Merge tag 'omap-devel-pm-for-v3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into next/pm

From: Tony Lindgren <tony@atomide.com>:

Here are some omap PM changes that reimplement omap PRCM I/O chain
code for wake-ups, and improve idle latencies for cpuidle.

* tag 'omap-devel-pm-for-v3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  ARM: OMAP2+: PM: fix IRQ_NOAUTOEN removal by mis-merge
  ARM: OMAP3: PM: cpuidle: optimize the clkdm idle latency in C1 state
  ARM: OMAP3: PM: cpuidle: optimize the PER latency in C1 state
  ARM: OMAP3: PM: cpuidle: default to C1 in next_valid_state
  ARM: OMAP3: PM: cleanup cam_pwrdm leftovers
  ARM: OMAP3: PM: call pre/post transition per powerdomain
  ARM: OMAP2+: powerdomain: allow pre/post transtion to be per pwrdm
  ARM: OMAP3: PM: Remove IO Daisychain control from cpuidle
  ARM: OMAP3PLUS: hwmod: reconfigure IO Daisychain during hwmod mux
  ARM: OMAP3+: PRM: Enable IO wake up
  ARM: OMAP4: PRM: Add IO Daisychain support
  ARM: OMAP3: PM: Move IO Daisychain function to omap3 prm file
  ARM: OMAP3: PM: correct enable/disable of daisy io chain
  ARM: OMAP2+: PRM: fix compile for OMAP4-only build

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

11 files changed, 216 insertions, 107 deletions

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index 207bc1c7759f..e6ae3fe5cdc6 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -77,20 +77,6 @@ static struct omap3_idle_statedata omap3_idle_data[] = {
 
 static struct powerdomain *mpu_pd, *core_pd, *per_pd, *cam_pd;
 
-static int _cpuidle_allow_idle(struct powerdomain *pwrdm,
-				struct clockdomain *clkdm)
-{
-	clkdm_allow_idle(clkdm);
-	return 0;
-}
-
-static int _cpuidle_deny_idle(struct powerdomain *pwrdm,
-				struct clockdomain *clkdm)
-{
-	clkdm_deny_idle(clkdm);
-	return 0;
-}
-
 static int __omap3_enter_idle(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv,
 				int index)
@@ -108,8 +94,8 @@ static int __omap3_enter_idle(struct cpuidle_device *dev,
 
 	/* Deny idle for C1 */
 	if (index == 0) {
-		pwrdm_for_each_clkdm(mpu_pd, _cpuidle_deny_idle);
-		pwrdm_for_each_clkdm(core_pd, _cpuidle_deny_idle);
+		clkdm_deny_idle(mpu_pd->pwrdm_clkdms[0]);
+		clkdm_deny_idle(core_pd->pwrdm_clkdms[0]);
 	}
 
 	/*
@@ -131,8 +117,8 @@ static int __omap3_enter_idle(struct cpuidle_device *dev,
 
 	/* Re-allow idle for C1 */
 	if (index == 0) {
-		pwrdm_for_each_clkdm(mpu_pd, _cpuidle_allow_idle);
-		pwrdm_for_each_clkdm(core_pd, _cpuidle_allow_idle);
+		clkdm_allow_idle(mpu_pd->pwrdm_clkdms[0]);
+		clkdm_allow_idle(core_pd->pwrdm_clkdms[0]);
 	}
 
 return_sleep_time:
@@ -178,7 +164,7 @@ static int next_valid_state(struct cpuidle_device *dev,
 	u32 mpu_deepest_state = PWRDM_POWER_RET;
 	u32 core_deepest_state = PWRDM_POWER_RET;
 	int idx;
-	int next_index = -1;
+	int next_index = 0; /* C1 is the default value */
 
 	if (enable_off_mode) {
 		mpu_deepest_state = PWRDM_POWER_OFF;
@@ -209,12 +195,6 @@ static int next_valid_state(struct cpuidle_device *dev,
 		}
 	}
 
