125 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)4 *5 * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>6 * and Jonas Aaberg <jonas.aberg@stericsson.com>.7 */8 9#include <linux/init.h>10#include <linux/cpuidle.h>11#include <linux/spinlock.h>12#include <linux/atomic.h>13#include <linux/smp.h>14#include <linux/mfd/dbx500-prcmu.h>15#include <linux/platform_data/arm-ux500-pm.h>16#include <linux/platform_device.h>17 18#include <asm/cpuidle.h>19 20static atomic_t master = ATOMIC_INIT(0);21static DEFINE_SPINLOCK(master_lock);22 23static inline int ux500_enter_idle(struct cpuidle_device *dev,24 struct cpuidle_driver *drv, int index)25{26 int this_cpu = smp_processor_id();27 bool recouple = false;28 29 if (atomic_inc_return(&master) == num_online_cpus()) {30 31 /* With this lock, we prevent the other cpu to exit and enter32 * this function again and become the master */33 if (!spin_trylock(&master_lock))34 goto wfi;35 36 /* decouple the gic from the A9 cores */37 if (prcmu_gic_decouple()) {38 spin_unlock(&master_lock);39 goto out;40 }41 42 /* If an error occur, we will have to recouple the gic43 * manually */44 recouple = true;45 46 /* At this state, as the gic is decoupled, if the other47 * cpu is in WFI, we have the guarantee it won't be wake48 * up, so we can safely go to retention */49 if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))50 goto out;51 52 /* The prcmu will be in charge of watching the interrupts53 * and wake up the cpus */54 if (prcmu_copy_gic_settings())55 goto out;56 57 /* Check in the meantime an interrupt did58 * not occur on the gic ... */59 if (prcmu_gic_pending_irq())60 goto out;61 62 /* ... and the prcmu */63 if (prcmu_pending_irq())64 goto out;65 66 /* Go to the retention state, the prcmu will wait for the67 * cpu to go WFI and this is what happens after exiting this68 * 'master' critical section */69 if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))70 goto out;71 72 /* When we switch to retention, the prcmu is in charge73 * of recoupling the gic automatically */74 recouple = false;75 76 spin_unlock(&master_lock);77 }78wfi:79 cpu_do_idle();80out:81 atomic_dec(&master);82 83 if (recouple) {84 prcmu_gic_recouple();85 spin_unlock(&master_lock);86 }87 88 return index;89}90 91static struct cpuidle_driver ux500_idle_driver = {92 .name = "ux500_idle",93 .owner = THIS_MODULE,94 .states = {95 ARM_CPUIDLE_WFI_STATE,96 {97 .enter = ux500_enter_idle,98 .exit_latency = 70,99 .target_residency = 260,100 .flags = CPUIDLE_FLAG_TIMER_STOP,101 .name = "ApIdle",102 .desc = "ARM Retention",103 },104 },105 .safe_state_index = 0,106 .state_count = 2,107};108 109static int dbx500_cpuidle_probe(struct platform_device *pdev)110{111 /* Configure wake up reasons */112 prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |113 PRCMU_WAKEUP(ABB));114 115 return cpuidle_register(&ux500_idle_driver, NULL);116}117 118static struct platform_driver dbx500_cpuidle_plat_driver = {119 .driver = {120 .name = "db8500-cpuidle",121 },122 .probe = dbx500_cpuidle_probe,123};124builtin_platform_driver(dbx500_cpuidle_plat_driver);125