drivers/cpuidle/driver.c

   1 /*
   2  * driver.c - driver support
   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/mutex.h>
  12 #include <linux/module.h>
  13 #include <linux/cpuidle.h>
  14 #include <linux/cpumask.h>
  15 #include <linux/clockchips.h>
  16
  17 #include "cpuidle.h"
  18
  19 DEFINE_SPINLOCK(cpuidle_driver_lock);
  20
  21 static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu);
  22 static struct cpuidle_driver * __cpuidle_get_cpu_driver(int cpu);
  23
  24 static void cpuidle_setup_broadcast_timer(void *arg)
  25 {
  26         int cpu = smp_processor_id();
  27         clockevents_notify((long)(arg), &cpu);
  28 }
  29
  30 static void __cpuidle_driver_init(struct cpuidle_driver *drv, int cpu)
  31 {
  32         int i;
  33
  34         drv->refcnt = 0;
  35
  36         for (i = drv->state_count - 1; i >= 0 ; i--) {
  37
  38                 if (!(drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP))
  39                         continue;
  40
  41                 drv->bctimer = 1;
  42                 on_each_cpu_mask(get_cpu_mask(cpu), cpuidle_setup_broadcast_timer,
  43                                  (void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, 1);
  44                 break;
  45         }
  46 }
  47
  48 static int __cpuidle_register_driver(struct cpuidle_driver *drv, int cpu)
  49 {
  50         if (!drv || !drv->state_count)
  51                 return -EINVAL;
  52
  53         if (cpuidle_disabled())
  54                 return -ENODEV;
  55
  56         if (__cpuidle_get_cpu_driver(cpu))
  57                 return -EBUSY;
  58
  59         __cpuidle_driver_init(drv, cpu);
  60
  61         __cpuidle_set_cpu_driver(drv, cpu);
  62
  63         return 0;
  64 }
  65
  66 static void __cpuidle_unregister_driver(struct cpuidle_driver *drv, int cpu)
  67 {
  68         if (drv != __cpuidle_get_cpu_driver(cpu))
  69                 return;
  70
  71         if (!WARN_ON(drv->refcnt > 0))
  72                 __cpuidle_set_cpu_driver(NULL, cpu);
  73
  74         if (drv->bctimer) {
  75                 drv->bctimer = 0;
  76                 on_each_cpu_mask(get_cpu_mask(cpu), cpuidle_setup_broadcast_timer,
  77                                  (void *)CLOCK_EVT_NOTIFY_BROADCAST_OFF, 1);
  78         }
  79 }
  80
  81 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
  82
  83 static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
  84
  85 static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
  86 {
  87         per_cpu(cpuidle_drivers, cpu) = drv;
  88 }
  89
  90 static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
  91 {
  92         return per_cpu(cpuidle_drivers, cpu);
  93 }
  94
  95 static void __cpuidle_unregister_all_cpu_driver(struct cpuidle_driver *drv)
  96 {
  97         int cpu;
  98         for_each_present_cpu(cpu)
  99                 __cpuidle_unregister_driver(drv, cpu);
 100 }
 101
 102 static int __cpuidle_register_all_cpu_driver(struct cpuidle_driver *drv)
 103 {
 104         int ret = 0;
 105         int i, cpu;
 106
 107         for_each_present_cpu(cpu) {
 108                 ret = __cpuidle_register_driver(drv, cpu);
 109                 if (ret)
 110                         break;
 111         }
 112
 113         if (ret)
 114                 for_each_present_cpu(i) {
 115                         if (i == cpu)
 116                                 break;
 117                         __cpuidle_unregister_driver(drv, i);
 118                 }
 119
 120
 121         return ret;
 122 }
 123
 124 int cpuidle_register_cpu_driver(struct cpuidle_driver *drv, int cpu)
 125 {
 126         int ret;
 127
 128         spin_lock(&cpuidle_driver_lock);
 129         ret = __cpuidle_register_driver(drv, cpu);
 130         spin_unlock(&cpuidle_driver_lock);
