--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * cmd_mbr.c -- MBR (Master Boot Record) handling command
+ *
+ * Copyright (C) 2020 Samsung Electronics
+ * author: Marek Szyprowski <m.szyprowski@samsung.com>
+ *
+ * based on the gpt command.
+ */
+
+#include <common.h>
+#include <blk.h>
+#include <command.h>
+#include <malloc.h>
+#include <part.h>
+
+/**
+ * extract_val() - Extract a value from the key=value pair list
+ * @str: pointer to string with key=values pairs
+ * @key: pointer to the key to search for
+ *
+ * The list of parameters is come separated, only a value for
+ * the given key is returend.
+ *
+ * Function allocates memory for the value, remember to free!
+ *
+ * Return: Pointer to allocated string with the value.
+ */
+static char *extract_val(const char *str, const char *key)
+{
+ char *v, *k;
+ char *s, *strcopy;
+ char *new = NULL;
+
+ strcopy = strdup(str);
+ if (strcopy == NULL)
+ return NULL;
+
+ s = strcopy;
+ while (s) {
+ v = strsep(&s, ",");
+ if (!v)
+ break;
+ k = strsep(&v, "=");
+ if (!k)
+ break;
+ if (strcmp(k, key) == 0) {
+ new = strdup(v);
+ break;
+ }
+ }
+
+ free(strcopy);
+
+ return new;
+}
+
+/**
+ * found_key() - Search for a key without a value in the parameter list
+ * @str: pointer to string with key
+ * @key: pointer to the key to search for
+ *
+ * The list of parameters is come separated.
+ *
+ * Return: True if key has been found.
+ */
+static bool found_key(const char *str, const char *key)
+{
+ char *k;
+ char *s, *strcopy;
+ bool result = false;
+
+ strcopy = strdup(str);
+ if (!strcopy)
+ return NULL;
+
+ s = strcopy;
+ while (s) {
+ k = strsep(&s, ",");
+ if (!k)
+ break;
+ if (strcmp(k, key) == 0) {
+ result = true;
+ break;
+ }
+ }
+
+ free(strcopy);
+
+ return result;
+}
+
+static int str_to_partitions(const char *str_part, int blksz,
+ unsigned long *disk_uuid, struct disk_partition **partitions,
+ int *parts_count)
+{
+ char *tok, *str, *s;
+ int i;
+ char *val, *p;
+ int p_count;
+ struct disk_partition *parts;
+ int errno = 0;
+ uint64_t size_ll, start_ll;
+
+ if (str_part == NULL)
+ return -1;
+
+ str = strdup(str_part);
+ if (str == NULL)
+ return -ENOMEM;
+
+ /* extract disk guid */
+ s = str;
+ val = extract_val(str, "uuid_disk");
+ if (val) {
+ val = strsep(&val, ";");
+ p = val;
+ *disk_uuid = ustrtoull(p, &p, 0);
+ free(val);
+ /* Move s to first partition */
+ strsep(&s, ";");
+ }
+ if (s == NULL) {
+ printf("Error: is the partitions string NULL-terminated?\n");
+ return -EINVAL;
+ }
+
+ /* remove the optional semicolon at the end of the string */
+ i = strlen(s) - 1;
+ if (s[i] == ';')
+ s[i] = '\0';
+
+ /* calculate expected number of partitions */
+ p_count = 1;
+ p = s;
+ while (*p) {
+ if (*p++ == ';')
+ p_count++;
+ }
+
+ /* allocate memory for partitions */
+ parts = calloc(sizeof(struct disk_partition), p_count);
+ if (parts == NULL)
+ return -ENOMEM;
+
+ /* retrieve partitions data from string */
+ for (i = 0; i < p_count; i++) {
+ tok = strsep(&s, ";");
+
+ if (tok == NULL)
+ break;
+
+ /* size */
+ val = extract_val(tok, "size");
+ if (!val) { /* 'size' is mandatory */
+ errno = -4;
+ goto err;
+ }
+ p = val;
+ if ((strcmp(p, "-") == 0)) {
+ /* auto extend the size */
+ parts[i].size = 0;
+ } else {
+ size_ll = ustrtoull(p, &p, 0);
+ parts[i].size = size_ll / blksz;
+ }
+ free(val);
+
+ /* start address */
+ val = extract_val(tok, "start");
+ if (val) { /* start address is optional */
+ p = val;
+ start_ll = ustrtoull(p, &p, 0);
+ parts[i].start = start_ll / blksz;
+ free(val);
+ }
+
+ /* system id */
+ val = extract_val(tok, "id");
+ if (!val) { /* '' is mandatory */
+ errno = -4;
+ goto err;
+ }
+ p = val;
+ parts[i].sys_ind = ustrtoul(p, &p, 0);
+ free(val);
+
+ /* bootable */
+ if (found_key(tok, "bootable"))
+ parts[i].bootable = PART_BOOTABLE;
+ }
+
+ *parts_count = p_count;
+ *partitions = parts;
+ free(str);
+
+ return 0;
+err:
+ free(str);
+ free(parts);
+
+ return errno;
+}
+
+static int do_write_mbr(struct blk_desc *dev, const char *str)
+{
+ unsigned long disk_uuid = 0;
+ struct disk_partition *partitions;
+ int blksz = dev->blksz;
+ int count;
+
+ if (str_to_partitions(str, blksz, &disk_uuid, &partitions, &count)) {
+ printf("MBR: failed to setup partitions from \"%s\"\n", str);
+ return -1;
+ }
+
+ if (layout_mbr_partitions(partitions, count, dev->lba)) {
+ printf("MBR: failed to layout partitions on the device\n");
+ free(partitions);
+ return -1;
+ }
+
+ if (write_mbr_partitions(dev, partitions, count, disk_uuid)) {
+ printf("MBR: failed to write partitions to the device\n");
+ free(partitions);
+ return -1;
+ }
+
+ return 0;
+}
+
+static int do_verify_mbr(struct blk_desc *dev, const char *str)
+{
+ unsigned long disk_uuid = 0;
