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
  15 #include "cpuidle.h"
  16
  17 DEFINE_SPINLOCK(cpuidle_driver_lock);
  18
  19 static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu);
  20 static struct cpuidle_driver * __cpuidle_get_cpu_driver(int cpu);
  21
  22 static void set_power_states(struct cpuidle_driver *drv)
  23 {
  24         int i;
  25
  26         /*
  27          * cpuidle driver should set the drv->power_specified bit
  28          * before registering if the driver provides
  29          * power_usage numbers.
  30          *
  31          * If power_specified is not set,
  32          * we fill in power_usage with decreasing values as the
  33          * cpuidle code has an implicit assumption that state Cn
  34          * uses less power than C(n-1).
  35          *
  36          * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
  37          * an power value of -1.  So we use -2, -3, etc, for other
  38          * c-states.
  39          */
  40         for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
  41                 drv->states[i].power_usage = -1 - i;
  42 }
  43
  44 static void __cpuidle_driver_init(struct cpuidle_driver *drv)
  45 {
  46         drv->refcnt = 0;
  47
  48         if (!drv->power_specified)
  49                 set_power_states(drv);
  50 }
  51
  52 static int __cpuidle_register_driver(struct cpuidle_driver *drv, int cpu)
  53 {
  54         if (!drv || !drv->state_count)
  55                 return -EINVAL;
  56
  57         if (cpuidle_disabled())
  58                 return -ENODEV;
  59
  60         if (__cpuidle_get_cpu_driver(cpu))
  61                 return -EBUSY;
  62
  63         __cpuidle_driver_init(drv);
  64
  65         __cpuidle_set_cpu_driver(drv, cpu);
  66
  67         return 0;
  68 }
  69
  70 static void __cpuidle_unregister_driver(struct cpuidle_driver *drv, int cpu)
  71 {
  72         if (drv != __cpuidle_get_cpu_driver(cpu))
  73                 return;
  74
  75         if (!WARN_ON(drv->refcnt > 0))
  76                 __cpuidle_set_cpu_driver(NULL, cpu);
  77 }
  78
  79 #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
  80
  81 static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
  82
  83 static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
  84 {
  85         per_cpu(cpuidle_drivers, cpu) = drv;
  86 }
  87
  88 static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
  89 {
  90         return per_cpu(cpuidle_drivers, cpu);
  91 }
  92
  93 static void __cpuidle_unregister_all_cpu_driver(struct cpuidle_driver *drv)
  94 {
  95         int cpu;
  96         for_each_present_cpu(cpu)
  97                 __cpuidle_unregister_driver(drv, cpu);
  98 }
  99
 100 static int __cpuidle_register_all_cpu_driver(struct cpuidle_driver *drv)
 101 {
 102         int ret = 0;
 103         int i, cpu;
 104
 105         for_each_present_cpu(cpu) {
 106                 ret = __cpuidle_register_driver(drv, cpu);
 107                 if (ret)
 108                         break;
 109         }
 110
 111         if (ret)
 112                 for_each_present_cpu(i) {
 113                         if (i == cpu)
 114                                 break;
 115                         __cpuidle_unregister_driver(drv, i);
 116                 }
 117
 118
 119         return ret;
 120 }
 121
 122 int cpuidle_register_cpu_driver(struct cpuidle_driver *drv, int cpu)
 123 {
 124         int ret;
 125
 126         spin_lock(&cpuidle_driver_lock);
 127         ret = __cpuidle_register_driver(drv, cpu);
 128         spin_unlock(&cpuidle_driver_lock);
 129
 130         return ret;
 131 }
 132
 133 void cpuidle_unregister_cpu_driver(struct cpuidle_driver *drv, int cpu)
 134 {
 135         spin_lock(&cpuidle_driver_lock);
