[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[Daniel Lezcano]

This patch adds the cpuidle driver for the ux500 SoC.
The boards saves 12mA with these states. It is based on the latest
cpuidle consolidation from Robert Lee.

The cpu can go to retention only if the other core is in WFI.

If the other cpu is in WFI and we decoupled the gic from the cores,
then we have the guarantee, it won't be wake up.

It is up to the prcmu firmware to recouple the gic automatically
after the power state mode is selected.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 arch/arm/mach-ux500/Makefile  |    1 +
 arch/arm/mach-ux500/cpuidle.c |  171 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 172 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/mach-ux500/cpuidle.c

diff --git a/arch/arm/mach-ux500/Makefile b/arch/arm/mach-ux500/Makefile
index fc7db5d..3b86b61 100644
--- a/arch/arm/mach-ux500/Makefile
+++ b/arch/arm/mach-ux500/Makefile
@@ -4,6 +4,7 @@
 
 obj-y				:= clock.o cpu.o devices.o devices-common.o \
 				   id.o usb.o timer.o
+obj-$(CONFIG_CPU_IDLE)          += cpuidle.o
 obj-$(CONFIG_CACHE_L2X0)	+= cache-l2x0.o
 obj-$(CONFIG_UX500_SOC_DB8500)	+= cpu-db8500.o devices-db8500.o
 obj-$(CONFIG_MACH_MOP500)	+= board-mop500.o board-mop500-sdi.o \
diff --git a/arch/arm/mach-ux500/cpuidle.c b/arch/arm/mach-ux500/cpuidle.c
new file mode 100644
index 0000000..b54884bd
--- /dev/null
+++ b/arch/arm/mach-ux500/cpuidle.c
@@ -0,0 +1,171 @@
+/*
+ * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
+ *
+ * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
+ * and Jonas Aaberg <jonas.aberg@stericsson.com>.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/cpuidle.h>
+#include <linux/clockchips.h>
+#include <linux/spinlock.h>
+#include <linux/atomic.h>
+#include <linux/smp.h>
+#include <linux/mfd/dbx500-prcmu.h>
+
+#include <asm/cpuidle.h>
+#include <asm/proc-fns.h>
+
+static atomic_t master = ATOMIC_INIT(0);
+static DEFINE_SPINLOCK(master_lock);
+static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
+
+static inline int ux500_enter_idle(struct cpuidle_device *dev,
+				   struct cpuidle_driver *drv, int index)
+{
+	int this_cpu = smp_processor_id();
+	bool recouple = false;
+
+	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &this_cpu);
+
+	if (atomic_inc_return(&master) == num_online_cpus()) {
+
+		/* With this lock, we prevent the other cpu to exit and enter
+		 * this function again and become the master */
+		if (!spin_trylock(&master_lock))
+			goto wfi;
+
+		/* decouple the gic from the A9 cores */
+		if (prcmu_gic_decouple())
+			goto out;
+
+		/* If an error occur, we will have to recouple the gic
+		 * manually */
+		recouple = true;
+
+		/* At this state, as the gic is decoupled, if the other
+		 * cpu is in WFI, we have the guarantee it won't be wake
+		 * up, so we can safely go to retention */
+		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
+			goto out;
+
+		/* The prcmu will be in charge of watching the interrupts
+		 * and wake up the cpus */
+		if (prcmu_copy_gic_settings())
+			goto out;
+
+		/* Check in the meantime an interrupt did
+		 * not occur on the gic ... */
+		if (prcmu_gic_pending_irq())
+			goto out;
+
+		/* ... and the prcmu */
+		if (prcmu_pending_irq())
+			goto out;
+
+		/* Go to the retention state, the prcmu will wait for the
+		 * cpu to go WFI and this is what happens after exiting this
+		 * 'master' critical section */
+		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
+			goto out;
+
+		/* When we switch to retention, the prcmu is in charge
+		 * of recoupling the gic automatically */
+		recouple = false;
+
+		spin_unlock(&master_lock);
+	}
+wfi:
+	cpu_do_idle();
+out:
+	atomic_dec(&master);
+
+	if (recouple) {
+		prcmu_gic_recouple();
+		spin_unlock(&master_lock);
+	}
+
+	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &this_cpu);
+
+	return index;
+}
+
+static struct cpuidle_driver ux500_idle_driver = {
+	.name = "ux500_idle",
+	.owner = THIS_MODULE,
+	.en_core_tk_irqen = 1,
+	.states = {
+		ARM_CPUIDLE_WFI_STATE,
+		{
+			.enter		  = ux500_enter_idle,
+			.exit_latency	  = 70,
+			.target_residency = 260,
+			.flags		  = CPUIDLE_FLAG_TIME_VALID,
+			.name		  = "ApIdle",
+			.desc		  = "ARM Retention",
+		},
+	},
+	.safe_state_index = 0,
+	.state_count = 2,
+};
+
+/*
+ * For each cpu, setup the broadcast timer because we will
+ * need to migrate the timers for the states >= ApIdle.
+ */
+static void ux500_setup_broadcast_timer(void *arg)
+{
+	int cpu = smp_processor_id();
+	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);
+}
+
+int __init ux500_idle_init(void)
+{
+	int ret, cpu;
+	struct cpuidle_device *device;
+
+        /* Configure wake up reasons */
+	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
+			     PRCMU_WAKEUP(ABB));
+
+	/*
+	 * Configure the timer broadcast for each cpu, that must
+	 * be done from the cpu context, so we use a smp cross
+	 * call with 'on_each_cpu'.
+	 */
+	on_each_cpu(ux500_setup_broadcast_timer, NULL, 1);
+
+	ret = cpuidle_register_driver(&ux500_idle_driver);
+	if (ret) {
+		printk(KERN_ERR "failed to register ux500 idle driver\n");
+		return ret;
+	}
+
+	for_each_online_cpu(cpu) {
+		device = &per_cpu(ux500_cpuidle_device, cpu);
+		device->cpu = cpu;
+		ret = cpuidle_register_device(device);
+		if (ret) {
+			printk(KERN_ERR "Failed to register cpuidle "
+			       "device for cpu%d\n", cpu);
+			goto out_unregister;
+		}
+	}
+out:
+	return ret;
+
+out_unregister:
+	for_each_online_cpu(cpu) {
+		device = &per_cpu(ux500_cpuidle_device, cpu);
+		cpuidle_unregister_device(device);
+	}
+
+	cpuidle_unregister_driver(&ux500_idle_driver);
+	goto out;
+}
+
+device_initcall(ux500_idle_init);
-- 
1.7.5.4

