1/*
2 * Remote Processor Framework
3 *
4 * Copyright (C) 2011 Texas Instruments, Inc.
5 * Copyright (C) 2011 Google, Inc.
6 *
7 * Ohad Ben-Cohen <ohad@wizery.com>
8 * Mark Grosen <mgrosen@ti.com>
9 * Brian Swetland <swetland@google.com>
10 * Fernando Guzman Lugo <fernando.lugo@ti.com>
11 * Suman Anna <s-anna@ti.com>
12 * Robert Tivy <rtivy@ti.com>
13 * Armando Uribe De Leon <x0095078@ti.com>
14 *
15 * This program is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU General Public License
17 * version 2 as published by the Free Software Foundation.
18 *
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22 * GNU General Public License for more details.
23 */
24
25#define pr_fmt(fmt)    "%s: " fmt, __func__
26
27#include <linux/kernel.h>
28#include <linux/debugfs.h>
29#include <linux/remoteproc.h>
30#include <linux/device.h>
31#include <linux/uaccess.h>
32
33#include "remoteproc_internal.h"
34
35/* remoteproc debugfs parent dir */
36static struct dentry *rproc_dbg;
37
38/*
39 * Some remote processors may support dumping trace logs into a shared
40 * memory buffer. We expose this trace buffer using debugfs, so users
41 * can easily tell what's going on remotely.
42 *
43 * We will most probably improve the rproc tracing facilities later on,
44 * but this kind of lightweight and simple mechanism is always good to have,
45 * as it provides very early tracing with little to no dependencies at all.
46 */
47static ssize_t rproc_trace_read(struct file *filp, char __user *userbuf,
48						size_t count, loff_t *ppos)
49{
50	struct rproc_mem_entry *trace = filp->private_data;
51	int len = strnlen(trace->va, trace->len);
52
53	return simple_read_from_buffer(userbuf, count, ppos, trace->va, len);
54}
55
56static const struct file_operations trace_rproc_ops = {
57	.read = rproc_trace_read,
58	.open = simple_open,
59	.llseek	= generic_file_llseek,
60};
61
62/*
63 * A state-to-string lookup table, for exposing a human readable state
64 * via debugfs. Always keep in sync with enum rproc_state
65 */
66static const char * const rproc_state_string[] = {
67	"offline",
68	"suspended",
69	"running",
70	"crashed",
71	"invalid",
72};
73
74/* expose the state of the remote processor via debugfs */
75static ssize_t rproc_state_read(struct file *filp, char __user *userbuf,
76						size_t count, loff_t *ppos)
77{
78	struct rproc *rproc = filp->private_data;
79	unsigned int state;
80	char buf[30];
81	int i;
82
83	state = rproc->state > RPROC_LAST ? RPROC_LAST : rproc->state;
84
85	i = scnprintf(buf, 30, "%.28s (%d)\n", rproc_state_string[state],
86							rproc->state);
87
88	return simple_read_from_buffer(userbuf, count, ppos, buf, i);
89}
90
91static const struct file_operations rproc_state_ops = {
92	.read = rproc_state_read,
93	.open = simple_open,
94	.llseek	= generic_file_llseek,
95};
96
97/* expose the name of the remote processor via debugfs */
98static ssize_t rproc_name_read(struct file *filp, char __user *userbuf,
99						size_t count, loff_t *ppos)
100{
101	struct rproc *rproc = filp->private_data;
102	/* need room for the name, a newline and a terminating null */
103	char buf[100];
104	int i;
105
106	i = scnprintf(buf, sizeof(buf), "%.98s\n", rproc->name);
107
108	return simple_read_from_buffer(userbuf, count, ppos, buf, i);
109}
110
111static const struct file_operations rproc_name_ops = {
112	.read = rproc_name_read,
113	.open = simple_open,
114	.llseek	= generic_file_llseek,
115};
116
117/* expose recovery flag via debugfs */
118static ssize_t rproc_recovery_read(struct file *filp, char __user *userbuf,
119				   size_t count, loff_t *ppos)
120{
121	struct rproc *rproc = filp->private_data;
122	char *buf = rproc->recovery_disabled ? "disabled\n" : "enabled\n";
123
124	return simple_read_from_buffer(userbuf, count, ppos, buf, strlen(buf));
125}
126
127/*
128 * By writing to the 'recovery' debugfs entry, we control the behavior of the
129 * recovery mechanism dynamically. The default value of this entry is "enabled".
