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_TIME_VALID | 71 CPUIDLE_FLAG_TIMER_STOP, 72 .name = "C1", 73 .desc = "ARM little-cluster power down", 74 }, 75 .state_count = 2, 76 }; 77 78 static const struct of_device_id bl_idle_state_match[] __initconst = { 79 { .compatible = "arm,idle-state", 80 .data = bl_enter_powerdown }, 81 { }, 82 }; 83 84 static struct cpuidle_driver bl_idle_big_driver = { 85 .name = "big_idle", 86 .owner = THIS_MODULE, 87 .states[0] = ARM_CPUIDLE_WFI_STATE, 88 .states[1] = { 89 .enter = bl_enter_powerdown, 90 .exit_latency = 500, 91 .target_residency = 2000, 92 .flags = CPUIDLE_FLAG_TIME_VALID | 93 CPUIDLE_FLAG_TIMER_STOP, 94 .name = "C1", 95 .desc = "ARM big-cluster power down", 96 }, 97 .state_count = 2, 98 }; 99 100 /* 101 * notrace prevents trace shims from getting inserted where they 102 * should not. Global jumps and ldrex/strex must not be inserted 103 * in power down sequences where caches and MMU may be turned off. 104 */ 105 static int notrace bl_powerdown_finisher(unsigned long arg) 106 { 107 /* MCPM works with HW CPU identifiers */ 108 unsigned int mpidr = read_cpuid_mpidr(); 109 unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); 110 unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); 111 112 mcpm_set_entry_vector(cpu, cluster, cpu_resume); 113 114 /* 115 * Residency value passed to mcpm_cpu_suspend back-end 116 * has to be given clear semantics. Set to 0 as a 117 * temporary value. 118 */ 119 mcpm_cpu_suspend(0); 120 121 /* return value != 0 means failure */ 122 return 1; 123 } 124 125 /** 126 * bl_enter_powerdown - Programs CPU to enter the specified state 127 * @dev: cpuidle device 128 * @drv: The target state to be programmed 129 * @idx: state index 130 * 131 * Called from the CPUidle framework to program the device to the 132 * specified target state selected by the governor. 133 */ 134 static int bl_enter_powerdown(struct cpuidle_device *dev, 135 struct cpuidle_driver *drv, int idx) 136 { 137 cpu_pm_enter(); 138 139 cpu_suspend(0, bl_powerdown_finisher); 140 141 /* signals the MCPM core that CPU is out of low power state */ 142 mcpm_cpu_powered_up(); 143 144 cpu_pm_exit(); 145 146 return idx; 147 } 148 149 static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id) 150 { 151 struct cpumask *cpumask; 152 int cpu; 153 154 cpumask = kzalloc(cpumask_size(), GFP_KERNEL); 155 if (!cpumask) 156 return -ENOMEM; 157 158 for_each_possible_cpu(cpu) 159 if (smp_cpuid_part(cpu) == part_id) 160 cpumask_set_cpu(cpu, cpumask); 161 162 drv->cpumask = cpumask; 163 164 return 0; 165 } 166 167 static const struct of_device_id compatible_machine_match[] = { 168 { .compatible = "arm,vexpress,v2p-ca15_a7" }, 169 { .compatible = "samsung,exynos5420" }, 170 { .compatible = "samsung,exynos5800" }, 171 {}, 172 }; 173 174 static int __init bl_idle_init(void) 175 { 176 int ret; 177 struct device_node *root = of_find_node_by_path("/"); 178 179 if (!root) 180 return -ENODEV; 181 182 /* 183 * Initialize the driver just for a compliant set of machines 184 */ 185 if (!of_match_node(compatible_machine_match, root)) 186 return -ENODEV; 187 /* 188 * For now the differentiation between little and big cores 189 * is based on the part number. A7 cores are considered little 190 * cores, A15 are considered big cores. This distinction may 191 * evolve in the future with a more generic matching approach. 192 */ 193 ret = bl_idle_driver_init(&bl_idle_little_driver, 194 ARM_CPU_PART_CORTEX_A7); 195 if (ret) 196 return ret; 197 198 ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15); 199 if (ret) 200 goto out_uninit_little; 201 202 /* Start at index 1, index 0 standard WFI */ 203 ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1); 204 if (ret < 0) 205 goto out_uninit_big; 206 207 /* Start at index 1, index 0 standard WFI */ 208 ret = dt_init_idle_driver(&bl_idle_little_driver, 209 bl_idle_state_match, 1); 210 if (ret < 0) 211 goto out_uninit_big; 212 213 ret = cpuidle_register(&bl_idle_little_driver, NULL); 214 if (ret) 215 goto out_uninit_big; 216 217 ret = cpuidle_register(&bl_idle_big_driver, NULL); 218 if (ret) 219 goto out_unregister_little; 220 221 return 0; 222 223 out_unregister_little: 224 cpuidle_unregister(&bl_idle_little_driver); 225 out_uninit_big: 226 kfree(bl_idle_big_driver.cpumask); 227 out_uninit_little: 228 kfree(bl_idle_little_driver.cpumask); 229 230 return ret; 231 } 232 device_initcall(bl_idle_init); 233