[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[Daniel Lezcano]

On 04/19/2012 02:46 PM, Daniel Lezcano wrote:
> This patch adds the cpuidle driver for the ux500 SoC.
> The boards saves 12mA with these states. It is based on the latest
> cpuidle consolidation from Robert Lee.
>
> The cpu can go to retention only if the other core is in WFI.
>
> If the other cpu is in WFI and we decoupled the gic from the cores,
> then we have the guarantee, it won't be wake up.
>
> It is up to the prcmu firmware to recouple the gic automatically
> after the power state mode is selected.
>
> Signed-off-by: Daniel Lezcano<daniel.lezcano@linaro.org>
> ---

Hi Linus,

can you consider this patch for inclusion, please ?

Thanks

-- Daniel

>   arch/arm/mach-ux500/Makefile  |    1 +
>   arch/arm/mach-ux500/cpuidle.c |  171 +++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 172 insertions(+), 0 deletions(-)
>   create mode 100644 arch/arm/mach-ux500/cpuidle.c
>
> diff --git a/arch/arm/mach-ux500/Makefile b/arch/arm/mach-ux500/Makefile
> index fc7db5d..3b86b61 100644
> --- a/arch/arm/mach-ux500/Makefile
> +++ b/arch/arm/mach-ux500/Makefile
> @@ -4,6 +4,7 @@
>
>   obj-y				:= clock.o cpu.o devices.o devices-common.o \
>   				   id.o usb.o timer.o
> +obj-$(CONFIG_CPU_IDLE)          += cpuidle.o
>   obj-$(CONFIG_CACHE_L2X0)	+= cache-l2x0.o
>   obj-$(CONFIG_UX500_SOC_DB8500)	+= cpu-db8500.o devices-db8500.o
>   obj-$(CONFIG_MACH_MOP500)	+= board-mop500.o board-mop500-sdi.o \
> diff --git a/arch/arm/mach-ux500/cpuidle.c b/arch/arm/mach-ux500/cpuidle.c
> new file mode 100644
> index 0000000..b54884bd
> --- /dev/null
> +++ b/arch/arm/mach-ux500/cpuidle.c
> @@ -0,0 +1,171 @@
> +/*
> + * Copyright (c) 2012 Linaro : Daniel Lezcano<daniel.lezcano@linaro.org>  (IBM)
> + *
> + * Based on the work of Rickard Andersson<rickard.andersson@stericsson.com>
> + * and Jonas Aaberg<jonas.aberg@stericsson.com>.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include<linux/module.h>
> +#include<linux/cpuidle.h>
> +#include<linux/clockchips.h>
> +#include<linux/spinlock.h>
> +#include<linux/atomic.h>
> +#include<linux/smp.h>
> +#include<linux/mfd/dbx500-prcmu.h>
> +
> +#include<asm/cpuidle.h>
> +#include<asm/proc-fns.h>
> +
> +static atomic_t master = ATOMIC_INIT(0);
> +static DEFINE_SPINLOCK(master_lock);
> +static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
> +
> +static inline int ux500_enter_idle(struct cpuidle_device *dev,
> +				   struct cpuidle_driver *drv, int index)
> +{
> +	int this_cpu = smp_processor_id();
> +	bool recouple = false;
> +
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,&this_cpu);
> +
> +	if (atomic_inc_return(&master) == num_online_cpus()) {
> +
> +		/* With this lock, we prevent the other cpu to exit and enter
> +		 * this function again and become the master */
> +		if (!spin_trylock(&master_lock))
> +			goto wfi;
> +
> +		/* decouple the gic from the A9 cores */
> +		if (prcmu_gic_decouple())
> +			goto out;
> +
> +		/* If an error occur, we will have to recouple the gic
> +		 * manually */
> +		recouple = true;
> +
> +		/* At this state, as the gic is decoupled, if the other
