ide: use ->tf_read in ide_read_error()

* Add IDE_TFLAG_IN_FEATURE taskfile flag for reading Feature
  register and handle it in ->tf_read.

* Convert ide_read_error() to use ->tf_read instead of ->INB,
  then uninline and export it.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index 1983b35..113db87 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -241,6 +241,8 @@
 	/* be sure we're looking at the low order bits */
 	tf_outb(ATA_DEVCTL_OBS & ~0x80, io_ports->ctl_addr);
 
+	if (task->tf_flags & IDE_TFLAG_IN_FEATURE)
+		tf->feature = tf_inb(io_ports->feature_addr);
 	if (task->tf_flags & IDE_TFLAG_IN_NSECT)
 		tf->nsect  = tf_inb(io_ports->nsect_addr);
 	if (task->tf_flags & IDE_TFLAG_IN_LBAL)
@@ -390,6 +392,19 @@
 	hwif->output_data = ata_output_data;
 }
 
+u8 ide_read_error(ide_drive_t *drive)
+{
+	ide_task_t task;
+
+	memset(&task, 0, sizeof(task));
+	task.tf_flags = IDE_TFLAG_IN_FEATURE;
+
+	drive->hwif->tf_read(drive, &task);
+
+	return task.tf.error;
+}
+EXPORT_SYMBOL_GPL(ide_read_error);
+
 void ide_fix_driveid (struct hd_driveid *id)
 {
 #ifndef __LITTLE_ENDIAN