-	/*
-	 * C1 is always valid.
-	 * So, no need to check for 'next_index == -1' outside
-	 * this loop.
-	 */
-
 	return next_index;
 }
 
@@ -228,23 +208,22 @@ static int next_valid_state(struct cpuidle_device *dev,
  * the device to the specified or a safer state.
  */
 static int omap3_enter_idle_bm(struct cpuidle_device *dev,
-				struct cpuidle_driver *drv,
+			       struct cpuidle_driver *drv,
 			       int index)
 {
 	int new_state_idx;
-	u32 core_next_state, per_next_state = 0, per_saved_state = 0, cam_state;
+	u32 core_next_state, per_next_state = 0, per_saved_state = 0;
 	struct omap3_idle_statedata *cx;
 	int ret;
 
 	/*
-	 * Prevent idle completely if CAM is active.
+	 * Use only C1 if CAM is active.
 	 * CAM does not have wakeup capability in OMAP3.
 	 */
-	cam_state = pwrdm_read_pwrst(cam_pd);
-	if (cam_state == PWRDM_POWER_ON) {
+	if (pwrdm_read_pwrst(cam_pd) == PWRDM_POWER_ON)
 		new_state_idx = drv->safe_state_index;
-		goto select_state;
-	}
+	else
+		new_state_idx = next_valid_state(dev, drv, index);
 
 	/*
 	 * FIXME: we currently manage device-specific idle states
@@ -254,24 +233,28 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
 	 *        its own code.
 	 */
 
-	/*
-	 * Prevent PER off if CORE is not in retention or off as this
-	 * would disable PER wakeups completely.
-	 */
-	cx = &omap3_idle_data[index];
+	/* Program PER state */
+	cx = &omap3_idle_data[new_state_idx];
 	core_next_state = cx->core_state;
 	per_next_state = per_saved_state = pwrdm_read_next_pwrst(per_pd);
-	if ((per_next_state == PWRDM_POWER_OFF) &&
-	    (core_next_state > PWRDM_POWER_RET))
-		per_next_state = PWRDM_POWER_RET;
+	if (new_state_idx == 0) {
+		/* In C1 do not allow PER state lower than CORE state */
+		if (per_next_state < core_next_state)
+			per_next_state = core_next_state;
+	} else {
+		/*
+		 * Prevent PER OFF if CORE is not in RETention or OFF as this
+		 * would disable PER wakeups completely.
+		 */
+		if ((per_next_state == PWRDM_POWER_OFF) &&
+		    (core_next_state > PWRDM_POWER_RET))
+			per_next_state = PWRDM_POWER_RET;
+	}
 
 	/* Are we changing PER target state? */
 	if (per_next_state != per_saved_state)
 		pwrdm_set_next_pwrst(per_pd, per_next_state);
 
-	new_state_idx = next_valid_state(dev, drv, index);
-
-select_state:
 	ret = omap3_enter_idle(dev, drv, new_state_idx);
 
 	/* Restore original PER state if it was modified */
@@ -288,7 +271,7 @@ struct cpuidle_driver omap3_idle_driver = {
 	.owner = 	THIS_MODULE,
 	.states = {
 		{
-			.enter		  = omap3_enter_idle,
+			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 2 + 2,
 			.target_residency = 5,
 			.flags		  = CPUIDLE_FLAG_TIME_VALID,
diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
index 13670aa84e58..e35a86bf4e1d 100644
--- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
+++ b/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;
 }
diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
index 773193670ea2..09f44d56e026 100644
--- a/arch/arm/mach-omap2/omap_hwmod.c
+++ b/arch/arm/mach-omap2/omap_hwmod.c
@@ -153,6 +153,7 @@
 #include "prm44xx.h"
 #include "prminst44xx.h"
 #include "mux.h"
+#include "pm.h"
 