> +		 * cpu is in WFI, we have the guarantee it won't be wake
> +		 * up, so we can safely go to retention */
> +		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
> +			goto out;
> +
> +		/* The prcmu will be in charge of watching the interrupts
> +		 * and wake up the cpus */
> +		if (prcmu_copy_gic_settings())
> +			goto out;
> +
> +		/* Check in the meantime an interrupt did
> +		 * not occur on the gic ... */
> +		if (prcmu_gic_pending_irq())
> +			goto out;
> +
> +		/* ... and the prcmu */
> +		if (prcmu_pending_irq())
> +			goto out;
> +
> +		/* Go to the retention state, the prcmu will wait for the
> +		 * cpu to go WFI and this is what happens after exiting this
> +		 * 'master' critical section */
> +		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
> +			goto out;
> +
> +		/* When we switch to retention, the prcmu is in charge
> +		 * of recoupling the gic automatically */
> +		recouple = false;
> +
> +		spin_unlock(&master_lock);
> +	}
> +wfi:
> +	cpu_do_idle();
> +out:
> +	atomic_dec(&master);
> +
> +	if (recouple) {
> +		prcmu_gic_recouple();
> +		spin_unlock(&master_lock);
> +	}
> +
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,&this_cpu);
> +
> +	return index;
> +}
> +
> +static struct cpuidle_driver ux500_idle_driver = {
> +	.name = "ux500_idle",
> +	.owner = THIS_MODULE,
> +	.en_core_tk_irqen = 1,
> +	.states = {
> +		ARM_CPUIDLE_WFI_STATE,
> +		{
> +			.enter		  = ux500_enter_idle,
> +			.exit_latency	  = 70,
> +			.target_residency = 260,
> +			.flags		  = CPUIDLE_FLAG_TIME_VALID,
> +			.name		  = "ApIdle",
> +			.desc		  = "ARM Retention",
> +		},
> +	},
> +	.safe_state_index = 0,
> +	.state_count = 2,
> +};
> +
> +/*
> + * For each cpu, setup the broadcast timer because we will
> + * need to migrate the timers for the states>= ApIdle.
> + */
> +static void ux500_setup_broadcast_timer(void *arg)
> +{
> +	int cpu = smp_processor_id();
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON,&cpu);
> +}
> +
> +int __init ux500_idle_init(void)
> +{
> +	int ret, cpu;
> +	struct cpuidle_device *device;
> +
> +        /* Configure wake up reasons */
> +	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
> +			     PRCMU_WAKEUP(ABB));
> +
> +	/*
> +	 * Configure the timer broadcast for each cpu, that must
> +	 * be done from the cpu context, so we use a smp cross
> +	 * call with 'on_each_cpu'.
> +	 */
> +	on_each_cpu(ux500_setup_broadcast_timer, NULL, 1);
> +
> +	ret = cpuidle_register_driver(&ux500_idle_driver);
> +	if (ret) {
> +		printk(KERN_ERR "failed to register ux500 idle driver\n");
> +		return ret;
> +	}
> +
> +	for_each_online_cpu(cpu) {
> +		device =&per_cpu(ux500_cpuidle_device, cpu);
> +		device->cpu = cpu;
> +		ret = cpuidle_register_device(device);
> +		if (ret) {
> +			printk(KERN_ERR "Failed to register cpuidle "
> +			       "device for cpu%d\n", cpu);
> +			goto out_unregister;
> +		}
> +	}
> +out:
> +	return ret;
> +
> +out_unregister:
> +	for_each_online_cpu(cpu) {
> +		device =&per_cpu(ux500_cpuidle_device, cpu);
> +		cpuidle_unregister_device(device);
> +	}
> +
> +	cpuidle_unregister_driver(&ux500_idle_driver);
> +	goto out;
> +}
> +
> +device_initcall(ux500_idle_init);