 131
 132         return ret;
 133 }
 134
 135 void cpuidle_unregister_cpu_driver(struct cpuidle_driver *drv, int cpu)
 136 {
 137         spin_lock(&cpuidle_driver_lock);
 138         __cpuidle_unregister_driver(drv, cpu);
 139         spin_unlock(&cpuidle_driver_lock);
 140 }
 141
 142 /**
 143  * cpuidle_register_driver - registers a driver
 144  * @drv: the driver
 145  */
 146 int cpuidle_register_driver(struct cpuidle_driver *drv)
 147 {
 148         int ret;
 149
 150         spin_lock(&cpuidle_driver_lock);
 151         ret = __cpuidle_register_all_cpu_driver(drv);
 152         spin_unlock(&cpuidle_driver_lock);
 153
 154         return ret;
 155 }
 156 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
 157
 158 /**
 159  * cpuidle_unregister_driver - unregisters a driver
 160  * @drv: the driver
 161  */
 162 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
 163 {
 164         spin_lock(&cpuidle_driver_lock);
 165         __cpuidle_unregister_all_cpu_driver(drv);
 166         spin_unlock(&cpuidle_driver_lock);
 167 }
 168 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
 169
 170 #else
 171
 172 static struct cpuidle_driver *cpuidle_curr_driver;
 173
 174 static inline void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
 175 {
 176         cpuidle_curr_driver = drv;
 177 }
 178
 179 static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
 180 {
 181         return cpuidle_curr_driver;
 182 }
 183
 184 /**
 185  * cpuidle_register_driver - registers a driver
 186  * @drv: the driver
 187  */
 188 int cpuidle_register_driver(struct cpuidle_driver *drv)
 189 {
 190         int ret, cpu;
 191
 192         cpu = get_cpu();
 193         spin_lock(&cpuidle_driver_lock);
 194         ret = __cpuidle_register_driver(drv, cpu);
 195         spin_unlock(&cpuidle_driver_lock);
 196         put_cpu();
 197
 198         return ret;
 199 }
 200 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
 201
 202 /**
 203  * cpuidle_unregister_driver - unregisters a driver
 204  * @drv: the driver
 205  */
 206 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
 207 {
 208         int cpu;
 209
 210         cpu = get_cpu();
 211         spin_lock(&cpuidle_driver_lock);
 212         __cpuidle_unregister_driver(drv, cpu);
 213         spin_unlock(&cpuidle_driver_lock);
 214         put_cpu();
 215 }
 216 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
 217 #endif
 218
 219 /**
 220  * cpuidle_get_driver - return the current driver
 221  */
 222 struct cpuidle_driver *cpuidle_get_driver(void)
 223 {
 224         struct cpuidle_driver *drv;
 225         int cpu;
 226
 227         cpu = get_cpu();
 228         drv = __cpuidle_get_cpu_driver(cpu);
 229         put_cpu();
 230
 231         return drv;
 232 }
 233 EXPORT_SYMBOL_GPL(cpuidle_get_driver);
 234
 235 /**
 236  * cpuidle_get_cpu_driver - return the driver tied with a cpu
 237  */
 238 struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
 239 {
 240         if (!dev)
 241                 return NULL;
 242
 243         return __cpuidle_get_cpu_driver(dev->cpu);
 244 }
 245 EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
 246
 247 struct cpuidle_driver *cpuidle_driver_ref(void)
 248 {
 249         struct cpuidle_driver *drv;
 250
 251         spin_lock(&cpuidle_driver_lock);
 252
 253         drv = cpuidle_get_driver();
 254         if (drv)
 255                 drv->refcnt++;
 256
 257         spin_unlock(&cpuidle_driver_lock);
 258         return drv;
 259 }
 260
 261 void cpuidle_driver_unref(void)
 262 {
 263         struct cpuidle_driver *drv = cpuidle_get_driver();
 264
 265         spin_lock(&cpuidle_driver_lock);
 266
 267         if (drv && !WARN_ON(drv->refcnt <= 0))
 268                 drv->refcnt--;
 269
 270         spin_unlock(&cpuidle_driver_lock);
 271 }