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author | Sascha Hauer <s.hauer@pengutronix.de> | 2013-04-04 12:01:22 +0200 |
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committer | Sascha Hauer <s.hauer@pengutronix.de> | 2013-06-02 12:35:13 +0200 |
commit | b27af5cdf36c099b2c4f29e9b71252cc8d66e223 (patch) | |
tree | 9e8d73eedf0054bf9998c61fd7b66dd79db09940 /common/partitions/dos.c | |
parent | 5014bf0cc55abd3d10ff71fb18187d479b8aeb21 (diff) | |
download | barebox-b27af5cdf36c099b2c4f29e9b71252cc8d66e223.tar.gz barebox-b27af5cdf36c099b2c4f29e9b71252cc8d66e223.tar.xz |
partition: DOS: Add parameter for the NT disk Signature
The NT disk Signature is a unique 32-bit value in the MBR allowing
to identify a MSDOS partitioned disk. The signature can be used to
specify the Linux rootfs.
This patch adds support for the NT disk Signature in the form of a
device parameter which can both be read and written.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'common/partitions/dos.c')
-rw-r--r-- | common/partitions/dos.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/common/partitions/dos.c b/common/partitions/dos.c index 597f9ba581..b9f31c3784 100644 --- a/common/partitions/dos.c +++ b/common/partitions/dos.c @@ -16,6 +16,8 @@ #include <disks.h> #include <init.h> #include <asm/unaligned.h> +#include <dma.h> +#include <linux/err.h> #include "parser.h" @@ -40,6 +42,74 @@ static int disk_guess_size(struct device_d *dev, struct partition_entry *table) return (int)size; } +static void *read_mbr(struct block_device *blk) +{ + void *buf = dma_alloc(SECTOR_SIZE); + int ret; + + ret = block_read(blk, buf, 0, 1); + if (ret) { + free(buf); + return NULL; + } + + return buf; +} + +static int write_mbr(struct block_device *blk, void *buf) +{ + int ret; + + ret = block_write(blk, buf, 0, 1); + if (ret) + return ret; + + return block_flush(blk); +} + +struct disk_signature_priv { + uint32_t signature; + struct block_device *blk; +}; + +static int dos_set_disk_signature(struct param_d *p, void *_priv) +{ + struct disk_signature_priv *priv = _priv; + struct block_device *blk = priv->blk; + void *buf; + __le32 *disksigp; + int ret; + + buf = read_mbr(blk); + if (!buf) + return -EIO; + + disksigp = buf + 0x1b8; + + *disksigp = cpu_to_le32(priv->signature); + + ret = write_mbr(blk, buf); + + free(buf); + + return ret; +} + +static int dos_get_disk_signature(struct param_d *p, void *_priv) +{ + struct disk_signature_priv *priv = _priv; + struct block_device *blk = priv->blk; + void *buf; + + buf = read_mbr(blk); + if (!buf) + return -EIO; + + priv->signature = le32_to_cpup((__le32 *)(buf + 0x1b8)); + + return 0; +} + /** * Check if a DOS like partition describes this block device * @param blk Block device to register to @@ -55,6 +125,7 @@ static void dos_partition(void *buf, struct block_device *blk, struct partition pentry; uint8_t *buffer = buf; int i; + struct disk_signature_priv *dsp; table = (struct partition_entry *)&buffer[446]; @@ -74,6 +145,23 @@ static void dos_partition(void *buf, struct block_device *blk, dev_dbg(blk->dev, "Skipping empty partition %d\n", i); } } + + dsp = xzalloc(sizeof(*dsp)); + dsp->blk = blk; + + /* + * This parameter contains the NT disk signature. This allows to + * to specify the Linux rootfs using the following syntax: + * + * root=PARTUUID=ssssssss-pp + * + * where ssssssss is a zero-filled hex representation of the 32-bit + * signature and pp is a zero-filled hex representation of the 1-based + * partition number. + */ + dev_add_param_int(blk->dev, "nt_signature", + dos_set_disk_signature, dos_get_disk_signature, + &dsp->signature, "%08x", dsp); } static struct partition_parser dos = { |