 /* Maximum microseconds to wait for OMAP module to softreset */
 #define MAX_MODULE_SOFTRESET_WAIT	10000
@@ -172,6 +173,9 @@ static LIST_HEAD(omap_hwmod_list);
 /* mpu_oh: used to add/remove MPU initiator from sleepdep list */
 static struct omap_hwmod *mpu_oh;
 
+/* io_chain_lock: used to serialize reconfigurations of the I/O chain */
+static DEFINE_SPINLOCK(io_chain_lock);
+
 /*
  * linkspace: ptr to a buffer that struct omap_hwmod_link records are
  * allocated from - used to reduce the number of small memory
@@ -1738,6 +1742,32 @@ static int _reset(struct omap_hwmod *oh)
 }
 
 /**
+ * _reconfigure_io_chain - clear any I/O chain wakeups and reconfigure chain
+ *
+ * Call the appropriate PRM function to clear any logged I/O chain
+ * wakeups and to reconfigure the chain.  This apparently needs to be
+ * done upon every mux change.  Since hwmods can be concurrently
+ * enabled and idled, hold a spinlock around the I/O chain
+ * reconfiguration sequence.  No return value.
+ *
+ * XXX When the PRM code is moved to drivers, this function can be removed,
+ * as the PRM infrastructure should abstract this.
+ */
+static void _reconfigure_io_chain(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&io_chain_lock, flags);
+
+	if (cpu_is_omap34xx() && omap3_has_io_chain_ctrl())
+		omap3xxx_prm_reconfigure_io_chain();
+	else if (cpu_is_omap44xx())
+		omap44xx_prm_reconfigure_io_chain();
+
+	spin_unlock_irqrestore(&io_chain_lock, flags);
+}
+
+/**
  * _enable - enable an omap_hwmod
  * @oh: struct omap_hwmod *
  *
@@ -1793,8 +1823,10 @@ static int _enable(struct omap_hwmod *oh)
 	/* Mux pins for device runtime if populated */
 	if (oh->mux && (!oh->mux->enabled ||
 			((oh->_state == _HWMOD_STATE_IDLE) &&
-			 oh->mux->pads_dynamic)))
+			 oh->mux->pads_dynamic))) {
 		omap_hwmod_mux(oh->mux, _HWMOD_STATE_ENABLED);
+		_reconfigure_io_chain();
+	}
 
 	_add_initiator_dep(oh, mpu_oh);
 
@@ -1883,8 +1915,10 @@ static int _idle(struct omap_hwmod *oh)
 		clkdm_hwmod_disable(oh->clkdm, oh);
 
 	/* Mux pins for device idle if populated */
-	if (oh->mux && oh->mux->pads_dynamic)
+	if (oh->mux && oh->mux->pads_dynamic) {
 		omap_hwmod_mux(oh->mux, _HWMOD_STATE_IDLE);
+		_reconfigure_io_chain();
+	}
 
 	oh->_state = _HWMOD_STATE_IDLE;
 
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 3a595e899724..e63fdd02c6f5 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -70,34 +70,6 @@ void (*omap3_do_wfi_sram)(void);
 
 static struct powerdomain *mpu_pwrdm, *neon_pwrdm;
 static struct powerdomain *core_pwrdm, *per_pwrdm;
-static struct powerdomain *cam_pwrdm;
-
-static void omap3_enable_io_chain(void)
-{
-	int timeout = 0;
-
-	omap2_prm_set_mod_reg_bits(OMAP3430_EN_IO_CHAIN_MASK, WKUP_MOD,
-				   PM_WKEN);
-	/* Do a readback to assure write has been done */
-	omap2_prm_read_mod_reg(WKUP_MOD, PM_WKEN);
-
-	while (!(omap2_prm_read_mod_reg(WKUP_MOD, PM_WKEN) &
-		 OMAP3430_ST_IO_CHAIN_MASK)) {
-		timeout++;
-		if (timeout > 1000) {
-			pr_err("Wake up daisy chain activation failed.\n");
-			return;
-		}
-		omap2_prm_set_mod_reg_bits(OMAP3430_ST_IO_CHAIN_MASK,
-					   WKUP_MOD, PM_WKEN);
-	}
-}
-
-static void omap3_disable_io_chain(void)
-{
-	omap2_prm_clear_mod_reg_bits(OMAP3430_EN_IO_CHAIN_MASK, WKUP_MOD,
-				     PM_WKEN);
-}
 
