[PATCH] block: support embedded device command line partition

[Caizhiyong]

From: Cai Zhiyong <caizhiyong@xxxxxxxxxx>

Read block device partition table from command line.
The partition used for fixed block device (eMMC) embedded device.
It is no MBR, save storage space. Bootloader can be easily accessed by
absolute address of data on the block device.
Users can easily change the partition.

This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
About the partition verbose reference "Documentation/block/cmdline-partition.txt"

Signed-off-by: Cai Zhiyong <caizhiyong@xxxxxxxxxx>
---
 Documentation/block/cmdline-partition.txt |  40 ++++
 block/partitions/Kconfig                  |   6 +
 block/partitions/Makefile                 |   1 +
 block/partitions/check.c                  |   4 +
 block/partitions/cmdline.c                | 326 ++++++++++++++++++++++++++++++
 block/partitions/cmdline.h                |   2 +
 6 files changed, 379 insertions(+)
 create mode 100644 Documentation/block/cmdline-partition.txt
 create mode 100644 block/partitions/cmdline.c
 create mode 100644 block/partitions/cmdline.h

diff --git a/Documentation/block/cmdline-partition.txt b/Documentation/block/cmdline-partition.txt
new file mode 100644
index 0000000..651863d
--- /dev/null
+++ b/Documentation/block/cmdline-partition.txt
@@ -0,0 +1,40 @@
+Embedded device command line partition
+=====================================================================
+
+Read block device partition table from command line.
+The partition used for fixed block device (eMMC) embedded device.
+It is no MBR, save storage space. Bootloader can be easily accessed
+by absolute address of data on the block device.
+Users can easily change the partition.
+
+The format for the command line is just like mtdparts:
+
+blkdevparts=<blkdev-def>[;<blkdev-def>]
+  <blkdev-def> := <blkdev-id>:<partdef>[,<partdef>]
+    <partdef> := <size>[@<offset>](part-name)
+
+<blkdev-id>
+    block device disk name, embedded device used fixed block device,
+    it's disk name also fixed. such as: mmcblk0, mmcblk1, mmcblk0boot0.
+
+<size>
+    partition size, in bytes, such as: 512, 1m, 1G.
+
+<offset>
+    partition start address, in bytes.
+
+(part-name)
+    partition name, kernel send uevent with "PARTNAME". application can create
+    a link to block device partition with the name "PARTNAME".
+    user space application can access partition by partition name.
+
+Example:
+    eMMC disk name is "mmcblk0" and "mmcblk0boot0"
+
+  bootargs:
+    'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)'
+
+  dmesg:
+    mmcblk0: p1(data0) p2(data1) p3()
+    mmcblk0boot0: p1(boot) p2(kernel)
+
diff --git a/block/partitions/Kconfig b/block/partitions/Kconfig
index 4cebb2f..2ebf251 100644
--- a/block/partitions/Kconfig
+++ b/block/partitions/Kconfig
@@ -260,3 +260,9 @@ config SYSV68_PARTITION
 	  partition table format used by Motorola Delta machines (using
 	  sysv68).
 	  Otherwise, say N.
+
+config CMDLINE_PARTITION
+	bool "Command line partition support" if PARTITION_ADVANCED
+	help
+	  Say Y here if you would read the partitions table from bootargs.
+	  The format for the command line is just like mtdparts.
diff --git a/block/partitions/Makefile b/block/partitions/Makefile
index 2be4d7b..4e9d584 100644
--- a/block/partitions/Makefile
+++ b/block/partitions/Makefile
@@ -19,3 +19,4 @@ obj-$(CONFIG_IBM_PARTITION) += ibm.o
 obj-$(CONFIG_EFI_PARTITION) += efi.o
 obj-$(CONFIG_KARMA_PARTITION) += karma.o
 obj-$(CONFIG_SYSV68_PARTITION) += sysv68.o
+obj-$(CONFIG_CMDLINE_PARTITION) += cmdline.o
diff --git a/block/partitions/check.c b/block/partitions/check.c
index 19ba207..9ac1df7 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -34,6 +34,7 @@
 #include "efi.h"
 #include "karma.h"
 #include "sysv68.h"
+#include "cmdline.h"
 
 int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
 
@@ -65,6 +66,9 @@ static int (*check_part[])(struct parsed_partitions *) = {
 	adfspart_check_ADFS,
 #endif
 
