1 /* 2 * Copyright (C) 2012 Freescale Semiconductor, Inc. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9 #include <linux/cpuidle.h> 10 #include <linux/module.h> 11 #include <asm/cpuidle.h> 12 13 #include "common.h" 14 #include "cpuidle.h" 15 #include "hardware.h" 16 17 static atomic_t master = ATOMIC_INIT(0); 18 static DEFINE_SPINLOCK(master_lock); 19 20 static int imx6q_enter_wait(struct cpuidle_device *dev, 21 struct cpuidle_driver *drv, int index) 22 { 23 if (atomic_inc_return(&master) == num_online_cpus()) { 24 /* 25 * With this lock, we prevent other cpu to exit and enter 26 * this function again and become the master. 27 */ 28 if (!spin_trylock(&master_lock)) 29 goto idle; 30 imx6_set_lpm(WAIT_UNCLOCKED); 31 cpu_do_idle(); 32 imx6_set_lpm(WAIT_CLOCKED); 33 spin_unlock(&master_lock); 34 goto done; 35 } 36 37 idle: 38 cpu_do_idle(); 39 done: 40 atomic_dec(&master); 41 42 return index; 43 } 44 45 static struct cpuidle_driver imx6q_cpuidle_driver = { 46 .name = "imx6q_cpuidle", 47 .owner = THIS_MODULE, 48 .states = { 49 /* WFI */ 50 ARM_CPUIDLE_WFI_STATE, 51 /* WAIT */ 52 { 53 .exit_latency = 50, 54 .target_residency = 75, 55 .flags = CPUIDLE_FLAG_TIMER_STOP, 56 .enter = imx6q_enter_wait, 57 .name = "WAIT", 58 .desc = "Clock off", 59 }, 60 }, 61 .state_count = 2, 62 .safe_state_index = 0, 63 }; 64 65 int __init imx6q_cpuidle_init(void) 66 { 67 /* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */ 68 imx6q_set_int_mem_clk_lpm(true); 69 70 return cpuidle_register(&imx6q_cpuidle_driver, NULL); 71 } 72