mmc: sdio: enable runtime PM for SDIO functions

Enable runtime PM for SDIO functions.

SDIO functions are initialized with a disabled runtime PM state,
and are set active (and their usage count is incremented)
only before potential drivers are probed.

SDIO function drivers that support runtime PM should call
pm_runtime_put_noidle() in their probe routine, and
pm_runtime_get_noresume() in their remove routine (very
similarly to PCI drivers).

In case a matching driver does not support runtime PM, power will
always be kept high (since the usage count is positive).

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>

2 files changed, 40 insertions, 3 deletions

diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 0dbd6fe66660..85561dde4c9d 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -734,6 +734,11 @@ int mmc_attach_sdio(struct mmc_host *host, u32 ocr)
                 err = sdio_init_func(host->card, i + 1);
                 if (err)
                         goto remove;
+
+                /*
+                 * Enable Runtime PM for this func
+                 */
+                pm_runtime_enable(&card->sdio_func[i]->dev);
         }
 
         mmc_release_host(host);
diff --git a/drivers/mmc/core/sdio_bus.c b/drivers/mmc/core/sdio_bus.c
index 256a968774a0..36374834fcff 100644
--- a/drivers/mmc/core/sdio_bus.c
+++ b/drivers/mmc/core/sdio_bus.c
@@ -126,21 +126,46 @@ static int sdio_bus_probe(struct device *dev)
         if (!id)
                 return -ENODEV;
 
+        /* Unbound SDIO functions are always suspended.
+         * During probe, the function is set active and the usage count
+         * is incremented.  If the driver supports runtime PM,
+         * it should call pm_runtime_put_noidle() in its probe routine and
+         * pm_runtime_get_noresume() in its remove routine.
+         */
+        ret = pm_runtime_get_sync(dev);
+        if (ret < 0)
+                goto out;
+
         /* Set the default block size so the driver is sure it's something
          * sensible. */
         sdio_claim_host(func);
         ret = sdio_set_block_size(func, 0);
         sdio_release_host(func);
         if (ret)
-                return ret;
+                goto disable_runtimepm;
+
+        ret = drv->probe(func, id);
+        if (ret)
+                goto disable_runtimepm;
 
-        return drv->probe(func, id);
+        return 0;
+
+disable_runtimepm:
+        pm_runtime_put_noidle(dev);
+out:
+        return ret;
 }
 
 static int sdio_bus_remove(struct device *dev)
 {
         struct sdio_driver *drv = to_sdio_driver(dev->driver);
         struct sdio_func *func = dev_to_sdio_func(dev);
+        int ret;
+
+        /* Make sure card is powered before invoking ->remove() */
+        ret = pm_runtime_get_sync(dev);
+        if (ret < 0)
+                goto out;
 
         drv->remove(func);
 
@@ -152,7 +177,14 @@ static int sdio_bus_remove(struct device *dev)
                 sdio_release_host(func);
         }
 
-        return 0;
+        /* First, undo the increment made directly above */
+        pm_runtime_put_noidle(dev);
+
+        /* Then undo the runtime PM settings in sdio_bus_probe() */
+        pm_runtime_put_noidle(dev);
+
+out:
+        return ret;
 }
 
 #ifdef CONFIG_PM_RUNTIME