1 files changed, 65 insertions, 1 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index ebfb3606f7a3..f0cb3ad3421f 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -169,6 +169,17 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
 			pr_debug("%s:     %d bytes transferred: %d\n",
 				mmc_hostname(host),
 				mrq->data->bytes_xfered, mrq->data->error);
+			if (mrq->lat_hist_enabled) {
+				ktime_t completion;
+				u_int64_t delta_us;
+
+				completion = ktime_get();
+				delta_us = ktime_us_delta(completion,
+							  mrq->io_start);
+				blk_update_latency_hist(&host->io_lat_s,
+					(mrq->data->flags & MMC_DATA_READ),
+					delta_us);
+			}
 			trace_mmc_blk_rw_end(cmd->opcode, cmd->arg, mrq->data);
 		}
 
@@ -577,6 +588,11 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
 	}
 
 	if (!err && areq) {
+		if (host->latency_hist_enabled) {
+			areq->mrq->io_start = ktime_get();
+			areq->mrq->lat_hist_enabled = 1;
+		} else
+			areq->mrq->lat_hist_enabled = 0;
 		trace_mmc_blk_rw_start(areq->mrq->cmd->opcode,
 				       areq->mrq->cmd->arg,
 				       areq->mrq->data);
@@ -1871,7 +1887,7 @@ void mmc_init_erase(struct mmc_card *card)
 }
 
 static unsigned int mmc_mmc_erase_timeout(struct mmc_card *card,
-				          unsigned int arg, unsigned int qty)
+					  unsigned int arg, unsigned int qty)
 {
 	unsigned int erase_timeout;
 
@@ -2777,6 +2793,54 @@ static void __exit mmc_exit(void)
 	destroy_workqueue(workqueue);
 }
 
+static ssize_t
+latency_hist_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct mmc_host *host = cls_dev_to_mmc_host(dev);
+
+	return blk_latency_hist_show(&host->io_lat_s, buf);
+}
+
+/*
+ * Values permitted 0, 1, 2.
+ * 0 -> Disable IO latency histograms (default)
+ * 1 -> Enable IO latency histograms
+ * 2 -> Zero out IO latency histograms
+ */
+static ssize_t
+latency_hist_store(struct device *dev, struct device_attribute *attr,
+		   const char *buf, size_t count)
+{
+	struct mmc_host *host = cls_dev_to_mmc_host(dev);
+	long value;
+
+	if (kstrtol(buf, 0, &value))
+		return -EINVAL;
+	if (value == BLK_IO_LAT_HIST_ZERO)
+		blk_zero_latency_hist(&host->io_lat_s);
+	else if (value == BLK_IO_LAT_HIST_ENABLE ||
+		 value == BLK_IO_LAT_HIST_DISABLE)
+		host->latency_hist_enabled = value;
+	return count;
+}
+
+static DEVICE_ATTR(latency_hist, S_IRUGO | S_IWUSR,
+		   latency_hist_show, latency_hist_store);
+
+void
+mmc_latency_hist_sysfs_init(struct mmc_host *host)
+{
+	if (device_create_file(&host->class_dev, &dev_attr_latency_hist))
+		dev_err(&host->class_dev,
+			"Failed to create latency_hist sysfs entry\n");
+}
+
+void
+mmc_latency_hist_sysfs_exit(struct mmc_host *host)
+{
+	device_remove_file(&host->class_dev, &dev_attr_latency_hist);
+}
+
 subsys_initcall(mmc_init);
 module_exit(mmc_exit);