-- 
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[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[Vincent Guittot]

Hi Daniel,

You can add my Ack on your patch

Vincent

On 19 April 2012 14:46, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
> This patch adds the cpuidle driver for the ux500 SoC.
> The boards saves 12mA with these states. It is based on the latest
> cpuidle consolidation from Robert Lee.
>
> The cpu can go to retention only if the other core is in WFI.
>
> If the other cpu is in WFI and we decoupled the gic from the cores,
> then we have the guarantee, it won't be wake up.
>
> It is up to the prcmu firmware to recouple the gic automatically
> after the power state mode is selected.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> ---
> ?arch/arm/mach-ux500/Makefile ?| ? ?1 +
> ?arch/arm/mach-ux500/cpuidle.c | ?171 +++++++++++++++++++++++++++++++++++++++++
> ?2 files changed, 172 insertions(+), 0 deletions(-)
> ?create mode 100644 arch/arm/mach-ux500/cpuidle.c
>
> diff --git a/arch/arm/mach-ux500/Makefile b/arch/arm/mach-ux500/Makefile
> index fc7db5d..3b86b61 100644
> --- a/arch/arm/mach-ux500/Makefile
> +++ b/arch/arm/mach-ux500/Makefile
> @@ -4,6 +4,7 @@
>
> ?obj-y ? ? ? ? ? ? ? ? ? ? ? ? ?:= clock.o cpu.o devices.o devices-common.o \
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? id.o usb.o timer.o
> +obj-$(CONFIG_CPU_IDLE) ? ? ? ? ?+= cpuidle.o
> ?obj-$(CONFIG_CACHE_L2X0) ? ? ? += cache-l2x0.o
> ?obj-$(CONFIG_UX500_SOC_DB8500) += cpu-db8500.o devices-db8500.o
> ?obj-$(CONFIG_MACH_MOP500) ? ? ?+= board-mop500.o board-mop500-sdi.o \
> diff --git a/arch/arm/mach-ux500/cpuidle.c b/arch/arm/mach-ux500/cpuidle.c
> new file mode 100644
> index 0000000..b54884bd
> --- /dev/null
> +++ b/arch/arm/mach-ux500/cpuidle.c
> @@ -0,0 +1,171 @@
> +/*
> + * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
> + *
> + * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
> + * and Jonas Aaberg <jonas.aberg@stericsson.com>.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/cpuidle.h>
> +#include <linux/clockchips.h>
> +#include <linux/spinlock.h>
> +#include <linux/atomic.h>
> +#include <linux/smp.h>
> +#include <linux/mfd/dbx500-prcmu.h>
> +
> +#include <asm/cpuidle.h>
> +#include <asm/proc-fns.h>
> +
> +static atomic_t master = ATOMIC_INIT(0);
> +static DEFINE_SPINLOCK(master_lock);
> +static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
> +
> +static inline int ux500_enter_idle(struct cpuidle_device *dev,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct cpuidle_driver *drv, int index)
> +{
> + ? ? ? int this_cpu = smp_processor_id();
> + ? ? ? bool recouple = false;
> +
> + ? ? ? clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &this_cpu);
> +
> + ? ? ? if (atomic_inc_return(&master) == num_online_cpus()) {
> +
> + ? ? ? ? ? ? ? /* With this lock, we prevent the other cpu to exit and enter
> + ? ? ? ? ? ? ? ?* this function again and become the master */
> + ? ? ? ? ? ? ? if (!spin_trylock(&master_lock))
> + ? ? ? ? ? ? ? ? ? ? ? goto wfi;
> +
> + ? ? ? ? ? ? ? /* decouple the gic from the A9 cores */
> + ? ? ? ? ? ? ? if (prcmu_gic_decouple())
> + ? ? ? ? ? ? ? ? ? ? ? goto out;
> +
> + ? ? ? ? ? ? ? /* If an error occur, we will have to recouple the gic
> + ? ? ? ? ? ? ? ?* manually */
> + ? ? ? ? ? ? ? recouple = true;
> +
> + ? ? ? ? ? ? ? /* At this state, as the gic is decoupled, if the other
> + ? ? ? ? ? ? ? ?* cpu is in WFI, we have the guarantee it won't be wake
> + ? ? ? ? ? ? ? ?* up, so we can safely go to retention */
> + ? ? ? ? ? ? ? if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
> + ? ? ? ? ? ? ? ? ? ? ? goto out;
> +
> + ? ? ? ? ? ? ? /* The prcmu will be in charge of watching the interrupts
> + ? ? ? ? ? ? ? ?* and wake up the cpus */
> + ? ? ? ? ? ? ? if (prcmu_copy_gic_settings())
