1 files changed, 133 insertions, 0 deletions
diff --git a/drivers/usb/gadget/debug.c b/drivers/usb/gadget/debug.c
new file mode 100644
index 000000000000..32a53299446c
--- /dev/null
+++ b/drivers/usb/gadget/debug.c
@@ -0,0 +1,133 @@
+/*
+ * 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;
+}