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-rw-r--r--include/linux/ata.h50
1 files changed, 50 insertions, 0 deletions
diff --git a/include/linux/ata.h b/include/linux/ata.h
index 4c3f50070033..a53318b8cbd0 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