+#ifdef CONFIG_CMDLINE_PARTITION
+	cmdline_partition,
+#endif
 #ifdef CONFIG_EFI_PARTITION
 	efi_partition,		/* this must come before msdos */
 #endif
diff --git a/block/partitions/cmdline.c b/block/partitions/cmdline.c
new file mode 100644
index 0000000..dc69483
--- /dev/null
+++ b/block/partitions/cmdline.c
@@ -0,0 +1,326 @@
+/*
+ * Copyright (C) 2013 HUAWEI
+ * Author: Cai Zhiyong <caizhiyong@xxxxxxxxxx>
+ *
+ * Read block device partition table from command line.
+ * The partition used for fixed block device (eMMC) embedded device.
+ * It is no MBR, save storage space. Bootloader can be easily accessed
+ * by absolute address of data on the block device.
+ * Users can easily change the partition.
+ *
+ * This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
+ * The format for the command line is just like mtdparts.
+ *
+ * Verbose config please reference "Documentation/block/cmdline-partition.txt"
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/module.h>
+#include <linux/ctype.h>
+
+#include "check.h"
+#include "cmdline.h"
+
+struct cmdline_subpart {
+	char name[BDEVNAME_SIZE]; /* partition name, such as 'rootfs' */
+	sector_t from;
+	sector_t size;
+	struct cmdline_subpart *next_subpart;
+};
+
+struct cmdline_parts {
+	char name[BDEVNAME_SIZE]; /* block device, such as 'mmcblk0' */
+	struct cmdline_subpart *subpart;
+	struct cmdline_parts *next_parts;
+};
+
+static char *cmdline_string;
+static struct cmdline_parts *cmdline_parts;
+
+static int parse_subpart(struct cmdline_subpart **subpart, char *cmdline)
+{
+	int ret = 0;
+	struct cmdline_subpart *new_subpart;
+
+	*subpart = NULL;
+
+	new_subpart = kzalloc(sizeof(struct cmdline_subpart), GFP_KERNEL);
+	if (!new_subpart)
+		return -ENOMEM;
+
+	if (*cmdline == '-') {
+		new_subpart->size = (sector_t)(~0ULL);
+		cmdline++;
+	} else {
+		new_subpart->size = (sector_t)memparse(cmdline, &cmdline);
+		if (new_subpart->size < (sector_t)PAGE_SIZE) {
+			pr_warn("cmdline partition size is invalid.");
+			ret = -EINVAL;
+			goto fail;
+		}
+	}
+
+	if (*cmdline == '@') {
+		cmdline++;
+		new_subpart->from = (sector_t)memparse(cmdline, &cmdline);
+	} else {
+		new_subpart->from = (sector_t)(~0ULL);
+	}
+
+	if (*cmdline == '(') {
+		int length;
+		char *next = strchr(++cmdline, ')');
+
+		if (!next) {
+			pr_warn("cmdline partition format is invalid.");
+			ret = -EINVAL;
+			goto fail;
+		}
+
+		length = min_t(int, next - cmdline,
+			       sizeof(new_subpart->name) - 1);
+		strncpy(new_subpart->name, cmdline, length);
+		new_subpart->name[length] = '\0';
+
+		cmdline = ++next;
+	} else
+		new_subpart->name[0] = '\0';
+
+	*subpart = new_subpart;
+	return 0;
+fail:
+	kfree(new_subpart);
+	return ret;
+}
+
+static void free_subpart(struct cmdline_parts *parts)
+{
+	struct cmdline_subpart *subpart;
+
+	while (parts->subpart) {
+		subpart = parts->subpart;
+		parts->subpart = subpart->next_subpart;
+		kfree(subpart);
+	}
+}
+
+static void free_parts(struct cmdline_parts **parts)
+{
+	struct cmdline_parts *next_parts;
+
+	while (*parts) {
+		next_parts = (*parts)->next_parts;
+		free_subpart(*parts);
+		kfree(*parts);
+		*parts = next_parts;
+	}
+}
+
+static int parse_parts(struct cmdline_parts **parts, const char *cmdline)
+{
+	int ret = -EINVAL;
+	char *next;
+	int length;
+	struct cmdline_subpart **next_subpart;
+	struct cmdline_parts *newparts;
+	char buf[BDEVNAME_SIZE + 32 + 4];
+
+	*parts = NULL;
+
+	newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
+	if (!newparts)
+		return -ENOMEM;
+
+	next = strchr(cmdline, ':');
+	if (!next) {
+		pr_warn("cmdline partition has not block device.");
+		goto fail;
+	}
+
+	length = min_t(int, next - cmdline, sizeof(newparts->name) - 1);
+	strncpy(newparts->name, cmdline, length);
+	newparts->name[length] = '\0';
+
+	next_subpart = &newparts->subpart;
+
+	while (next && *(++next)) {
+		cmdline = next;