130 *
131 * The 'recovery' debugfs entry supports these commands:
132 *
133 * enabled:	When enabled, the remote processor will be automatically
134 *		recovered whenever it crashes. Moreover, if the remote
135 *		processor crashes while recovery is disabled, it will
136 *		be automatically recovered too as soon as recovery is enabled.
137 *
138 * disabled:	When disabled, a remote processor will remain in a crashed
139 *		state if it crashes. This is useful for debugging purposes;
140 *		without it, debugging a crash is substantially harder.
141 *
142 * recover:	This function will trigger an immediate recovery if the
143 *		remote processor is in a crashed state, without changing
144 *		or checking the recovery state (enabled/disabled).
145 *		This is useful during debugging sessions, when one expects
146 *		additional crashes to happen after enabling recovery. In this
147 *		case, enabling recovery will make it hard to debug subsequent
148 *		crashes, so it's recommended to keep recovery disabled, and
149 *		instead use the "recover" command as needed.
150 */
151static ssize_t
152rproc_recovery_write(struct file *filp, const char __user *user_buf,
153		     size_t count, loff_t *ppos)
154{
155	struct rproc *rproc = filp->private_data;
156	char buf[10];
157	int ret;
158
159	if (count < 1 || count > sizeof(buf))
160		return count;
161
162	ret = copy_from_user(buf, user_buf, count);
163	if (ret)
164		return -EFAULT;
165
166	/* remove end of line */
167	if (buf[count - 1] == '\n')
168		buf[count - 1] = '\0';
169
170	if (!strncmp(buf, "enabled", count)) {
171		rproc->recovery_disabled = false;
172		/* if rproc has crashed, trigger recovery */
173		if (rproc->state == RPROC_CRASHED)
174			rproc_trigger_recovery(rproc);
175	} else if (!strncmp(buf, "disabled", count)) {
176		rproc->recovery_disabled = true;
177	} else if (!strncmp(buf, "recover", count)) {
178		/* if rproc has crashed, trigger recovery */
179		if (rproc->state == RPROC_CRASHED)
180			rproc_trigger_recovery(rproc);
181	}
182
183	return count;
184}
185
186static const struct file_operations rproc_recovery_ops = {
187	.read = rproc_recovery_read,
188	.write = rproc_recovery_write,
189	.open = simple_open,
190	.llseek = generic_file_llseek,
191};
192
193void rproc_remove_trace_file(struct dentry *tfile)
194{
195	debugfs_remove(tfile);
196}
197
198struct dentry *rproc_create_trace_file(const char *name, struct rproc *rproc,
199					struct rproc_mem_entry *trace)
200{
201	struct dentry *tfile;
202
203	tfile = debugfs_create_file(name, 0400, rproc->dbg_dir,
204						trace, &trace_rproc_ops);
205	if (!tfile) {
206		dev_err(&rproc->dev, "failed to create debugfs trace entry\n");
207		return NULL;
208	}
209
210	return tfile;
211}
212
213void rproc_delete_debug_dir(struct rproc *rproc)
214{
215	if (!rproc->dbg_dir)
216		return;
217
218	debugfs_remove_recursive(rproc->dbg_dir);
219}
220
221void rproc_create_debug_dir(struct rproc *rproc)
222{
223	struct device *dev = &rproc->dev;
224
225	if (!rproc_dbg)
226		return;
227
228	rproc->dbg_dir = debugfs_create_dir(dev_name(dev), rproc_dbg);
229	if (!rproc->dbg_dir)
230		return;
231
232	debugfs_create_file("name", 0400, rproc->dbg_dir,
233					rproc, &rproc_name_ops);
234	debugfs_create_file("state", 0400, rproc->dbg_dir,
235					rproc, &rproc_state_ops);
236	debugfs_create_file("recovery", 0400, rproc->dbg_dir,
237					rproc, &rproc_recovery_ops);
238}
239
240void __init rproc_init_debugfs(void)
241{
242	if (debugfs_initialized()) {
243		rproc_dbg = debugfs_create_dir(KBUILD_MODNAME, NULL);
244		if (!rproc_dbg)
245			pr_err("can't create debugfs dir\n");
246	}
247}
248
249void __exit rproc_exit_debugfs(void)
250{
251	debugfs_remove(rproc_dbg);
252}
253