[PATCH] powerpc: reorg RTAS delay code

This patch attempts to handle RTAS "busy" return codes in a more simple
and consistent manner.  Typical callers of RTAS shouldn't have to
manage wait times and delay calls.

This patch also changes the kernel to use msleep() rather than udelay()
when a runtime delay is necessary.  This will avoid CPU soft lockups
for extended delay conditions.

Signed-off-by: John Rose <johnrose@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 16 insertions, 14 deletions

diff --git a/arch/powerpc/kernel/rtas-rtc.c b/arch/powerpc/kernel/rtas-rtc.c
index 34d073fb6091..77578c093dda 100644
--- a/arch/powerpc/kernel/rtas-rtc.c
+++ b/arch/powerpc/kernel/rtas-rtc.c
@@ -14,19 +14,20 @@
 unsigned long __init rtas_get_boot_time(void)
 {
 	int ret[8];
-	int error, wait_time;
+	int error;
+	unsigned int wait_time;
 	u64 max_wait_tb;
 
 	max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
 	do {
 		error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
-		if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
-			wait_time = rtas_extended_busy_delay_time(error);
+
+		wait_time = rtas_busy_delay_time(error);
+		if (wait_time) {
 			/* This is boot time so we spin. */
 			udelay(wait_time*1000);
-			error = RTAS_CLOCK_BUSY;
 		}
-	} while (error == RTAS_CLOCK_BUSY && (get_tb() < max_wait_tb));
+	} while (wait_time && (get_tb() < max_wait_tb));
 
 	if (error != 0 && printk_ratelimit()) {
 		printk(KERN_WARNING "error: reading the clock failed (%d)\n",
@@ -44,24 +45,25 @@ unsigned long __init rtas_get_boot_time(void)
 void rtas_get_rtc_time(struct rtc_time *rtc_tm)
 {
         int ret[8];
-	int error, wait_time;
+	int error;
+	unsigned int wait_time;
 	u64 max_wait_tb;
 
 	max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
 	do {
 		error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
-		if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
+
+		wait_time = rtas_busy_delay_time(error);
+		if (wait_time) {
 			if (in_interrupt() && printk_ratelimit()) {
 				memset(rtc_tm, 0, sizeof(struct rtc_time));
 				printk(KERN_WARNING "error: reading clock"
 				       " would delay interrupt\n");
 				return;	/* delay not allowed */
 			}
-			wait_time = rtas_extended_busy_delay_time(error);
 			msleep(wait_time);
-			error = RTAS_CLOCK_BUSY;
 		}
-	} while (error == RTAS_CLOCK_BUSY && (get_tb() < max_wait_tb));
+	} while (wait_time && (get_tb() < max_wait_tb));
 
         if (error != 0 && printk_ratelimit()) {
                 printk(KERN_WARNING "error: reading the clock failed (%d)\n",
@@ -88,14 +90,14 @@ int rtas_set_rtc_time(struct rtc_time *tm)
 				  tm->tm_year + 1900, tm->tm_mon + 1,
 				  tm->tm_mday, tm->tm_hour, tm->tm_min,
 				  tm->tm_sec, 0);
-		if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
+
+		wait_time = rtas_busy_delay_time(error);
+		if (wait_time) {
 			if (in_interrupt())
 				return 1;	/* probably decrementer */
-			wait_time = rtas_extended_busy_delay_time(error);
 			msleep(wait_time);
-			error = RTAS_CLOCK_BUSY;
 		}
-	} while (error == RTAS_CLOCK_BUSY && (get_tb() < max_wait_tb));
+	} while (wait_time && (get_tb() < max_wait_tb));
 
         if (error != 0 && printk_ratelimit())
                 printk(KERN_WARNING "error: setting the clock failed (%d)\n",