> + ? ? ? ? ? ? ? ? ? ? ? goto out;
> +
> + ? ? ? ? ? ? ? /* Check in the meantime an interrupt did
> + ? ? ? ? ? ? ? ?* not occur on the gic ... */
> + ? ? ? ? ? ? ? if (prcmu_gic_pending_irq())
> + ? ? ? ? ? ? ? ? ? ? ? goto out;
> +
> + ? ? ? ? ? ? ? /* ... and the prcmu */
> + ? ? ? ? ? ? ? if (prcmu_pending_irq())
> + ? ? ? ? ? ? ? ? ? ? ? goto out;
> +
> + ? ? ? ? ? ? ? /* Go to the retention state, the prcmu will wait for the
> + ? ? ? ? ? ? ? ?* cpu to go WFI and this is what happens after exiting this
> + ? ? ? ? ? ? ? ?* 'master' critical section */
> + ? ? ? ? ? ? ? if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
> + ? ? ? ? ? ? ? ? ? ? ? goto out;
> +
> + ? ? ? ? ? ? ? /* When we switch to retention, the prcmu is in charge
> + ? ? ? ? ? ? ? ?* of recoupling the gic automatically */
> + ? ? ? ? ? ? ? recouple = false;
> +
> + ? ? ? ? ? ? ? spin_unlock(&master_lock);
> + ? ? ? }
> +wfi:
> + ? ? ? cpu_do_idle();
> +out:
> + ? ? ? atomic_dec(&master);
> +
> + ? ? ? if (recouple) {
> + ? ? ? ? ? ? ? prcmu_gic_recouple();
> + ? ? ? ? ? ? ? spin_unlock(&master_lock);
> + ? ? ? }
> +
> + ? ? ? clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &this_cpu);
> +
> + ? ? ? return index;
> +}
> +
> +static struct cpuidle_driver ux500_idle_driver = {
> + ? ? ? .name = "ux500_idle",
> + ? ? ? .owner = THIS_MODULE,
> + ? ? ? .en_core_tk_irqen = 1,
> + ? ? ? .states = {
> + ? ? ? ? ? ? ? ARM_CPUIDLE_WFI_STATE,
> + ? ? ? ? ? ? ? {
> + ? ? ? ? ? ? ? ? ? ? ? .enter ? ? ? ? ? ?= ux500_enter_idle,
> + ? ? ? ? ? ? ? ? ? ? ? .exit_latency ? ? = 70,
> + ? ? ? ? ? ? ? ? ? ? ? .target_residency = 260,
> + ? ? ? ? ? ? ? ? ? ? ? .flags ? ? ? ? ? ?= CPUIDLE_FLAG_TIME_VALID,
> + ? ? ? ? ? ? ? ? ? ? ? .name ? ? ? ? ? ? = "ApIdle",
> + ? ? ? ? ? ? ? ? ? ? ? .desc ? ? ? ? ? ? = "ARM Retention",
> + ? ? ? ? ? ? ? },
> + ? ? ? },
> + ? ? ? .safe_state_index = 0,
> + ? ? ? .state_count = 2,
> +};
> +
> +/*
> + * For each cpu, setup the broadcast timer because we will
> + * need to migrate the timers for the states >= ApIdle.
> + */
> +static void ux500_setup_broadcast_timer(void *arg)
> +{
> + ? ? ? int cpu = smp_processor_id();
> + ? ? ? clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);
> +}
> +
> +int __init ux500_idle_init(void)
> +{
> + ? ? ? int ret, cpu;
> + ? ? ? struct cpuidle_device *device;
> +
> + ? ? ? ?/* Configure wake up reasons */
> + ? ? ? prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ?PRCMU_WAKEUP(ABB));
> +
> + ? ? ? /*
> + ? ? ? ?* Configure the timer broadcast for each cpu, that must
> + ? ? ? ?* be done from the cpu context, so we use a smp cross
> + ? ? ? ?* call with 'on_each_cpu'.
> + ? ? ? ?*/
> + ? ? ? on_each_cpu(ux500_setup_broadcast_timer, NULL, 1);
> +
> + ? ? ? ret = cpuidle_register_driver(&ux500_idle_driver);
> + ? ? ? if (ret) {
> + ? ? ? ? ? ? ? printk(KERN_ERR "failed to register ux500 idle driver\n");
> + ? ? ? ? ? ? ? return ret;
> + ? ? ? }
> +
> + ? ? ? for_each_online_cpu(cpu) {
> + ? ? ? ? ? ? ? device = &per_cpu(ux500_cpuidle_device, cpu);
> + ? ? ? ? ? ? ? device->cpu = cpu;
> + ? ? ? ? ? ? ? ret = cpuidle_register_device(device);
> + ? ? ? ? ? ? ? if (ret) {
> + ? ? ? ? ? ? ? ? ? ? ? printk(KERN_ERR "Failed to register cpuidle "
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?"device for cpu%d\n", cpu);
> + ? ? ? ? ? ? ? ? ? ? ? goto out_unregister;
> + ? ? ? ? ? ? ? }
> + ? ? ? }
> +out:
> + ? ? ? return ret;
> +
> +out_unregister:
> + ? ? ? for_each_online_cpu(cpu) {
> + ? ? ? ? ? ? ? device = &per_cpu(ux500_cpuidle_device, cpu);
> + ? ? ? ? ? ? ? cpuidle_unregister_device(device);
> + ? ? ? }
> +
> + ? ? ? cpuidle_unregister_driver(&ux500_idle_driver);
> + ? ? ? goto out;
> +}
> +
> +device_initcall(ux500_idle_init);
> --
> 1.7.5.4
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev at lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev

