Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 1 | /* |
| 2 | * cpuidle.c - core cpuidle infrastructure |
| 3 | * |
| 4 | * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> |
| 5 | * Shaohua Li <shaohua.li@intel.com> |
| 6 | * Adam Belay <abelay@novell.com> |
| 7 | * |
| 8 | * This code is licenced under the GPL. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/kernel.h> |
| 12 | #include <linux/mutex.h> |
| 13 | #include <linux/sched.h> |
| 14 | #include <linux/notifier.h> |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 15 | #include <linux/pm_qos_params.h> |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 16 | #include <linux/cpu.h> |
| 17 | #include <linux/cpuidle.h> |
| 18 | |
| 19 | #include "cpuidle.h" |
| 20 | |
| 21 | DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 22 | |
| 23 | DEFINE_MUTEX(cpuidle_lock); |
| 24 | LIST_HEAD(cpuidle_detected_devices); |
| 25 | static void (*pm_idle_old)(void); |
| 26 | |
| 27 | static int enabled_devices; |
| 28 | |
| 29 | /** |
| 30 | * cpuidle_idle_call - the main idle loop |
| 31 | * |
| 32 | * NOTE: no locks or semaphores should be used here |
| 33 | */ |
| 34 | static void cpuidle_idle_call(void) |
| 35 | { |
| 36 | struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices); |
| 37 | struct cpuidle_state *target_state; |
| 38 | int next_state; |
| 39 | |
| 40 | /* check if the device is ready */ |
| 41 | if (!dev || !dev->enabled) { |
| 42 | if (pm_idle_old) |
| 43 | pm_idle_old(); |
| 44 | else |
| 45 | local_irq_enable(); |
| 46 | return; |
| 47 | } |
| 48 | |
| 49 | /* ask the governor for the next state */ |
| 50 | next_state = cpuidle_curr_governor->select(dev); |
| 51 | if (need_resched()) |
| 52 | return; |
| 53 | target_state = &dev->states[next_state]; |
| 54 | |
| 55 | /* enter the state and update stats */ |
| 56 | dev->last_residency = target_state->enter(dev, target_state); |
| 57 | dev->last_state = target_state; |
| 58 | target_state->time += dev->last_residency; |
| 59 | target_state->usage++; |
| 60 | |
| 61 | /* give the governor an opportunity to reflect on the outcome */ |
| 62 | if (cpuidle_curr_governor->reflect) |
| 63 | cpuidle_curr_governor->reflect(dev); |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * cpuidle_install_idle_handler - installs the cpuidle idle loop handler |
| 68 | */ |
| 69 | void cpuidle_install_idle_handler(void) |
| 70 | { |
| 71 | if (enabled_devices && (pm_idle != cpuidle_idle_call)) { |
| 72 | /* Make sure all changes finished before we switch to new idle */ |
| 73 | smp_wmb(); |
| 74 | pm_idle = cpuidle_idle_call; |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler |
| 80 | */ |
| 81 | void cpuidle_uninstall_idle_handler(void) |
| 82 | { |
| 83 | if (enabled_devices && (pm_idle != pm_idle_old)) { |
| 84 | pm_idle = pm_idle_old; |
| 85 | cpu_idle_wait(); |
| 86 | } |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * cpuidle_pause_and_lock - temporarily disables CPUIDLE |
| 91 | */ |
| 92 | void cpuidle_pause_and_lock(void) |
| 93 | { |
| 94 | mutex_lock(&cpuidle_lock); |
