[PATCHv2 6/6] OMAP3: CPUidle: Added peripheral pwrdm checks into bm check

[Tero Kristo <tero.kristo@nokia.com>]

From: Tero Kristo <tero.kristo@nokia.com>

Following checks are made (and their reasoning):

- If CAM domain is active, prevent idle completely
  * CAM pwrdm does not have HW wakeup capability
- If PER is likely to remain on, prevent PER off
  * Saves on unnecessary context save/restore
- If CORE domain is active, prevent PER off-mode
  * PER off in this case would prevent wakeups from PER completely
- Only allow CORE off, if all peripheral domains are off
  * CORE off will cause a chipwide reset

Also, enabled CHECK_BM flag for C2, as this is needed for the camera case.

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
---
 arch/arm/mach-omap2/cpuidle34xx.c |  118 ++++++++++++++++++++++++++++++++++--
 1 files changed, 111 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index 4a81ef1..dad64a9 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -58,7 +58,8 @@ struct omap3_processor_cx {
 
 struct omap3_processor_cx omap3_power_states[OMAP3_MAX_STATES];
 struct omap3_processor_cx current_cx_state;
-struct powerdomain *mpu_pd, *core_pd;
+struct powerdomain *mpu_pd, *core_pd, *per_pd, *iva2_pd;
+struct powerdomain *sgx_pd, *usb_pd, *cam_pd, *dss_pd;
 
 /*
  * The latencies/thresholds for various C states have
@@ -92,6 +93,22 @@ static int omap3_idle_bm_check(void)
 }
 
 /**
+ * pwrdm_get_idle_state - Get the power state a pwrdm will enter during idle
+ * @pwrdm: powerdomain to check state for
+ *
+ * Checks if the powerdomain can enter idle or not, if yes, will return
+ * the programmed target state for the domain. Otherwise will indicate
+ * that the domain will stay on.
+ * Returns the power state the pwrdm will enter.
+ */
+static int pwrdm_get_idle_state(struct powerdomain *pwrdm)
+{
+	if (pwrdm_can_idle(pwrdm))
+		return pwrdm_read_next_pwrst(pwrdm);
+	return PWRDM_POWER_ON;
+}
+
+/**
  * omap3_enter_idle - Programs OMAP3 to enter the specified state
  * @dev: cpuidle device
  * @state: The target state to be programmed
@@ -153,14 +170,94 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
 			       struct cpuidle_state *state)
 {
 	struct cpuidle_state *new_state = state;
-
-	if ((state->flags & CPUIDLE_FLAG_CHECK_BM) && omap3_idle_bm_check()) {
-		BUG_ON(!dev->safe_state);
-		new_state = dev->safe_state;
+	u32 per_state = 0, saved_per_state = 0, cam_state, usb_state;
+	u32 iva2_state, sgx_state, dss_state, new_core_state;
+	struct omap3_processor_cx *cx;
+	int ret;
+
+	if (state->flags & CPUIDLE_FLAG_CHECK_BM) {
+		if (omap3_idle_bm_check()) {
+			BUG_ON(!dev->safe_state);
+			new_state = dev->safe_state;
+			goto select_state;
+		}
+		cx = cpuidle_get_statedata(state);
+		new_core_state = cx->core_state;
+
+		/* Check if CORE is active, if yes, fallback to inactive */
+		if (!pwrdm_can_idle(core_pd))
+			new_core_state = PWRDM_POWER_INACTIVE;
+
+		/*
+		 * Prevent idle completely if CAM is active.
+		 * CAM does not have wakeup capability in OMAP3.
+		 */
+		cam_state = pwrdm_get_idle_state(cam_pd);
+		if (cam_state == PWRDM_POWER_ON) {
+			new_state = dev->safe_state;
+			goto select_state;
+		}
+
+		/*
+		 * Check if PER can idle or not. If we are not likely
+		 * to idle, deny PER off. This prevents unnecessary
+		 * context save/restore.
+		 */
+		saved_per_state = pwrdm_read_next_pwrst(per_pd);
+		if (pwrdm_can_idle(per_pd)) {
+			per_state = saved_per_state;
+			/*
+			 * Prevent PER off if CORE is active as this
+			 * would disable PER wakeups completely
+			 */
+			if (per_state == PWRDM_POWER_OFF &&
+			    new_core_state > PWRDM_POWER_RET)
+				per_state = PWRDM_POWER_RET;
+
+		} else if (saved_per_state == PWRDM_POWER_OFF)
+			per_state = PWRDM_POWER_RET;
+
+		/*
+		 * If we are attempting CORE off, check if any other
+		 * powerdomains are at retention or higher. CORE off causes
+		 * chipwide reset which would reset these domains also.
+		 */
+		if (new_core_state == PWRDM_POWER_OFF) {
+			dss_state = pwrdm_get_idle_state(dss_pd);
+			iva2_state = pwrdm_get_idle_state(iva2_pd);
+			sgx_state = pwrdm_get_idle_state(sgx_pd);
+			usb_state = pwrdm_get_idle_state(usb_pd);
+
+			if (cam_state > PWRDM_POWER_OFF ||
+			    dss_state > PWRDM_POWER_OFF ||
+			    iva2_state > PWRDM_POWER_OFF ||
+			    per_state > PWRDM_POWER_OFF ||
+			    sgx_state > PWRDM_POWER_OFF ||
+			    usb_state > PWRDM_POWER_OFF)
+				new_core_state = PWRDM_POWER_RET;
+		}
+
+		/* Fallback to new target core state */
+		while (cx->core_state > new_core_state) {
+			state--;
+			cx = cpuidle_get_statedata(state);
+		}
+		new_state = state;
+
+		/* Are we changing PER target state? */
+		if (per_state != saved_per_state)
+			pwrdm_set_next_pwrst(per_pd, per_state);
 	}
 
