bootstd: mmc: Add a bootdev driver

Add a bootdev driver for MMC. It mostly just calls the bootdev helper
function.

Add a function to obtain the block device for an MMC controller.

Fix up the comment for mmc_get_blk_desc() while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>

MAINTAINERS

@@ -702,6 +702,7 @@ F:	boot/bootmeth*.c
 F:	boot/bootstd.c
 F:	cmd/bootdev.c
 F:	cmd/bootflow.c
+F:	drivers/mmc/mmc_bootdev.c
 F:	include/bootdev.h
 F:	include/bootflow.h
 F:	include/bootmeth.h

drivers/mmc/Makefile

@@ -5,6 +5,11 @@
 
 obj-y += mmc.o
 obj-$(CONFIG_$(SPL_)DM_MMC) += mmc-uclass.o
+
+ifdef CONFIG_$(SPL_TPL_)DM_MMC
+obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += mmc_bootdev.o
+endif
+
 obj-$(CONFIG_$(SPL_)MMC_WRITE) += mmc_write.o
 obj-$(CONFIG_MMC_PWRSEQ) += mmc-pwrseq.o
 obj-$(CONFIG_MMC_SDHCI_ADMA_HELPERS) += sdhci-adma.o

drivers/mmc/mmc-uclass.c

@@ -8,6 +8,7 @@
 #define LOG_CATEGORY UCLASS_MMC
 
 #include <common.h>
+#include <bootdev.h>
 #include <log.h>
 #include <mmc.h>
 #include <dm.h>
@@ -315,6 +316,20 @@ int mmc_get_next_devnum(void)
 	return blk_find_max_devnum(IF_TYPE_MMC);
 }
 
+int mmc_get_blk(struct udevice *dev, struct udevice **blkp)
+{
+	struct udevice *blk;
+	int ret;
+
+	device_find_first_child_by_uclass(dev, UCLASS_BLK, &blk);
+	ret = device_probe(blk);
+	if (ret)
+		return ret;
+	*blkp = blk;
+
+	return 0;
+}
+
 struct blk_desc *mmc_get_blk_desc(struct mmc *mmc)
 {
 	struct blk_desc *desc;
@@ -406,6 +421,10 @@ int mmc_bind(struct udevice *dev, struct mmc *mmc, const struct mmc_config *cfg)
 	mmc->cfg = cfg;
 	mmc->priv = dev;
 
+	ret = bootdev_setup_for_dev(dev, "mmc_bootdev");
+	if (ret)
+		return log_msg_ret("bootdev", ret);
+
 	/* the following chunk was from mmc_register() */
 
 	/* Setup dsr related values */
@@ -424,12 +443,16 @@ int mmc_bind(struct udevice *dev, struct mmc *mmc, const struct mmc_config *cfg)
 int mmc_unbind(struct udevice *dev)
 {
 	struct udevice *bdev;
+	int ret;
 
 	device_find_first_child_by_uclass(dev, UCLASS_BLK, &bdev);
 	if (bdev) {
 		device_remove(bdev, DM_REMOVE_NORMAL);
 		device_unbind(bdev);
 	}
+	ret = bootdev_unbind_dev(dev);
+	if (ret)
+		return log_msg_ret("bootdev", ret);
 
 	return 0;
 }

drivers/mmc/mmc_bootdev.c

@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootdevice for MMC
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#include <common.h>
+#include <bootdev.h>
+#include <dm.h>
+#include <mmc.h>
+
+static int mmc_get_bootflow(struct udevice *dev, struct bootflow_iter *iter,
+			    struct bootflow *bflow)
+{
+	struct udevice *mmc_dev = dev_get_parent(dev);
+	struct udevice *blk;
+	int ret;
+
+	ret = mmc_get_blk(mmc_dev, &blk);
+	/*
+	 * If there is no media, indicate that no more partitions should be
+	 * checked
+	 */
+	if (ret == -EOPNOTSUPP)
+		ret = -ESHUTDOWN;
+	if (ret)
+		return log_msg_ret("blk", ret);
+	assert(blk);
+	ret = bootdev_find_in_blk(dev, blk, iter, bflow);
+	if (ret)
+		return log_msg_ret("find", ret);
+
+	return 0;
+}
+
+static int mmc_bootdev_bind(struct udevice *dev)
+{
+	struct bootdev_uc_plat *ucp = dev_get_uclass_plat(dev);
+
+	ucp->prio = BOOTDEVP_0_INTERNAL_FAST;
+
+	return 0;
+}
+
+struct bootdev_ops mmc_bootdev_ops = {
+	.get_bootflow	= mmc_get_bootflow,
+};
+
+static const struct udevice_id mmc_bootdev_ids[] = {
+	{ .compatible = "u-boot,bootdev-mmc" },
+	{ }
+};
+
+U_BOOT_DRIVER(mmc_bootdev) = {
+	.name		= "mmc_bootdev",
+	.id		= UCLASS_BOOTDEV,
+	.ops		= &mmc_bootdev_ops,
+	.bind		= mmc_bootdev_bind,
+	.of_match	= mmc_bootdev_ids,
+};

include/mmc.h

@@ -956,10 +956,20 @@ int mmc_get_env_dev(void);
  * mmc_get_blk_desc() - Get the block descriptor for an MMC device
  *
  * @mmc:	MMC device
- * Return: block device if found, else NULL
+ * Return: block descriptor if found, else NULL
  */
 struct blk_desc *mmc_get_blk_desc(struct mmc *mmc);
 
+/**
+ * mmc_get_blk() - Get the block device for an MMC device
+ *
+ * @dev:	MMC device
+ * @blkp:	Returns pointer to probed block device on sucesss
+ *
+ * Return: 0 on success, -ve on error
+ */
+int mmc_get_blk(struct udevice *dev, struct udevice **blkp);
+
 /**
  * mmc_send_ext_csd() - read the extended CSD register
  *