From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Mon, 23 Apr 2012 07:52:44 +0200 Subject: [PATCH] ARM: ux500: add the cpuidle driver for WFI and ARM retention In-Reply-To: <1334839592-32251-1-git-send-email-daniel.lezcano@linaro.org> References: <1334839592-32251-1-git-send-email-daniel.lezcano@linaro.org> Message-ID: <4F94EE2C.1060503@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 > --- 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 (IBM) > + * > + * Based on the work of Rickard Andersson > + * and Jonas Aaberg. > + * > + * 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 > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > +#include > + > +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); -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog