mmc: core: Disable card detect during shutdown

It's seems prone to problems by allowing card detect and its corresponding
mmc_rescan() work to run, during platform shutdown. For example, we may end
up turning off the power while initializing a card, which potentially could
damage it.

To avoid this scenario, let's add ->shutdown_pre() callback for the mmc host
class device and then turn of the card detect from there.

Reported-by: Al Cooper <alcooperx@gmail.com>
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211203141555.105351-1-ulf.hansson@linaro.org

drivers/mmc/core/core.c

@@ -2264,7 +2264,7 @@ void mmc_start_host(struct mmc_host *host)
 	_mmc_detect_change(host, 0, false);
 }
 
-void mmc_stop_host(struct mmc_host *host)
+void __mmc_stop_host(struct mmc_host *host)
 {
 	if (host->slot.cd_irq >= 0) {
 		mmc_gpio_set_cd_wake(host, false);
@@ -2273,6 +2273,11 @@ void mmc_stop_host(struct mmc_host *host)
 
 	host->rescan_disable = 1;
 	cancel_delayed_work_sync(&host->detect);
+}
+
+void mmc_stop_host(struct mmc_host *host)
+{
+	__mmc_stop_host(host);
 
 	/* clear pm flags now and let card drivers set them as needed */
 	host->pm_flags = 0;

drivers/mmc/core/core.h

@@ -70,6 +70,7 @@ static inline void mmc_delay(unsigned int ms)
 
 void mmc_rescan(struct work_struct *work);
 void mmc_start_host(struct mmc_host *host);
+void __mmc_stop_host(struct mmc_host *host);
 void mmc_stop_host(struct mmc_host *host);
 
 void _mmc_detect_change(struct mmc_host *host, unsigned long delay,

drivers/mmc/core/host.c

@@ -80,9 +80,18 @@ static void mmc_host_classdev_release(struct device *dev)
 	kfree(host);
 }
 
+static int mmc_host_classdev_shutdown(struct device *dev)
+{
+	struct mmc_host *host = cls_dev_to_mmc_host(dev);
+
+	__mmc_stop_host(host);
+	return 0;
+}
+
 static struct class mmc_host_class = {
 	.name		= "mmc_host",
 	.dev_release	= mmc_host_classdev_release,
+	.shutdown_pre	= mmc_host_classdev_shutdown,
 	.pm		= MMC_HOST_CLASS_DEV_PM_OPS,
 };