linux/drivers/remoteproc/remoteproc_debugfs.c
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   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 > 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        if (rproc_dbg)
 252                debugfs_remove(rproc_dbg);
 253}
 254
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