OMAP3: Fixed crash bug with serial + suspend

It was possible for an unhandled interrupt to occur if there was incoming
serial traffic during wakeup from suspend. This was caused by the code
in arch-arm/mach-omap2/serial.c keeping interrupt enabled all the time,
but not acking its interrupts. Applies on top of PM branch.

Use the PM begin/end hooks to ensure that the "serial idle" interrupts
are disabled during the suspend path.  Also, since begin/end hooks are
now used, use the suspend_state that is passed in the begin hook instead
of the enter hook as per the platform_suspend_ops docs.

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

3 files changed, 36 insertions, 2 deletions

diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 528f725722a2..b07efb26de18 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -296,6 +296,8 @@ out:
 }
 
 #ifdef CONFIG_SUSPEND
+static suspend_state_t suspend_state;
+
 static int omap3_pm_prepare(void)
 {
         disable_hlt();
@@ -342,11 +344,11 @@ restore:
         return ret;
 }
 
-static int omap3_pm_enter(suspend_state_t state)
+static int omap3_pm_enter(suspend_state_t unused)
 {
         int ret = 0;
 
-        switch (state) {
+        switch (suspend_state) {
         case PM_SUSPEND_STANDBY:
         case PM_SUSPEND_MEM:
                 ret = omap3_pm_suspend();
@@ -363,7 +365,24 @@ static void omap3_pm_finish(void)
         enable_hlt();
 }
 
+/* Hooks to enable / disable UART interrupts during suspend */
+static int omap3_pm_begin(suspend_state_t state)
+{
+        suspend_state = state;
+        omap_uart_enable_irqs(0);
+        return 0;
+}
+
+static void omap3_pm_end(void)
+{
+        suspend_state = PM_SUSPEND_ON;
+        omap_uart_enable_irqs(1);
+        return;
+}
+
 static struct platform_suspend_ops omap_pm_ops = {
+        .begin          = omap3_pm_begin,
+        .end            = omap3_pm_end,
         .prepare        = omap3_pm_prepare,
         .enter          = omap3_pm_enter,
         .finish         = omap3_pm_finish,
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index c82ec95cd79e..5352d05b42d6 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -435,6 +435,20 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
         WARN_ON(ret);
 }
 
+void omap_uart_enable_irqs(int enable)
+{
+        int ret;
+        struct omap_uart_state *uart;
+
+        list_for_each_entry(uart, &uart_list, node) {
+                if (enable)
+                        ret = request_irq(uart->p->irq, omap_uart_interrupt,
+                                IRQF_SHARED, "serial idle", (void *)uart);
+                else
+                        free_irq(uart->p->irq, (void *)uart);
+        }
+}
+
 static ssize_t sleep_timeout_show(struct kobject *kobj,
                                   struct kobj_attribute *attr,
                                   char *buf)
diff --git a/arch/arm/plat-omap/include/mach/serial.h b/arch/arm/plat-omap/include/mach/serial.h
index 13abd02d1527..def0529c75eb 100644
--- a/arch/arm/plat-omap/include/mach/serial.h
+++ b/arch/arm/plat-omap/include/mach/serial.h
@@ -59,6 +59,7 @@ extern void omap_uart_check_wakeup(void);
 extern void omap_uart_prepare_suspend(void);
 extern void omap_uart_prepare_idle(int num);
 extern void omap_uart_resume_idle(int num);
+extern void omap_uart_enable_irqs(int enable);
 #endif
 
 #endif