ppc64: rtas rtc fixes from Todd Inglett

arch/ppc64/kernel/chrp_setup.c

@@ -72,6 +72,7 @@ extern void openpic_init_IRQ(void);
 
 extern void find_and_init_phbs(void);
 
+extern void pSeries_get_boot_time(struct rtc_time *rtc_time);
 extern void pSeries_get_rtc_time(struct rtc_time *rtc_time);
 extern int  pSeries_set_rtc_time(struct rtc_time *rtc_time);
 void pSeries_calibrate_decr(void);
@@ -256,7 +257,7 @@ chrp_init(unsigned long r3, unsigned long r4, unsigned long r5,
 	ppc_md.power_off      = rtas_power_off;
 	ppc_md.halt           = rtas_halt;
 
-	ppc_md.get_boot_time  = pSeries_get_rtc_time;
+	ppc_md.get_boot_time  = pSeries_get_boot_time;
 	ppc_md.get_rtc_time   = pSeries_get_rtc_time;
 	ppc_md.set_rtc_time   = pSeries_set_rtc_time;
 	ppc_md.calibrate_decr = pSeries_calibrate_decr;

arch/ppc64/kernel/rtas.c

@@ -24,6 +24,7 @@
 #include <asm/machdep.h>
 #include <asm/paca.h>
 #include <asm/page.h>
+#include <asm/param.h>
 #include <asm/system.h>
 #include <asm/abs_addr.h>
 #include <asm/udbg.h>
@@ -178,6 +179,26 @@ rtas_call(int token, int nargs, int nret,
 	return (ulong)((nret > 0) ? rtas_args->rets[0] : 0);
 }
 
+/* Given an RTAS status code of 990n compute the hinted delay of 10^n
+ * (last digit) milliseconds.  For now we bound at n=3 (1 sec).
+ */
+unsigned int
+rtas_extended_busy_delay_time(int status)
+{
+	int order = status - 9900;
+	unsigned int ms;
+
+	if (order < 0)
+		order = 0;	/* RTC depends on this for -2 clock busy */
+	else if (order > 3)
+		order = 3;	/* bound */
+
+	/* Use microseconds for reasonable accuracy */
+	for (ms = 1000; order > 0; order--)
+		ms = ms * 10;
+	return ms / (1000000/HZ); /* round down is fine */
+}
+
 #define FLASH_BLOCK_LIST_VERSION (1UL)
 static void
 rtas_flash_firmware(void)

arch/ppc64/kernel/rtc.c

@@ -35,6 +35,7 @@
 #include <linux/spinlock.h>
 #include <linux/bcd.h>
 
+#include <asm/hardirq.h>
 #include <asm/io.h>
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -340,20 +341,63 @@ void iSeries_get_boot_time(struct rtc_time *tm)
 #endif
 
 #ifdef CONFIG_PPC_PSERIES
-void pSeries_get_rtc_time(struct rtc_time *rtc_tm)
+#define MAX_RTC_WAIT 5000	/* 5 sec */
+#define RTAS_CLOCK_BUSY (-2)
+void pSeries_get_boot_time(struct rtc_time *rtc_tm)
 {
 	unsigned long ret[8];
-        int error;
-	int count;
+	int error, wait_time;
+	unsigned long max_wait_tb;
 
-	/*
-	 * error -2 is clock busy, we keep retrying a few times to see
-	 * if it will come good  -- paulus
+	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, (void *)&ret);
+		if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
+			wait_time = rtas_extended_busy_delay_time(error);
+			/* 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));
+
+	if (error != 0) {
+		printk(KERN_WARNING "error: reading the clock failed (%d)\n",
+			error);
+		return;
+	}
+
+	rtc_tm->tm_sec = ret[5];
+	rtc_tm->tm_min = ret[4];
+	rtc_tm->tm_hour = ret[3];
+	rtc_tm->tm_mday = ret[2];
+	rtc_tm->tm_mon = ret[1] - 1;
+	rtc_tm->tm_year = ret[0] - 1900;
+}
+
+/* NOTE: get_rtc_time will get an error if executed in interrupt context
+ * and if a delay is needed to read the clock.  In this case we just
+ * silently return without updating rtc_tm.
  */
-	count = 0;
+void pSeries_get_rtc_time(struct rtc_time *rtc_tm)
+{
+        unsigned long ret[8];
+	int error, wait_time;
+	unsigned long 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, (void *)&ret);
-	} while (error == -2 && ++count < 1000);
+		if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
+			if (in_interrupt()) {
+				printk(KERN_WARNING "error: reading clock would delay interrupt\n");
+				return;	/* delay not allowed */
+			}
+			wait_time = rtas_extended_busy_delay_time(error);
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(wait_time);
+			error = RTAS_CLOCK_BUSY;
+		}
+	} while (error == RTAS_CLOCK_BUSY && (__get_tb() < max_wait_tb));
 
         if (error != 0) {
                 printk(KERN_WARNING "error: reading the clock failed (%d)\n",
@@ -371,20 +415,24 @@ void pSeries_get_rtc_time(struct rtc_time *rtc_tm)
 
 int pSeries_set_rtc_time(struct rtc_time *tm)
 {
-        int error;
-	int count;
+	int error, wait_time;
+	unsigned long max_wait_tb;
 
-	/*
-	 * error -2 is clock busy, we keep retrying a few times to see
-	 * if it will come good  -- paulus
-	 */
-	count = 0;
+	max_wait_tb = __get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
 	do {
 	        error = rtas_call(rtas_token("set-time-of-day"), 7, 1, NULL,
 				  tm->tm_year + 1900, tm->tm_mon + 1, 
 				  tm->tm_mday, tm->tm_hour, tm->tm_min, 
 				  tm->tm_sec, 0);
-	} while (error == -2 && ++count < 1000);
+		if (error == RTAS_CLOCK_BUSY || rtas_is_extended_busy(error)) {
+			if (in_interrupt())
+				return 1;	/* probably decrementer */
+			wait_time = rtas_extended_busy_delay_time(error);
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(wait_time);
+			error = RTAS_CLOCK_BUSY;
+		}
+	} while (error == RTAS_CLOCK_BUSY && (__get_tb() < max_wait_tb));
 
         if (error != 0)
                 printk(KERN_WARNING "error: setting the clock failed (%d)\n",

include/asm-ppc64/rtas.h

@@ -166,6 +166,13 @@ extern void rtas_restart(char *cmd);
 extern void rtas_power_off(void);
 extern void rtas_halt(void);
 
+/* Given an RTAS status code of 9900..9905 compute the hinted delay */
+unsigned int rtas_extended_busy_delay_time(int status);
+static inline int rtas_is_extended_busy(int status)
+{
+	return status >= 9900 && status <= 9909;
+}
+
 /* Some RTAS ops require a data buffer and that buffer must be < 4G.
  * Rather than having a memory allocator, just use this buffer
  * (get the lock first), make the RTAS call.  Copy the data instead