| 95 | cpuidle_uninstall_idle_handler(); |
| 96 | } |
| 97 | |
| 98 | EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); |
| 99 | |
| 100 | /** |
| 101 | * cpuidle_resume_and_unlock - resumes CPUIDLE operation |
| 102 | */ |
| 103 | void cpuidle_resume_and_unlock(void) |
| 104 | { |
| 105 | cpuidle_install_idle_handler(); |
| 106 | mutex_unlock(&cpuidle_lock); |
| 107 | } |
| 108 | |
| 109 | EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); |
| 110 | |
| 111 | /** |
| 112 | * cpuidle_enable_device - enables idle PM for a CPU |
| 113 | * @dev: the CPU |
| 114 | * |
| 115 | * This function must be called between cpuidle_pause_and_lock and |
| 116 | * cpuidle_resume_and_unlock when used externally. |
| 117 | */ |
| 118 | int cpuidle_enable_device(struct cpuidle_device *dev) |
| 119 | { |
| 120 | int ret, i; |
| 121 | |
| 122 | if (dev->enabled) |
| 123 | return 0; |
| 124 | if (!cpuidle_curr_driver || !cpuidle_curr_governor) |
| 125 | return -EIO; |
| 126 | if (!dev->state_count) |
| 127 | return -EINVAL; |
| 128 | |
| 129 | if ((ret = cpuidle_add_state_sysfs(dev))) |
| 130 | return ret; |
| 131 | |
| 132 | if (cpuidle_curr_governor->enable && |
| 133 | (ret = cpuidle_curr_governor->enable(dev))) |
| 134 | goto fail_sysfs; |
| 135 | |
| 136 | for (i = 0; i < dev->state_count; i++) { |
| 137 | dev->states[i].usage = 0; |
| 138 | dev->states[i].time = 0; |
| 139 | } |
| 140 | dev->last_residency = 0; |
| 141 | dev->last_state = NULL; |
| 142 | |
| 143 | smp_wmb(); |
| 144 | |
| 145 | dev->enabled = 1; |
| 146 | |
| 147 | enabled_devices++; |
| 148 | return 0; |
| 149 | |
| 150 | fail_sysfs: |
| 151 | cpuidle_remove_state_sysfs(dev); |
| 152 | |
| 153 | return ret; |
| 154 | } |
| 155 | |
| 156 | EXPORT_SYMBOL_GPL(cpuidle_enable_device); |
| 157 | |
| 158 | /** |
| 159 | * cpuidle_disable_device - disables idle PM for a CPU |
| 160 | * @dev: the CPU |
| 161 | * |
| 162 | * This function must be called between cpuidle_pause_and_lock and |
| 163 | * cpuidle_resume_and_unlock when used externally. |
| 164 | */ |
| 165 | void cpuidle_disable_device(struct cpuidle_device *dev) |
| 166 | { |
| 167 | if (!dev->enabled) |
| 168 | return; |
| 169 | if (!cpuidle_curr_driver || !cpuidle_curr_governor) |
| 170 | return; |
| 171 | |
| 172 | dev->enabled = 0; |
| 173 | |
| 174 | if (cpuidle_curr_governor->disable) |
| 175 | cpuidle_curr_governor->disable(dev); |
| 176 | |
| 177 | cpuidle_remove_state_sysfs(dev); |
| 178 | enabled_devices--; |
| 179 | } |
| 180 | |
| 181 | EXPORT_SYMBOL_GPL(cpuidle_disable_device); |
| 182 | |
| 183 | /** |
| 184 | * cpuidle_register_device - registers a CPU's idle PM feature |
| 185 | * @dev: the cpu |
| 186 | */ |
| 187 | int cpuidle_register_device(struct cpuidle_device *dev) |
| 188 | { |
| 189 | int ret; |
| 190 | struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); |
| 191 | |
| 192 | if (!sys_dev) |
| 193 | return -EINVAL; |
| 194 | if (!try_module_get(cpuidle_curr_driver->owner)) |
| 195 | return -EINVAL; |
| 196 | |
| 197 | init_completion(&dev->kobj_unregister); |
| 198 | |
| 199 | mutex_lock(&cpuidle_lock); |
