[PATCH] libata: return sense data in HDIO_DRIVE_CMD ioctl

Make the HDIO_DRIVE_CMD ioctl in libata (ATA command pass through) return a
few ATA registers to userspace, following the same convention as the
drivers/ide implementation of the same ioctl.  This is needed to support ATA
commands like CHECK POWER MODE, which return information in nsectors.

This fixes "hdparm -C" on SATA drives.

Forcing the sense data read via the cc flag causes spurious check conditions,
so we filter these out (following the ATA command pass-through specification
T10/04-262r7).

Signed-off-by: Eran Tromer <eran@tromer.org>
Acked-by: Tejun Heo <htejun@gmail.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 39 insertions, 7 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index b0d0cc41f3e8..7af2a4ba4990 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -164,10 +164,10 @@ int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
 {
         int rc = 0;
         u8 scsi_cmd[MAX_COMMAND_SIZE];
-        u8 args[4], *argbuf = NULL;
+        u8 args[4], *argbuf = NULL, *sensebuf = NULL;
         int argsize = 0;
-        struct scsi_sense_hdr sshdr;
         enum dma_data_direction data_dir;
+        int cmd_result;
 
         if (arg == NULL)
                 return -EINVAL;
@@ -175,6 +175,10 @@ int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
         if (copy_from_user(args, arg, sizeof(args)))
                 return -EFAULT;
 
+        sensebuf = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
+        if (!sensebuf)
+                return -ENOMEM;
+
         memset(scsi_cmd, 0, sizeof(scsi_cmd));
 
         if (args[3]) {
@@ -191,7 +195,7 @@ int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
                 data_dir = DMA_FROM_DEVICE;
         } else {
                 scsi_cmd[1]  = (3 << 1); /* Non-data */
-                /* scsi_cmd[2] is already 0 -- no off.line, cc, or data xfer */
+                scsi_cmd[2]  = 0x20;     /* cc but no off.line or data xfer */
                 data_dir = DMA_NONE;
         }
 
@@ -210,18 +214,46 @@ int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
 
         /* Good values for timeout and retries?  Values below
            from scsi_ioctl_send_command() for default case... */
-        if (scsi_execute_req(scsidev, scsi_cmd, data_dir, argbuf, argsize,
-                             &sshdr, (10*HZ), 5)) {
+        cmd_result = scsi_execute(scsidev, scsi_cmd, data_dir, argbuf, argsize,
+                                  sensebuf, (10*HZ), 5, 0);
+
+        if (driver_byte(cmd_result) == DRIVER_SENSE) {/* sense data available */
+                u8 *desc = sensebuf + 8;
+                cmd_result &= ~(0xFF<<24); /* DRIVER_SENSE is not an error */
+
+                /* If we set cc then ATA pass-through will cause a
+                 * check condition even if no error. Filter that. */
+                if (cmd_result & SAM_STAT_CHECK_CONDITION) {
+                        struct scsi_sense_hdr sshdr;
+                        scsi_normalize_sense(sensebuf, SCSI_SENSE_BUFFERSIZE,
+                                              &sshdr);
+                        if (sshdr.sense_key==0 &&
+                            sshdr.asc==0 && sshdr.ascq==0)
+                                cmd_result &= ~SAM_STAT_CHECK_CONDITION;
+                }
+
+                /* Send userspace a few ATA registers (same as drivers/ide) */
+                if (sensebuf[0] == 0x72 &&     /* format is "descriptor" */
+                    desc[0] == 0x09 ) {        /* code is "ATA Descriptor" */
+                        args[0] = desc[13];    /* status */
+                        args[1] = desc[3];     /* error */
+                        args[2] = desc[5];     /* sector count (0:7) */
+                        if (copy_to_user(arg, args, sizeof(args)))
+                                rc = -EFAULT;
+                }
+        }
+
+
+        if (cmd_result) {
                 rc = -EIO;
                 goto error;
         }
 
-        /* Need code to retrieve data from check condition? */
-
         if ((argbuf)
          && copy_to_user(arg + sizeof(args), argbuf, argsize))
                 rc = -EFAULT;
 error:
+        kfree(sensebuf);
         kfree(argbuf);
         return rc;
 }