ARM: OMAP2+: PM/powerdomain: move omap_set_pwrdm_state() to powerdomain code

Move omap_set_pwrdm_state() from the PM code to the powerdomain code,
and refactor it to split it up into several functions.  A subsequent patch
will rename it to conform with the existing powerdomain function names.

This version includes some additional documentation, based on a
suggestion from Jean Pihet.  It also modifies omap_set_pwrdm_state()
to not bail out early unless both the powerdomain current power state
and the next power state are equal.  (Previously it would terminate
early if the next power state was equal to the target power state,
which was insufficiently rigorous.)

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Jean Pihet <jean.pihet@newoldbits.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Tero Kristo <t-kristo@ti.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/arch/arm/mach-omap2/powerdomain.h b/arch/arm/mach-omap2/powerdomain.h
index 7c1534bb16e9..93e7df824650 100644
--- a/arch/arm/mach-omap2/powerdomain.h
+++ b/arch/arm/mach-omap2/powerdomain.h
@@ -162,6 +162,16 @@ struct powerdomain {
  * @pwrdm_disable_hdwr_sar: Disable Hardware Save-Restore feature for a pd
  * @pwrdm_set_lowpwrstchange: Enable pd transitions from a shallow to deep sleep
  * @pwrdm_wait_transition: Wait for a pd state transition to complete
+ *
+ * Regarding @pwrdm_set_lowpwrstchange: On the OMAP2 and 3-family
+ * chips, a powerdomain's power state is not allowed to directly
+ * transition from one low-power state (e.g., CSWR) to another
+ * low-power state (e.g., OFF) without first waking up the
+ * powerdomain.  This wastes energy.  So OMAP4 chips support the
+ * ability to transition a powerdomain power state directly from one
+ * low-power state to another.  The function pointed to by
+ * @pwrdm_set_lowpwrstchange is intended to configure the OMAP4
+ * hardware powerdomain state machine to enable this feature.
  */
 struct pwrdm_ops {
         int     (*pwrdm_set_next_pwrst)(struct powerdomain *pwrdm, u8 pwrst);
@@ -228,10 +238,11 @@ bool pwrdm_has_hdwr_sar(struct powerdomain *pwrdm);
 int pwrdm_state_switch(struct powerdomain *pwrdm);
 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);
 
+extern int omap_set_pwrdm_state(struct powerdomain *pwrdm, u8 state);
+
 extern void omap242x_powerdomains_init(void);
 extern void omap243x_powerdomains_init(void);
 extern void omap3xxx_powerdomains_init(void);