dev->dev_private;
155 struct msm_gpu *gpu = priv->gpu;
156 int ret = 0;
157
158 if (!gpu)
159 return -ENODEV;
160
161 mutex_lock(&gpu->lock);
162
163 if (perf->open) {
164 ret = -EBUSY;
165 goto out;
166 }
167
168 file->private_data = perf;
169 perf->open = true;
170 perf->cnt = 0;
171 perf->buftot = 0;
172 perf->bufpos = 0;
173 msm_gpu_perfcntr_start(gpu);
174 perf->next_jiffies = jiffies + SAMPLE_TIME;
175
176out:
177 mutex_unlock(lock: &gpu->lock);
178 return ret;
179}
180
181static int perf_release(struct inode *inode, struct file *file)
182{
183 struct msm_perf_state *perf = inode->i_private;
184 struct msm_drm_private *priv = perf->dev->dev_private;
185 msm_gpu_perfcntr_stop(gpu: priv->gpu);
186 perf->open = false;
187 return 0;
188}
189
190
191static const struct file_operations perf_debugfs_fops = {
192 .owner = THIS_MODULE,
193 .open = perf_open,
194 .read = perf_read,
195 .llseek = no_llseek,
196 .release = perf_release,
197};
198
199int msm_perf_debugfs_init(struct drm_minor *minor)
200{
201 struct msm_drm_private *priv = minor->dev->dev_private;
202 struct msm_perf_state *perf;
203
204 /* only create on first minor: */
205 if (priv->perf)
206 return 0;
207
208 perf = kzalloc(size: sizeof(*perf), GFP_KERNEL);
209 if (!perf)
210 return -ENOMEM;
211
212 perf->dev = minor->dev;
213
214 mutex_init(&perf->read_lock);
215 priv->perf = perf;
216
217 debugfs_create_file(name: "perf", S_IFREG | S_IRUGO, parent: minor->debugfs_root,
218 data: perf, fops: &perf_debugfs_fops);
219 return 0;
220}
221
222void msm_perf_debugfs_cleanup(struct msm_drm_private *priv)
223{
224 struct msm_perf_state *perf = priv->perf;
225
226 if (!perf)
227 return;
228
229 priv->perf = NULL;
230
231 mutex_destroy(lock: &perf->read_lock);
232
233 kfree(objp: perf);
234}
235
236#endif
237

source code of linux/drivers/gpu/drm/msm/msm_perf.c