| 200 | |
| 201 | per_cpu(cpuidle_devices, dev->cpu) = dev; |
| 202 | list_add(&dev->device_list, &cpuidle_detected_devices); |
| 203 | if ((ret = cpuidle_add_sysfs(sys_dev))) { |
| 204 | mutex_unlock(&cpuidle_lock); |
| 205 | module_put(cpuidle_curr_driver->owner); |
| 206 | return ret; |
| 207 | } |
| 208 | |
| 209 | cpuidle_enable_device(dev); |
| 210 | cpuidle_install_idle_handler(); |
| 211 | |
| 212 | mutex_unlock(&cpuidle_lock); |
| 213 | |
| 214 | return 0; |
| 215 | |
| 216 | } |
| 217 | |
| 218 | EXPORT_SYMBOL_GPL(cpuidle_register_device); |
| 219 | |
| 220 | /** |
| 221 | * cpuidle_unregister_device - unregisters a CPU's idle PM feature |
| 222 | * @dev: the cpu |
| 223 | */ |
| 224 | void cpuidle_unregister_device(struct cpuidle_device *dev) |
| 225 | { |
| 226 | struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); |
| 227 | |
| 228 | cpuidle_pause_and_lock(); |
| 229 | |
| 230 | cpuidle_disable_device(dev); |
| 231 | |
| 232 | cpuidle_remove_sysfs(sys_dev); |
| 233 | list_del(&dev->device_list); |
| 234 | wait_for_completion(&dev->kobj_unregister); |
| 235 | per_cpu(cpuidle_devices, dev->cpu) = NULL; |
| 236 | |
| 237 | cpuidle_resume_and_unlock(); |
| 238 | |
| 239 | module_put(cpuidle_curr_driver->owner); |
| 240 | } |
| 241 | |
| 242 | EXPORT_SYMBOL_GPL(cpuidle_unregister_device); |
| 243 | |
| 244 | #ifdef CONFIG_SMP |
| 245 | |
| 246 | static void smp_callback(void *v) |
| 247 | { |
| 248 | /* we already woke the CPU up, nothing more to do */ |
| 249 | } |
| 250 | |
| 251 | /* |
| 252 | * This function gets called when a part of the kernel has a new latency |
| 253 | * requirement. This means we need to get all processors out of their C-state, |
| 254 | * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that |
| 255 | * wakes them all right up. |
| 256 | */ |
| 257 | static int cpuidle_latency_notify(struct notifier_block *b, |
| 258 | unsigned long l, void *v) |
| 259 | { |
| 260 | smp_call_function(smp_callback, NULL, 0, 1); |
| 261 | return NOTIFY_OK; |
| 262 | } |
| 263 | |
| 264 | static struct notifier_block cpuidle_latency_notifier = { |
| 265 | .notifier_call = cpuidle_latency_notify, |
| 266 | }; |
| 267 | |
Mark Gross | d82b351 | 2008-02-04 22:30:08 -0800 | [diff] [blame] | 268 | static inline void latency_notifier_init(struct notifier_block *n) |
| 269 | { |
| 270 | pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); |
| 271 | } |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 272 | |
| 273 | #else /* CONFIG_SMP */ |
| 274 | |
| 275 | #define latency_notifier_init(x) do { } while (0) |
| 276 | |
| 277 | #endif /* CONFIG_SMP */ |
| 278 | |
| 279 | /** |
| 280 | * cpuidle_init - core initializer |
| 281 | */ |
| 282 | static int __init cpuidle_init(void) |
| 283 | { |
| 284 | int ret; |
| 285 | |
| 286 | pm_idle_old = pm_idle; |
| 287 | |
| 288 | ret = cpuidle_add_class_sysfs(&cpu_sysdev_class); |
| 289 | if (ret) |
| 290 | return ret; |
| 291 | |
| 292 | latency_notifier_init(&cpuidle_latency_notifier); |
| 293 | |
| 294 | return 0; |
| 295 | } |
| 296 | |
| 297 | core_initcall(cpuidle_init); |