1 /* 2 * Copyright (c) 2013 ARM/Linaro 3 * 4 * Authors: Daniel Lezcano <daniel.lezcano@linaro.org> 5 * Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> 6 * Nicolas Pitre <nicolas.pitre@linaro.org> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * Maintainer: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> 13 * Maintainer: Daniel Lezcano <daniel.lezcano@linaro.org> 14 */ 15 #include <linux/cpuidle.h> 16 #include <linux/cpu_pm.h> 17 #include <linux/slab.h> 18 #include <linux/of.h> 19 20 #include <asm/cpu.h> 21 #include <asm/cputype.h> 22 #include <asm/cpuidle.h> 23 #include <asm/mcpm.h> 24 #include <asm/smp_plat.h> 25 #include <asm/suspend.h> 26 27 #include "dt_idle_states.h" 28 29 static int bl_enter_powerdown(struct cpuidle_device *dev, 30 struct cpuidle_driver *drv, int idx); 31 32 /* 33 * NB: Owing to current menu governor behaviour big and LITTLE 34 * index 1 states have to define exit_latency and target_residency for 35 * cluster state since, when all CPUs in a cluster hit it, the cluster 36 * can be shutdown. This means that when a single CPU enters this state 37 * the exit_latency and target_residency values are somewhat overkill. 38 * There is no notion of cluster states in the menu governor, so CPUs 39 * have to define CPU states where possibly the cluster will be shutdown 40 * depending on the state of other CPUs. idle states entry and exit happen 41 * at random times; however the cluster state provides target_residency 42 * values as if all CPUs in a cluster enter the state at once; this is 43 * somewhat optimistic and behaviour should be fixed either in the governor 44 * or in the MCPM back-ends. 45 * To make this driver 100% generic the number of states and the exit_latency 46 * target_residency values must be obtained from device tree bindings. 47 * 48 * exit_latency: refers to the TC2 vexpress test chip and depends on the 49 * current cluster operating point. It is the time it takes to get the CPU 50 * up and running when the CPU is powered up on cluster wake-up from shutdown. 51 * Current values for big and LITTLE clusters are provided for clusters 52 * running at default operating points. 53 * 54 * target_residency: it is the minimum amount of time the cluster has 55 * to be down to break even in terms of power consumption. cluster 56 * shutdown has inherent dynamic power costs (L2 writebacks to DRAM 57 * being the main factor) that depend on the current operating points. 58 * The current values for both clusters are provided for a CPU whose half 59 * of L2 lines are dirty and require cleaning to DRAM, and takes into 60 * account leakage static power values related to the vexpress TC2 testchip. 61 */ 62 static struct cpuidle_driver bl_idle_little_driver = { 63 .name = "little_idle", 64 .owner = THIS_MODULE, 65 .states[0] = ARM_CPUIDLE_WFI_STATE, 66 .states[1] = { 67 .enter = bl_enter_powerdown, 68 .exit_latency = 700, 69 .target_residency = 2500, 70 .flags = CPUIDLE_FLAG_TIMER_STOP, 71 .name = "C1", 72 .desc = "ARM little-cluster power down", 73 }, 74 .state_count = 2, 75 }; 76 77 static const struct of_device_id bl_idle_state_match[] __initconst = { 78 { .compatible = "arm,idle-state", 79 .data = bl_enter_powerdown }, 80 { }, 81 }; 82 83 static struct cpuidle_driver bl_idle_big_driver = { 84 .name = "big_idle", 85 .owner = THIS_MODULE, 86 .states[0] = ARM_CPUIDLE_WFI_STATE, 87 .states[1] = { 88 .enter = bl_enter_powerdown, 89 .exit_latency = 500, 90 .target_residency = 2000, 91 .flags = CPUIDLE_FLAG_TIMER_STOP, 92 .name = "C1", 93 .desc = "ARM big-cluster power down", 94 }, 95 .state_count = 2, 