diff options
Diffstat (limited to 'arch/arm/mach-ux500/cpuidle.c')
| -rw-r--r-- | arch/arm/mach-ux500/cpuidle.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/arch/arm/mach-ux500/cpuidle.c b/arch/arm/mach-ux500/cpuidle.c new file mode 100644 index 00000000000..b54884bd254 --- /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); |