// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Read flash partition table from command line
 *
 * Copyright © 2002      SYSGO Real-Time Solutions GmbH
 * Copyright © 2002-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * The format for the command line is as follows:
 *
 * mtdparts=<mtddef>[;<mtddef]
 * <mtddef>  := <mtd-id>:<partdef>[,<partdef>]
 * <partdef> := <size>[@<offset>][<name>][ro][lk]
 * <mtd-id>  := unique name used in mapping driver/device (mtd->name)
 * <size>    := standard linux memsize OR "-" to denote all remaining space
 *              size is automatically truncated at end of device
 *              if specified or truncated size is 0 the part is skipped
 * <offset>  := standard linux memsize
 *              if omitted the part will immediately follow the previous part
 *              or 0 if the first part
 * <name>    := '(' NAME ')'
 *              NAME will appear in /proc/mtd
 *
 * <size> and <offset> can be specified such that the parts are out of order
 * in physical memory and may even overlap.
 *
 * The parts are assigned MTD numbers in the order they are specified in the
 * command line regardless of their order in physical memory.
 *
 * Examples:
 *
 * 1 NOR Flash, with 1 single writable partition:
 * edb7312-nor:-
 *
 * 1 NOR Flash with 2 partitions, 1 NAND with one
 * edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)
 */

#define pr_fmt(fmt)     "mtd: " fmt

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/module.h>
#include <linux/err.h>

/* debug macro */
#if 0
#define dbg(x) do { printk("DEBUG-CMDLINE-PART: "); printk x; } while(0)
#else
#define dbg(x)
#endif


/* special size referring to all the remaining space in a partition */
#define SIZE_REMAINING ULLONG_MAX
#define OFFSET_CONTINUOUS ULLONG_MAX

struct cmdline_mtd_partition {
        struct cmdline_mtd_partition *next;
        char *mtd_id;
        int num_parts;
        struct mtd_partition *parts;
};

/* mtdpart_setup() parses into here */
static struct cmdline_mtd_partition *partitions;

/* the command line passed to mtdpart_setup() */
static char *mtdparts;
static char *cmdline;
static int cmdline_parsed;

/*
 * Parse one partition definition for an MTD. Since there can be many
 * comma separated partition definitions, this function calls itself
 * recursively until no more partition definitions are found. Nice side
 * effect: the memory to keep the mtd_partition structs and the names
 * is allocated upon the last definition being found. At that point the
 * syntax has been verified ok.
 */
static struct mtd_partition * newpart(char *s,
                                      char **retptr,
                                      int *num_parts,
                                      int this_part,
                                      unsigned char **extra_mem_ptr,
                                      int extra_mem_size)
{
        struct mtd_partition *parts;
        unsigned long long size, offset = OFFSET_CONTINUOUS;
        char *name;
        int name_len;
        unsigned char *extra_mem;
        char delim;
        unsigned int mask_flags;

        /* fetch the partition size */
        if (*s == '-') {
                /* assign all remaining space to this partition */
                size = SIZE_REMAINING;
                s++;
        } else {
                size = memparse(s, &s);
                if (!size) {
                        pr_err("partition has size 0\n");
                        return ERR_PTR(-EINVAL);
                }
        }

        /* fetch partition name and flags */
        mask_flags = 0; /* this is going to be a regular partition */
        delim = 0;

        /* check for offset */
        if (*s == '@') {
                s++;
                offset = memparse(s, &s);
        }

        /* now look for name */
        if (*s == '(')
                delim = ')';

        if (delim) {
                char *p;

                name = ++s;
                p = strchr(name, delim);
                if (!p) {
                        pr_err("no closing %c found in partition name\n", delim);
                        return ERR_PTR(-EINVAL);
                }
                name_len = p - name;
                s = p + 1;
        } else {
                name = NULL;
                name_len = 13; /* Partition_000 */
        }

        /* record name length for memory allocation later */
        extra_mem_size += name_len + 1;

