mmc: init mmc block devices on probe

MMC devices accessed exclusively via the driver model were not
being initialized before being exposed as block devices, causing
issues in scenarios where the MMC device is first accessed via the
uclass block interface.

Signed-off-by: Fiach Antaw <fiach.antaw@uqconnect.edu.au>

drivers/mmc/mmc-uclass.c

@@ -254,6 +254,17 @@ static int mmc_select_hwpart(struct udevice *bdev, int hwpart)
 	return mmc_switch_part(mmc, hwpart);
 }
 
+static int mmc_blk_probe(struct udevice *dev)
+{
+	struct blk_desc *block_dev = dev_get_uclass_platdata(dev);
+	int dev_num = block_dev->devnum;
+	struct mmc *mmc = find_mmc_device(dev_num);
+
+	if (!mmc)
+		return -ENODEV;
+	return mmc_init(mmc);
+}
+
 static const struct blk_ops mmc_blk_ops = {
 	.read	= mmc_bread,
 #ifndef CONFIG_SPL_BUILD
@@ -267,6 +278,7 @@ U_BOOT_DRIVER(mmc_blk) = {
 	.name		= "mmc_blk",
 	.id		= UCLASS_BLK,
 	.ops		= &mmc_blk_ops,
+	.probe		= mmc_blk_probe,
 };
 #endif /* CONFIG_BLK */