Merge "mmc: host: Add Ring buffer logging for MMC."

6 files changed, 195 insertions, 0 deletions

diff --git a/drivers/mmc/core/Kconfig b/drivers/mmc/core/Kconfig
index 57cc6b29b2d0..9e0ccdc44d6b 100644
--- a/drivers/mmc/core/Kconfig
+++ b/drivers/mmc/core/Kconfig
@@ -2,6 +2,17 @@
 # MMC core configuration
 #
 
+config MMC_RING_BUFFER
+	bool "MMC_RING_BUFFER"
+	depends on MMC
+	default n
+	help
+	  This enables the ring buffer tracing of significant
+	  events for mmc driver to provide command history for
+	  debugging purpose.
+
+	  If unsure, say N.
+
 config MMC_EMBEDDED_SDIO
 	boolean "MMC embedded SDIO device support (EXPERIMENTAL)"
 	help
diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile
index 2c25138f28b7..60781dd192ab 100644
--- a/drivers/mmc/core/Makefile
+++ b/drivers/mmc/core/Makefile
@@ -10,3 +10,4 @@ mmc_core-y			:= core.o bus.o host.o \
 				   quirks.o slot-gpio.o
 mmc_core-$(CONFIG_OF)		+= pwrseq.o pwrseq_simple.o pwrseq_emmc.o
 mmc_core-$(CONFIG_DEBUG_FS)	+= debugfs.o
+obj-$(CONFIG_MMC_RING_BUFFER)	+= ring_buffer.o
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index f6a54a8e1076..333f691a73c7 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -26,6 +26,8 @@
 
 #include <linux/mmc/host.h>
 #include <linux/mmc/card.h>
+#include <linux/mmc/ring_buffer.h>
+
 #include <linux/mmc/slot-gpio.h>
 
 #include "core.h"
@@ -869,6 +871,7 @@ int mmc_add_host(struct mmc_host *host)
 	mmc_add_host_debugfs(host);
 #endif
 	mmc_host_clk_sysfs_init(host);
+	mmc_trace_init(host);
 
 	err = sysfs_create_group(&host->class_dev.kobj, &clk_scaling_attr_grp);
 	if (err)
diff --git a/drivers/mmc/core/ring_buffer.c b/drivers/mmc/core/ring_buffer.c
new file mode 100644
index 000000000000..83945e1cae40
--- /dev/null
+++ b/drivers/mmc/core/ring_buffer.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2017, 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/mmc/ring_buffer.h>
+#include <linux/mmc/host.h>
+
+void mmc_stop_tracing(struct mmc_host *mmc)
+{
+	mmc->trace_buf.stop_tracing = true;
+}
+
+void mmc_trace_write(struct mmc_host *mmc,
+			const char *fmt, ...)
+{
+	unsigned int idx;
+	va_list args;
+	char *event;
+	unsigned long flags;
+	char str[MMC_TRACE_EVENT_SZ];
+
+	if (unlikely(!mmc->trace_buf.data) ||
+			unlikely(mmc->trace_buf.stop_tracing))
+		return;
+
+	/*
+	 * Here an increment and modulus is used to keep
+	 * index within array bounds. The cast to unsigned is
+	 * necessary so increment and rolover wraps to 0 correctly
+	 */
+	spin_lock_irqsave(&mmc->trace_buf.trace_lock, flags);
+	mmc->trace_buf.wr_idx += 1;
+	idx = ((unsigned int)mmc->trace_buf.wr_idx) &
+			(MMC_TRACE_RBUF_NUM_EVENTS - 1);
+	spin_unlock_irqrestore(&mmc->trace_buf.trace_lock, flags);
+
+	/* Catch some unlikely machine specific wrap-around bug */
+	if (unlikely(idx > (MMC_TRACE_RBUF_NUM_EVENTS - 1))) {
+		pr_err("%s: %s: Invalid idx:%d for mmc trace, tracing stopped !\n",
+			mmc_hostname(mmc), __func__, idx);
+		mmc_stop_tracing(mmc);
+		return;
+	}
+
+	event = &mmc->trace_buf.data[idx * MMC_TRACE_EVENT_SZ];
+	va_start(args, fmt);
+	snprintf(str, MMC_TRACE_EVENT_SZ, "<%d> %lld: %s: %s",
+		raw_smp_processor_id(),
+		ktime_to_ns(ktime_get()),
+		mmc_hostname(mmc), fmt);
+	memset(event, '\0', MMC_TRACE_EVENT_SZ);
+	vscnprintf(event, MMC_TRACE_EVENT_SZ, str, args);
+	va_end(args);
+}
+
+void mmc_trace_init(struct mmc_host *mmc)
+{
+	BUILD_BUG_ON_NOT_POWER_OF_2(MMC_TRACE_RBUF_NUM_EVENTS);
+
+	mmc->trace_buf.data = (char *)
+				__get_free_pages(GFP_KERNEL|__GFP_ZERO,
+				MMC_TRACE_RBUF_SZ_ORDER);
+
+	if (!mmc->trace_buf.data) {
+		pr_err("%s: %s: Unable to allocate trace for mmc\n",
+			__func__, mmc_hostname(mmc));
+		return;
+	}
+
+	spin_lock_init(&mmc->trace_buf.trace_lock);
+	mmc->trace_buf.wr_idx = -1;
+}
+
+void mmc_trace_free(struct mmc_host *mmc)
+{
+	if (mmc->trace_buf.data)
+		free_pages((unsigned long)mmc->trace_buf.data,
+			MMC_TRACE_RBUF_SZ_ORDER);
+}
+
+void mmc_dump_trace_buffer(struct mmc_host *mmc, struct seq_file *s)
+{
+	unsigned int idx, cur_idx;
+	unsigned int N = MMC_TRACE_RBUF_NUM_EVENTS - 1;
+	char *event;
+	unsigned long flags;
+
+	if (!mmc->trace_buf.data)
+		return;
+
+	spin_lock_irqsave(&mmc->trace_buf.trace_lock, flags);
+	idx = ((unsigned int)mmc->trace_buf.wr_idx) & N;
+	cur_idx = (idx + 1) & N;
+
+	do {
+		event = &mmc->trace_buf.data[cur_idx * MMC_TRACE_EVENT_SZ];
+		if (s)
+			seq_printf(s, "%s", (char *)event);
+		else
+			pr_err("%s", (char *)event);
+		cur_idx = (cur_idx + 1) & N;
+		if (cur_idx == idx) {
+			event =
+			  &mmc->trace_buf.data[cur_idx * MMC_TRACE_EVENT_SZ];
+			if (s)
+				seq_printf(s, "latest_event: %s",
+					(char *)event);
+			else
+				pr_err("latest_event: %s", (char *)event);
+			break;
+		}
+	} while (1);
+	spin_unlock_irqrestore(&mmc->trace_buf.trace_lock, flags);
+}
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 276dbf19805b..804d89a825fc 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -22,6 +22,7 @@
 #include <linux/mmc/core.h>
 #include <linux/mmc/card.h>
 #include <linux/mmc/pm.h>
+#include <linux/mmc/ring_buffer.h>
 
