[PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention
Vincent Guittot
vincent.guittot at linaro.org
Mon Apr 23 03:55:02 EDT 2012
Hi Daniel,
You can add my Ack on your patch
Vincent
On 19 April 2012 14:46, Daniel Lezcano <daniel.lezcano at 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 at 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 at linaro.org> (IBM)
> + *
> + * Based on the work of Rickard Andersson <rickard.andersson at stericsson.com>
> + * and Jonas Aaberg <jonas.aberg at 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
>
>
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