[PATCH 1/3] OMAP: PM: formalize idle notifications

[PATCH 1/3] OMAP: PM: formalize idle notifications

[Kevin Hilman]

Currently in the idle path, we have custom function calls into device
code to handle device specific actions that need to be coordinated CPU
idle transitions. Rather than continue this ad-hoc method of calling
device code from the PM core, create a formal way for device/driver
code to register for idle notifications.

Idle notifications are done late in the idle path when interrupts are
disabled, hence use atomic notifier chains.  These notifications will
also be atomic with respect to CPU idle transitions.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
 arch/arm/mach-omap2/pm.c                 |   26 ++++++++++++++++++++++++++
 arch/arm/mach-omap2/pm24xx.c             |    4 ++++
 arch/arm/mach-omap2/pm34xx.c             |    5 +++++
 arch/arm/plat-omap/include/plat/common.h |   11 +++++++++++
 4 files changed, 46 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-omap2/pm.c b/arch/arm/mach-omap2/pm.c
index 59ca03b..343e8d6 100644
--- a/arch/arm/mach-omap2/pm.c
+++ b/arch/arm/mach-omap2/pm.c
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/err.h>
+#include <linux/notifier.h>
 
 #include <plat/omap-pm.h>
 #include <plat/omap_device.h>
@@ -28,6 +29,31 @@ static struct device *iva_dev;
 static struct device *l3_dev;
 static struct device *dsp_dev;
 
+/* idle notifications late in the idle path (atomic, interrupts disabled) */
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
+
+void omap_idle_notifier_register(struct notifier_block *n)
+{
+	atomic_notifier_chain_register(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(omap_idle_notifier_register);
+
+void omap_idle_notifier_unregister(struct notifier_block *n)
+{
+	atomic_notifier_chain_unregister(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(omap_idle_notifier_unregister);
+
+void omap_idle_notifier_start(void)
+{
+	atomic_notifier_call_chain(&idle_notifier, OMAP_IDLE_START, NULL);
+}
+
+void omap_idle_notifier_end(void)
+{
+	atomic_notifier_call_chain(&idle_notifier, OMAP_IDLE_END, NULL);
+}
+
 struct device *omap2_get_mpuss_device(void)
 {
 	WARN_ON_ONCE(!mpu_dev);
diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
index a40457d..cb1b333 100644
--- a/arch/arm/mach-omap2/pm24xx.c
+++ b/arch/arm/mach-omap2/pm24xx.c
@@ -108,6 +108,8 @@ static void omap2_enter_full_retention(void)
 
 	omap2_gpio_prepare_for_idle(PWRDM_POWER_RET);
 
+	omap_idle_notifier_start();
+
 	if (omap2_pm_debug) {
 		omap2_pm_dump(0, 0, 0);
 		getnstimeofday(&ts_preidle);
@@ -140,6 +142,8 @@ no_sleep:
 		tmp = timespec_to_ns(&ts_idle) * NSEC_PER_USEC;
 		omap2_pm_dump(0, 1, tmp);
 	}
+
+	omap_idle_notifier_end();
 	omap2_gpio_resume_after_idle();
 
 	clk_enable(osc_ck);
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 75c0cd1..713bd04 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -37,6 +37,7 @@
 #include <plat/prcm.h>
 #include <plat/gpmc.h>
 #include <plat/dma.h>
+#include <plat/common.h>
 
 #include <asm/tlbflush.h>
 
@@ -375,6 +376,8 @@ void omap_sram_idle(void)
 	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON)
 		pwrdm_set_next_pwrst(neon_pwrdm, mpu_next_state);
 
+	omap_idle_notifier_start();
+
 	/* 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);
@@ -471,6 +474,8 @@ void omap_sram_idle(void)
 		omap3_disable_io_chain();
 	}
 
+	omap_idle_notifier_end();
+
 	pwrdm_post_transition();
 
 	omap2_clkdm_allow_idle(mpu_pwrdm->pwrdm_clkdms[0]);
diff --git a/arch/arm/plat-omap/include/plat/common.h b/arch/arm/plat-omap/include/plat/common.h
index a9d69a0..1ca32cf 100644
--- a/arch/arm/plat-omap/include/plat/common.h
+++ b/arch/arm/plat-omap/include/plat/common.h
@@ -27,6 +27,8 @@
 #ifndef __ARCH_ARM_MACH_OMAP_COMMON_H
 #define __ARCH_ARM_MACH_OMAP_COMMON_H
 
+#include <linux/notifier.h>
+
 #include <plat/i2c.h>
 
 struct sys_timer;
@@ -95,4 +97,13 @@ extern struct device *omap2_get_iva_device(void);
 extern struct device *omap2_get_l3_device(void);
 extern struct device *omap4_get_dsp_device(void);
 
+#define OMAP_IDLE_START 1
+#define OMAP_IDLE_END	2
+
+/* idle notifications late in the idle path (atomic, interrupts disabled) */
+extern void omap_idle_notifier_register(struct notifier_block *n);
+extern void omap_idle_notifier_unregister(struct notifier_block *n);
+extern void omap_idle_notifier_start(void);
+extern void omap_idle_notifier_end(void);
+
 #endif /* __ARCH_ARM_MACH_OMAP_COMMON_H */
-- 
1.7.2.1

[PATCH 2/3] OMAP: INTC: use idle notifier for autoidle management

[Kevin Hilman]

Move INTC autoidle management from custom hook to use the new idle
notifier.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
 arch/arm/mach-omap2/irq.c              |   36 +++++++++++++++++++++----------
 arch/arm/mach-omap2/pm34xx.c           |    3 --
 arch/arm/plat-omap/include/plat/irqs.h |    2 -
 3 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/arch/arm/mach-omap2/irq.c b/arch/arm/mach-omap2/irq.c
index 32eeabe..cb51f74 100644
--- a/arch/arm/mach-omap2/irq.c
+++ b/arch/arm/mach-omap2/irq.c
@@ -14,10 +14,12 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/notifier.h>
+
+#include <plat/common.h>
 #include <mach/hardware.h>
 #include <asm/mach/irq.h>
 
