cpufreq_userspace.c 5.9 KB

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  1. /*
  2. * linux/drivers/cpufreq/cpufreq_userspace.c
  3. *
  4. * Copyright (C) 2001 Russell King
  5. * (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
  6. *
  7. * This program is free software; you can redistribute it and/or modify
  8. * it under the terms of the GNU General Public License version 2 as
  9. * published by the Free Software Foundation.
  10. *
  11. */
  12. #include <linux/kernel.h>
  13. #include <linux/module.h>
  14. #include <linux/smp.h>
  15. #include <linux/init.h>
  16. #include <linux/spinlock.h>
  17. #include <linux/interrupt.h>
  18. #include <linux/cpufreq.h>
  19. #include <linux/cpu.h>
  20. #include <linux/types.h>
  21. #include <linux/fs.h>
  22. #include <linux/sysfs.h>
  23. #include <linux/mutex.h>
  24. #include <asm/uaccess.h>
  25. /**
  26. * A few values needed by the userspace governor
  27. */
  28. static unsigned int cpu_max_freq[NR_CPUS];
  29. static unsigned int cpu_min_freq[NR_CPUS];
  30. static unsigned int cpu_cur_freq[NR_CPUS]; /* current CPU freq */
  31. static unsigned int cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
  32. static unsigned int cpu_is_managed[NR_CPUS];
  33. static DEFINE_MUTEX (userspace_mutex);
  34. #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
  35. /* keep track of frequency transitions */
  36. static int
  37. userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
  38. void *data)
  39. {
  40. struct cpufreq_freqs *freq = data;
  41. dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n", freq->cpu, freq->new);
  42. cpu_cur_freq[freq->cpu] = freq->new;
  43. return 0;
  44. }
  45. static struct notifier_block userspace_cpufreq_notifier_block = {
  46. .notifier_call = userspace_cpufreq_notifier
  47. };
  48. /**
  49. * cpufreq_set - set the CPU frequency
  50. * @freq: target frequency in kHz
  51. * @cpu: CPU for which the frequency is to be set
  52. *
  53. * Sets the CPU frequency to freq.
  54. */
  55. static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
  56. {
  57. int ret = -EINVAL;
  58. dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  59. mutex_lock(&userspace_mutex);
  60. if (!cpu_is_managed[policy->cpu])
  61. goto err;
  62. cpu_set_freq[policy->cpu] = freq;
  63. if (freq < cpu_min_freq[policy->cpu])
  64. freq = cpu_min_freq[policy->cpu];
  65. if (freq > cpu_max_freq[policy->cpu])
  66. freq = cpu_max_freq[policy->cpu];
  67. /*
  68. * We're safe from concurrent calls to ->target() here
  69. * as we hold the userspace_mutex lock. If we were calling
  70. * cpufreq_driver_target, a deadlock situation might occur:
  71. * A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
  72. * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
  73. */
  74. ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  75. err:
  76. mutex_unlock(&userspace_mutex);
  77. return ret;
  78. }
  79. /************************** sysfs interface ************************/
  80. static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
  81. {
  82. return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
  83. }
  84. static ssize_t
  85. store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
  86. {
  87. unsigned int freq = 0;
  88. unsigned int ret;
  89. ret = sscanf (buf, "%u", &freq);
  90. if (ret != 1)
  91. return -EINVAL;
  92. cpufreq_set(freq, policy);
  93. return count;
  94. }
  95. static struct freq_attr freq_attr_scaling_setspeed =
  96. {
  97. .attr = { .name = "scaling_setspeed", .mode = 0644, .owner = THIS_MODULE },
  98. .show = show_speed,
  99. .store = store_speed,
  100. };
  101. static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
  102. unsigned int event)
  103. {
  104. unsigned int cpu = policy->cpu;
  105. int rc = 0;
  106. switch (event) {
  107. case CPUFREQ_GOV_START:
  108. if (!cpu_online(cpu))
  109. return -EINVAL;
  110. BUG_ON(!policy->cur);
  111. mutex_lock(&userspace_mutex);
  112. rc = sysfs_create_file (&policy->kobj,
  113. &freq_attr_scaling_setspeed.attr);
  114. if (rc)
  115. goto start_out;
  116. cpu_is_managed[cpu] = 1;
  117. cpu_min_freq[cpu] = policy->min;
  118. cpu_max_freq[cpu] = policy->max;
  119. cpu_cur_freq[cpu] = policy->cur;
  120. cpu_set_freq[cpu] = policy->cur;
  121. dprintk("managing cpu %u started (%u - %u kHz, currently %u kHz)\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu]);
  122. start_out:
  123. mutex_unlock(&userspace_mutex);
  124. break;
  125. case CPUFREQ_GOV_STOP:
  126. mutex_lock(&userspace_mutex);
  127. cpu_is_managed[cpu] = 0;
  128. cpu_min_freq[cpu] = 0;
  129. cpu_max_freq[cpu] = 0;
  130. cpu_set_freq[cpu] = 0;
  131. sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
  132. dprintk("managing cpu %u stopped\n", cpu);
  133. mutex_unlock(&userspace_mutex);
  134. break;
  135. case CPUFREQ_GOV_LIMITS:
  136. mutex_lock(&userspace_mutex);
  137. dprintk("limit event for cpu %u: %u - %u kHz,"
  138. "currently %u kHz, last set to %u kHz\n",
  139. cpu, policy->min, policy->max,
  140. cpu_cur_freq[cpu], cpu_set_freq[cpu]);
  141. if (policy->max < cpu_set_freq[cpu]) {
  142. __cpufreq_driver_target(policy, policy->max,
  143. CPUFREQ_RELATION_H);
  144. }
  145. else if (policy->min > cpu_set_freq[cpu]) {
  146. __cpufreq_driver_target(policy, policy->min,
  147. CPUFREQ_RELATION_L);
  148. }
  149. else {
  150. __cpufreq_driver_target(policy, cpu_set_freq[cpu],
  151. CPUFREQ_RELATION_L);
  152. }
  153. cpu_min_freq[cpu] = policy->min;
  154. cpu_max_freq[cpu] = policy->max;
  155. cpu_cur_freq[cpu] = policy->cur;
  156. mutex_unlock(&userspace_mutex);
  157. break;
  158. }
  159. return rc;
  160. }
  161. struct cpufreq_governor cpufreq_gov_userspace = {
  162. .name = "userspace",
  163. .governor = cpufreq_governor_userspace,
  164. .owner = THIS_MODULE,
  165. };
  166. EXPORT_SYMBOL(cpufreq_gov_userspace);
  167. static int __init cpufreq_gov_userspace_init(void)
  168. {
  169. cpufreq_register_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
  170. return cpufreq_register_governor(&cpufreq_gov_userspace);
  171. }
  172. static void __exit cpufreq_gov_userspace_exit(void)
  173. {
  174. cpufreq_unregister_governor(&cpufreq_gov_userspace);
  175. cpufreq_unregister_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
  176. }
  177. MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
  178. MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
  179. MODULE_LICENSE ("GPL");
  180. fs_initcall(cpufreq_gov_userspace_init);
  181. module_exit(cpufreq_gov_userspace_exit);