[PATCH] libata: implement ata_wait_register()

As waiting for some register bits to change seems to be a common
operation shared by some controllers, implement helper function
ata_wait_register().  This function also takes care of register write
flushing.

Note that the condition is inverted, the wait is over when the masked
value does NOT match @val.  As we're waiting for bits to change, this
test is more powerful and allows the function to be used in more
places.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/libata.h b/include/linux/libata.h
index d5fd5c06e755..dd5bcb5d29b5 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -543,6 +543,9 @@ extern unsigned int ata_busy_sleep(struct ata_port *ap,
                                    unsigned long timeout);
 extern void ata_port_queue_task(struct ata_port *ap, void (*fn)(void *),
                                 void *data, unsigned long delay);
+extern u32 ata_wait_register(void __iomem *reg, u32 mask, u32 val,
+                             unsigned long interval_msec,
+                             unsigned long timeout_msec);
 
 /*
  * Default driver ops implementations