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(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(ptr, rem, "%%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(ptr, rem, "\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, &totaltime,
 91				ARRAY_SIZE(cntrs), cntrs);
 92		if (ret < 0)
 93			return ret;
 94
 95		val = totaltime ? 1000 * activetime / totaltime : 0;
 96		n = snprintf(ptr, rem, "%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(ptr, rem, "\t%5d.%02d",
104					val / 100, val % 100);
105			ptr += n;
106			rem -= n;
107		}
108	}
109
110	n = snprintf(ptr, rem, "\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(buf, &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(&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(&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(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	.release = perf_release,
196};
197
198int msm_perf_debugfs_init(struct drm_minor *minor)
199{
200	struct msm_drm_private *priv = minor->dev->dev_private;
201	struct msm_perf_state *perf;
202
203	/* only create on first minor: */
204	if (priv->perf)
205		return 0;
206
207	perf = kzalloc(sizeof(*perf), GFP_KERNEL);
208	if (!perf)
209		return -ENOMEM;
210
211	perf->dev = minor->dev;
212
213	mutex_init(&perf->read_lock);
214	priv->perf = perf;
215
216	debugfs_create_file("perf", S_IFREG | S_IRUGO, minor->debugfs_root,
217			    perf, &perf_debugfs_fops);
218	return 0;
219}
220
221void msm_perf_debugfs_cleanup(struct msm_drm_private *priv)
222{
223	struct msm_perf_state *perf = priv->perf;
224
225	if (!perf)
226		return;
227
228	priv->perf = NULL;
229
230	mutex_destroy(&perf->read_lock);
231
232	kfree(perf);
233}
234
235#endif