-
 /* selected INTC register offsets */
 
 #define INTC_REVISION		0x0000
@@ -186,6 +188,24 @@ int omap_irq_pending(void)
 	return 0;
 }
 
+static int omap3_intc_idle_notifier(struct notifier_block *n,
+				      unsigned long val,
+				      void *p)
+{
+	if (val == OMAP_IDLE_START)
+		/* Disable autoidle as it can stall interrupt controller */
+		intc_bank_write_reg(0, &irq_banks[0], INTC_SYSCONFIG);
+	else
+		/* Re-enable autoidle */
+		intc_bank_write_reg(1, &irq_banks[0], INTC_SYSCONFIG);
+
+	return 0;
+}
+
+static struct notifier_block omap3_intc_notifier = {
+	.notifier_call = omap3_intc_idle_notifier,
+};
+
 void __init omap_init_irq(void)
 {
 	unsigned long nr_of_irqs = 0;
@@ -224,6 +244,9 @@ void __init omap_init_irq(void)
 		set_irq_handler(i, handle_level_irq);
 		set_irq_flags(i, IRQF_VALID);
 	}
+
+	if (cpu_is_omap34xx())
+		omap_idle_notifier_register(&omap3_intc_notifier);
 }
 
 #ifdef CONFIG_ARCH_OMAP3
@@ -282,15 +305,4 @@ void omap3_intc_suspend(void)
 	omap_ack_irq(0);
 }
 
-void omap3_intc_prepare_idle(void)
-{
-	/* Disable autoidle as it can stall interrupt controller */
-	intc_bank_write_reg(0, &irq_banks[0], INTC_SYSCONFIG);
-}
-
-void omap3_intc_resume_idle(void)
-{
-	/* Re-enable autoidle */
-	intc_bank_write_reg(1, &irq_banks[0], INTC_SYSCONFIG);
-}
 #endif /* CONFIG_ARCH_OMAP3 */
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 713bd04..4674748 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -407,8 +407,6 @@ void omap_sram_idle(void)
 		}
 	}
 
-	omap3_intc_prepare_idle();
-
 	/*
 	* On EMU/HS devices ROM code restores a SRDC value
 	* from scratchpad which has automatic self refresh on timeout
@@ -454,7 +452,6 @@ void omap_sram_idle(void)
 					       OMAP3430_GR_MOD,
 					       OMAP3_PRM_VOLTCTRL_OFFSET);
 	}
-	omap3_intc_resume_idle();
 
 	/* PER */
 	if (per_next_state < PWRDM_POWER_ON) {
diff --git a/arch/arm/plat-omap/include/plat/irqs.h b/arch/arm/plat-omap/include/plat/irqs.h
index 65e20a6..b87c211 100644
--- a/arch/arm/plat-omap/include/plat/irqs.h
+++ b/arch/arm/plat-omap/include/plat/irqs.h
@@ -424,8 +424,6 @@ extern int omap_irq_pending(void);
 void omap_intc_save_context(void);
 void omap_intc_restore_context(void);
 void omap3_intc_suspend(void);
-void omap3_intc_prepare_idle(void);
-void omap3_intc_resume_idle(void);
 #endif
 
 #include <mach/hardware.h>
-- 
1.7.2.1

[PATCH 3/3] OMAP: UART: use atomic idle notifiers

[Kevin Hilman]

Convert UART idle management routines from custom hooks in the core
idle path to use new idle notifiers.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
 arch/arm/mach-omap2/pm24xx.c             |    9 +---
 arch/arm/mach-omap2/pm34xx.c             |    8 ---
 arch/arm/mach-omap2/serial.c             |   71 +++++++++++++++++++----------
 arch/arm/plat-omap/include/plat/serial.h |    2 -
 4 files changed, 47 insertions(+), 43 deletions(-)

diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
index cb1b333..47644d2 100644
--- a/arch/arm/mach-omap2/pm24xx.c
+++ b/arch/arm/mach-omap2/pm24xx.c
@@ -40,6 +40,7 @@
 #include <plat/sram.h>
 #include <plat/dma.h>
 #include <plat/board.h>
+#include <plat/common.h>
 
 #include "prm.h"
 #include "prm-regbits-24xx.h"
@@ -120,19 +121,11 @@ static void omap2_enter_full_retention(void)
 	if (omap_irq_pending())
 		goto no_sleep;
 
-	omap_uart_prepare_idle(0);
-	omap_uart_prepare_idle(1);
-	omap_uart_prepare_idle(2);
-
 	/* Jump to SRAM suspend code */
 	omap2_sram_suspend(sdrc_read_reg(SDRC_DLLA_CTRL),
 			   OMAP_SDRC_REGADDR(SDRC_DLLA_CTRL),
 			   OMAP_SDRC_REGADDR(SDRC_POWER));
 
-	omap_uart_resume_idle(2);
-	omap_uart_resume_idle(1);
-	omap_uart_resume_idle(0);
-
 no_sleep:
 	if (omap2_pm_debug) {
 		unsigned long long tmp;
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 4674748..eaed95d 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -390,8 +390,6 @@ void omap_sram_idle(void)
 
 	/* PER */
 	if (per_next_state < PWRDM_POWER_ON) {
-		omap_uart_prepare_idle(2);
-		omap_uart_prepare_idle(3);
 		omap2_gpio_prepare_for_idle(per_next_state);
 		if (per_next_state == PWRDM_POWER_OFF)
 				omap3_per_save_context();
@@ -399,8 +397,6 @@ void omap_sram_idle(void)
 
