Although the commit "98af057092f8f0dabe63c5df08adc2bbfbddb1d2
 ARM: 6126/1: ARM mpcore_wdt: fix build failure and other fixes"
resolved long standing mpcore_wdt driver build problems, it
introduced an error in the relationship between the MPcore watchdog
timer clock rate and mpcore_margin, "MPcore timer margin in seconds",
such that watchdog timeouts are now arbitrary rather than the number
of seconds specified by mpcore_margin.

This change restores mpcore_wdt_keepalive() to its equivalent
implementation prior to commit 98af057 such that watchdog timeouts now
occur as specified by mpcore_margin.

The variable 'mpcore_timer_rate' which caused that build failure was
replaced by 'twd_timer_rate'. Adding exported function to obtain
'twd_timer_rate' value in mpcore_wdt driver.

MPCORE_WATCHDOG needed to build 'mpcore_wdt' already depends on
HAVE_ARM_TWD needed to build 'smp_twd', so from the point of view of
'mpcore_wdt' driver the exported function will always exist.

Signed-off-by: Valentine Barshak <vbarshak@mvista.com>
Signed-off-by: Vitaly Kuzmichev <vkuzmichev@mvista.com>
---

 arch/arm/include/asm/smp_twd.h |    1 +
 arch/arm/kernel/smp_twd.c      |    7 +++++++
 drivers/watchdog/mpcore_wdt.c  |    4 +---
 3 files changed, 9 insertions(+), 3 deletions(-)

--- a/arch/arm/include/asm/smp_twd.h
+++ b/arch/arm/include/asm/smp_twd.h
@@ -33,6 +33,7 @@ struct twd_local_timer name __initdata =
 };
 
 int twd_local_timer_register(struct twd_local_timer *);
+unsigned long twd_timer_get_rate(void);
 
 #ifdef CONFIG_HAVE_ARM_TWD
 void twd_local_timer_of_register(void);
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -10,6 +10,7 @@
  */
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/export.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -376,6 +377,13 @@ int __init twd_local_timer_register(stru
 	return twd_local_timer_common_register();
 }
 
+/* Needed by mpcore_wdt */
+unsigned long twd_timer_get_rate(void)
+{
+	return twd_timer_rate;
+}
+EXPORT_SYMBOL_GPL(twd_timer_get_rate);
+
 #ifdef CONFIG_OF
 const static struct of_device_id twd_of_match[] __initconst = {
 	{ .compatible = "arm,cortex-a9-twd-timer",	},
--- a/drivers/watchdog/mpcore_wdt.c
+++ b/drivers/watchdog/mpcore_wdt.c
@@ -101,9 +101,7 @@ static void mpcore_wdt_keepalive(struct
 
 	spin_lock(&wdt_lock);
 	/* Assume prescale is set to 256 */
-	count =  __raw_readl(wdt->base + TWD_WDOG_COUNTER);
-	count = (0xFFFFFFFFU - count) * (HZ / 5);
-	count = (count / 256) * mpcore_margin;
+	count = (twd_timer_get_rate() / 256) * mpcore_margin;
 
 	/* Reload the counter */
 	writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