+ struct disk_partition *partitions;
+ int blksz = dev->blksz;
+ int count, i, ret = 1;
+
+ if (str_to_partitions(str, blksz, &disk_uuid, &partitions, &count)) {
+ printf("MBR: failed to setup partitions from \"%s\"\n", str);
+ return -1;
+ }
+
+ for (i = 0; i < count; i++) {
+ struct disk_partition p;
+
+ if (part_get_info(dev, i+1, &p))
+ goto fail;
+
+ if ((partitions[i].size && p.size < partitions[i].size) ||
+ (partitions[i].start && p.start < partitions[i].start) ||
+ (p.sys_ind != partitions[i].sys_ind))
+ goto fail;
+ }
+ ret = 0;
+fail:
+ free(partitions);
+ return ret;
+}
+
+static int do_mbr(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+{
+ const char *parts = NULL;
+ int ret = CMD_RET_SUCCESS;
+ int dev = 0;
+ char *ep;
+ struct blk_desc *blk_dev_desc = NULL;
+
+ if (argc != 4 && argc != 5)
+ return CMD_RET_USAGE;
+
+ dev = (int)simple_strtoul(argv[3], &ep, 10);
+ if (!ep || ep[0] != '\0') {
+ printf("'%s' is not a number\n", argv[3]);
+ return CMD_RET_USAGE;
+ }
+ blk_dev_desc = blk_get_dev(argv[2], dev);
+ if (!blk_dev_desc) {
+ printf("%s: %s dev %d NOT available\n",
+ __func__, argv[2], dev);
+ return CMD_RET_FAILURE;
+ }
+
+ if ((strcmp(argv[1], "write") == 0)) {
+ parts = (argc == 5) ? argv[4] : env_get("mbr_parts");
+ printf("MBR: write ");
+ ret = do_write_mbr(blk_dev_desc, parts);
+ } else if ((strcmp(argv[1], "verify") == 0)) {
+ printf("MBR: verify ");
+ parts = (argc == 5) ? argv[4] : env_get("mbr_parts");
+ ret = do_verify_mbr(blk_dev_desc, parts);
+ } else {
+ return CMD_RET_USAGE;
+ }
+
+ if (ret) {
+ printf("error!\n");
+ return CMD_RET_FAILURE;
+ }
+
+ printf("success!\n");
+ return CMD_RET_SUCCESS;
+}
+
+U_BOOT_CMD(mbr, CONFIG_SYS_MAXARGS, 1, do_mbr,
+ "MBR (Master Boot Record)",
+ "<command> <interface> <dev> <partitions_list>\n"
+ " - MBR partition table restoration utility\n"
+ " Restore or check partition information on a device connected\n"
+ " to the given block interface\n"
+ " Example usage:\n"
+ " mbr write mmc 0 [\"${mbr_parts}\"]\n"
+ " mbr verify mmc 0 [\"${partitions}\"]\n"
+);
--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0+
+
+mbr command
+===========
+
+Synopsis
+--------
+
+::
+
+ mbr verify [interface] [device no] [partition list]
+ mbr write [interface] [device no] [partition list]
+
+Description
+-----------
+
+The mbr command lets users create or verify the MBR (Master Boot Record)
+partition layout based on the provided text description. The partition
+layout is alternatively read from the 'mbr_parts' environment variable.
+This can be used in scripts to help system image flashing tools to ensure
+proper partition layout.
+
+The syntax of the text description of the partition list is similar to
+the one used by the 'gpt' command.
+
+Supported partition parameters are:
+
+* name (currently ignored)
+* start (partition start offset in bytes)
+* size (in bytes or '-' to expand it to the whole free area)
+* bootable (boolean flag)
+* id (MBR partition type)
+
+If one wants to create more than 4 partitions, an 'Extended' primary
+partition (with 0x05 ID) has to be explicitly provided as a one of the
+first 4 entries.
+
+Here is an example how to create a 6 partitions (3 on the 'extended
+volume'), some of the predefined sizes:
+
+::
+
+ => setenv mbr_parts 'name=boot,start=4M,size=128M,bootable,id=0x0e;
+ name=rootfs,size=3072M,id=0x83;
+ name=system-data,size=512M,id=0x83;
+ name=[ext],size=-,id=0x05;
+ name=user,size=-,id=0x83;
+ name=modules,size=100M,id=0x83;
+ name=ramdisk,size=8M,id=0x83'
+ => mbr write mmc 0
+
+To check if the layout on the MMC #0 storage device matches the provided
+text description one has to issue following command (assuming that
+mbr_parts environment variable is set):
+
+::
+
+ => mbr verify mmc 0
+
+The verify sub-command is especially useful in the system update scripts:
+
+::
+
+ => if mbr verify mmc 0; then
+ echo MBR layout needs to be updated
+ ...
+ fi
+
+The 'mbr write' command returns 0 on success write or 1 on failure.
+
+The 'mbr verify' returns 0 if the layout matches the one on the storage
+device or 1 if not.
+
+Configuration
+-------------
+
+To use the mbr command you must specify CONFIG_CMD_MBR=y.
+
+Return value
+------------
+
+The variable *$?* takes the following values
+
++---+------------------------------+
+| 0 | mbr write was succesful |
++---+------------------------------+
+| 1 | mbr write failed |
++---+------------------------------+
+| 0 | mbr verify was succesful |
++---+------------------------------+
+| 1 | mbr verify was not succesful |
++---+------------------------------+
+|-1 | invalid arguments |
++---+------------------------------+
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