        /* test for options */
        if (strncmp(s, "ro", 2) == 0) {
                mask_flags |= MTD_WRITEABLE;
                s += 2;
        }

        /* if lk is found do NOT unlock the MTD partition*/
        if (strncmp(s, "lk", 2) == 0) {
                mask_flags |= MTD_POWERUP_LOCK;
                s += 2;
        }

        /* test if more partitions are following */
        if (*s == ',') {
                if (size == SIZE_REMAINING) {
                        pr_err("no partitions allowed after a fill-up partition\n");
                        return ERR_PTR(-EINVAL);
                }
                /* more partitions follow, parse them */
                parts = newpart(s + 1, &s, num_parts, this_part + 1,
                                &extra_mem, extra_mem_size);
                if (IS_ERR(parts))
                        return parts;
        } else {
                /* this is the last partition: allocate space for all */
                int alloc_size;

                *num_parts = this_part + 1;
                alloc_size = *num_parts * sizeof(struct mtd_partition) +
                             extra_mem_size;

                parts = kzalloc(alloc_size, GFP_KERNEL);
                if (!parts)
                        return ERR_PTR(-ENOMEM);
                extra_mem = (unsigned char *)(parts + *num_parts);
        }

        /*
         * enter this partition (offset will be calculated later if it is
         * OFFSET_CONTINUOUS at this point)
         */
        parts[this_part].size = size;
        parts[this_part].offset = offset;
        parts[this_part].mask_flags = mask_flags;
        if (name)
                strlcpy(extra_mem, name, name_len + 1);
        else
                sprintf(extra_mem, "Partition_%03d", this_part);
        parts[this_part].name = extra_mem;
        extra_mem += name_len + 1;

        dbg(("partition %d: name <%s>, offset %llx, size %llx, mask flags %x\n",
             this_part, parts[this_part].name, parts[this_part].offset,
             parts[this_part].size, parts[this_part].mask_flags));

        /* return (updated) pointer to extra_mem memory */
        if (extra_mem_ptr)
                *extra_mem_ptr = extra_mem;

        /* return (updated) pointer command line string */
        *retptr = s;

        /* return partition table */
        return parts;
}

/*
 * Parse the command line.
 */
static int mtdpart_setup_real(char *s)
{
        cmdline_parsed = 1;

        for( ; s != NULL; )
        {
                struct cmdline_mtd_partition *this_mtd;
                struct mtd_partition *parts;
                int mtd_id_len, num_parts;
                char *p, *mtd_id;

                mtd_id = s;

                /* fetch <mtd-id> */
                p = strchr(s, ':');
                if (!p) {
                        pr_err("no mtd-id\n");
                        return -EINVAL;
                }
                mtd_id_len = p - mtd_id;

                dbg(("parsing <%s>\n", p+1));

                /*
                 * parse one mtd. have it reserve memory for the
                 * struct cmdline_mtd_partition and the mtd-id string.
                 */
                parts = newpart(p + 1,          /* cmdline */
                                &s,             /* out: updated cmdline ptr */
                                &num_parts,     /* out: number of parts */
                                0,              /* first partition */
                                (unsigned char**)&this_mtd, /* out: extra mem */
                                mtd_id_len + 1 + sizeof(*this_mtd) +
                                sizeof(void*)-1 /*alignment*/);
                if (IS_ERR(parts)) {
                        /*
                         * An error occurred. We're either:
                         * a) out of memory, or
                         * b) in the middle of the partition spec
                         * Either way, this mtd is hosed and we're
                         * unlikely to succeed in parsing any more
                         */
                         return PTR_ERR(parts);
                 }

                /* align this_mtd */
                this_mtd = (struct cmdline_mtd_partition *)
                                ALIGN((unsigned long)this_mtd, sizeof(void *));
                /* enter results */
                this_mtd->parts = parts;
                this_mtd->num_parts = num_parts;
                this_mtd->mtd_id = (char*)(this_mtd + 1);
                strlcpy(this_mtd->mtd_id, mtd_id, mtd_id_len + 1);

