diff options
Diffstat (limited to 'include/linux/ata.h')
| -rw-r--r-- | include/linux/ata.h | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/include/linux/ata.h b/include/linux/ata.h index 4c3f5007003..a53318b8cbd 100644 --- a/include/linux/ata.h +++ b/include/linux/ata.h @@ -782,6 +782,56 @@ static inline int atapi_id_dmadir(const u16 *dev_id) return ata_id_major_version(dev_id) >= 7 && (dev_id[62] & 0x8000); } +/* + * ata_id_is_lba_capacity_ok() performs a sanity check on + * the claimed LBA capacity value for the device. + * + * Returns 1 if LBA capacity looks sensible, 0 otherwise. + * + * It is called only once for each device. + */ +static inline int ata_id_is_lba_capacity_ok(u16 *id) +{ + unsigned long lba_sects, chs_sects, head, tail; + + /* No non-LBA info .. so valid! */ + if (id[ATA_ID_CYLS] == 0) + return 1; + + lba_sects = ata_id_u32(id, ATA_ID_LBA_CAPACITY); + + /* + * The ATA spec tells large drives to return + * C/H/S = 16383/16/63 independent of their size. + * Some drives can be jumpered to use 15 heads instead of 16. + * Some drives can be jumpered to use 4092 cyls instead of 16383. + */ + if ((id[ATA_ID_CYLS] == 16383 || + (id[ATA_ID_CYLS] == 4092 && id[ATA_ID_CUR_CYLS] == 16383)) && + id[ATA_ID_SECTORS] == 63 && + (id[ATA_ID_HEADS] == 15 || id[ATA_ID_HEADS] == 16) && + (lba_sects >= 16383 * 63 * id[ATA_ID_HEADS])) + return 1; + + chs_sects = id[ATA_ID_CYLS] * id[ATA_ID_HEADS] * id[ATA_ID_SECTORS]; + + /* perform a rough sanity check on lba_sects: within 10% is OK */ + if (lba_sects - chs_sects < chs_sects/10) + return 1; + + /* some drives have the word order reversed */ + head = (lba_sects >> 16) & 0xffff; + tail = lba_sects & 0xffff; + lba_sects = head | (tail << 16); + + if (lba_sects - chs_sects < chs_sects/10) { + *(__le32 *)&id[ATA_ID_LBA_CAPACITY] = __cpu_to_le32(lba_sects); + return 1; /* LBA capacity is (now) good */ + } + + return 0; /* LBA capacity value may be bad */ +} + static inline void ata_id_to_hd_driveid(u16 *id) { #ifdef __BIG_ENDIAN |