ARM: OMAP5 / DRA7: Enable CPU RET on suspend

On OMAP5 / DRA7, prevent a CPU powerdomain OFF and resulting MPU OSWR
and instead attempt a CPU RET and side effect, MPU RET in suspend.

NOTE: the hardware was originally designed to be capable of achieving
deep power states such as OFF and OSWR, however due to various issues
and risks, deepest valid state was determined to be CSWR - hence we use
the errata framework to handle this case.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
[nm@ti.com: updates]
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>

4 files changed, 17 insertions, 3 deletions

diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
index 207fce2d6932..297352f214df 100644
--- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
+++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
@@ -242,6 +242,10 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
                 save_state = 1;
                 break;
         case PWRDM_POWER_RET:
+                if (IS_PM44XX_ERRATUM(PM_OMAP4_CPU_OSWR_DISABLE)) {
+                        save_state = 0;
+                        break;
+                }
         default:
                 /*
                  * CPUx CSWR is invalid hardware state. Also CPUx OSWR
diff --git a/arch/arm/mach-omap2/omap-wakeupgen.c b/arch/arm/mach-omap2/omap-wakeupgen.c
index e844e1603d76..f961c46453b9 100644
--- a/arch/arm/mach-omap2/omap-wakeupgen.c
+++ b/arch/arm/mach-omap2/omap-wakeupgen.c
@@ -32,6 +32,7 @@
 #include "soc.h"
 #include "omap4-sar-layout.h"
 #include "common.h"
+#include "pm.h"
 
 #define AM43XX_NR_REG_BANKS     7
 #define AM43XX_IRQS             224
@@ -381,7 +382,7 @@ static struct notifier_block irq_notifier_block = {
 static void __init irq_pm_init(void)
 {
         /* FIXME: Remove this when MPU OSWR support is added */
-        if (!soc_is_omap54xx())
+        if (!IS_PM44XX_ERRATUM(PM_OMAP4_CPU_OSWR_DISABLE))
                 cpu_pm_register_notifier(&irq_notifier_block);
 }
 #else
diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index e150102d6c06..425bfcd67db6 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -101,6 +101,7 @@ static inline void enable_omap3630_toggle_l2_on_restore(void) { }
 #endif          /* defined(CONFIG_PM) && defined(CONFIG_ARCH_OMAP3) */
 
 #define PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD      (1 << 0)
+#define PM_OMAP4_CPU_OSWR_DISABLE               (1 << 1)
 
 #if defined(CONFIG_PM) && defined(CONFIG_ARCH_OMAP4)
 extern u16 pm44xx_errata;
diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c
index b6f243db200d..64df620075a5 100644
--- a/arch/arm/mach-omap2/pm44xx.c
+++ b/arch/arm/mach-omap2/pm44xx.c
@@ -36,6 +36,8 @@ struct power_state {
         struct list_head node;
 };
 
+static u32 cpu_suspend_state = PWRDM_POWER_OFF;
+
 static LIST_HEAD(pwrst_list);
 
 #ifdef CONFIG_SUSPEND
@@ -66,7 +68,7 @@ static int omap4_pm_suspend(void)
          * domain CSWR is not supported by hardware.
          * More details can be found in OMAP4430 TRM section 4.3.4.2.
          */
-        omap4_enter_lowpower(cpu_id, PWRDM_POWER_OFF);
+        omap4_enter_lowpower(cpu_id, cpu_suspend_state);
 
         /* Restore next powerdomain state */
         list_for_each_entry(pwrst, &pwrst_list, node) {
@@ -112,8 +114,11 @@ static int __init pwrdms_setup(struct powerdomain *pwrdm, void *unused)
          * through hotplug path and CPU0 explicitly programmed
          * further down in the code path
          */
-        if (!strncmp(pwrdm->name, "cpu", 3))
+        if (!strncmp(pwrdm->name, "cpu", 3)) {
+                if (IS_PM44XX_ERRATUM(PM_OMAP4_CPU_OSWR_DISABLE))
+                        cpu_suspend_state = PWRDM_POWER_RET;
                 return 0;
+        }
 
         pwrst = kmalloc(sizeof(struct power_state), GFP_ATOMIC);
         if (!pwrst)
@@ -238,6 +243,9 @@ int __init omap4_pm_init_early(void)
         if (cpu_is_omap446x())
                 pm44xx_errata |= PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD;
 
+        if (soc_is_omap54xx() || soc_is_dra7xx())
+                pm44xx_errata |= PM_OMAP4_CPU_OSWR_DISABLE;
+
         return 0;
 }