 static void omap3_core_save_context(void)
 {
@@ -299,24 +271,22 @@ void omap_sram_idle(void)
 	/* Enable IO-PAD and IO-CHAIN wakeups */
 	per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
 	core_next_state = pwrdm_read_next_pwrst(core_pwrdm);
-	if (omap3_has_io_wakeup() &&
-	    (per_next_state < PWRDM_POWER_ON ||
-	     core_next_state < PWRDM_POWER_ON)) {
-		omap2_prm_set_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD, PM_WKEN);
-		if (omap3_has_io_chain_ctrl())
-			omap3_enable_io_chain();
-	}
 
-	pwrdm_pre_transition();
+	if (mpu_next_state < PWRDM_POWER_ON) {
+		pwrdm_pre_transition(mpu_pwrdm);
+		pwrdm_pre_transition(neon_pwrdm);
+	}
 
 	/* PER */
 	if (per_next_state < PWRDM_POWER_ON) {
+		pwrdm_pre_transition(per_pwrdm);
 		per_going_off = (per_next_state == PWRDM_POWER_OFF) ? 1 : 0;
 		omap2_gpio_prepare_for_idle(per_going_off);
 	}
 
 	/* CORE */
 	if (core_next_state < PWRDM_POWER_ON) {
+		pwrdm_pre_transition(core_pwrdm);
 		if (core_next_state == PWRDM_POWER_OFF) {
 			omap3_core_save_context();
 			omap3_cm_save_context();
@@ -369,26 +339,20 @@ void omap_sram_idle(void)
 			omap2_prm_clear_mod_reg_bits(OMAP3430_AUTO_OFF_MASK,
 					       OMAP3430_GR_MOD,
 					       OMAP3_PRM_VOLTCTRL_OFFSET);
+		pwrdm_post_transition(core_pwrdm);
 	}
 	omap3_intc_resume_idle();
 
-	pwrdm_post_transition();
-
 	/* PER */
-	if (per_next_state < PWRDM_POWER_ON)
+	if (per_next_state < PWRDM_POWER_ON) {
 		omap2_gpio_resume_after_idle();
-
-	/* Disable IO-PAD and IO-CHAIN wakeup */
-	if (omap3_has_io_wakeup() &&
-	    (per_next_state < PWRDM_POWER_ON ||
-	     core_next_state < PWRDM_POWER_ON)) {
-		omap2_prm_clear_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD,
-					     PM_WKEN);
-		if (omap3_has_io_chain_ctrl())
-			omap3_disable_io_chain();
+		pwrdm_post_transition(per_pwrdm);
 	}
 
-	clkdm_allow_idle(mpu_pwrdm->pwrdm_clkdms[0]);
+	if (mpu_next_state < PWRDM_POWER_ON) {
+		pwrdm_post_transition(mpu_pwrdm);
+		pwrdm_post_transition(neon_pwrdm);
+	}
 }
 
 static void omap3_pm_idle(void)
@@ -749,7 +713,6 @@ int __init omap3_pm_init(void)
 	neon_pwrdm = pwrdm_lookup("neon_pwrdm");
 	per_pwrdm = pwrdm_lookup("per_pwrdm");
 	core_pwrdm = pwrdm_lookup("core_pwrdm");
-	cam_pwrdm = pwrdm_lookup("cam_pwrdm");
 