+select_state:
 	dev->last_state = new_state;
-	return omap3_enter_idle(dev, new_state);
+	ret = omap3_enter_idle(dev, new_state);
+
+	/* Restore potentially tampered PER state */
+	if (per_state != saved_per_state)
+		pwrdm_set_next_pwrst(per_pd, saved_per_state);
+
+	return ret;
 }
 
 DEFINE_PER_CPU(struct cpuidle_device, omap3_idle_dev);
@@ -224,7 +321,8 @@ void omap_init_power_states(void)
 			cpuidle_params_table[OMAP3_STATE_C2].threshold;
 	omap3_power_states[OMAP3_STATE_C2].mpu_state = PWRDM_POWER_INACTIVE;
 	omap3_power_states[OMAP3_STATE_C2].core_state = PWRDM_POWER_INACTIVE;
-	omap3_power_states[OMAP3_STATE_C2].flags = CPUIDLE_FLAG_TIME_VALID;
+	omap3_power_states[OMAP3_STATE_C2].flags = CPUIDLE_FLAG_TIME_VALID |
+				CPUIDLE_FLAG_CHECK_BM;
 
 	/* C3 . MPU CSWR + Core inactive */
 	omap3_power_states[OMAP3_STATE_C3].valid =
@@ -322,6 +420,12 @@ int __init omap3_idle_init(void)
 
 	mpu_pd = pwrdm_lookup("mpu_pwrdm");
 	core_pd = pwrdm_lookup("core_pwrdm");
+	per_pd = pwrdm_lookup("per_pwrdm");
+	iva2_pd = pwrdm_lookup("iva2_pwrdm");
+	sgx_pd = pwrdm_lookup("sgx_pwrdm");
+	usb_pd = pwrdm_lookup("usbhost_pwrdm");
+	cam_pd = pwrdm_lookup("cam_pwrdm");
+	dss_pd = pwrdm_lookup("dss_pwrdm");
 
 	omap_init_power_states();
 	cpuidle_register_driver(&omap3_idle_driver);
-- 
1.5.4.3