[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[Rickard Andersson]

Should not the driver be located in the 'drivers/cpuidle/' directory?

BR
Rickard
> This patch adds the cpuidle driver for the ux500 SoC.
> The boards saves 12mA with these states. It is based on the latest
> cpuidle consolidation from Robert Lee.
>
> The cpu can go to retention only if the other core is in WFI.
>
> If the other cpu is in WFI and we decoupled the gic from the cores,
> then we have the guarantee, it won't be wake up.
>
> It is up to the prcmu firmware to recouple the gic automatically
> after the power state mode is selected.
>
> Signed-off-by: Daniel Lezcano<daniel.lezcano@linaro.org>
> ---
>   arch/arm/mach-ux500/Makefile  |    1 +
>   arch/arm/mach-ux500/cpuidle.c |  171 +++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 172 insertions(+), 0 deletions(-)
>   create mode 100644 arch/arm/mach-ux500/cpuidle.c
>
> diff --git a/arch/arm/mach-ux500/Makefile b/arch/arm/mach-ux500/Makefile
> index fc7db5d..3b86b61 100644
> --- a/arch/arm/mach-ux500/Makefile
> +++ b/arch/arm/mach-ux500/Makefile
> @@ -4,6 +4,7 @@
>
>   obj-y				:= clock.o cpu.o devices.o devices-common.o \
>   				   id.o usb.o timer.o
> +obj-$(CONFIG_CPU_IDLE)          += cpuidle.o
>   obj-$(CONFIG_CACHE_L2X0)	+= cache-l2x0.o
>   obj-$(CONFIG_UX500_SOC_DB8500)	+= cpu-db8500.o devices-db8500.o
>   obj-$(CONFIG_MACH_MOP500)	+= board-mop500.o board-mop500-sdi.o \
> diff --git a/arch/arm/mach-ux500/cpuidle.c b/arch/arm/mach-ux500/cpuidle.c
> new file mode 100644
> index 0000000..b54884bd
> --- /dev/null
> +++ b/arch/arm/mach-ux500/cpuidle.c
> @@ -0,0 +1,171 @@
> +/*
> + * Copyright (c) 2012 Linaro : Daniel Lezcano<daniel.lezcano@linaro.org>  (IBM)
> + *
> + * Based on the work of Rickard Andersson<rickard.andersson@stericsson.com>
> + * and Jonas Aaberg<jonas.aberg@stericsson.com>.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include<linux/module.h>
> +#include<linux/cpuidle.h>
> +#include<linux/clockchips.h>
> +#include<linux/spinlock.h>
> +#include<linux/atomic.h>
> +#include<linux/smp.h>
> +#include<linux/mfd/dbx500-prcmu.h>
> +
> +#include<asm/cpuidle.h>
> +#include<asm/proc-fns.h>
> +
> +static atomic_t master = ATOMIC_INIT(0);
> +static DEFINE_SPINLOCK(master_lock);
> +static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
> +
> +static inline int ux500_enter_idle(struct cpuidle_device *dev,
> +				   struct cpuidle_driver *drv, int index)
> +{
> +	int this_cpu = smp_processor_id();
> +	bool recouple = false;
> +
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,&this_cpu);
> +
> +	if (atomic_inc_return(&master) == num_online_cpus()) {
> +
> +		/* With this lock, we prevent the other cpu to exit and enter
> +		 * this function again and become the master */
> +		if (!spin_trylock(&master_lock))
> +			goto wfi;
> +
> +		/* decouple the gic from the A9 cores */
> +		if (prcmu_gic_decouple())
> +			goto out;
> +
> +		/* If an error occur, we will have to recouple the gic
> +		 * manually */
> +		recouple = true;
> +
> +		/* At this state, as the gic is decoupled, if the other
> +		 * cpu is in WFI, we have the guarantee it won't be wake