 	neon_clkdm = clkdm_lookup("neon_clkdm");
 	mpu_clkdm = clkdm_lookup("mpu_clkdm");
diff --git a/arch/arm/mach-omap2/powerdomain.c b/arch/arm/mach-omap2/powerdomain.c
index 96114901b932..eefe179045e6 100644
--- a/arch/arm/mach-omap2/powerdomain.c
+++ b/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;
 }
 
diff --git a/arch/arm/mach-omap2/powerdomain.h b/arch/arm/mach-omap2/powerdomain.h
index 8f88d65c46ea..a6a4604801ad 100644
--- a/arch/arm/mach-omap2/powerdomain.h
+++ b/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);
diff --git a/arch/arm/mach-omap2/prcm-common.h b/arch/arm/mach-omap2/prcm-common.h
index 6da3ba483ad1..fca23cbea708 100644
--- a/arch/arm/mach-omap2/prcm-common.h
+++ b/arch/arm/mach-omap2/prcm-common.h
@@ -410,6 +410,14 @@
  */
 #define MAX_MODULE_HARDRESET_WAIT		10000
 
+/*
+ * Maximum time(us) it takes to output the signal WUCLKOUT of the last
+ * pad of the I/O ring after asserting WUCLKIN high.  Tero measured
+ * the actual time at 7 to 8 microseconds on OMAP3 and 2 to 4
+ * microseconds on OMAP4, so this timeout may be too high.
+ */
+#define MAX_IOPAD_LATCH_TIME			100
+
 # ifndef __ASSEMBLER__
 extern void __iomem *prm_base;
 extern void __iomem *cm_base;
diff --git a/arch/arm/mach-omap2/prm2xxx_3xxx.c b/arch/arm/mach-omap2/prm2xxx_3xxx.c
index 21cb74003a56..a0309dea6794 100644
--- a/arch/arm/mach-omap2/prm2xxx_3xxx.c
+++ b/arch/arm/mach-omap2/prm2xxx_3xxx.c
@@ -302,11 +302,59 @@ void omap3xxx_prm_restore_irqen(u32 *saved_mask)
 				OMAP3_PRM_IRQENABLE_MPU_OFFSET);
 }
 
+/**
+ * omap3xxx_prm_reconfigure_io_chain - clear latches and reconfigure I/O chain
+ *
+ * Clear any previously-latched I/O wakeup events and ensure that the
+ * I/O wakeup gates are aligned with the current mux settings.  Works
+ * by asserting WUCLKIN, waiting for WUCLKOUT to be asserted, and then
+ * deasserting WUCLKIN and clearing the ST_IO_CHAIN WKST bit.  No
+ * return value.
+ */
+void omap3xxx_prm_reconfigure_io_chain(void)
+{
+	int i = 0;
+
+	omap2_prm_set_mod_reg_bits(OMAP3430_EN_IO_CHAIN_MASK, WKUP_MOD,
+				   PM_WKEN);
+
+	omap_test_timeout(omap2_prm_read_mod_reg(WKUP_MOD, PM_WKST) &
+			  OMAP3430_ST_IO_CHAIN_MASK,
+			  MAX_IOPAD_LATCH_TIME, i);
+	if (i == MAX_IOPAD_LATCH_TIME)
+		pr_warn("PRM: I/O chain clock line assertion timed out\n");
+
+	omap2_prm_clear_mod_reg_bits(OMAP3430_EN_IO_CHAIN_MASK, WKUP_MOD,
+				     PM_WKEN);
+
+	omap2_prm_set_mod_reg_bits(OMAP3430_ST_IO_CHAIN_MASK, WKUP_MOD,
+				   PM_WKST);
+
+	omap2_prm_read_mod_reg(WKUP_MOD, PM_WKST);
+}
+
+/**
+ * omap3xxx_prm_enable_io_wakeup - enable wakeup events from I/O wakeup latches
+ *
+ * Activates the I/O wakeup event latches and allows events logged by
+ * those latches to signal a wakeup event to the PRCM.  For I/O
+ * wakeups to occur, WAKEUPENABLE bits must be set in the pad mux
+ * registers, and omap3xxx_prm_reconfigure_io_chain() must be called.
+ * No return value.
+ */
+static void __init omap3xxx_prm_enable_io_wakeup(void)
+{
+	if (omap3_has_io_wakeup())
+		omap2_prm_set_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD,
+					   PM_WKEN);
+}
+
 static int __init omap3xxx_prcm_init(void)
 {
 	int ret = 0;
 