 	/* CORE */
 	if (core_next_state < PWRDM_POWER_ON) {
-		omap_uart_prepare_idle(0);
-		omap_uart_prepare_idle(1);
 		if (core_next_state == PWRDM_POWER_OFF) {
 			omap3_core_save_context();
 			omap3_prcm_save_context();
@@ -445,8 +441,6 @@ void omap_sram_idle(void)
 			omap3_sram_restore_context();
 			omap2_sms_restore_context();
 		}
-		omap_uart_resume_idle(0);
-		omap_uart_resume_idle(1);
 		if (core_next_state == PWRDM_POWER_OFF)
 			prm_clear_mod_reg_bits(OMAP3430_AUTO_OFF_MASK,
 					       OMAP3430_GR_MOD,
@@ -459,8 +453,6 @@ void omap_sram_idle(void)
 		omap2_gpio_resume_after_idle();
 		if (per_prev_state == PWRDM_POWER_OFF)
 			omap3_per_restore_context();
-		omap_uart_resume_idle(2);
-		omap_uart_resume_idle(3);
 	}
 
 	/* Disable IO-PAD and IO-CHAIN wakeup */
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index becf0e3..8a619ff 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -73,6 +73,7 @@ struct omap_uart_state {
 	u32 padconf;
 	u32 dma_enabled;
 
+	struct powerdomain *pwrdm;
 	struct clk *ick;
 	struct clk *fck;
 	int clocked;
@@ -389,39 +390,31 @@ static void omap_uart_idle_timer(unsigned long data)
 	omap_uart_allow_sleep(uart);
 }
 
-void omap_uart_prepare_idle(int num)
+static void omap_uart_prepare_idle(struct omap_uart_state *uart)
 {
-	struct omap_uart_state *uart;
-
-	list_for_each_entry(uart, &uart_list, node) {
-		if (num == uart->num && uart->can_sleep) {
-			omap_uart_disable_clocks(uart);
-			return;
-		}
-	}
+	if (uart->can_sleep &&
+	    pwrdm_read_next_pwrst(uart->pwrdm) < PWRDM_POWER_ON)
+		omap_uart_disable_clocks(uart);
 }
 
-void omap_uart_resume_idle(int num)
+static void omap_uart_resume_idle(struct omap_uart_state *uart)
 {
-	struct omap_uart_state *uart;
+	if (uart->can_sleep &&
+	    pwrdm_read_next_pwrst(uart->pwrdm) < PWRDM_POWER_ON) {
+		omap_uart_enable_clocks(uart);
 
-	list_for_each_entry(uart, &uart_list, node) {
-		if (num == uart->num) {
-			omap_uart_enable_clocks(uart);
-
-			/* Check for IO pad wakeup */
-			if (cpu_is_omap34xx() && uart->padconf) {
-				u16 p = omap_ctrl_readw(uart->padconf);
-
-				if (p & OMAP3_PADCONF_WAKEUPEVENT0)
-					omap_uart_block_sleep(uart);
-			}
+		/* Check for IO pad wakeup */
+		if (cpu_is_omap34xx() && uart->padconf) {
+			u16 p = omap_ctrl_readw(uart->padconf);
 
-			/* Check for normal UART wakeup */
-			if (__raw_readl(uart->wk_st) & uart->wk_mask)
+			if (p & OMAP3_PADCONF_WAKEUPEVENT0)
 				omap_uart_block_sleep(uart);
-			return;
 		}
+
+		/* Check for normal UART wakeup */
+		if (__raw_readl(uart->wk_st) & uart->wk_mask)
+			omap_uart_block_sleep(uart);
+		return;
 	}
 }
 
@@ -474,6 +467,27 @@ static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
 	return IRQ_NONE;
 }
 
+static int omap_uart_idle_notifier(struct notifier_block *n,
+				   unsigned long val,
+				   void *p)
+{
+	struct omap_uart_state *uart;
+
+	if (val == OMAP_IDLE_START)
+		list_for_each_entry(uart, &uart_list, node)
+			omap_uart_prepare_idle(uart);
+	else
+		list_for_each_entry(uart, &uart_list, node)
+			omap_uart_resume_idle(uart);
+
+	return 0;
+}
+
+static bool omap_uart_notifier_enabled;
+static struct notifier_block omap_uart_notifier = {
+	.notifier_call = omap_uart_idle_notifier,
+};
+
 static void omap_uart_idle_init(struct omap_uart_state *uart)
 {
 	int ret;
@@ -549,6 +563,11 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
 	ret = request_threaded_irq(uart->irq, NULL, omap_uart_interrupt,
 				   IRQF_SHARED, "serial idle", (void *)uart);
 	WARN_ON(ret);
+
+	if (!omap_uart_notifier_enabled) {
+		omap_idle_notifier_register(&omap_uart_notifier);
+		omap_uart_notifier_enabled = true;
+	}
 }
 
 void omap_uart_enable_irqs(int enable)
@@ -731,6 +750,8 @@ void __init omap_serial_init_port(int port)
 			break;
 
 	oh = uart->oh;
+	uart->pwrdm = omap_hwmod_get_pwrdm(oh);
+	WARN_ON(!uart->pwrdm);
 	uart->dma_enabled = 0;
 #ifndef CONFIG_SERIAL_OMAP
 	name = "serial8250";
diff --git a/arch/arm/plat-omap/include/plat/serial.h b/arch/arm/plat-omap/include/plat/serial.h
index 19145f5..d3ee47b 100644
--- a/arch/arm/plat-omap/include/plat/serial.h
+++ b/arch/arm/plat-omap/include/plat/serial.h
@@ -99,8 +99,6 @@ extern void omap_serial_init_port(int port);
 extern int omap_uart_can_sleep(void);
 extern void omap_uart_check_wakeup(void);
 extern void omap_uart_prepare_suspend(void);
-extern void omap_uart_prepare_idle(int num);
-extern void omap_uart_resume_idle(int num);
 extern void omap_uart_enable_irqs(int enable);
 #endif
 
-- 
1.7.2.1

[PATCH 3/3] OMAP: UART: use atomic idle notifiers

[Govindraj]

Thanks Kevin,

works fine tested on 3630sdp/zoom3 board.

