disk: dos: add code for creating MBR partition layout

Add a code for creating and writing MBR partition layout. The code generates
similar layout of EBRs (Exteneded Block Records) and logical volumes as
Linux's fdisk utility.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
This commit is contained in:
Marek Szyprowski 2020-12-23 13:55:14 +01:00 committed by Tom Rini
parent cb571f91c6
commit 20bd5ac6e4
3 changed files with 174 additions and 0 deletions

View File

@ -320,6 +320,173 @@ int is_valid_dos_buf(void *buf)
return test_block_type(buf) == DOS_MBR ? 0 : -1; return test_block_type(buf) == DOS_MBR ? 0 : -1;
} }
#if CONFIG_IS_ENABLED(CMD_MBR)
static void lba_to_chs(lbaint_t lba, unsigned char *rc, unsigned char *rh,
unsigned char *rs)
{
unsigned int c, h, s;
/* use fixed CHS geometry */
unsigned int sectpertrack = 63;
unsigned int heads = 255;
c = (lba + 1) / sectpertrack / heads;
h = (lba + 1) / sectpertrack - c * heads;
s = (lba + 1) - (c * heads + h) * sectpertrack;
if (c > 1023) {
c = 1023;
h = 254;
s = 63;
}
*rc = c & 0xff;
*rh = h;
*rs = s + ((c & 0x300) >> 2);
}
static void mbr_fill_pt_entry(dos_partition_t *pt, lbaint_t start,
lbaint_t relative, lbaint_t size, uchar sys_ind, bool bootable)
{
pt->boot_ind = bootable ? 0x80 : 0x00;
pt->sys_ind = sys_ind;
lba_to_chs(start, &pt->cyl, &pt->head, &pt->sector);
lba_to_chs(start + size - 1, &pt->end_cyl, &pt->end_head, &pt->end_sector);
put_unaligned_le32(relative, &pt->start4);
put_unaligned_le32(size, &pt->size4);
}
int write_mbr_partitions(struct blk_desc *dev,
struct disk_partition *p, int count, unsigned int disksig)
{
ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, dev->blksz);
lbaint_t ext_part_start = 0, ext_part_size = 0, ext_part_sect = 0;
dos_partition_t *pt;
int i;
memset(buffer, 0, dev->blksz);
buffer[DOS_PART_MAGIC_OFFSET] = 0x55;
buffer[DOS_PART_MAGIC_OFFSET + 1] = 0xaa;
put_unaligned_le32(disksig, &buffer[DOS_PART_DISKSIG_OFFSET]);
pt = (dos_partition_t *) (buffer + DOS_PART_TBL_OFFSET);
/* create all primary partitions */
for (i = 0; i < 4 && i < count; i++, pt++) {
mbr_fill_pt_entry(pt, p[i].start, p[i].start, p[i].size,
p[i].sys_ind, p[i].bootable);
if (is_extended(p[i].sys_ind)) {
ext_part_start = p[i].start;
ext_part_size = p[i].size;
ext_part_sect = p[i].start;
}
}
if (i < count && !ext_part_start) {
printf("%s: extended partition is needed for more than 4 partitions\n",
__func__);
return -1;
}
/* write MBR */
if (blk_dwrite(dev, 0, 1, buffer) != 1) {
printf("%s: failed writing 'MBR' (1 blks at 0x0)\n",
__func__);
return -1;
}
/* create extended volumes */
for (; i < count; i++) {
lbaint_t next_ebr = 0;
memset(buffer, 0, dev->blksz);
buffer[DOS_PART_MAGIC_OFFSET] = 0x55;
buffer[DOS_PART_MAGIC_OFFSET + 1] = 0xaa;
pt = (dos_partition_t *) (buffer + DOS_PART_TBL_OFFSET);
mbr_fill_pt_entry(pt, p[i].start, p[i].start - ext_part_sect,
p[i].size, p[i].sys_ind, p[i].bootable);
if (i + 1 < count) {
pt++;
next_ebr = p[i].start + p[i].size;
mbr_fill_pt_entry(pt, next_ebr,
next_ebr - ext_part_start,
p[i+1].start + p[i+1].size - next_ebr,
DOS_PART_TYPE_EXTENDED, 0);
}
/* write EBR */
if (blk_dwrite(dev, ext_part_sect, 1, buffer) != 1) {
printf("%s: failed writing 'EBR' (1 blks at 0x%lx)\n",
__func__, ext_part_sect);
return -1;
}
ext_part_sect = next_ebr;
}
return 0;
}
int layout_mbr_partitions(struct disk_partition *p, int count,
lbaint_t total_sectors)
{
struct disk_partition *ext = NULL;
int i, j;
lbaint_t ext_vol_start;
/* calculate primary partitions start and size if needed */
if (!p[0].start)
p[0].start = DOS_PART_DEFAULT_GAP;
for (i = 0; i < 4 && i < count; i++) {
if (!p[i].start)
p[i].start = p[i - 1].start + p[i - 1].size;
if (!p[i].size) {
lbaint_t end = total_sectors;
lbaint_t allocated = 0;
for (j = i + 1; j < 4 && j < count; j++) {
if (p[j].start) {
end = p[j].start;
break;
}
allocated += p[j].size;
}
p[i].size = end - allocated - p[i].start;
}
if (p[i].sys_ind == 0x05)
ext = &p[i];
}
if (i >= 4 && !ext) {
printf("%s: extended partition is needed for more than 4 partitions\n",
__func__);
return -1;
}
/* calculate extended volumes start and size if needed */
ext_vol_start = ext->start;
for (i = 4; i < count; i++) {
if (!p[i].start)
p[i].start = ext_vol_start + DOS_PART_DEFAULT_GAP;
if (!p[i].size) {
lbaint_t end = ext->start + ext->size;
lbaint_t allocated = 0;
for (j = i + 1; j < count; j++) {
if (p[j].start) {
end = p[j].start - DOS_PART_DEFAULT_GAP;
break;
}
allocated += p[j].size + DOS_PART_DEFAULT_GAP;
}
p[i].size = end - allocated - p[i].start;
}
ext_vol_start = p[i].start + p[i].size;
}
return 0;
}
#endif
int write_mbr_sector(struct blk_desc *dev_desc, void *buf) int write_mbr_sector(struct blk_desc *dev_desc, void *buf)
{ {
if (is_valid_dos_buf(buf)) if (is_valid_dos_buf(buf))

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@ -19,6 +19,8 @@
#define DOS_PART_TYPE_EXTENDED_LBA 0x0F #define DOS_PART_TYPE_EXTENDED_LBA 0x0F
#define DOS_PART_TYPE_EXTENDED_LINUX 0x85 #define DOS_PART_TYPE_EXTENDED_LINUX 0x85
#define DOS_PART_DEFAULT_GAP 2048
typedef struct dos_partition { typedef struct dos_partition {
unsigned char boot_ind; /* 0x80 - active */ unsigned char boot_ind; /* 0x80 - active */
unsigned char head; /* starting head */ unsigned char head; /* starting head */

View File

@ -474,6 +474,11 @@ int is_valid_dos_buf(void *buf);
*/ */
int write_mbr_sector(struct blk_desc *dev_desc, void *buf); int write_mbr_sector(struct blk_desc *dev_desc, void *buf);
int write_mbr_partitions(struct blk_desc *dev,
struct disk_partition *p, int count, unsigned int disksig);
int layout_mbr_partitions(struct disk_partition *p, int count,
lbaint_t total_sectors);
#endif #endif