> +		 * up, so we can safely go to retention */
> +		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
> +			goto out;
> +
> +		/* The prcmu will be in charge of watching the interrupts
> +		 * and wake up the cpus */
> +		if (prcmu_copy_gic_settings())
> +			goto out;
> +
> +		/* Check in the meantime an interrupt did
> +		 * not occur on the gic ... */
> +		if (prcmu_gic_pending_irq())
> +			goto out;
> +
> +		/* ... and the prcmu */
> +		if (prcmu_pending_irq())
> +			goto out;
> +
> +		/* Go to the retention state, the prcmu will wait for the
> +		 * cpu to go WFI and this is what happens after exiting this
> +		 * 'master' critical section */
> +		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
> +			goto out;
> +
> +		/* When we switch to retention, the prcmu is in charge
> +		 * of recoupling the gic automatically */
> +		recouple = false;
> +
> +		spin_unlock(&master_lock);
> +	}
> +wfi:
> +	cpu_do_idle();
> +out:
> +	atomic_dec(&master);
> +
> +	if (recouple) {
> +		prcmu_gic_recouple();
> +		spin_unlock(&master_lock);
> +	}
> +
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,&this_cpu);
> +
> +	return index;
> +}
> +
> +static struct cpuidle_driver ux500_idle_driver = {
> +	.name = "ux500_idle",
> +	.owner = THIS_MODULE,
> +	.en_core_tk_irqen = 1,
> +	.states = {
> +		ARM_CPUIDLE_WFI_STATE,
> +		{
> +			.enter		  = ux500_enter_idle,
> +			.exit_latency	  = 70,
> +			.target_residency = 260,
> +			.flags		  = CPUIDLE_FLAG_TIME_VALID,
> +			.name		  = "ApIdle",
> +			.desc		  = "ARM Retention",
> +		},
> +	},
> +	.safe_state_index = 0,
> +	.state_count = 2,
> +};
> +
> +/*
> + * For each cpu, setup the broadcast timer because we will
> + * need to migrate the timers for the states>= ApIdle.
> + */
> +static void ux500_setup_broadcast_timer(void *arg)
> +{
> +	int cpu = smp_processor_id();
> +	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON,&cpu);
> +}
> +
> +int __init ux500_idle_init(void)
> +{
> +	int ret, cpu;
> +	struct cpuidle_device *device;
> +
> +        /* Configure wake up reasons */
> +	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
> +			     PRCMU_WAKEUP(ABB));
> +
> +	/*
> +	 * Configure the timer broadcast for each cpu, that must
> +	 * be done from the cpu context, so we use a smp cross
> +	 * call with 'on_each_cpu'.
> +	 */
> +	on_each_cpu(ux500_setup_broadcast_timer, NULL, 1);
> +
> +	ret = cpuidle_register_driver(&ux500_idle_driver);
> +	if (ret) {
> +		printk(KERN_ERR "failed to register ux500 idle driver\n");
> +		return ret;
> +	}
> +
> +	for_each_online_cpu(cpu) {
> +		device =&per_cpu(ux500_cpuidle_device, cpu);
> +		device->cpu = cpu;
> +		ret = cpuidle_register_device(device);
> +		if (ret) {
> +			printk(KERN_ERR "Failed to register cpuidle "
> +			       "device for cpu%d\n", cpu);
> +			goto out_unregister;
> +		}
> +	}
> +out:
> +	return ret;
> +
> +out_unregister:
> +	for_each_online_cpu(cpu) {
> +		device =&per_cpu(ux500_cpuidle_device, cpu);
> +		cpuidle_unregister_device(device);
> +	}
> +
> +	cpuidle_unregister_driver(&ux500_idle_driver);
> +	goto out;
> +}
> +
> +device_initcall(ux500_idle_init);