+		next = strchr(cmdline, ',');
+
+		length = (!next) ? (sizeof(buf) - 1) :
+			min_t(int, next - cmdline, sizeof(buf) - 1);
+
+		strncpy(buf, cmdline, length);
+		buf[length] = '\0';
+
+		ret = parse_subpart(next_subpart, buf);
+		if (ret)
+			goto fail;
+
+		next_subpart = &(*next_subpart)->next_subpart;
+	}
+
+	if (!newparts->subpart) {
+		pr_warn("cmdline partition has not valid partition.");
+		goto fail;
+	}
+
+	*parts = newparts;
+
+	return 0;
+fail:
+	free_subpart(newparts);
+	kfree(newparts);
+	return ret;
+}
+
+static int parse_cmdline(struct cmdline_parts **parts, const char *cmdline)
+{
+	int ret;
+	char *buf;
+	char *pbuf;
+	char *next;
+	struct cmdline_parts **next_parts;
+
+	*parts = NULL;
+
+	next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	next_parts = parts;
+
+	while (next && *pbuf) {
+		next = strchr(pbuf, ';');
+		if (next)
+			*next = '\0';
+
+		ret = parse_parts(next_parts, pbuf);
+		if (ret)
+			goto fail;
+
+		if (next)
+			pbuf = ++next;
+
+		next_parts = &(*next_parts)->next_parts;
+	}
+
+	if (!*parts) {
+		pr_warn("cmdline partition has not valid partition.");
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	ret = 0;
+done:
+	kfree(buf);
+	return ret;
+
+fail:
+	free_parts(parts);
+	goto done;
+}
+
+/*
+ * Purpose: allocate cmdline partitions.
+ * Returns:
+ * -1 if unable to read the partition table
+ *  0 if this isn't our partition table
+ *  1 if successful
+ */
+static int parse_partitions(struct parsed_partitions *state,
+			    struct cmdline_parts *parts)
+{
+	int slot;
+	sector_t from = 0;
+	sector_t disk_size;
+	char buf[BDEVNAME_SIZE];
+	struct cmdline_subpart *subpart;
+
+	bdevname(state->bdev, buf);
+
+	while (parts && strncmp(buf, parts->name, BDEVNAME_SIZE))
+		parts = parts->next_parts;
+
+	if (!parts)
+		return 0;
+
+	disk_size = get_capacity(state->bdev->bd_disk) << 9;
+
+	for (slot = 1, subpart = parts->subpart;
+	     subpart && slot < state->limit;
+	     subpart = subpart->next_subpart, slot++) {
+		int label_min;
+		struct partition_meta_info *info;
+		char tmp[sizeof(info->volname) + 4];
+
+		if (subpart->from == (sector_t)(~0ULL))
+			subpart->from = from;
+		else
+			from = subpart->from;
+
+		if (from >= disk_size)
+			break;
+
+		if (subpart->size > (disk_size - from))
+			subpart->size = disk_size - from;
+
+		from += subpart->size;
+
+		put_partition(state, slot, subpart->from >> 9,
+			      subpart->size >> 9);
+
+		info = &state->parts[slot].info;
+
+		label_min = min_t(int, sizeof(info->volname) - 1,
+				  sizeof(subpart->name));
+		strncpy(info->volname, subpart->name, label_min);
+		info->volname[label_min] = '\0';
+
+		snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
+		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+
+		state->parts[slot].has_info = true;
+	}
+
+	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+
+	return 1;
+}
+
+static int __init cmdline_parts_setup(char *s)
+{
+	cmdline_string = s;
+	return 1;
+}
+__setup("blkdevparts=", cmdline_parts_setup);
+
+/*
+ * Purpose: allocate cmdline partitions.
+ * Returns:
+ * -1 if unable to read the partition table
+ *  0 if this isn't our partition table
+ *  1 if successful
+ */
+int cmdline_partition(struct parsed_partitions *state)
+{
+	if (cmdline_string) {
+		if (cmdline_parts)
+			free_parts(&cmdline_parts);
+
+		if (parse_cmdline(&cmdline_parts, cmdline_string))
+			goto fail;
+
+		cmdline_string = NULL;
+	}
+
+	if (!cmdline_parts)
+		return 0;
+
+	return parse_partitions(state, cmdline_parts);
+
+fail:
+	cmdline_string = NULL;
+	return -1;
+}
diff --git a/block/partitions/cmdline.h b/block/partitions/cmdline.h
new file mode 100644
index 0000000..26e0f8d
--- /dev/null
+++ b/block/partitions/cmdline.h
@@ -0,0 +1,2 @@
+
+int cmdline_partition(struct parsed_partitions *state);
-- 
1.8.1.5

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