Tested-by: Govindraj.R <govindraj.raja@ti.com>

Regards,
Govindraj.R

On Thu, Oct 21, 2010 at 5:01 AM, Kevin Hilman
<khilman@deeprootsystems.com> wrote:
> Convert UART idle management routines from custom hooks in the core
> idle path to use new idle notifiers.
>
> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
> ---
> ?arch/arm/mach-omap2/pm24xx.c ? ? ? ? ? ? | ? ?9 +---
> ?arch/arm/mach-omap2/pm34xx.c ? ? ? ? ? ? | ? ?8 ---
> ?arch/arm/mach-omap2/serial.c ? ? ? ? ? ? | ? 71 +++++++++++++++++++----------
> ?arch/arm/plat-omap/include/plat/serial.h | ? ?2 -
> ?4 files changed, 47 insertions(+), 43 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
> index cb1b333..47644d2 100644
> --- a/arch/arm/mach-omap2/pm24xx.c
> +++ b/arch/arm/mach-omap2/pm24xx.c
> @@ -40,6 +40,7 @@
> ?#include <plat/sram.h>
> ?#include <plat/dma.h>
> ?#include <plat/board.h>
> +#include <plat/common.h>
>
> ?#include "prm.h"
> ?#include "prm-regbits-24xx.h"
> @@ -120,19 +121,11 @@ static void omap2_enter_full_retention(void)
> ? ? ? ?if (omap_irq_pending())
> ? ? ? ? ? ? ? ?goto no_sleep;
>
> - ? ? ? omap_uart_prepare_idle(0);
> - ? ? ? omap_uart_prepare_idle(1);
> - ? ? ? omap_uart_prepare_idle(2);
> -
> ? ? ? ?/* Jump to SRAM suspend code */
> ? ? ? ?omap2_sram_suspend(sdrc_read_reg(SDRC_DLLA_CTRL),
> ? ? ? ? ? ? ? ? ? ? ? ? ? OMAP_SDRC_REGADDR(SDRC_DLLA_CTRL),
> ? ? ? ? ? ? ? ? ? ? ? ? ? OMAP_SDRC_REGADDR(SDRC_POWER));
>
> - ? ? ? omap_uart_resume_idle(2);
> - ? ? ? omap_uart_resume_idle(1);
> - ? ? ? omap_uart_resume_idle(0);
> -
> ?no_sleep:
> ? ? ? ?if (omap2_pm_debug) {
> ? ? ? ? ? ? ? ?unsigned long long tmp;
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index 4674748..eaed95d 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -390,8 +390,6 @@ void omap_sram_idle(void)
>
> ? ? ? ?/* PER */
> ? ? ? ?if (per_next_state < PWRDM_POWER_ON) {
> - ? ? ? ? ? ? ? omap_uart_prepare_idle(2);
> - ? ? ? ? ? ? ? omap_uart_prepare_idle(3);
> ? ? ? ? ? ? ? ?omap2_gpio_prepare_for_idle(per_next_state);
> ? ? ? ? ? ? ? ?if (per_next_state == PWRDM_POWER_OFF)
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?omap3_per_save_context();
> @@ -399,8 +397,6 @@ void omap_sram_idle(void)
>
> ? ? ? ?/* CORE */
> ? ? ? ?if (core_next_state < PWRDM_POWER_ON) {
> - ? ? ? ? ? ? ? omap_uart_prepare_idle(0);
> - ? ? ? ? ? ? ? omap_uart_prepare_idle(1);
> ? ? ? ? ? ? ? ?if (core_next_state == PWRDM_POWER_OFF) {
> ? ? ? ? ? ? ? ? ? ? ? ?omap3_core_save_context();
> ? ? ? ? ? ? ? ? ? ? ? ?omap3_prcm_save_context();
> @@ -445,8 +441,6 @@ void omap_sram_idle(void)
> ? ? ? ? ? ? ? ? ? ? ? ?omap3_sram_restore_context();
> ? ? ? ? ? ? ? ? ? ? ? ?omap2_sms_restore_context();
> ? ? ? ? ? ? ? ?}
> - ? ? ? ? ? ? ? omap_uart_resume_idle(0);
> - ? ? ? ? ? ? ? omap_uart_resume_idle(1);
> ? ? ? ? ? ? ? ?if (core_next_state == PWRDM_POWER_OFF)
> ? ? ? ? ? ? ? ? ? ? ? ?prm_clear_mod_reg_bits(OMAP3430_AUTO_OFF_MASK,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? OMAP3430_GR_MOD,
> @@ -459,8 +453,6 @@ void omap_sram_idle(void)
> ? ? ? ? ? ? ? ?omap2_gpio_resume_after_idle();
> ? ? ? ? ? ? ? ?if (per_prev_state == PWRDM_POWER_OFF)
> ? ? ? ? ? ? ? ? ? ? ? ?omap3_per_restore_context();
> - ? ? ? ? ? ? ? omap_uart_resume_idle(2);
> - ? ? ? ? ? ? ? omap_uart_resume_idle(3);
> ? ? ? ?}
>
> ? ? ? ?/* Disable IO-PAD and IO-CHAIN wakeup */
> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
> index becf0e3..8a619ff 100644
> --- a/arch/arm/mach-omap2/serial.c
> +++ b/arch/arm/mach-omap2/serial.c
> @@ -73,6 +73,7 @@ struct omap_uart_state {
> ? ? ? ?u32 padconf;
> ? ? ? ?u32 dma_enabled;
>
> + ? ? ? struct powerdomain *pwrdm;
> ? ? ? ?struct clk *ick;
> ? ? ? ?struct clk *fck;
> ? ? ? ?int clocked;
> @@ -389,39 +390,31 @@ static void omap_uart_idle_timer(unsigned long data)
> ? ? ? ?omap_uart_allow_sleep(uart);
> ?}
>
> -void omap_uart_prepare_idle(int num)
> +static void omap_uart_prepare_idle(struct omap_uart_state *uart)
> ?{
> - ? ? ? struct omap_uart_state *uart;
> -
> - ? ? ? list_for_each_entry(uart, &uart_list, node) {
> - ? ? ? ? ? ? ? if (num == uart->num && uart->can_sleep) {
> - ? ? ? ? ? ? ? ? ? ? ? omap_uart_disable_clocks(uart);
> - ? ? ? ? ? ? ? ? ? ? ? return;
> - ? ? ? ? ? ? ? }
> - ? ? ? }
