ARM: OMAP4+: CPUidle: Deprecate use of omap4_mpuss_read_prev_context_state()

Current OMAP4 CPUIdle driver is using omap4_mpuss_read_prev_context_state()
to check whether the MPU cluster lost context or not before calling
cpu_cluster_pm_exit().  This was initially done an optimization for
corner cases, where if the cluster low power entry fails for some
reason, the cluster context restore gets skipped.  However, since
reading the previous context is expensive (involving slow accesses to
the PRCM), it's better to avoid it and simply check the target cluster
state instead.

Moving forward, OMAP CPUidle drivers needs to be moved to drivers/idle/*
once the PRM/CM code gets moved to drivers. This patch also reduces one
dependency with platform code for idle driver movement.

Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
[khilman@linaro.org: minor changelog edits]
Signed-off-by: Kevin Hilman <khilman@linaro.org>

arch/arm/mach-omap2/common.h

@@ -249,7 +249,6 @@ extern int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state);
 extern int omap4_finish_suspend(unsigned long cpu_state);
 extern void omap4_cpu_resume(void);
 extern int omap4_hotplug_cpu(unsigned int cpu, unsigned int power_state);
-extern u32 omap4_mpuss_read_prev_context_state(void);
 #else
 static inline int omap4_enter_lowpower(unsigned int cpu,
 					unsigned int power_state)
@@ -277,10 +276,6 @@ static inline int omap4_finish_suspend(unsigned long cpu_state)
 static inline void omap4_cpu_resume(void)
 {}
 
-static inline u32 omap4_mpuss_read_prev_context_state(void)
-{
-	return 0;
-}
 #endif
 
 struct omap_sdrc_params;

arch/arm/mach-omap2/cpuidle44xx.c

@@ -145,7 +145,8 @@ static int omap4_enter_idle_coupled(struct cpuidle_device *dev,
 	 * Call idle CPU cluster PM exit notifier chain
 	 * to restore GIC and wakeupgen context.
 	 */
-	if (omap4_mpuss_read_prev_context_state())
+	if ((cx->mpu_state == PWRDM_POWER_RET) &&
+		(cx->mpu_logic_state == PWRDM_POWER_OFF))
 		cpu_cluster_pm_exit();
 
 fail:

arch/arm/mach-omap2/omap-mpuss-lowpower.c

@@ -139,20 +139,6 @@ static inline void cpu_clear_prev_logic_pwrst(unsigned int cpu_id)
 	}
 }
 
-/**
- * omap4_mpuss_read_prev_context_state:
- * Function returns the MPUSS previous context state
- */
-u32 omap4_mpuss_read_prev_context_state(void)
-{
-	u32 reg;
-
-	reg = omap4_prminst_read_inst_reg(OMAP4430_PRM_PARTITION,
-		OMAP4430_PRM_MPU_INST, OMAP4_RM_MPU_MPU_CONTEXT_OFFSET);
-	reg &= OMAP4430_LOSTCONTEXT_DFF_MASK;
-	return reg;
-}
-
 /*
  * Store the CPU cluster state for L2X0 low power operations.
  */