ide: allow ide_dev_read_id() to be called from the IRQ context

* Un-static __ide_wait_stat().

* Allow ide_dev_read_id() helper to be called from the IRQ context by
  adding irq_ctx flag and using mdelay()/__ide_wait_stat() when needed.

* Switch ide_driveid_update() to set irq_ctx flag.

This change is needed for the consecutive patch which fixes races in
handling of user-space SET XFER commands but for improved bisectability
and clarity it is better to do it in a separate patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/ide.h b/include/linux/ide.h
index edc93a6..cb6cd04 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1081,6 +1081,7 @@
 
 int ide_busy_sleep(ide_drive_t *, unsigned long, int);
 
+int __ide_wait_stat(ide_drive_t *, u8, u8, unsigned long, u8 *);
 int ide_wait_stat(ide_startstop_t *, ide_drive_t *, u8, u8, unsigned long);
 
 ide_startstop_t ide_do_park_unpark(ide_drive_t *, struct request *);
@@ -1169,7 +1170,7 @@
 
 int ide_taskfile_ioctl(ide_drive_t *, unsigned long);
 
-int ide_dev_read_id(ide_drive_t *, u8, u16 *);
+int ide_dev_read_id(ide_drive_t *, u8, u16 *, int);
 
 extern int ide_driveid_update(ide_drive_t *);
 extern int ide_config_drive_speed(ide_drive_t *, u8);