 	if (cpu_is_omap34xx()) {
+		omap3xxx_prm_enable_io_wakeup();
 		ret = omap_prcm_register_chain_handler(&omap3_prcm_irq_setup);
 		if (!ret)
 			irq_set_status_flags(omap_prcm_event_to_irq("io"),
diff --git a/arch/arm/mach-omap2/prm2xxx_3xxx.h b/arch/arm/mach-omap2/prm2xxx_3xxx.h
index 70ac2a19dc5f..a8c946f318ab 100644
--- a/arch/arm/mach-omap2/prm2xxx_3xxx.h
+++ b/arch/arm/mach-omap2/prm2xxx_3xxx.h
@@ -303,6 +303,8 @@ extern int omap2_prm_is_hardreset_asserted(s16 prm_mod, u8 shift);
 extern int omap2_prm_assert_hardreset(s16 prm_mod, u8 shift);
 extern int omap2_prm_deassert_hardreset(s16 prm_mod, u8 rst_shift, u8 st_shift);
 
+#endif	/* CONFIG_ARCH_OMAP4 */
+
 /* OMAP3-specific VP functions */
 u32 omap3_prm_vp_check_txdone(u8 vp_id);
 void omap3_prm_vp_clear_txdone(u8 vp_id);
@@ -315,14 +317,14 @@ extern u32 omap3_prm_vcvp_read(u8 offset);
 extern void omap3_prm_vcvp_write(u32 val, u8 offset);
 extern u32 omap3_prm_vcvp_rmw(u32 mask, u32 bits, u8 offset);
 
+extern void omap3xxx_prm_reconfigure_io_chain(void);
+
 /* PRM interrupt-related functions */
 extern void omap3xxx_prm_read_pending_irqs(unsigned long *events);
 extern void omap3xxx_prm_ocp_barrier(void);
 extern void omap3xxx_prm_save_and_clear_irqen(u32 *saved_mask);
 extern void omap3xxx_prm_restore_irqen(u32 *saved_mask);
 
-#endif	/* CONFIG_ARCH_OMAP4 */
-
 #endif
 
 /*
diff --git a/arch/arm/mach-omap2/prm44xx.c b/arch/arm/mach-omap2/prm44xx.c
index f106d21ff581..bb727c2d9337 100644
--- a/arch/arm/mach-omap2/prm44xx.c
+++ b/arch/arm/mach-omap2/prm44xx.c
@@ -233,10 +233,71 @@ void omap44xx_prm_restore_irqen(u32 *saved_mask)
 				 OMAP4_PRM_IRQENABLE_MPU_2_OFFSET);
 }
 
