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/*
* Copyright (c) 2015, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/rwlock.h>
#include <linux/debugfs.h>
#include "debug.h"
#define dbg_inc(i) ((i+1) % DBG_MAX_MSG)
#define ENABLE_EVENT_LOG 1
unsigned int enable_event_log = ENABLE_EVENT_LOG;
module_param(enable_event_log, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(enable_event_log, "enable event logging in debug buffer");
static struct {
char buf[DBG_MAX_MSG][DBG_MSG_LEN]; /* buffer */
unsigned idx; /* index */
rwlock_t lck; /* lock */
struct dentry *root;
} __maybe_unused dbg_buffer = {
.idx = 0,
.lck = __RW_LOCK_UNLOCKED(lck),
.root = NULL
};
void __maybe_unused put_timestamp(char *tbuf)
{
unsigned long long t;
unsigned long nanosec_rem;
unsigned long flags;
write_lock_irqsave(&dbg_buffer.lck, flags);
t = cpu_clock(smp_processor_id());
write_unlock_irqrestore(&dbg_buffer.lck, flags);
nanosec_rem = do_div(t, 1000000000)/1000;
snprintf(tbuf, TIME_BUF_LEN, "[%5lu.%06lu]: ", (unsigned long)t,
nanosec_rem);
}
void __maybe_unused add_event_to_buf(char *tbuf)
{
unsigned long flags;
char *buf;
write_lock_irqsave(&dbg_buffer.lck, flags);
buf = dbg_buffer.buf[dbg_buffer.idx];
memcpy(buf, tbuf, DBG_MSG_LEN);
dbg_buffer.idx = (dbg_buffer.idx + 1) % DBG_MAX_MSG;
write_unlock_irqrestore(&dbg_buffer.lck, flags);
}
static int dbg_read_buf_show(struct seq_file *s, void *unused)
{
unsigned long flags;
unsigned i;
read_lock_irqsave(&dbg_buffer.lck, flags);
i = dbg_buffer.idx;
if (strnlen(dbg_buffer.buf[i], DBG_MSG_LEN))
seq_printf(s, "%s\n", dbg_buffer.buf[i]);
for (i = dbg_inc(i); i != dbg_buffer.idx; i = dbg_inc(i)) {
if (!strnlen(dbg_buffer.buf[i], DBG_MSG_LEN))
continue;
seq_printf(s, "%s\n", dbg_buffer.buf[i]);
}
read_unlock_irqrestore(&dbg_buffer.lck, flags);
return 0;
}
static int dbg_read_buf_open(struct inode *inode, struct file *file)
{
return single_open(file, dbg_read_buf_show, inode->i_private);
}
const struct file_operations dbg_read_buf_fops = {
.open = dbg_read_buf_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
int debug_debugfs_init(void)
{
struct dentry *root;
struct dentry *file;
int ret;
root = debugfs_create_dir("debug", NULL);
if (!root) {
ret = -ENOMEM;
goto err0;
}
dbg_buffer.root = root;
file = debugfs_create_file("read_buf", S_IRUGO, root,
NULL, &dbg_read_buf_fops);
if (!file) {
ret = -ENOMEM;
goto err1;
}
return 0;
err1:
debugfs_remove_recursive(root);
err0:
return ret;
}
void debug_debugfs_exit(void)
{
debugfs_remove_recursive(dbg_buffer.root);
dbg_buffer.root = NULL;
}
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