> + ? ? ? if (uart->can_sleep &&
> + ? ? ? ? ? pwrdm_read_next_pwrst(uart->pwrdm) < PWRDM_POWER_ON)
> + ? ? ? ? ? ? ? omap_uart_disable_clocks(uart);
> ?}
>
> -void omap_uart_resume_idle(int num)
> +static void omap_uart_resume_idle(struct omap_uart_state *uart)
> ?{
> - ? ? ? struct omap_uart_state *uart;
> + ? ? ? if (uart->can_sleep &&
> + ? ? ? ? ? pwrdm_read_next_pwrst(uart->pwrdm) < PWRDM_POWER_ON) {
> + ? ? ? ? ? ? ? omap_uart_enable_clocks(uart);
>
> - ? ? ? list_for_each_entry(uart, &uart_list, node) {
> - ? ? ? ? ? ? ? if (num == uart->num) {
> - ? ? ? ? ? ? ? ? ? ? ? omap_uart_enable_clocks(uart);
> -
> - ? ? ? ? ? ? ? ? ? ? ? /* Check for IO pad wakeup */
> - ? ? ? ? ? ? ? ? ? ? ? if (cpu_is_omap34xx() && uart->padconf) {
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? u16 p = omap_ctrl_readw(uart->padconf);
> -
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? if (p & OMAP3_PADCONF_WAKEUPEVENT0)
> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? omap_uart_block_sleep(uart);
> - ? ? ? ? ? ? ? ? ? ? ? }
> + ? ? ? ? ? ? ? /* Check for IO pad wakeup */
> + ? ? ? ? ? ? ? if (cpu_is_omap34xx() && uart->padconf) {
> + ? ? ? ? ? ? ? ? ? ? ? u16 p = omap_ctrl_readw(uart->padconf);
>
> - ? ? ? ? ? ? ? ? ? ? ? /* Check for normal UART wakeup */
> - ? ? ? ? ? ? ? ? ? ? ? if (__raw_readl(uart->wk_st) & uart->wk_mask)
> + ? ? ? ? ? ? ? ? ? ? ? if (p & OMAP3_PADCONF_WAKEUPEVENT0)
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?omap_uart_block_sleep(uart);
> - ? ? ? ? ? ? ? ? ? ? ? return;
> ? ? ? ? ? ? ? ?}
> +
> + ? ? ? ? ? ? ? /* Check for normal UART wakeup */
> + ? ? ? ? ? ? ? if (__raw_readl(uart->wk_st) & uart->wk_mask)
> + ? ? ? ? ? ? ? ? ? ? ? omap_uart_block_sleep(uart);
> + ? ? ? ? ? ? ? return;
> ? ? ? ?}
> ?}
>
> @@ -474,6 +467,27 @@ static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
> ? ? ? ?return IRQ_NONE;
> ?}
>
> +static int omap_uart_idle_notifier(struct notifier_block *n,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?unsigned long val,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?void *p)
> +{
> + ? ? ? struct omap_uart_state *uart;
> +
> + ? ? ? if (val == OMAP_IDLE_START)
> + ? ? ? ? ? ? ? list_for_each_entry(uart, &uart_list, node)
> + ? ? ? ? ? ? ? ? ? ? ? omap_uart_prepare_idle(uart);
> + ? ? ? else
> + ? ? ? ? ? ? ? list_for_each_entry(uart, &uart_list, node)
> + ? ? ? ? ? ? ? ? ? ? ? omap_uart_resume_idle(uart);
> +
> + ? ? ? return 0;
> +}
> +
> +static bool omap_uart_notifier_enabled;
> +static struct notifier_block omap_uart_notifier = {
> + ? ? ? .notifier_call = omap_uart_idle_notifier,
> +};
> +
> ?static void omap_uart_idle_init(struct omap_uart_state *uart)
> ?{
> ? ? ? ?int ret;
> @@ -549,6 +563,11 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
> ? ? ? ?ret = request_threaded_irq(uart->irq, NULL, omap_uart_interrupt,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? IRQF_SHARED, "serial idle", (void *)uart);
> ? ? ? ?WARN_ON(ret);
> +
> + ? ? ? if (!omap_uart_notifier_enabled) {
> + ? ? ? ? ? ? ? omap_idle_notifier_register(&omap_uart_notifier);
> + ? ? ? ? ? ? ? omap_uart_notifier_enabled = true;
> + ? ? ? }
> ?}
>
> ?void omap_uart_enable_irqs(int enable)
> @@ -731,6 +750,8 @@ void __init omap_serial_init_port(int port)
> ? ? ? ? ? ? ? ? ? ? ? ?break;
>
> ? ? ? ?oh = uart->oh;
> + ? ? ? uart->pwrdm = omap_hwmod_get_pwrdm(oh);
> + ? ? ? WARN_ON(!uart->pwrdm);
> ? ? ? ?uart->dma_enabled = 0;
> ?#ifndef CONFIG_SERIAL_OMAP
> ? ? ? ?name = "serial8250";
> diff --git a/arch/arm/plat-omap/include/plat/serial.h b/arch/arm/plat-omap/include/plat/serial.h
> index 19145f5..d3ee47b 100644
> --- a/arch/arm/plat-omap/include/plat/serial.h
> +++ b/arch/arm/plat-omap/include/plat/serial.h
> @@ -99,8 +99,6 @@ extern void omap_serial_init_port(int port);
> ?extern int omap_uart_can_sleep(void);
> ?extern void omap_uart_check_wakeup(void);
> ?extern void omap_uart_prepare_suspend(void);
> -extern void omap_uart_prepare_idle(int num);
> -extern void omap_uart_resume_idle(int num);
> ?extern void omap_uart_enable_irqs(int enable);
> ?#endif
>
> --
> 1.7.2.1
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-omap" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at ?http://vger.kernel.org/majordomo-info.html
>