 #define MMC_AUTOSUSPEND_DELAY_MS	3000
 
@@ -571,6 +572,7 @@ struct mmc_host {
 	} perf;
 	bool perf_enable;
 #endif
+	struct mmc_trace_buffer trace_buf;
 	enum dev_state dev_status;
 	bool			wakeup_on_idle;
 	struct mmc_cmdq_context_info	cmdq_ctx;
diff --git a/include/linux/mmc/ring_buffer.h b/include/linux/mmc/ring_buffer.h
new file mode 100644
index 000000000000..e6bf163ffcfe
--- /dev/null
+++ b/include/linux/mmc/ring_buffer.h
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2017, 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.
+ *
+ */
+
+#ifndef __MMC_RING_BUFFER__
+#define __MMC_RING_BUFFER__
+
+#include <linux/mmc/card.h>
+#include <linux/smp.h>
+
+#include "core.h"
+
+#define MMC_TRACE_RBUF_SZ_ORDER	2	/* 2^2 pages */
+#define MMC_TRACE_RBUF_SZ	(PAGE_SIZE * (1 << MMC_TRACE_RBUF_SZ_ORDER))
+#define MMC_TRACE_EVENT_SZ	256
+#define MMC_TRACE_RBUF_NUM_EVENTS	(MMC_TRACE_RBUF_SZ / MMC_TRACE_EVENT_SZ)
+
+struct mmc_host;
+struct mmc_trace_buffer {
+	int	wr_idx;
+	bool stop_tracing;
+	spinlock_t trace_lock;
+	char *data;
+};
+
+#ifdef CONFIG_MMC_RING_BUFFER
+void mmc_stop_tracing(struct mmc_host *mmc);
+void mmc_trace_write(struct mmc_host *mmc, const char *fmt, ...);
+void mmc_trace_init(struct mmc_host *mmc);
+void mmc_trace_free(struct mmc_host *mmc);
+void mmc_dump_trace_buffer(struct mmc_host *mmc, struct seq_file *s);
+#else
+static inline void mmc_stop_tracing(struct mmc_host *mmc) {}
+static inline void mmc_trace_write(struct mmc_host *mmc,
+		const char *fmt, ...) {}
+static inline void mmc_trace_init(struct mmc_host *mmc) {}
+static inline void mmc_trace_free(struct mmc_host *mmc) {}
+static inline void mmc_dump_trace_buffer(struct mmc_host *mmc,
+		struct seq_file *s) {}
+#endif
+
+#define MMC_TRACE(mmc, fmt, ...) \
+		mmc_trace_write(mmc, fmt, ##__VA_ARGS__)
+
+#endif /* __MMC_RING_BUFFER__ */