ide: add struct ide_taskfile (take 2)

* Don't set write-only ide_task_t.hobRegister[6] and ide_task_t.hobRegister[7]
  in idedisk_set_max_address_ext().

* Add struct ide_taskfile and use it in ide_task_t instead of tfRegister[]
  and hobRegister[].

* Remove no longer needed IDE_CONTROL_OFFSET_HOB define.

* Add #ifndef/#endif __KERNEL__ around definitions of {task,hob}_struct_t.

While at it:

* Use ATA_LBA define for LBA bit (0x40) as suggested by Tejun Heo.

v2:
* Add missing newlines. (Noticed by Sergei)

* Use ~ATA_LBA instead of 0xBF. (Noticed by Sergei)

* Use unnamed unions for error/feature and status/command.
  (Suggested by Sergei).

There should be no functionality changes caused by this patch.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index f4e8a0c..4aac1cc 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -642,9 +642,9 @@
 
 int ide_ata66_check (ide_drive_t *drive, ide_task_t *args)
 {
-	if ((args->tfRegister[IDE_COMMAND_OFFSET] == WIN_SETFEATURES) &&
-	    (args->tfRegister[IDE_SECTOR_OFFSET] > XFER_UDMA_2) &&
-	    (args->tfRegister[IDE_FEATURE_OFFSET] == SETFEATURES_XFER)) {
+	if (args->tf.command == WIN_SETFEATURES &&
+	    args->tf.lbal > XFER_UDMA_2 &&
+	    args->tf.feature == SETFEATURES_XFER) {
 		if (eighty_ninty_three(drive) == 0) {
 			printk(KERN_WARNING "%s: UDMA speeds >UDMA33 cannot "
 					    "be set\n", drive->name);
@@ -662,9 +662,9 @@
  */
 int set_transfer (ide_drive_t *drive, ide_task_t *args)
 {
-	if ((args->tfRegister[IDE_COMMAND_OFFSET] == WIN_SETFEATURES) &&
-	    (args->tfRegister[IDE_SECTOR_OFFSET] >= XFER_SW_DMA_0) &&
-	    (args->tfRegister[IDE_FEATURE_OFFSET] == SETFEATURES_XFER) &&
+	if (args->tf.command == WIN_SETFEATURES &&
+	    args->tf.lbal >= XFER_SW_DMA_0 &&
+	    args->tf.feature == SETFEATURES_XFER &&
 	    (drive->id->dma_ultra ||
 	     drive->id->dma_mword ||
 	     drive->id->dma_1word))