mmc: core: Extend sysfs with DSR register

Export DSR register through sysfs same as we did for the CID, CSD and
OCR registers.

Signed-off-by: Bojan Prtvar <prtvar.b@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 3dd0861..0123936 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -678,6 +678,22 @@
 MMC_DEV_ATTR(ocr, "%08x\n", card->ocr);
 
 
+static ssize_t mmc_dsr_show(struct device *dev,
+                           struct device_attribute *attr,
+                           char *buf)
+{
+       struct mmc_card *card = mmc_dev_to_card(dev);
+       struct mmc_host *host = card->host;
+
+       if (card->csd.dsr_imp && host->dsr_req)
+               return sprintf(buf, "0x%x\n", host->dsr);
+       else
+               /* return default DSR value */
+               return sprintf(buf, "0x%x\n", 0x404);
+}
+
+static DEVICE_ATTR(dsr, S_IRUGO, mmc_dsr_show, NULL);
+
 static struct attribute *sd_std_attrs[] = {
 	&dev_attr_cid.attr,
 	&dev_attr_csd.attr,
@@ -692,6 +708,7 @@
 	&dev_attr_oemid.attr,
 	&dev_attr_serial.attr,
 	&dev_attr_ocr.attr,
+	&dev_attr_dsr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(sd_std);