mmc: block: Enable runtime pm for mmc blkdevice

Once the mmc blkdevice is being probed, runtime pm will be enabled.
By using runtime autosuspend, the power save operations can be done
when request inactivity occurs for a certain time. Right now the
selected timeout value is set to 3 s. Obviously this value will likely
need to be configurable somehow since it needs to be trimmed depending
on the power save algorithm.

For SD-combo cards, we are still leaving the enablement of runtime PM
to the SDIO init sequence since it depends on the capabilities of the
SDIO func driver.

Moreover, when the blk device is being suspended, we make sure the device
will be runtime resumed. The reason for doing this is that we want the
host suspend sequence to be unaware of any runtime power save operations
done for the card in this phase. Thus it can just handle the suspend as
the card is fully powered from a runtime perspective.

Finally, this patch prepares to make it possible to move BKOPS handling
into the runtime callbacks for the mmc bus_ops. Thus IDLE BKOPS can be
accomplished.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index dc0cb5929c64..0f86144b0c51 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -971,6 +971,29 @@ void mmc_release_host(struct mmc_host *host)
 EXPORT_SYMBOL(mmc_release_host);
 
 /*
+ * This is a helper function, which fetches a runtime pm reference for the
+ * card device and also claims the host.
+ */
+void mmc_get_card(struct mmc_card *card)
+{
+        pm_runtime_get_sync(&card->dev);
+        mmc_claim_host(card->host);
+}
+EXPORT_SYMBOL(mmc_get_card);
+
+/*
+ * This is a helper function, which releases the host and drops the runtime
+ * pm reference for the card device.
+ */
+void mmc_put_card(struct mmc_card *card)
+{
+        mmc_release_host(card->host);
+        pm_runtime_mark_last_busy(&card->dev);
+        pm_runtime_put_autosuspend(&card->dev);
+}
+EXPORT_SYMBOL(mmc_put_card);
+
+/*
  * Internal function that does the actual ios call to the host driver,
  * optionally printing some debug output.
  */