/* * 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);