[PATCH 3/3] OMAP: UART: use atomic idle notifiers

[Kevin Hilman]

Govindraj <govindraj.ti@gmail.com> writes:

> Thanks Kevin,
>
> works fine tested on 3630sdp/zoom3 board.
>
> Tested-by: Govindraj.R <govindraj.raja@ti.com>

Govindraj,  thanks for testing!

Kevin

>
> On Thu, Oct 21, 2010 at 5:01 AM, Kevin Hilman
> <khilman@deeprootsystems.com> wrote:
>> Convert UART idle management routines from custom hooks in the core
>> idle path to use new idle notifiers.
>>
>> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
>> ---
>> ?arch/arm/mach-omap2/pm24xx.c ? ? ? ? ? ? | ? ?9 +---
>> ?arch/arm/mach-omap2/pm34xx.c ? ? ? ? ? ? | ? ?8 ---
>> ?arch/arm/mach-omap2/serial.c ? ? ? ? ? ? | ? 71 +++++++++++++++++++----------
>> ?arch/arm/plat-omap/include/plat/serial.h | ? ?2 -
>> ?4 files changed, 47 insertions(+), 43 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
>> index cb1b333..47644d2 100644
>> --- a/arch/arm/mach-omap2/pm24xx.c
>> +++ b/arch/arm/mach-omap2/pm24xx.c
>> @@ -40,6 +40,7 @@
>> ?#include <plat/sram.h>
>> ?#include <plat/dma.h>
>> ?#include <plat/board.h>
>> +#include <plat/common.h>
>>
>> ?#include "prm.h"
>> ?#include "prm-regbits-24xx.h"
>> @@ -120,19 +121,11 @@ static void omap2_enter_full_retention(void)
>> ? ? ? ?if (omap_irq_pending())
>> ? ? ? ? ? ? ? ?goto no_sleep;
>>
>> - ? ? ? omap_uart_prepare_idle(0);
>> - ? ? ? omap_uart_prepare_idle(1);
>> - ? ? ? omap_uart_prepare_idle(2);
>> -
>> ? ? ? ?/* Jump to SRAM suspend code */
>> ? ? ? ?omap2_sram_suspend(sdrc_read_reg(SDRC_DLLA_CTRL),
>> ? ? ? ? ? ? ? ? ? ? ? ? ? OMAP_SDRC_REGADDR(SDRC_DLLA_CTRL),
>> ? ? ? ? ? ? ? ? ? ? ? ? ? OMAP_SDRC_REGADDR(SDRC_POWER));
>>
>> - ? ? ? omap_uart_resume_idle(2);
>> - ? ? ? omap_uart_resume_idle(1);
>> - ? ? ? omap_uart_resume_idle(0);
>> -
>> ?no_sleep:
>> ? ? ? ?if (omap2_pm_debug) {
>> ? ? ? ? ? ? ? ?unsigned long long tmp;
>> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
>> index 4674748..eaed95d 100644
>> --- a/arch/arm/mach-omap2/pm34xx.c
>> +++ b/arch/arm/mach-omap2/pm34xx.c
>> @@ -390,8 +390,6 @@ void omap_sram_idle(void)
>>
>> ? ? ? ?/* PER */
>> ? ? ? ?if (per_next_state < PWRDM_POWER_ON) {
>> - ? ? ? ? ? ? ? omap_uart_prepare_idle(2);
>> - ? ? ? ? ? ? ? omap_uart_prepare_idle(3);
>> ? ? ? ? ? ? ? ?omap2_gpio_prepare_for_idle(per_next_state);
>> ? ? ? ? ? ? ? ?if (per_next_state == PWRDM_POWER_OFF)
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?omap3_per_save_context();
>> @@ -399,8 +397,6 @@ void omap_sram_idle(void)
>>
>> ? ? ? ?/* CORE */
>> ? ? ? ?if (core_next_state < PWRDM_POWER_ON) {
>> - ? ? ? ? ? ? ? omap_uart_prepare_idle(0);
>> - ? ? ? ? ? ? ? omap_uart_prepare_idle(1);
>> ? ? ? ? ? ? ? ?if (core_next_state == PWRDM_POWER_OFF) {
>> ? ? ? ? ? ? ? ? ? ? ? ?omap3_core_save_context();
>> ? ? ? ? ? ? ? ? ? ? ? ?omap3_prcm_save_context();
>> @@ -445,8 +441,6 @@ void omap_sram_idle(void)
>> ? ? ? ? ? ? ? ? ? ? ? ?omap3_sram_restore_context();
>> ? ? ? ? ? ? ? ? ? ? ? ?omap2_sms_restore_context();
>> ? ? ? ? ? ? ? ?}
>> - ? ? ? ? ? ? ? omap_uart_resume_idle(0);
>> - ? ? ? ? ? ? ? omap_uart_resume_idle(1);
>> ? ? ? ? ? ? ? ?if (core_next_state == PWRDM_POWER_OFF)
>> ? ? ? ? ? ? ? ? ? ? ? ?prm_clear_mod_reg_bits(OMAP3430_AUTO_OFF_MASK,
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? OMAP3430_GR_MOD,
>> @@ -459,8 +453,6 @@ void omap_sram_idle(void)
>> ? ? ? ? ? ? ? ?omap2_gpio_resume_after_idle();
>> ? ? ? ? ? ? ? ?if (per_prev_state == PWRDM_POWER_OFF)
>> ? ? ? ? ? ? ? ? ? ? ? ?omap3_per_restore_context();
>> - ? ? ? ? ? ? ? omap_uart_resume_idle(2);
>> - ? ? ? ? ? ? ? omap_uart_resume_idle(3);
>> ? ? ? ?}
>>
>> ? ? ? ?/* Disable IO-PAD and IO-CHAIN wakeup */
>> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
>> index becf0e3..8a619ff 100644
>> --- a/arch/arm/mach-omap2/serial.c
>> +++ b/arch/arm/mach-omap2/serial.c
>> @@ -73,6 +73,7 @@ struct omap_uart_state {
>> ? ? ? ?u32 padconf;
>> ? ? ? ?u32 dma_enabled;
>>
>> + ? ? ? struct powerdomain *pwrdm;
>> ? ? ? ?struct clk *ick;
>> ? ? ? ?struct clk *fck;
>> ? ? ? ?int clocked;
>> @@ -389,39 +390,31 @@ static void omap_uart_idle_timer(unsigned long data)
>> ? ? ? ?omap_uart_allow_sleep(uart);
>> ?}
>>
>> -void omap_uart_prepare_idle(int num)
>> +static void omap_uart_prepare_idle(struct omap_uart_state *uart)
>> ?{
>> - ? ? ? struct omap_uart_state *uart;
>> -
>> - ? ? ? list_for_each_entry(uart, &uart_list, node) {
>> - ? ? ? ? ? ? ? if (num == uart->num && uart->can_sleep) {
>> - ? ? ? ? ? ? ? ? ? ? ? omap_uart_disable_clocks(uart);
