[PATCH V4 2/4] ARM: smp_twd: mpcore_wdt: Fix watchdog counter loading

[Vitaly Kuzmichev]

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 at mvista.com>
Signed-off-by: Vitaly Kuzmichev <vkuzmichev at mvista.com>
---

Forgot to change EXPORT_SYMBOL -> EXPORT_SYMBOL_GPL, sorry
Other patches are unchanged.

 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(-)

diff --git a/arch/arm/include/asm/smp_twd.h b/arch/arm/include/asm/smp_twd.h
index fed9981..38130b1 100644
--- a/arch/arm/include/asm/smp_twd.h
+++ b/arch/arm/include/asm/smp_twd.h
@@ -24,5 +24,6 @@ extern void __iomem *twd_base;
 
 int twd_timer_ack(void);
 void twd_timer_setup(struct clock_event_device *);
+unsigned long twd_timer_get_rate(void);
 
 #endif
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 2c277d4..dd64fae 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -142,3 +142,10 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
 
 	clockevents_register_device(clk);
 }
+
+/* Needed by mpcore_wdt */
+unsigned long twd_timer_get_rate(void)
+{
+	return twd_timer_rate;
+}
+EXPORT_SYMBOL_GPL(twd_timer_get_rate);
diff --git a/drivers/watchdog/mpcore_wdt.c b/drivers/watchdog/mpcore_wdt.c
index 2b4af22..efde50b 100644
--- a/drivers/watchdog/mpcore_wdt.c
+++ b/drivers/watchdog/mpcore_wdt.c
@@ -99,9 +99,7 @@ static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
 
 	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);
-- 
1.7.3.4