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 <soc/imx/cpuidle.h> 14 15 #include "common.h" 16 #include "cpuidle.h" 17 #include "hardware.h" 18 19 static atomic_t master = ATOMIC_INIT(0); 20 static DEFINE_SPINLOCK(master_lock); 21 22 static int imx6q_enter_wait(struct cpuidle_device *dev, 23 struct cpuidle_driver *drv, int index) 24 { 25 if (atomic_inc_return(&master) == num_online_cpus()) { 26 /* 27 * With this lock, we prevent other cpu to exit and enter 28 * this function again and become the master. 29 */ 30 if (!spin_trylock(&master_lock)) 31 goto idle; 32 imx6_set_lpm(WAIT_UNCLOCKED); 33 cpu_do_idle(); 34 imx6_set_lpm(WAIT_CLOCKED); 35 spin_unlock(&master_lock); 36 goto done; 37 } 38 39 idle: 40 cpu_do_idle(); 41 done: 42 atomic_dec(&master); 43 44 return index; 45 } 46 47 static struct cpuidle_driver imx6q_cpuidle_driver = { 48 .name = "imx6q_cpuidle", 49 .owner = THIS_MODULE, 50 .states = { 51 /* WFI */ 52 ARM_CPUIDLE_WFI_STATE, 53 /* WAIT */ 54 { 55 .exit_latency = 50, 56 .target_residency = 75, 57 .flags = CPUIDLE_FLAG_TIMER_STOP, 58 .enter = imx6q_enter_wait, 59 .name = "WAIT", 60 .desc = "Clock off", 61 }, 62 }, 63 .state_count = 2, 64 .safe_state_index = 0, 65 }; 66 67 /* 68 * i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from waking the 69 * CPUs when they are in wait(unclocked) state. As the hardware workaround isn't 70 * applicable to all boards, disable the deeper idle state when the workaround 71 * isn't present and the FEC is in use. 72 */ 73 void imx6q_cpuidle_fec_irqs_used(void) 74 { 75 imx6q_cpuidle_driver.states[1].disabled = true; 76 } 77 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_used); 78 79 void imx6q_cpuidle_fec_irqs_unused(void) 80 { 81 imx6q_cpuidle_driver.states[1].disabled = false; 82 } 83 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_unused); 84 85 int __init imx6q_cpuidle_init(void) 86 { 87 /* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */ 88 imx6_set_int_mem_clk_lpm(true); 89 90 return cpuidle_register(&imx6q_cpuidle_driver, NULL); 91 } 92