>> - ? ? ? ? ? ? ? ? ? ? ? return;
>> - ? ? ? ? ? ? ? }
>> - ? ? ? }
>> + ? ? ? if (uart->can_sleep &&
>> + ? ? ? ? ? pwrdm_read_next_pwrst(uart->pwrdm) < PWRDM_POWER_ON)
>> + ? ? ? ? ? ? ? omap_uart_disable_clocks(uart);
>> ?}
>>
>> -void omap_uart_resume_idle(int num)
>> +static void omap_uart_resume_idle(struct omap_uart_state *uart)
>> ?{
>> - ? ? ? struct omap_uart_state *uart;
>> + ? ? ? if (uart->can_sleep &&
>> + ? ? ? ? ? pwrdm_read_next_pwrst(uart->pwrdm) < PWRDM_POWER_ON) {
>> + ? ? ? ? ? ? ? omap_uart_enable_clocks(uart);
>>
>> - ? ? ? list_for_each_entry(uart, &uart_list, node) {
>> - ? ? ? ? ? ? ? if (num == uart->num) {
>> - ? ? ? ? ? ? ? ? ? ? ? omap_uart_enable_clocks(uart);
>> -
>> - ? ? ? ? ? ? ? ? ? ? ? /* Check for IO pad wakeup */
>> - ? ? ? ? ? ? ? ? ? ? ? if (cpu_is_omap34xx() && uart->padconf) {
>> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? u16 p = omap_ctrl_readw(uart->padconf);
>> -
>> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? if (p & OMAP3_PADCONF_WAKEUPEVENT0)
>> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? omap_uart_block_sleep(uart);
>> - ? ? ? ? ? ? ? ? ? ? ? }
>> + ? ? ? ? ? ? ? /* Check for IO pad wakeup */
>> + ? ? ? ? ? ? ? if (cpu_is_omap34xx() && uart->padconf) {
>> + ? ? ? ? ? ? ? ? ? ? ? u16 p = omap_ctrl_readw(uart->padconf);
>>
>> - ? ? ? ? ? ? ? ? ? ? ? /* Check for normal UART wakeup */
>> - ? ? ? ? ? ? ? ? ? ? ? if (__raw_readl(uart->wk_st) & uart->wk_mask)
>> + ? ? ? ? ? ? ? ? ? ? ? if (p & OMAP3_PADCONF_WAKEUPEVENT0)
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?omap_uart_block_sleep(uart);
>> - ? ? ? ? ? ? ? ? ? ? ? return;
>> ? ? ? ? ? ? ? ?}
>> +
>> + ? ? ? ? ? ? ? /* Check for normal UART wakeup */
>> + ? ? ? ? ? ? ? if (__raw_readl(uart->wk_st) & uart->wk_mask)
>> + ? ? ? ? ? ? ? ? ? ? ? omap_uart_block_sleep(uart);
>> + ? ? ? ? ? ? ? return;
>> ? ? ? ?}
>> ?}
>>
>> @@ -474,6 +467,27 @@ static irqreturn_t omap_uart_interrupt(int irq, void *dev_id)
>> ? ? ? ?return IRQ_NONE;
>> ?}
>>
>> +static int omap_uart_idle_notifier(struct notifier_block *n,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?unsigned long val,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?void *p)
>> +{
>> + ? ? ? struct omap_uart_state *uart;
>> +
>> + ? ? ? if (val == OMAP_IDLE_START)
>> + ? ? ? ? ? ? ? list_for_each_entry(uart, &uart_list, node)
>> + ? ? ? ? ? ? ? ? ? ? ? omap_uart_prepare_idle(uart);
>> + ? ? ? else
>> + ? ? ? ? ? ? ? list_for_each_entry(uart, &uart_list, node)
>> + ? ? ? ? ? ? ? ? ? ? ? omap_uart_resume_idle(uart);
>> +
>> + ? ? ? return 0;
>> +}
>> +
>> +static bool omap_uart_notifier_enabled;
>> +static struct notifier_block omap_uart_notifier = {
>> + ? ? ? .notifier_call = omap_uart_idle_notifier,
>> +};
>> +
>> ?static void omap_uart_idle_init(struct omap_uart_state *uart)
>> ?{
>> ? ? ? ?int ret;
>> @@ -549,6 +563,11 @@ static void omap_uart_idle_init(struct omap_uart_state *uart)
>> ? ? ? ?ret = request_threaded_irq(uart->irq, NULL, omap_uart_interrupt,
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? IRQF_SHARED, "serial idle", (void *)uart);
>> ? ? ? ?WARN_ON(ret);
>> +
>> + ? ? ? if (!omap_uart_notifier_enabled) {
>> + ? ? ? ? ? ? ? omap_idle_notifier_register(&omap_uart_notifier);
>> + ? ? ? ? ? ? ? omap_uart_notifier_enabled = true;
>> + ? ? ? }
>> ?}
>>
>> ?void omap_uart_enable_irqs(int enable)
>> @@ -731,6 +750,8 @@ void __init omap_serial_init_port(int port)
>> ? ? ? ? ? ? ? ? ? ? ? ?break;
>>
>> ? ? ? ?oh = uart->oh;
>> + ? ? ? uart->pwrdm = omap_hwmod_get_pwrdm(oh);
>> + ? ? ? WARN_ON(!uart->pwrdm);
>> ? ? ? ?uart->dma_enabled = 0;
>> ?#ifndef CONFIG_SERIAL_OMAP
>> ? ? ? ?name = "serial8250";
>> diff --git a/arch/arm/plat-omap/include/plat/serial.h b/arch/arm/plat-omap/include/plat/serial.h
>> index 19145f5..d3ee47b 100644
>> --- a/arch/arm/plat-omap/include/plat/serial.h
>> +++ b/arch/arm/plat-omap/include/plat/serial.h
>> @@ -99,8 +99,6 @@ extern void omap_serial_init_port(int port);
>> ?extern int omap_uart_can_sleep(void);
>> ?extern void omap_uart_check_wakeup(void);
>> ?extern void omap_uart_prepare_suspend(void);
>> -extern void omap_uart_prepare_idle(int num);
>> -extern void omap_uart_resume_idle(int num);
>> ?extern void omap_uart_enable_irqs(int enable);
>> ?#endif
>>
>> --
>> 1.7.2.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-omap" in
>> the body of a message to majordomo at vger.kernel.org
>> More majordomo info at ?http://vger.kernel.org/majordomo-info.html
>>