96 }; 97 98 /* 99 * notrace prevents trace shims from getting inserted where they 100 * should not. Global jumps and ldrex/strex must not be inserted 101 * in power down sequences where caches and MMU may be turned off. 102 */ 103 static int notrace bl_powerdown_finisher(unsigned long arg) 104 { 105 /* MCPM works with HW CPU identifiers */ 106 unsigned int mpidr = read_cpuid_mpidr(); 107 unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); 108 unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); 109 110 mcpm_set_entry_vector(cpu, cluster, cpu_resume); 111 mcpm_cpu_suspend(); 112 113 /* return value != 0 means failure */ 114 return 1; 115 } 116 117 /** 118 * bl_enter_powerdown - Programs CPU to enter the specified state 119 * @dev: cpuidle device 120 * @drv: The target state to be programmed 121 * @idx: state index 122 * 123 * Called from the CPUidle framework to program the device to the 124 * specified target state selected by the governor. 125 */ 126 static int bl_enter_powerdown(struct cpuidle_device *dev, 127 struct cpuidle_driver *drv, int idx) 128 { 129 cpu_pm_enter(); 130 131 cpu_suspend(0, bl_powerdown_finisher); 132 133 /* signals the MCPM core that CPU is out of low power state */ 134 mcpm_cpu_powered_up(); 135 136 cpu_pm_exit(); 137 138 return idx; 139 } 140 141 static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id) 142 { 143 struct cpumask *cpumask; 144 int cpu; 145 146 cpumask = kzalloc(cpumask_size(), GFP_KERNEL); 147 if (!cpumask) 148 return -ENOMEM; 149 150 for_each_possible_cpu(cpu) 151 if (smp_cpuid_part(cpu) == part_id) 152 cpumask_set_cpu(cpu, cpumask); 153 154 drv->cpumask = cpumask; 155 156 return 0; 157 } 158 159 static const struct of_device_id compatible_machine_match[] = { 160 { .compatible = "arm,vexpress,v2p-ca15_a7" }, 161 { .compatible = "samsung,exynos5420" }, 162 { .compatible = "samsung,exynos5800" }, 163 {}, 164 }; 165 166 static int __init bl_idle_init(void) 167 { 168 int ret; 169 struct device_node *root = of_find_node_by_path("/"); 170 171 if (!root) 172 return -ENODEV; 173 174 /* 175 * Initialize the driver just for a compliant set of machines 176 */ 177 if (!of_match_node(compatible_machine_match, root)) 178 return -ENODEV; 179 180 if (!mcpm_is_available()) 181 return -EUNATCH; 182 183 /* 184 * For now the differentiation between little and big cores 185 * is based on the part number. A7 cores are considered little 186 * cores, A15 are considered big cores. This distinction may 187 * evolve in the future with a more generic matching approach. 188 */ 189 ret = bl_idle_driver_init(&bl_idle_little_driver, 190 ARM_CPU_PART_CORTEX_A7); 191 if (ret) 192 return ret; 193 194 ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15); 195 if (ret) 196 goto out_uninit_little; 197 198 /* Start at index 1, index 0 standard WFI */ 199 ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1); 200 if (ret < 0) 201 goto out_uninit_big; 202 203 /* Start at index 1, index 0 standard WFI */ 204 ret = dt_init_idle_driver(&bl_idle_little_driver, 205 bl_idle_state_match, 1); 206 if (ret < 0) 207 goto out_uninit_big; 208 209 ret = cpuidle_register(&bl_idle_little_driver, NULL); 210 if (ret) 211 goto out_uninit_big; 212 213 ret = cpuidle_register(&bl_idle_big_driver, NULL); 214 if (ret) 215 goto out_unregister_little; 216 217 return 0; 218 219 out_unregister_little: 220 cpuidle_unregister(&bl_idle_little_driver); 221 out_uninit_big: 222 kfree(bl_idle_big_driver.cpumask); 223 out_uninit_little: 224 kfree(bl_idle_little_driver.cpumask); 225 226 return ret; 227 } 228 device_initcall(bl_idle_init); 229