ARM: OMAP2+: powerdomain: allow pre/post transtion to be per pwrdm

Iteration over all power domains in the idle path is unnecessary since
only power domains that are transitioning need to be accounted for.
Also PRCM register accesses are known to be expensive, so the
additional latency added to the idle path is signficiant.

In order allow the pre/post transitions to be isolated and called
per-pwrdm, change the API so passing in a specific power domain will
trigger the pre/post transtion accounting for only that specific power
domain.  Passing NULL means iterating over all power domains as is
current behavior.
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Grazvydas Ignotas <notasas@gmail.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

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

@@ -255,7 +255,7 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
 		return -ENXIO;
 	}
 
-	pwrdm_pre_transition();
+	pwrdm_pre_transition(NULL);
 
 	/*
 	 * Check MPUSS next state and save interrupt controller if needed.
@@ -287,7 +287,7 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
 	wakeup_cpu = smp_processor_id();
 	set_cpu_next_pwrst(wakeup_cpu, PWRDM_POWER_ON);
 
-	pwrdm_post_transition();
+	pwrdm_post_transition(NULL);
 
 	return 0;
 }

arch/arm/mach-omap2/pm34xx.c

@@ -273,7 +273,7 @@ void omap_sram_idle(void)
 	per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
 	core_next_state = pwrdm_read_next_pwrst(core_pwrdm);
 
-	pwrdm_pre_transition();
+	pwrdm_pre_transition(NULL);
 
 	/* PER */
 	if (per_next_state < PWRDM_POWER_ON) {
@@ -338,7 +338,7 @@ void omap_sram_idle(void)
 	}
 	omap3_intc_resume_idle();
 
-	pwrdm_post_transition();
+	pwrdm_post_transition(NULL);
 
 	/* PER */
 	if (per_next_state < PWRDM_POWER_ON)

arch/arm/mach-omap2/powerdomain.c

@@ -981,15 +981,23 @@ int pwrdm_state_switch(struct powerdomain *pwrdm)
 	return ret;
 }
 
-int pwrdm_pre_transition(void)
+int pwrdm_pre_transition(struct powerdomain *pwrdm)
 {
-	pwrdm_for_each(_pwrdm_pre_transition_cb, NULL);
+	if (pwrdm)
+		_pwrdm_pre_transition_cb(pwrdm, NULL);
+	else
+		pwrdm_for_each(_pwrdm_pre_transition_cb, NULL);
+
 	return 0;
 }
 
-int pwrdm_post_transition(void)
+int pwrdm_post_transition(struct powerdomain *pwrdm)
 {
-	pwrdm_for_each(_pwrdm_post_transition_cb, NULL);
+	if (pwrdm)
+		_pwrdm_post_transition_cb(pwrdm, NULL);
+	else
+		pwrdm_for_each(_pwrdm_post_transition_cb, NULL);
+
 	return 0;
 }
 

arch/arm/mach-omap2/powerdomain.h

@@ -213,8 +213,8 @@ bool pwrdm_has_hdwr_sar(struct powerdomain *pwrdm);
 int pwrdm_wait_transition(struct powerdomain *pwrdm);
 
 int pwrdm_state_switch(struct powerdomain *pwrdm);
-int pwrdm_pre_transition(void);
-int pwrdm_post_transition(void);
+int pwrdm_pre_transition(struct powerdomain *pwrdm);
+int pwrdm_post_transition(struct powerdomain *pwrdm);
 int pwrdm_set_lowpwrstchange(struct powerdomain *pwrdm);
 int pwrdm_get_context_loss_count(struct powerdomain *pwrdm);
 bool pwrdm_can_ever_lose_context(struct powerdomain *pwrdm);