mmc: add support for card-detection polling

Some hosts (and boards that use mmc_spi) do not use interrupts on the CD
line, so they can't trigger mmc_detect_change. We want to poll the card
and see if there was a change. 1 second poll interval seems resonable.

This patch also implements .get_cd() host operation, that could be used
by the hosts that are able to report card-detect status without need to
talk MMC.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 01ced4c5a61d..ede5d1e2e20d 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -638,6 +638,9 @@ void mmc_rescan(struct work_struct *work)
                  */
                 mmc_bus_put(host);
 
+                if (host->ops->get_cd && host->ops->get_cd(host) == 0)
+                        goto out;
+
                 mmc_claim_host(host);
 
                 mmc_power_up(host);
@@ -652,7 +655,7 @@ void mmc_rescan(struct work_struct *work)
                 if (!err) {
                         if (mmc_attach_sdio(host, ocr))
                                 mmc_power_off(host);
-                        return;
+                        goto out;
                 }
 
                 /*
@@ -662,7 +665,7 @@ void mmc_rescan(struct work_struct *work)
                 if (!err) {
                         if (mmc_attach_sd(host, ocr))
                                 mmc_power_off(host);
-                        return;
+                        goto out;
                 }
 
                 /*
@@ -672,7 +675,7 @@ void mmc_rescan(struct work_struct *work)
                 if (!err) {
                         if (mmc_attach_mmc(host, ocr))
                                 mmc_power_off(host);
-                        return;
+                        goto out;
                 }
 
                 mmc_release_host(host);
@@ -683,6 +686,9 @@ void mmc_rescan(struct work_struct *work)
 
                 mmc_bus_put(host);
         }
+out:
+        if (host->caps & MMC_CAP_NEEDS_POLL)
+                mmc_schedule_delayed_work(&host->detect, HZ);
 }
 
 void mmc_start_host(struct mmc_host *host)