ppc_cbe_cpufreq.c 3.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * cpufreq driver for the cell processor
  4. *
  5. * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-2007
  6. *
  7. * Author: Christian Krafft <krafft@de.ibm.com>
  8. */
  9. #include <linux/cpufreq.h>
  10. #include <linux/module.h>
  11. #include <linux/of_platform.h>
  12. #include <asm/machdep.h>
  13. #include <asm/prom.h>
  14. #include <asm/cell-regs.h>
  15. #include "ppc_cbe_cpufreq.h"
  16. /* the CBE supports an 8 step frequency scaling */
  17. static struct cpufreq_frequency_table cbe_freqs[] = {
  18. {0, 1, 0},
  19. {0, 2, 0},
  20. {0, 3, 0},
  21. {0, 4, 0},
  22. {0, 5, 0},
  23. {0, 6, 0},
  24. {0, 8, 0},
  25. {0, 10, 0},
  26. {0, 0, CPUFREQ_TABLE_END},
  27. };
  28. /*
  29. * hardware specific functions
  30. */
  31. static int set_pmode(unsigned int cpu, unsigned int slow_mode)
  32. {
  33. int rc;
  34. if (cbe_cpufreq_has_pmi)
  35. rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
  36. else
  37. rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
  38. pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
  39. return rc;
  40. }
  41. /*
  42. * cpufreq functions
  43. */
  44. static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
  45. {
  46. struct cpufreq_frequency_table *pos;
  47. const u32 *max_freqp;
  48. u32 max_freq;
  49. int cur_pmode;
  50. struct device_node *cpu;
  51. cpu = of_get_cpu_node(policy->cpu, NULL);
  52. if (!cpu)
  53. return -ENODEV;
  54. pr_debug("init cpufreq on CPU %d\n", policy->cpu);
  55. /*
  56. * Let's check we can actually get to the CELL regs
  57. */
  58. if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
  59. !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
  60. pr_info("invalid CBE regs pointers for cpufreq\n");
  61. of_node_put(cpu);
  62. return -EINVAL;
  63. }
  64. max_freqp = of_get_property(cpu, "clock-frequency", NULL);
  65. of_node_put(cpu);
  66. if (!max_freqp)
  67. return -EINVAL;
  68. /* we need the freq in kHz */
  69. max_freq = *max_freqp / 1000;
  70. pr_debug("max clock-frequency is at %u kHz\n", max_freq);
  71. pr_debug("initializing frequency table\n");
  72. /* initialize frequency table */
  73. cpufreq_for_each_entry(pos, cbe_freqs) {
  74. pos->frequency = max_freq / pos->driver_data;
  75. pr_debug("%d: %d\n", (int)(pos - cbe_freqs), pos->frequency);
  76. }
  77. /* if DEBUG is enabled set_pmode() measures the latency
  78. * of a transition */
  79. policy->cpuinfo.transition_latency = 25000;
  80. cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
  81. pr_debug("current pmode is at %d\n",cur_pmode);
  82. policy->cur = cbe_freqs[cur_pmode].frequency;
  83. #ifdef CONFIG_SMP
  84. cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
  85. #endif
  86. policy->freq_table = cbe_freqs;
  87. cbe_cpufreq_pmi_policy_init(policy);
  88. return 0;
  89. }
  90. static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
  91. {
  92. cbe_cpufreq_pmi_policy_exit(policy);
  93. return 0;
  94. }
  95. static int cbe_cpufreq_target(struct cpufreq_policy *policy,
  96. unsigned int cbe_pmode_new)
  97. {
  98. pr_debug("setting frequency for cpu %d to %d kHz, " \
  99. "1/%d of max frequency\n",
  100. policy->cpu,
  101. cbe_freqs[cbe_pmode_new].frequency,
  102. cbe_freqs[cbe_pmode_new].driver_data);
  103. return set_pmode(policy->cpu, cbe_pmode_new);
  104. }
  105. static struct cpufreq_driver cbe_cpufreq_driver = {
  106. .verify = cpufreq_generic_frequency_table_verify,
  107. .target_index = cbe_cpufreq_target,
  108. .init = cbe_cpufreq_cpu_init,
  109. .exit = cbe_cpufreq_cpu_exit,
  110. .name = "cbe-cpufreq",
  111. .flags = CPUFREQ_CONST_LOOPS,
  112. };
  113. /*
  114. * module init and destoy
  115. */
  116. static int __init cbe_cpufreq_init(void)
  117. {
  118. int ret;
  119. if (!machine_is(cell))
  120. return -ENODEV;
  121. cbe_cpufreq_pmi_init();
  122. ret = cpufreq_register_driver(&cbe_cpufreq_driver);
  123. if (ret)
  124. cbe_cpufreq_pmi_exit();
  125. return ret;
  126. }
  127. static void __exit cbe_cpufreq_exit(void)
  128. {
  129. cpufreq_unregister_driver(&cbe_cpufreq_driver);
  130. cbe_cpufreq_pmi_exit();
  131. }
  132. module_init(cbe_cpufreq_init);
  133. module_exit(cbe_cpufreq_exit);
  134. MODULE_LICENSE("GPL");
  135. MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");