[RFC,v2,3/5] block: add support for partition table defined in OF

diff --git a/block/partitions/Kconfig b/block/partitions/Kconfig
index 7aff4eb81c60..8534f7544f26 100644
--- a/block/partitions/Kconfig
+++ b/block/partitions/Kconfig
@@ -270,4 +270,12 @@  config CMDLINE_PARTITION
 	  Say Y here if you want to read the partition table from bootargs.
 	  The format for the command line is just like mtdparts.
 
+config OF_PARTITION
+	bool "Command line partition support" if PARTITION_ADVANCED
+	depends on OF
+	help
+	  Say Y here if you want to enable support for partition table
+	  defined in Device Tree. (mainly for eMMC)
+	  The format for the command line is just like MTD fixed-partition schema.
+
 endmenu
diff --git a/block/partitions/Makefile b/block/partitions/Makefile
index a7f05cdb02a8..25d424922c6e 100644
--- a/block/partitions/Makefile
+++ b/block/partitions/Makefile
@@ -12,6 +12,7 @@  obj-$(CONFIG_CMDLINE_PARTITION) += cmdline.o
 obj-$(CONFIG_MAC_PARTITION) += mac.o
 obj-$(CONFIG_LDM_PARTITION) += ldm.o
 obj-$(CONFIG_MSDOS_PARTITION) += msdos.o
+obj-$(CONFIG_OF_PARTITION) += of.o
 obj-$(CONFIG_OSF_PARTITION) += osf.o
 obj-$(CONFIG_SGI_PARTITION) += sgi.o
 obj-$(CONFIG_SUN_PARTITION) += sun.o
diff --git a/block/partitions/check.h b/block/partitions/check.h
index 8d70a880c372..e5c1c61eb353 100644
--- a/block/partitions/check.h
+++ b/block/partitions/check.h
@@ -62,6 +62,7 @@  int karma_partition(struct parsed_partitions *state);
 int ldm_partition(struct parsed_partitions *state);
 int mac_partition(struct parsed_partitions *state);
 int msdos_partition(struct parsed_partitions *state);
+int of_partition(struct parsed_partitions *state);
 int osf_partition(struct parsed_partitions *state);
 int sgi_partition(struct parsed_partitions *state);
 int sun_partition(struct parsed_partitions *state);
diff --git a/block/partitions/core.c b/block/partitions/core.c
index abad6c83db8f..dc21734b00ec 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -43,6 +43,9 @@  static int (*const check_part[])(struct parsed_partitions *) = {
 #ifdef CONFIG_CMDLINE_PARTITION
 	cmdline_partition,
 #endif
+#ifdef CONFIG_OF_PARTITION
+	of_partition,		/* cmdline have priority to OF */
+#endif
 #ifdef CONFIG_EFI_PARTITION
 	efi_partition,		/* this must come before msdos */
 #endif
diff --git a/block/partitions/of.c b/block/partitions/of.c
new file mode 100644
index 000000000000..fdc033107bcb
--- /dev/null
+++ b/block/partitions/of.c
@@ -0,0 +1,144 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/blkdev.h>
+#include <linux/major.h>
+#include <linux/of.h>
+#include "check.h"
+
+#define BOOT0_STR	"boot0"
+#define BOOT1_STR	"boot1"
+
+static struct device_node *get_partitions_node(struct device_node *disk_np,
+					       struct gendisk *disk)
+{
+	const char *node_name = "partitions";
+
+	/*
+	 * JEDEC specification 4.4 for eMMC introduced 3 additional partition
+	 * present on every eMMC. These additional partition are always hardcoded
+	 * from the eMMC driver as boot0, boot1 and rpmb. While rpmb is used to
+	 * store keys and exposed as a char device, the other 2 are exposed as
+	 * real separate disk with the boot0/1 appended to the disk name.
+	 *
+	 * Here we parse the disk_name in search for such suffix and select
+	 * the correct partition node.
+	 */
+	if (disk->major == MMC_BLOCK_MAJOR) {
+		const char *disk_name = disk->disk_name;
+
+		if (!memcmp(disk_name + strlen(disk_name) - strlen(BOOT0_STR),
+			    BOOT0_STR, sizeof(BOOT0_STR)))
+			node_name = "partitions-boot0";
+		if (!memcmp(disk_name + strlen(disk_name) - strlen(BOOT1_STR),
+			    BOOT1_STR, sizeof(BOOT1_STR)))
+			node_name = "partitions-boot1";
+	}
+
+	return of_get_child_by_name(disk_np, node_name);
+}
+
+static int validate_of_partition(struct device_node *np, int slot)
+{
+	int a_cells, s_cells;
+	const __be32 *reg;
+	u64 offset, size;
+	int len;
+
+	reg = of_get_property(np, "reg", &len);
+
+	a_cells = of_n_addr_cells(np);
+	s_cells = of_n_size_cells(np);
+
+	/*
+	 * Validate offset conversion from bytes to sectors.
+	 * Only the first partition is allowed to have offset 0.
+	 */
+	offset = of_read_number(reg, a_cells);
+	if (do_div(offset, SECTOR_SIZE) ||
+	    (slot > 1 && !offset))
+		return -EINVAL;
+
+	/* Validate size conversion from bytes to sectors */
+	size = of_read_number(reg + a_cells, s_cells);
+	if (do_div(size, SECTOR_SIZE) || !size)
+		return -EINVAL;
+
+	return 0;
+}
+
+static void add_of_partition(struct parsed_partitions *state, int slot,
+			     struct device_node *np)
+{
+	struct partition_meta_info *info;
+	char tmp[sizeof(info->volname) + 4];
+	int a_cells, s_cells;
+	const char *partname;
+	const __be32 *reg;
+	u64 offset, size;
+	int len;
+
+	reg = of_get_property(np, "reg", &len);
+
+	a_cells = of_n_addr_cells(np);
+	s_cells = of_n_size_cells(np);
+
+	/* Convert bytes to sector size */
+	offset = of_read_number(reg, a_cells) / SECTOR_SIZE;
+	size = of_read_number(reg + a_cells, s_cells) / SECTOR_SIZE;
+
+	put_partition(state, slot, offset, size);
+
+	if (of_property_read_bool(np, "read-only"))
+		state->parts[slot].flags |= ADDPART_FLAG_READONLY;
+
+	info = &state->parts[slot].info;
+	partname = of_get_property(np, "label", &len);
+	strscpy(info->volname, partname, sizeof(info->volname));
+
+	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
+	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+}
+
+int of_partition(struct parsed_partitions *state)
+{
+	struct device_node *disk_np, *partitions_np, *np;
+	struct device *ddev = disk_to_dev(state->disk);
+	int slot;
+
+	disk_np = of_node_get(ddev->parent->of_node);
+	if (!disk_np)
+		return 0;
+
+	partitions_np = get_partitions_node(disk_np, state->disk);
+	if (!partitions_np)
+		return 0;
+
+	/* Check if child are over the limit */
+	slot = of_get_child_count(partitions_np);
+	if (slot >= state->limit)
+		goto err;
+
+	slot = 1;
+	/* Validate parition offset and size */
+	for_each_child_of_node(partitions_np, np) {
+		if (validate_of_partition(np, slot))
+			goto err;
+
+		slot++;
+	}
+
+	slot = 1;
+	for_each_child_of_node(partitions_np, np) {
+		add_of_partition(state, slot, np);
+
+		slot++;
+	}
+
+	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+
+	return 1;
+err:
+	of_node_put(partitions_np);
+	of_node_put(disk_np);
+	return -1;
+}