1 /* 2 * Copyright (C) 2014 Imagination Technologies 3 * Author: Paul Burton <paul.burton@mips.com> 4 * 5 * This program is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License as published by the 7 * Free Software Foundation; either version 2 of the License, or (at your 8 * option) any later version. 9 */ 10 11 #include <linux/cpu_pm.h> 12 #include <linux/cpuidle.h> 13 #include <linux/init.h> 14 15 #include <asm/idle.h> 16 #include <asm/pm-cps.h> 17 18 /* Enumeration of the various idle states this driver may enter */ 19 enum cps_idle_state { 20 STATE_WAIT = 0, /* MIPS wait instruction, coherent */ 21 STATE_NC_WAIT, /* MIPS wait instruction, non-coherent */ 22 STATE_CLOCK_GATED, /* Core clock gated */ 23 STATE_POWER_GATED, /* Core power gated */ 24 STATE_COUNT 25 }; 26 27 static int cps_nc_enter(struct cpuidle_device *dev, 28 struct cpuidle_driver *drv, int index) 29 { 30 enum cps_pm_state pm_state; 31 int err; 32 33 /* 34 * At least one core must remain powered up & clocked in order for the 35 * system to have any hope of functioning. 36 * 37 * TODO: don't treat core 0 specially, just prevent the final core 38 * TODO: remap interrupt affinity temporarily 39 */ 40 if (cpus_are_siblings(0, dev->cpu) && (index > STATE_NC_WAIT)) 41 index = STATE_NC_WAIT; 42 43 /* Select the appropriate cps_pm_state */ 44 switch (index) { 45 case STATE_NC_WAIT: 46 pm_state = CPS_PM_NC_WAIT; 47 break; 48 case STATE_CLOCK_GATED: 49 pm_state = CPS_PM_CLOCK_GATED; 50 break; 51 case STATE_POWER_GATED: 52 pm_state = CPS_PM_POWER_GATED; 53 break; 54 default: 55 BUG(); 56 return -EINVAL; 57 } 58 59 /* Notify listeners the CPU is about to power down */ 60 if ((pm_state == CPS_PM_POWER_GATED) && cpu_pm_enter()) 61 return -EINTR; 62 63 /* Enter that state */ 64 err = cps_pm_enter_state(pm_state); 65 66 /* Notify listeners the CPU is back up */ 67 if (pm_state == CPS_PM_POWER_GATED) 68 cpu_pm_exit(); 69 70 return err ?: index; 71 } 72 73 static struct cpuidle_driver cps_driver = { 74 .name = "cpc_cpuidle", 75 .owner = THIS_MODULE, 76 .states = { 77 [STATE_WAIT] = MIPS_CPUIDLE_WAIT_STATE, 78 [STATE_NC_WAIT] = { 79 .enter = cps_nc_enter, 80 .exit_latency = 200, 81 .target_residency = 450, 82 .name = "nc-wait", 83 .desc = "non-coherent MIPS wait", 84 }, 85 [STATE_CLOCK_GATED] = { 86 .enter = cps_nc_enter, 87 .exit_latency = 300, 88 .target_residency = 700, 89 .flags = CPUIDLE_FLAG_TIMER_STOP, 90 .name = "clock-gated", 91 .desc = "core clock gated", 92 }, 93 [STATE_POWER_GATED] = { 94 .enter = cps_nc_enter, 95 .exit_latency = 600, 96 .target_residency = 1000, 97 .flags = CPUIDLE_FLAG_TIMER_STOP, 98 .name = "power-gated", 99 .desc = "core power gated", 100 }, 101 }, 102 .state_count = STATE_COUNT, 103 .safe_state_index = 0, 104 }; 105 106 static void __init cps_cpuidle_unregister(void) 107 { 108 int cpu; 109 struct cpuidle_device *device; 110 111 for_each_possible_cpu(cpu) { 112 device = &per_cpu(cpuidle_dev, cpu); 113 cpuidle_unregister_device(device); 114 } 115 116 cpuidle_unregister_driver(&cps_driver); 117 } 118 119 static int __init cps_cpuidle_init(void) 120 { 121 int err, cpu, i; 122 struct cpuidle_device *device; 123 124 /* Detect supported states */ 125 if (!cps_pm_support_state(CPS_PM_POWER_GATED)) 126 cps_driver.state_count = STATE_CLOCK_GATED + 1; 127 if (!cps_pm_support_state(CPS_PM_CLOCK_GATED)) 128 cps_driver.state_count = STATE_NC_WAIT + 1; 129 if (!cps_pm_support_state(CPS_PM_NC_WAIT)) 130 cps_driver.state_count = STATE_WAIT + 1; 131 132 /* Inform the user if some states are unavailable */ 133 if (cps_driver.state_count < STATE_COUNT) { 134 pr_info("cpuidle-cps: limited to "); 135 switch (cps_driver.state_count - 1) { 136 case STATE_WAIT: 137 pr_cont("coherent wait\n"); 138 break; 139 case STATE_NC_WAIT: 140 pr_cont("non-coherent wait\n"); 141 break; 142 case STATE_CLOCK_GATED: 143 pr_cont("clock gating\n"); 144 break; 145 } 146 } 147 148 /* 149 * Set the coupled flag on the appropriate states if this system 150 * requires it. 151 */ 152 if (coupled_coherence) 153 for (i = STATE_NC_WAIT; i < cps_driver.state_count; i++) 154 cps_driver.states[i].flags |= CPUIDLE_FLAG_COUPLED; 155 156 err = cpuidle_register_driver(&cps_driver); 157 if (err) { 158 pr_err("Failed to register CPS cpuidle driver\n"); 159 return err; 160 } 161 162 for_each_possible_cpu(cpu) { 163 device = &per_cpu(cpuidle_dev, cpu); 164 device->cpu = cpu; 165 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED 166 cpumask_copy(&device->coupled_cpus, &cpu_sibling_map[cpu]); 167 #endif 168 169 err = cpuidle_register_device(device); 170 if (err) { 171 pr_err("Failed to register CPU%d cpuidle device\n", 172 cpu); 173 goto err_out; 174 } 175 } 176 177 return 0; 178 err_out: 179 cps_cpuidle_unregister(); 180 return err; 181 } 182 device_initcall(cps_cpuidle_init); 183