[PATCH v3 20/33] swim: Deduplicate polling loops

[Finn Thain <fthain@linux-m68k.org>]

Replace duplicated polling loops with poll_timeout_us(). Change the
interruptible sleep to uninterruptible because signal delivery shouldn't
be allowed to shorten delays required by the drive hardware.

Change the timeout for the !STEP transition to 20 ms in accordance with
the maximum interval required by the UPD72070 spec. The existing 1 second
timeout is impractical considering the number of steps in a typical seek.

Change the return type of swim_readbit() to bool because that way the
bit names make sense i.e. the reader doesn't have to remember to invert
the active-low logic used for drive signals.

Fixes: 8852ecd97488 ("m68k: mac - Add SWIM floppy support")
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
---
Changed since v1:
 - Dropped swim_readbit_timeout_atomic() as it's no longer needed.
---
 drivers/block/swim.c | 39 ++++++++-------------------------------
 1 file changed, 8 insertions(+), 31 deletions(-)

diff --git a/drivers/block/swim.c b/drivers/block/swim.c
index ea4663945505..59e00fb2bff5 100644
--- a/drivers/block/swim.c
+++ b/drivers/block/swim.c
@@ -19,6 +19,7 @@
 #include <linux/major.h>
 #include <linux/mutex.h>
 #include <linux/hdreg.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>
@@ -296,7 +297,7 @@ static inline void swim_action(struct swim __iomem *base, int action)
 	local_irq_restore(flags);
 }
 
-static inline int swim_readbit(struct swim __iomem *base, int bit)
+static inline bool swim_readbit(struct swim __iomem *base, int bit)
 {
 	int stat;
 
@@ -309,6 +310,9 @@ static inline int swim_readbit(struct swim __iomem *base, int bit)
 	return (stat & SENSE) == 0;
 }
 
+#define swim_readbit_timeout(base, bit, val, timeout_us) \
+	poll_timeout_us(, swim_readbit(base, bit) == val, 1000, timeout_us, false)
+
 static inline void swim_drive(struct swim __iomem *base,
 			      enum drive_location location)
 {
@@ -331,16 +335,8 @@ static inline void swim_motor(struct swim __iomem *base,
 			      enum motor_action action)
 {
 	if (action == ON) {
-		int i;
-
 		swim_action(base, MOTOR_ON);
-
-		for (i = 0; i < 2*HZ; i++) {
-			if (swim_readbit(base, MOTOR_ON))
-				break;
-			set_current_state(TASK_INTERRUPTIBLE);
-			schedule_timeout(1);
-		}
+		swim_readbit_timeout(base, MOTOR_ON, true, 2000 * 1000);
 	} else if (action == OFF) {
 		swim_action(base, MOTOR_OFF);
 		swim_write(base, phase, RELAX | PHASE_PIN_DIR);
@@ -349,16 +345,8 @@ static inline void swim_motor(struct swim __iomem *base,
 
 static inline void swim_eject(struct swim __iomem *base)
 {
-	int i;
-
 	swim_action(base, EJECT);
-
-	for (i = 0; i < 2*HZ; i++) {
-		if (!swim_readbit(base, DISK_IN))
-			break;
-		set_current_state(TASK_INTERRUPTIBLE);
-		schedule_timeout(1);
-	}
+	swim_readbit_timeout(base, DISK_IN, false, 2000 * 1000);
 }
 
 static inline void swim_head(struct swim __iomem *base, enum head head)
@@ -373,19 +361,8 @@ static inline void swim_head(struct swim __iomem *base, enum head head)
 
 static inline int swim_step(struct swim __iomem *base)
 {
-	int wait;
-
 	swim_action(base, STEP);
-
-	for (wait = 0; wait < HZ; wait++) {
-
-		set_current_state(TASK_INTERRUPTIBLE);
-		schedule_timeout(1);
-
-		if (!swim_readbit(base, STEP))
-			return 0;
-	}
-	return -1;
+	return swim_readbit_timeout(base, STEP, false, 20 * 1000);
 }
 
 static inline int swim_track00(struct swim __iomem *base)
-- 
2.52.0