sparc-us3-cpufreq.c 4.9 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /* us3_cpufreq.c: UltraSPARC-III cpu frequency support
  3. *
  4. * Copyright (C) 2003 David S. Miller (davem@redhat.com)
  5. *
  6. * Many thanks to Dominik Brodowski for fixing up the cpufreq
  7. * infrastructure in order to make this driver easier to implement.
  8. */
  9. #include <linux/kernel.h>
  10. #include <linux/module.h>
  11. #include <linux/sched.h>
  12. #include <linux/smp.h>
  13. #include <linux/cpufreq.h>
  14. #include <linux/threads.h>
  15. #include <linux/slab.h>
  16. #include <linux/init.h>
  17. #include <asm/head.h>
  18. #include <asm/timer.h>
  19. static struct cpufreq_driver *cpufreq_us3_driver;
  20. struct us3_freq_percpu_info {
  21. struct cpufreq_frequency_table table[4];
  22. };
  23. /* Indexed by cpu number. */
  24. static struct us3_freq_percpu_info *us3_freq_table;
  25. /* UltraSPARC-III has three dividers: 1, 2, and 32. These are controlled
  26. * in the Safari config register.
  27. */
  28. #define SAFARI_CFG_DIV_1 0x0000000000000000UL
  29. #define SAFARI_CFG_DIV_2 0x0000000040000000UL
  30. #define SAFARI_CFG_DIV_32 0x0000000080000000UL
  31. #define SAFARI_CFG_DIV_MASK 0x00000000C0000000UL
  32. static void read_safari_cfg(void *arg)
  33. {
  34. unsigned long ret, *val = arg;
  35. __asm__ __volatile__("ldxa [%%g0] %1, %0"
  36. : "=&r" (ret)
  37. : "i" (ASI_SAFARI_CONFIG));
  38. *val = ret;
  39. }
  40. static void update_safari_cfg(void *arg)
  41. {
  42. unsigned long reg, *new_bits = arg;
  43. read_safari_cfg(&reg);
  44. reg &= ~SAFARI_CFG_DIV_MASK;
  45. reg |= *new_bits;
  46. __asm__ __volatile__("stxa %0, [%%g0] %1\n\t"
  47. "membar #Sync"
  48. : /* no outputs */
  49. : "r" (reg), "i" (ASI_SAFARI_CONFIG)
  50. : "memory");
  51. }
  52. static unsigned long get_current_freq(unsigned int cpu, unsigned long safari_cfg)
  53. {
  54. unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
  55. unsigned long ret;
  56. switch (safari_cfg & SAFARI_CFG_DIV_MASK) {
  57. case SAFARI_CFG_DIV_1:
  58. ret = clock_tick / 1;
  59. break;
  60. case SAFARI_CFG_DIV_2:
  61. ret = clock_tick / 2;
  62. break;
  63. case SAFARI_CFG_DIV_32:
  64. ret = clock_tick / 32;
  65. break;
  66. default:
  67. BUG();
  68. }
  69. return ret;
  70. }
  71. static unsigned int us3_freq_get(unsigned int cpu)
  72. {
  73. unsigned long reg;
  74. if (smp_call_function_single(cpu, read_safari_cfg, &reg, 1))
  75. return 0;
  76. return get_current_freq(cpu, reg);
  77. }
  78. static int us3_freq_target(struct cpufreq_policy *policy, unsigned int index)
  79. {
  80. unsigned int cpu = policy->cpu;
  81. unsigned long new_bits, new_freq;
  82. new_freq = sparc64_get_clock_tick(cpu) / 1000;
  83. switch (index) {
  84. case 0:
  85. new_bits = SAFARI_CFG_DIV_1;
  86. new_freq /= 1;
  87. break;
  88. case 1:
  89. new_bits = SAFARI_CFG_DIV_2;
  90. new_freq /= 2;
  91. break;
  92. case 2:
  93. new_bits = SAFARI_CFG_DIV_32;
  94. new_freq /= 32;
  95. break;
  96. default:
  97. BUG();
  98. }
  99. return smp_call_function_single(cpu, update_safari_cfg, &new_bits, 1);
  100. }
  101. static int __init us3_freq_cpu_init(struct cpufreq_policy *policy)
  102. {
  103. unsigned int cpu = policy->cpu;
  104. unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
  105. struct cpufreq_frequency_table *table =
  106. &us3_freq_table[cpu].table[0];
  107. table[0].driver_data = 0;
  108. table[0].frequency = clock_tick / 1;
  109. table[1].driver_data = 1;
  110. table[1].frequency = clock_tick / 2;
  111. table[2].driver_data = 2;
  112. table[2].frequency = clock_tick / 32;
  113. table[3].driver_data = 0;
  114. table[3].frequency = CPUFREQ_TABLE_END;
  115. policy->cpuinfo.transition_latency = 0;
  116. policy->cur = clock_tick;
  117. policy->freq_table = table;
  118. return 0;
  119. }
  120. static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
  121. {
  122. if (cpufreq_us3_driver)
  123. us3_freq_target(policy, 0);
  124. return 0;
  125. }
  126. static int __init us3_freq_init(void)
  127. {
  128. unsigned long manuf, impl, ver;
  129. int ret;
  130. if (tlb_type != cheetah && tlb_type != cheetah_plus)
  131. return -ENODEV;
  132. __asm__("rdpr %%ver, %0" : "=r" (ver));
  133. manuf = ((ver >> 48) & 0xffff);
  134. impl = ((ver >> 32) & 0xffff);
  135. if (manuf == CHEETAH_MANUF &&
  136. (impl == CHEETAH_IMPL ||
  137. impl == CHEETAH_PLUS_IMPL ||
  138. impl == JAGUAR_IMPL ||
  139. impl == PANTHER_IMPL)) {
  140. struct cpufreq_driver *driver;
  141. ret = -ENOMEM;
  142. driver = kzalloc(sizeof(*driver), GFP_KERNEL);
  143. if (!driver)
  144. goto err_out;
  145. us3_freq_table = kzalloc((NR_CPUS * sizeof(*us3_freq_table)),
  146. GFP_KERNEL);
  147. if (!us3_freq_table)
  148. goto err_out;
  149. driver->init = us3_freq_cpu_init;
  150. driver->verify = cpufreq_generic_frequency_table_verify;
  151. driver->target_index = us3_freq_target;
  152. driver->get = us3_freq_get;
  153. driver->exit = us3_freq_cpu_exit;
  154. strcpy(driver->name, "UltraSPARC-III");
  155. cpufreq_us3_driver = driver;
  156. ret = cpufreq_register_driver(driver);
  157. if (ret)
  158. goto err_out;
  159. return 0;
  160. err_out:
  161. if (driver) {
  162. kfree(driver);
  163. cpufreq_us3_driver = NULL;
  164. }
  165. kfree(us3_freq_table);
  166. us3_freq_table = NULL;
  167. return ret;
  168. }
  169. return -ENODEV;
  170. }
  171. static void __exit us3_freq_exit(void)
  172. {
  173. if (cpufreq_us3_driver) {
  174. cpufreq_unregister_driver(cpufreq_us3_driver);
  175. kfree(cpufreq_us3_driver);
  176. cpufreq_us3_driver = NULL;
  177. kfree(us3_freq_table);
  178. us3_freq_table = NULL;
  179. }
  180. }
  181. MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  182. MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
  183. MODULE_LICENSE("GPL");
  184. module_init(us3_freq_init);
  185. module_exit(us3_freq_exit);