mmc: sd: add reset bus_ops callback

Enable power cycle and re-initialization of SD cards via the reset
bus_ops. Power cycling a buggy SD card sometimes helps it get back on
track.

Signed-off-by: Johan Rudholm <johanru@axis.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/sd.c

@@ -1197,6 +1197,12 @@ static int mmc_sd_power_restore(struct mmc_host *host)
 	return ret;
 }
 
+static int mmc_sd_reset(struct mmc_host *host)
+{
+	mmc_power_cycle(host, host->card->ocr);
+	return mmc_sd_power_restore(host);
+}
+
 static const struct mmc_bus_ops mmc_sd_ops = {
 	.remove = mmc_sd_remove,
 	.detect = mmc_sd_detect,
@@ -1207,6 +1213,7 @@ static const struct mmc_bus_ops mmc_sd_ops = {
 	.power_restore = mmc_sd_power_restore,
 	.alive = mmc_sd_alive,
 	.shutdown = mmc_sd_suspend,
+	.reset = mmc_sd_reset,
 };
 
 /*