From 36bde09c509d77aa9d2612bb23c26253969aff28 Mon Sep 17 00:00:00 2001
From: Sayali Lokhande <sayalil@codeaurora.org>
Date: Thu, 24 Nov 2016 17:43:12 +0530
Subject: [PATCH] mmc: core: Add sysfs entry to print ring buffer

Add sysfs entry to print MMC ring buffer events.
usage: cat /sys/kernel/debug/mmc0/ring_buffer

Change-Id: I1fb6b0f65a11cd574e56df9937a96acd74a84341
Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>
---
 drivers/mmc/core/debugfs.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
index c894f64c2e38..a0d31ded04db 100644
--- a/drivers/mmc/core/debugfs.c
+++ b/drivers/mmc/core/debugfs.c
@@ -32,6 +32,26 @@ module_param(fail_request, charp, 0);
 #endif /* CONFIG_FAIL_MMC_REQUEST */
 
 /* The debugfs functions are optimized away when CONFIG_DEBUG_FS isn't set. */
+static int mmc_ring_buffer_show(struct seq_file *s, void *data)
+{
+	struct mmc_host *mmc = s->private;
+
+	mmc_dump_trace_buffer(mmc, s);
+	return 0;
+}
+
+static int mmc_ring_buffer_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mmc_ring_buffer_show, inode->i_private);
+}
+
+static const struct file_operations mmc_ring_buffer_fops = {
+	.open		= mmc_ring_buffer_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
 static int mmc_ios_show(struct seq_file *s, void *data)
 {
 	static const char *vdd_str[] = {
@@ -368,6 +388,11 @@ void mmc_add_host_debugfs(struct mmc_host *host)
 		&host->cmdq_thist_enabled))
 		goto err_node;
 
+#ifdef CONFIG_MMC_RING_BUFFER
+	if (!debugfs_create_file("ring_buffer", S_IRUSR,
+				root, host, &mmc_ring_buffer_fops))
+		goto err_node;
+#endif
 #ifdef CONFIG_MMC_CLKGATE
 	if (!debugfs_create_u32("clk_delay", (S_IRUSR | S_IWUSR),
 				root, &host->clk_delay))