[PATCH 1/3] OMAP: PM: formalize idle notifications

[Tony Lindgren]

* Kevin Hilman <khilman@deeprootsystems.com> [101020 16:22]:
> Currently in the idle path, we have custom function calls into device
> code to handle device specific actions that need to be coordinated CPU
> idle transitions. Rather than continue this ad-hoc method of calling
> device code from the PM core, create a formal way for device/driver
> code to register for idle notifications.
> 
> Idle notifications are done late in the idle path when interrupts are
> disabled, hence use atomic notifier chains.  These notifications will
> also be atomic with respect to CPU idle transitions.

...

> +EXPORT_SYMBOL_GPL(omap_idle_notifier_register);
> +EXPORT_SYMBOL_GPL(omap_idle_notifier_unregister);

Let's rather set this up as a generic framework to avoid adding
more omap specific frameworks to the drivers.

Regards,

Tony

[PATCH 1/3] OMAP: PM: formalize idle notifications

[Kevin Hilman]

Tony Lindgren <tony@atomide.com> writes:

> * Kevin Hilman <khilman@deeprootsystems.com> [101020 16:22]:
>> Currently in the idle path, we have custom function calls into device
>> code to handle device specific actions that need to be coordinated CPU
>> idle transitions. Rather than continue this ad-hoc method of calling
>> device code from the PM core, create a formal way for device/driver
>> code to register for idle notifications.
>> 
>> Idle notifications are done late in the idle path when interrupts are
>> disabled, hence use atomic notifier chains.  These notifications will
>> also be atomic with respect to CPU idle transitions.
>
> ...
>
>> +EXPORT_SYMBOL_GPL(omap_idle_notifier_register);
>> +EXPORT_SYMBOL_GPL(omap_idle_notifier_unregister);
>
> Let's rather set this up as a generic framework to avoid adding
> more omap specific frameworks to the drivers.

Hmm, I thought I removed those EXPORT_SYMBOLs, just for that reason.  

I actually don't really intend these to be used from drivers, but only
from OMAP-specific device code.  We currently use these manly for errata
purposes, but also for UART debug purposes, and only from device code
currently.

That being said, I did consider a generic framework for this (x86_64 has
it's own idle notfiers as well), and this topic something already on the
table for LPC PM miniconf.  However, at least for OMAP, the location of
when the notifiers are triggered has to be in OMAP-specific code.  It
cannot be in the ARM-generic idle path (like they do in x86_64.)

The reason is because the idle notifiers have to be called *after* the
OMAP-specific idle path has programmed the next power states for the
various power domains.  That way, the idle notifiers can read the next
power state regs and make decisons on what they need to do (or not to
do) based on whether he power domain is going to RET, OFF, etc.

Kevin