Merge branch 'for-next/mci'

4 files changed, 69 insertions, 5 deletions

diff --git a/common/Kconfig b/common/Kconfig
index bddf802d3b..939cfab4f7 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -704,6 +704,27 @@ config FLEXIBLE_BOOTARGS
 	  to replace parts of the bootargs string without reconstructing it
 	  completely.
 
+config MMCBLKDEV_ROOTARG
+	bool
+	prompt "Support 'root=mmcblkXpN' cmdline appending"
+	depends on FLEXIBLE_BOOTARGS
+	depends on MCI
+	depends on OFTREE
+	help
+	  Enable this option to append 'root=mmcblkXpN' to the cmdline instead
+	  of 'root=PARTUUID=XYZ'. Don't enable this option if your used linux
+	  kernel doesn't contain commit [1]. The first linux kernel release
+	  containing that commit is v5.10-rc1.
+
+	  The appending only happen if barebox 'linux.bootargs.bootm.appendroot'
+	  variable is set or the used blspec entry contains 'linux-appendroot'.
+
+	  Note: It is crucial that the kernel device tree and the barebox device
+	  tree uses the same mmc aliases.
+
+	  [1] fa2d0aa96941 ("mmc: core: Allow setting slot index via device tree
+	      alias")
+
 config BAREBOX_UPDATE
 	bool "In-system barebox update infrastructure"
 
diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
index 017f25d35f..a160b98894 100644
--- a/drivers/mci/mci-core.c
+++ b/drivers/mci/mci-core.c
@@ -426,8 +426,10 @@ static void mci_part_add(struct mci *mci, uint64_t size,
 	part->part_cfg = part_cfg;
 	part->idx = idx;
 
-	if (area_type == MMC_BLK_DATA_AREA_MAIN)
+	if (area_type == MMC_BLK_DATA_AREA_MAIN) {
 		part->blk.cdev.device_node = mci->host->hw_dev->device_node;
+		part->blk.cdev.flags |= DEVFS_IS_MCI_MAIN_PART_DEV;
+	}
 
 	mci->nr_parts++;
 }
diff --git a/fs/fs.c b/fs/fs.c
index f4baba81e7..73584d57e1 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -2845,6 +2845,33 @@ out:
 }
 EXPORT_SYMBOL(chdir);
 
+static char *get_linux_mmcblkdev(struct fs_device_d *fsdev)
+{
+	struct cdev *cdevm, *cdev;
+	int id, partnum;
+
+	cdevm = fsdev->cdev->master;
+	id = of_alias_get_id(cdevm->device_node, "mmc");
+	if (id < 0)
+		return NULL;
+
+	partnum = 1; /* linux partitions are 1 based */
+	list_for_each_entry(cdev, &cdevm->partitions, partition_entry) {
+
+		/*
+		 * Partname is not guaranteed but this partition cdev is listed
+		 * in the partitions list so we need to count it instead of
+		 * skipping it.
+		 */
+		if (cdev->partname &&
+		    !strcmp(cdev->partname, fsdev->cdev->partname))
+			return basprintf("root=/dev/mmcblk%dp%d", id, partnum);
+		partnum++;
+	}
+
+	return NULL;
+}
+
 /*
  * Mount a device to a directory.
  * We do this by registering a new device on which the filesystem
@@ -2933,11 +2960,19 @@ int mount(const char *device, const char *fsname, const char *pathname,
 
 	fsdev->vfsmount.mnt_root = fsdev->sb.s_root;
 
-	if (!fsdev->linux_rootarg && fsdev->cdev && fsdev->cdev->partuuid[0] != 0) {
-		char *str = basprintf("root=PARTUUID=%s",
-					fsdev->cdev->partuuid);
+	if (!fsdev->linux_rootarg && fsdev->cdev) {
+		char *str = NULL;
+
+		if (IS_ENABLED(CONFIG_MMCBLKDEV_ROOTARG) &&
+		    fsdev->cdev->master &&
+		    cdev_is_mci_main_part_dev(fsdev->cdev->master))
+			str = get_linux_mmcblkdev(fsdev);
+
+		if (!str && fsdev->cdev->partuuid[0] != 0)
+			str = basprintf("root=PARTUUID=%s", fsdev->cdev->partuuid);
 
-		fsdev_set_linux_rootarg(fsdev, str);
+		if (str)
+			fsdev_set_linux_rootarg(fsdev, str);
 	}
 
 	path_put(&path);
diff --git a/include/driver.h b/include/driver.h
index 0d43b36148..d84fe35d50 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -496,6 +496,7 @@ int cdev_erase(struct cdev *cdev, loff_t count, loff_t offset);
 #define DEVFS_PARTITION_READONLY	(1U << 1)
 #define DEVFS_IS_CHARACTER_DEV		(1U << 3)
 #define DEVFS_PARTITION_FROM_TABLE	(1U << 4)
+#define DEVFS_IS_MCI_MAIN_PART_DEV	(1U << 5)
 
 struct cdev *devfs_add_partition(const char *devname, loff_t offset,
 		loff_t size, unsigned int flags, const char *name);
@@ -509,6 +510,11 @@ static inline void cdev_create_default_automount(struct cdev *cdev)
 }
 #endif
 
+static inline bool cdev_is_mci_main_part_dev(struct cdev *cdev)
+{
+	return cdev->flags & DEVFS_IS_MCI_MAIN_PART_DEV;
+}
+
 #define DEVFS_PARTITION_APPEND		0
 
 /**