 136         __cpuidle_unregister_driver(drv, cpu);
 137         spin_unlock(&cpuidle_driver_lock);
 138 }
 139
 140 /**
 141  * cpuidle_register_driver - registers a driver
 142  * @drv: the driver
 143  */
 144 int cpuidle_register_driver(struct cpuidle_driver *drv)
 145 {
 146         int ret;
 147
 148         spin_lock(&cpuidle_driver_lock);
 149         ret = __cpuidle_register_all_cpu_driver(drv);
 150         spin_unlock(&cpuidle_driver_lock);
 151
 152         return ret;
 153 }
 154 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
 155
 156 /**
 157  * cpuidle_unregister_driver - unregisters a driver
 158  * @drv: the driver
 159  */
 160 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
 161 {
 162         spin_lock(&cpuidle_driver_lock);
 163         __cpuidle_unregister_all_cpu_driver(drv);
 164         spin_unlock(&cpuidle_driver_lock);
 165 }
 166 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
 167
 168 #else
 169
 170 static struct cpuidle_driver *cpuidle_curr_driver;
 171
 172 static inline void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
 173 {
 174         cpuidle_curr_driver = drv;
 175 }
 176
 177 static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
 178 {
 179         return cpuidle_curr_driver;
 180 }
 181
 182 /**
 183  * cpuidle_register_driver - registers a driver
 184  * @drv: the driver
 185  */
 186 int cpuidle_register_driver(struct cpuidle_driver *drv)
 187 {
 188         int ret, cpu;
 189
 190         cpu = get_cpu();
 191         spin_lock(&cpuidle_driver_lock);
 192         ret = __cpuidle_register_driver(drv, cpu);
 193         spin_unlock(&cpuidle_driver_lock);
 194         put_cpu();
 195
 196         return ret;
 197 }
 198 EXPORT_SYMBOL_GPL(cpuidle_register_driver);
 199
 200 /**
 201  * cpuidle_unregister_driver - unregisters a driver
 202  * @drv: the driver
 203  */
 204 void cpuidle_unregister_driver(struct cpuidle_driver *drv)
 205 {
 206         int cpu;
 207
 208         cpu = get_cpu();
 209         spin_lock(&cpuidle_driver_lock);
 210         __cpuidle_unregister_driver(drv, cpu);
 211         spin_unlock(&cpuidle_driver_lock);
 212         put_cpu();
 213 }
 214 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
 215 #endif
 216
 217 /**
 218  * cpuidle_get_driver - return the current driver
 219  */
 220 struct cpuidle_driver *cpuidle_get_driver(void)
 221 {
 222         struct cpuidle_driver *drv;
 223         int cpu;
 224
 225         cpu = get_cpu();
 226         drv = __cpuidle_get_cpu_driver(cpu);
 227         put_cpu();
 228
 229         return drv;
 230 }
 231 EXPORT_SYMBOL_GPL(cpuidle_get_driver);
 232
 233 /**
 234  * cpuidle_get_cpu_driver - return the driver tied with a cpu
 235  */
 236 struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
 237 {
 238         struct cpuidle_driver *drv;
 239
 240         if (!dev)
 241                 return NULL;
 242
 243         spin_lock(&cpuidle_driver_lock);
 244         drv = __cpuidle_get_cpu_driver(dev->cpu);
 245         spin_unlock(&cpuidle_driver_lock);
 246
 247         return drv;
 248 }
 249 EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
 250
 251 struct cpuidle_driver *cpuidle_driver_ref(void)
 252 {
 253         struct cpuidle_driver *drv;
 254
 255         spin_lock(&cpuidle_driver_lock);
 256
 257         drv = cpuidle_get_driver();
 258         drv->refcnt++;
 259
 260         spin_unlock(&cpuidle_driver_lock);
 261         return drv;
 262 }
 263
 264 void cpuidle_driver_unref(void)
 265 {
 266         struct cpuidle_driver *drv = cpuidle_get_driver();
 267
 268         spin_lock(&cpuidle_driver_lock);
 269
 270         if (drv && !WARN_ON(drv->refcnt <= 0))
 271                 drv->refcnt--;
 272
 273         spin_unlock(&cpuidle_driver_lock);
 274 }