[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[Daniel Lezcano]

On 04/23/2012 09:57 AM, Rickard Andersson wrote:
> Should not the driver be located in the 'drivers/cpuidle/' directory?

We had a discussion about moving the cpuidle drivers to this directory 
but there are too much dependencies between the arch specific code and 
the drivers and Russell thinks there is no real benefit of moving these 
drivers out arch/arm.

http://www.spinics.net/lists/arm-kernel/msg155454.html

The discussion is at91 specific but as this work was part of moving the 
drivers to the 'drivers' directory in general. I assumed the same rule 
applied to the ux500 cpuidle driver.

The current driver has the WFI and the ApIdle states and could be moved 
to drivers directory without complicating the dependencies but that 
won't be consistent with the rest of the drivers location (not only ARM) 
and I am not sure that will be still the case with the next states 
'ApSleep' and 'ApDeepSleep'.

IMO we should put this driver in arch/arm/mach-ux500, and, in the 
future, if we are able to move all the SoC cpuidle drivers to the 
'drivers' directory then this driver will be moved too.

Thanks
   -- Daniel

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[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[Linus Walleij]

On Mon, Apr 23, 2012 at 7:52 AM, Daniel Lezcano
<daniel.lezcano@linaro.org> wrote:

> Hi Linus,
>
> can you consider this patch for inclusion, please ?

Yepps, patch applied with Vicent's ACK.

Thanks,
Linus Walleij

[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention

[Daniel Lezcano]

On 04/24/2012 11:09 AM, Linus Walleij wrote:
> On Mon, Apr 23, 2012 at 7:52 AM, Daniel Lezcano
> <daniel.lezcano@linaro.org>  wrote:
>
>> Hi Linus,
>>
>> can you consider this patch for inclusion, please ?
> Yepps, patch applied with Vicent's ACK.

Great, thanks !

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