powerpc/macio: Rework hotplug media bay support

The hotplug mediabay has tendrils deep into drivers/ide code
which makes a libata port reather difficult. In addition it's
ugly and could be done better.

This reworks the interface between the mediabay and the rest
of the world so that:

   - Any macio_driver can now have a mediabay_event callback
which will be called when that driver sits on a mediabay and
it's been either plugged or unplugged. The device type is
passed as an argument. We can now move all the IDE cruft
into the IDE driver itself

   - A check_media_bay() function can be used to take a peek
at the type of device currently in the bay if any, a cleaner
variant of the previous function with the same name.

   - A pair of lock/unlock functions are exposed to allow the
IDE driver to block the hotplug callbacks during the initial
setup and probing of the bay in order to avoid nasty race
conditions.

   - The mediabay code no longer needs to spin on the status
register of the IDE interface when it detects an IDE device,
this is done just fine by the IDE code itself

Overall, less code, simpler, and allows for another driver
than our old drivers/ide based one.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 16 insertions, 11 deletions

diff --git a/arch/powerpc/include/asm/mediabay.h b/arch/powerpc/include/asm/mediabay.h
index b2efb332580..11037a4133e 100644
--- a/arch/powerpc/include/asm/mediabay.h
+++ b/arch/powerpc/include/asm/mediabay.h
@@ -17,26 +17,31 @@
 #define MB_POWER	6	/* media bay contains a Power device (???) */
 #define MB_NO		7	/* media bay contains nothing */
 
-/* Number of bays in the machine or 0 */
-extern int media_bay_count;
+struct macio_dev;
 
-#ifdef CONFIG_BLK_DEV_IDE_PMAC
-#include <linux/ide.h>
+#ifdef CONFIG_PMAC_MEDIABAY
 
-int check_media_bay_by_base(unsigned long base, int what);
-/* called by IDE PMAC host driver to register IDE controller for media bay */
-int media_bay_set_ide_infos(struct device_node *which_bay, unsigned long base,
-			    int irq, ide_hwif_t *hwif);
+/* Check the content type of the bay, returns MB_NO if the bay is still
+ * transitionning
+ */
+extern int check_media_bay(struct macio_dev *bay);
 
-int check_media_bay(struct device_node *which_bay, int what);
+/* The ATA driver uses the calls below to temporarily hold on the
+ * media bay callbacks while initializing the interface
+ */
+extern void lock_media_bay(struct macio_dev *bay);
+extern void unlock_media_bay(struct macio_dev *bay);
 
 #else
 
-static inline int check_media_bay(struct device_node *which_bay, int what)
+static inline int check_media_bay(struct macio_dev *bay)
 {
-	return -ENODEV;
+	return MB_NO;
 }
 
+static inline void lock_media_bay(struct macio_dev *bay) { }
+static inline void unlock_media_bay(struct macio_dev *bay) { }
+
 #endif
 
 #endif /* __KERNEL__ */