                /* link into chain */
                this_mtd->next = partitions;
                partitions = this_mtd;

                dbg(("mtdid=<%s> num_parts=<%d>\n",
                     this_mtd->mtd_id, this_mtd->num_parts));


                /* EOS - we're done */
                if (*s == 0)
                        break;

                /* does another spec follow? */
                if (*s != ';') {
                        pr_err("bad character after partition (%c)\n", *s);
                        return -EINVAL;
                }
                s++;
        }

        return 0;
}

/*
 * Main function to be called from the MTD mapping driver/device to
 * obtain the partitioning information. At this point the command line
 * arguments will actually be parsed and turned to struct mtd_partition
 * information. It returns partitions for the requested mtd device, or
 * the first one in the chain if a NULL mtd_id is passed in.
 */
static int parse_cmdline_partitions(struct mtd_info *master,
                                    const struct mtd_partition **pparts,
                                    struct mtd_part_parser_data *data)
{
        unsigned long long offset;
        int i, err;
        struct cmdline_mtd_partition *part;
        const char *mtd_id = master->name;

        /* parse command line */
        if (!cmdline_parsed) {
                err = mtdpart_setup_real(cmdline);
                if (err)
                        return err;
        }

        /*
         * Search for the partition definition matching master->name.
         * If master->name is not set, stop at first partition definition.
         */
        for (part = partitions; part; part = part->next) {
                if ((!mtd_id) || (!strcmp(part->mtd_id, mtd_id)))
                        break;
        }

        if (!part)
                return 0;

        for (i = 0, offset = 0; i < part->num_parts; i++) {
                if (part->parts[i].offset == OFFSET_CONTINUOUS)
                        part->parts[i].offset = offset;
                else
                        offset = part->parts[i].offset;

                if (part->parts[i].size == SIZE_REMAINING)
                        part->parts[i].size = master->size - offset;

                if (offset + part->parts[i].size > master->size) {
                        pr_warn("%s: partitioning exceeds flash size, truncating\n",
                                part->mtd_id);
                        part->parts[i].size = master->size - offset;
                }
                offset += part->parts[i].size;

                if (part->parts[i].size == 0) {
                        pr_warn("%s: skipping zero sized partition\n",
                                part->mtd_id);
                        part->num_parts--;
                        memmove(&part->parts[i], &part->parts[i + 1],
                                sizeof(*part->parts) * (part->num_parts - i));
                        i--;
                }
        }

        *pparts = kmemdup(part->parts, sizeof(*part->parts) * part->num_parts,
                          GFP_KERNEL);
        if (!*pparts)
                return -ENOMEM;

        return part->num_parts;
}


/*
 * This is the handler for our kernel parameter, called from
 * main.c::checksetup(). Note that we can not yet kmalloc() anything,
 * so we only save the commandline for later processing.
 *
 * This function needs to be visible for bootloaders.
 */
static int __init mtdpart_setup(char *s)
{
        cmdline = s;
        return 1;
}

__setup("mtdparts=", mtdpart_setup);

static struct mtd_part_parser cmdline_parser = {
        .parse_fn = parse_cmdline_partitions,
        .name = "cmdlinepart",
};

static int __init cmdline_parser_init(void)
{
        if (mtdparts)
                mtdpart_setup(mtdparts);
        register_mtd_parser(&cmdline_parser);
        return 0;
}

static void __exit cmdline_parser_exit(void)
{
        deregister_mtd_parser(&cmdline_parser);
}

module_init(cmdline_parser_init);
module_exit(cmdline_parser_exit);

MODULE_PARM_DESC(mtdparts, "Partitioning specification");
module_param(mtdparts, charp, 0);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marius Groeger <mag@sysgo.de>");
MODULE_DESCRIPTION("Command line configuration of MTD partitions");