+/**
+ * omap44xx_prm_reconfigure_io_chain - clear latches and reconfigure I/O chain
+ *
+ * Clear any previously-latched I/O wakeup events and ensure that the
+ * I/O wakeup gates are aligned with the current mux settings.  Works
+ * by asserting WUCLKIN, waiting for WUCLKOUT to be asserted, and then
+ * deasserting WUCLKIN and waiting for WUCLKOUT to be deasserted.
+ * No return value. XXX Are the final two steps necessary?
+ */
+void omap44xx_prm_reconfigure_io_chain(void)
+{
+	int i = 0;
+
+	/* Trigger WUCLKIN enable */
+	omap4_prm_rmw_inst_reg_bits(OMAP4430_WUCLK_CTRL_MASK,
+				    OMAP4430_WUCLK_CTRL_MASK,
+				    OMAP4430_PRM_DEVICE_INST,
+				    OMAP4_PRM_IO_PMCTRL_OFFSET);
+	omap_test_timeout(
+		(((omap4_prm_read_inst_reg(OMAP4430_PRM_DEVICE_INST,
+					   OMAP4_PRM_IO_PMCTRL_OFFSET) &
+		   OMAP4430_WUCLK_STATUS_MASK) >>
+		  OMAP4430_WUCLK_STATUS_SHIFT) == 1),
+		MAX_IOPAD_LATCH_TIME, i);
+	if (i == MAX_IOPAD_LATCH_TIME)
+		pr_warn("PRM: I/O chain clock line assertion timed out\n");
+
+	/* Trigger WUCLKIN disable */
+	omap4_prm_rmw_inst_reg_bits(OMAP4430_WUCLK_CTRL_MASK, 0x0,
+				    OMAP4430_PRM_DEVICE_INST,
+				    OMAP4_PRM_IO_PMCTRL_OFFSET);
+	omap_test_timeout(
+		(((omap4_prm_read_inst_reg(OMAP4430_PRM_DEVICE_INST,
+					   OMAP4_PRM_IO_PMCTRL_OFFSET) &
+		   OMAP4430_WUCLK_STATUS_MASK) >>
+		  OMAP4430_WUCLK_STATUS_SHIFT) == 0),
+		MAX_IOPAD_LATCH_TIME, i);
+	if (i == MAX_IOPAD_LATCH_TIME)
+		pr_warn("PRM: I/O chain clock line deassertion timed out\n");
+
+	return;
+}
+
+/**
+ * omap44xx_prm_enable_io_wakeup - enable wakeup events from I/O wakeup latches
+ *
+ * Activates the I/O wakeup event latches and allows events logged by
+ * those latches to signal a wakeup event to the PRCM.  For I/O wakeups
+ * to occur, WAKEUPENABLE bits must be set in the pad mux registers, and
+ * omap44xx_prm_reconfigure_io_chain() must be called.  No return value.
+ */
+static void __init omap44xx_prm_enable_io_wakeup(void)
+{
+	omap4_prm_rmw_inst_reg_bits(OMAP4430_GLOBAL_WUEN_MASK,
+				    OMAP4430_GLOBAL_WUEN_MASK,
+				    OMAP4430_PRM_DEVICE_INST,
+				    OMAP4_PRM_IO_PMCTRL_OFFSET);
+}
+
 static int __init omap4xxx_prcm_init(void)
 {
-	if (cpu_is_omap44xx())
+	if (cpu_is_omap44xx()) {
+		omap44xx_prm_enable_io_wakeup();
 		return omap_prcm_register_chain_handler(&omap4_prcm_irq_setup);
+	}
 	return 0;
 }
 subsys_initcall(omap4xxx_prcm_init);
diff --git a/arch/arm/mach-omap2/prm44xx.h b/arch/arm/mach-omap2/prm44xx.h
index 7978092946db..ee72ae6bd8c9 100644
--- a/arch/arm/mach-omap2/prm44xx.h
+++ b/arch/arm/mach-omap2/prm44xx.h
@@ -763,6 +763,8 @@ extern u32 omap4_prm_vcvp_read(u8 offset);
 extern void omap4_prm_vcvp_write(u32 val, u8 offset);
 extern u32 omap4_prm_vcvp_rmw(u32 mask, u32 bits, u8 offset);
 
+extern void omap44xx_prm_reconfigure_io_chain(void);
+
 /* PRM interrupt-related functions */
 extern void omap44xx_prm_read_pending_irqs(unsigned long *events);
 extern void omap44xx_prm_ocp_barrier(void);