[RFC/PATCH 3/6] mmc: add general runtime PM support

[ohad@wizery.com (Ohad Ben-Cohen)]

Add Runtime PM handlers to mmc, which calls mmc_power_save_host
and mmc_power_restore_host in respond to runtime_suspend and
runtime_resume events.

Runtime PM is still disabled by default, so this patch alone
has no immediate effect.

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
---
 drivers/mmc/core/bus.c |   35 +++++++++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
index 49d9dca..27902b4 100644
--- a/drivers/mmc/core/bus.c
+++ b/drivers/mmc/core/bus.c
@@ -14,6 +14,7 @@
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/pm_runtime.h>
 
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
@@ -137,6 +138,39 @@ static int mmc_bus_resume(struct device *dev)
 	return ret;
 }
 
+static int mmc_runtime_suspend(struct device *dev)
+{
+	int status = 0;
+	struct mmc_card *card = dev_to_mmc_card(dev);
+
+	mmc_power_save_host(card->host);
+
+	return status;
+}
+
+static int mmc_runtime_resume(struct device *dev)
+{
+	int status = 0;
+	struct mmc_card *card = dev_to_mmc_card(dev);
+
+	mmc_power_restore_host(card->host);
+
+	return status;
+}
+
+static int mmc_runtime_idle(struct device *dev)
+{
+	struct mmc_card *card = dev_to_mmc_card(dev);
+
+	return pm_runtime_suspend(dev);
+}
+
+static const struct dev_pm_ops mmc_bus_pm_ops = {
+	.runtime_suspend	= mmc_runtime_suspend,
+	.runtime_resume		= mmc_runtime_resume,
+	.runtime_idle		= mmc_runtime_idle,
+};
+
 static struct bus_type mmc_bus_type = {
 	.name		= "mmc",
 	.dev_attrs	= mmc_dev_attrs,
@@ -146,6 +180,7 @@ static struct bus_type mmc_bus_type = {
 	.remove		= mmc_bus_remove,
 	.suspend	= mmc_bus_suspend,
 	.resume		= mmc_bus_resume,
+	.pm		= &mmc_bus_pm_ops,
 };
 
 int mmc_register_bus(void)
-- 
1.7.0.4