mmc: add runtime PM handlers

Add MMC runtime PM handlers, which call mmc_power_save_host
and mmc_power_restore_host in response 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>
Tested-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

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>
@@ -141,6 +142,41 @@ static int mmc_bus_resume(struct device *dev)
 	return ret;
 }
 
+#ifdef CONFIG_PM_RUNTIME
+
+static int mmc_runtime_suspend(struct device *dev)
+{
+	struct mmc_card *card = mmc_dev_to_card(dev);
+
+	return mmc_power_save_host(card->host);
+}
+
+static int mmc_runtime_resume(struct device *dev)
+{
+	struct mmc_card *card = mmc_dev_to_card(dev);
+
+	return mmc_power_restore_host(card->host);
+}
+
+static int mmc_runtime_idle(struct device *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,
+};
+
+#define MMC_PM_OPS_PTR	(&mmc_bus_pm_ops)
+
+#else /* !CONFIG_PM_RUNTIME */
+
+#define MMC_PM_OPS_PTR	NULL
+
+#endif /* !CONFIG_PM_RUNTIME */
+
 static struct bus_type mmc_bus_type = {
 	.name		= "mmc",
 	.dev_attrs	= mmc_dev_attrs,
@@ -150,6 +186,7 @@ static struct bus_type mmc_bus_type = {
 	.remove		= mmc_bus_remove,
 	.suspend	= mmc_bus_suspend,
 	.resume		= mmc_bus_resume,
+	.pm		= MMC_PM_OPS_PTR,
 };
 
 int mmc_register_bus(void)