[libata] support for > 512 byte sectors (e.g. 4K Native)

This change enables my x86 machine to recognize and talk to a
"Native 4K" SATA device.

When I started working on this, I didn't know Matthew Wilcox had
posted a similar patch 2 years ago:
  http://git.kernel.org/?p=linux/kernel/git/willy/ata.git;a=shortlog;h=refs/heads/ata-large-sectors

Gwendal Grignou pointed me at the the above code and small portions of
this patch include Matthew's work. That's why Mathew is first on the
"Signed-off-by:". I've NOT included his use of a bitmap to determine
512 vs Native for ATA command block size - just used a simple table.
And bugs are almost certainly mine.

Lastly, the patch has been tested with a native 4K 'Engineering
Sample' drive provided by Hitachi GST.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Grant Grundler <grundler@google.com>
Reviewed-by: Gwendal Grignou <gwendal@google.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 40 insertions, 6 deletions

diff --git a/include/linux/ata.h b/include/linux/ata.h
index fe6e681a9d74..0c4929fa34d3 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -89,6 +89,7 @@ enum {
         ATA_ID_SPG              = 98,
         ATA_ID_LBA_CAPACITY_2   = 100,
         ATA_ID_SECTOR_SIZE      = 106,
+        ATA_ID_LOGICAL_SECTOR_SIZE      = 117,  /* and 118 */
         ATA_ID_LAST_LUN         = 126,
         ATA_ID_DLF              = 128,
         ATA_ID_CSFO             = 129,
@@ -640,16 +641,49 @@ static inline int ata_id_flush_ext_enabled(const u16 *id)
         return (id[ATA_ID_CFS_ENABLE_2] & 0x2400) == 0x2400;
 }
 
-static inline int ata_id_has_large_logical_sectors(const u16 *id)
+static inline u32 ata_id_logical_sector_size(const u16 *id)
 {
-        if ((id[ATA_ID_SECTOR_SIZE] & 0xc000) != 0x4000)
-                return 0;
-        return id[ATA_ID_SECTOR_SIZE] & (1 << 13);
+        /* T13/1699-D Revision 6a, Sep 6, 2008. Page 128.
+         * IDENTIFY DEVICE data, word 117-118.
+         * 0xd000 ignores bit 13 (logical:physical > 1)
+         */
+        if ((id[ATA_ID_SECTOR_SIZE] & 0xd000) == 0x5000)
+                return (((id[ATA_ID_LOGICAL_SECTOR_SIZE+1] << 16)
+                         + id[ATA_ID_LOGICAL_SECTOR_SIZE]) * sizeof(u16)) ;
+        return ATA_SECT_SIZE;
+}
+
+static inline u8 ata_id_log2_per_physical_sector(const u16 *id)
+{
+        /* T13/1699-D Revision 6a, Sep 6, 2008. Page 128.
+         * IDENTIFY DEVICE data, word 106.
+         * 0xe000 ignores bit 12 (logical sector > 512 bytes)
+         */
+        if ((id[ATA_ID_SECTOR_SIZE] & 0xe000) == 0x6000)
+                return (id[ATA_ID_SECTOR_SIZE] & 0xf);
+        return 0;
 }
 
-static inline u16 ata_id_logical_per_physical_sectors(const u16 *id)
+/* Offset of logical sectors relative to physical sectors.
+ *
+ * If device has more than one logical sector per physical sector
+ * (aka 512 byte emulation), vendors might offset the "sector 0" address
+ * so sector 63 is "naturally aligned" - e.g. FAT partition table.
+ * This avoids Read/Mod/Write penalties when using FAT partition table
+ * and updating "well aligned" (FS perspective) physical sectors on every
+ * transaction.
+ */
+static inline u16 ata_id_logical_sector_offset(const u16 *id,
+         u8 log2_per_phys)
 {
-        return 1 << (id[ATA_ID_SECTOR_SIZE] & 0xf);
+        u16 word_209 = id[209];
+
+        if ((log2_per_phys > 1) && (word_209 & 0xc000) == 0x4000) {
+                u16 first = word_209 & 0x3fff;
+                if (first > 0)
+                        return (1 << log2_per_phys) - first;
+        }
+        return 0;
 }
 
 static inline int ata_id_has_lba48(const u16 *id)