kirkwood-cpufreq.c 4.8 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
  4. *
  5. * Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
  6. */
  7. #include <linux/kernel.h>
  8. #include <linux/module.h>
  9. #include <linux/clk.h>
  10. #include <linux/cpufreq.h>
  11. #include <linux/of_device.h>
  12. #include <linux/platform_device.h>
  13. #include <linux/io.h>
  14. #include <asm/proc-fns.h>
  15. #define CPU_SW_INT_BLK BIT(28)
  16. static struct priv
  17. {
  18. struct clk *cpu_clk;
  19. struct clk *ddr_clk;
  20. struct clk *powersave_clk;
  21. struct device *dev;
  22. void __iomem *base;
  23. } priv;
  24. #define STATE_CPU_FREQ 0x01
  25. #define STATE_DDR_FREQ 0x02
  26. /*
  27. * Kirkwood can swap the clock to the CPU between two clocks:
  28. *
  29. * - cpu clk
  30. * - ddr clk
  31. *
  32. * The frequencies are set at runtime before registering this table.
  33. */
  34. static struct cpufreq_frequency_table kirkwood_freq_table[] = {
  35. {0, STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
  36. {0, STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
  37. {0, 0, CPUFREQ_TABLE_END},
  38. };
  39. static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
  40. {
  41. return clk_get_rate(priv.powersave_clk) / 1000;
  42. }
  43. static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
  44. unsigned int index)
  45. {
  46. unsigned int state = kirkwood_freq_table[index].driver_data;
  47. unsigned long reg;
  48. local_irq_disable();
  49. /* Disable interrupts to the CPU */
  50. reg = readl_relaxed(priv.base);
  51. reg |= CPU_SW_INT_BLK;
  52. writel_relaxed(reg, priv.base);
  53. switch (state) {
  54. case STATE_CPU_FREQ:
  55. clk_set_parent(priv.powersave_clk, priv.cpu_clk);
  56. break;
  57. case STATE_DDR_FREQ:
  58. clk_set_parent(priv.powersave_clk, priv.ddr_clk);
  59. break;
  60. }
  61. /* Wait-for-Interrupt, while the hardware changes frequency */
  62. cpu_do_idle();
  63. /* Enable interrupts to the CPU */
  64. reg = readl_relaxed(priv.base);
  65. reg &= ~CPU_SW_INT_BLK;
  66. writel_relaxed(reg, priv.base);
  67. local_irq_enable();
  68. return 0;
  69. }
  70. /* Module init and exit code */
  71. static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
  72. {
  73. cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
  74. return 0;
  75. }
  76. static struct cpufreq_driver kirkwood_cpufreq_driver = {
  77. .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
  78. .get = kirkwood_cpufreq_get_cpu_frequency,
  79. .verify = cpufreq_generic_frequency_table_verify,
  80. .target_index = kirkwood_cpufreq_target,
  81. .init = kirkwood_cpufreq_cpu_init,
  82. .name = "kirkwood-cpufreq",
  83. .attr = cpufreq_generic_attr,
  84. };
  85. static int kirkwood_cpufreq_probe(struct platform_device *pdev)
  86. {
  87. struct device_node *np;
  88. int err;
  89. priv.dev = &pdev->dev;
  90. priv.base = devm_platform_ioremap_resource(pdev, 0);
  91. if (IS_ERR(priv.base))
  92. return PTR_ERR(priv.base);
  93. np = of_cpu_device_node_get(0);
  94. if (!np) {
  95. dev_err(&pdev->dev, "failed to get cpu device node\n");
  96. return -ENODEV;
  97. }
  98. priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
  99. if (IS_ERR(priv.cpu_clk)) {
  100. dev_err(priv.dev, "Unable to get cpuclk\n");
  101. err = PTR_ERR(priv.cpu_clk);
  102. goto out_node;
  103. }
  104. err = clk_prepare_enable(priv.cpu_clk);
  105. if (err) {
  106. dev_err(priv.dev, "Unable to prepare cpuclk\n");
  107. goto out_node;
  108. }
  109. kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
  110. priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
  111. if (IS_ERR(priv.ddr_clk)) {
  112. dev_err(priv.dev, "Unable to get ddrclk\n");
  113. err = PTR_ERR(priv.ddr_clk);
  114. goto out_cpu;
  115. }
  116. err = clk_prepare_enable(priv.ddr_clk);
  117. if (err) {
  118. dev_err(priv.dev, "Unable to prepare ddrclk\n");
  119. goto out_cpu;
  120. }
  121. kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
  122. priv.powersave_clk = of_clk_get_by_name(np, "powersave");
  123. if (IS_ERR(priv.powersave_clk)) {
  124. dev_err(priv.dev, "Unable to get powersave\n");
  125. err = PTR_ERR(priv.powersave_clk);
  126. goto out_ddr;
  127. }
  128. err = clk_prepare_enable(priv.powersave_clk);
  129. if (err) {
  130. dev_err(priv.dev, "Unable to prepare powersave clk\n");
  131. goto out_ddr;
  132. }
  133. err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
  134. if (err) {
  135. dev_err(priv.dev, "Failed to register cpufreq driver\n");
  136. goto out_powersave;
  137. }
  138. of_node_put(np);
  139. return 0;
  140. out_powersave:
  141. clk_disable_unprepare(priv.powersave_clk);
  142. out_ddr:
  143. clk_disable_unprepare(priv.ddr_clk);
  144. out_cpu:
  145. clk_disable_unprepare(priv.cpu_clk);
  146. out_node:
  147. of_node_put(np);
  148. return err;
  149. }
  150. static int kirkwood_cpufreq_remove(struct platform_device *pdev)
  151. {
  152. cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
  153. clk_disable_unprepare(priv.powersave_clk);
  154. clk_disable_unprepare(priv.ddr_clk);
  155. clk_disable_unprepare(priv.cpu_clk);
  156. return 0;
  157. }
  158. static struct platform_driver kirkwood_cpufreq_platform_driver = {
  159. .probe = kirkwood_cpufreq_probe,
  160. .remove = kirkwood_cpufreq_remove,
  161. .driver = {
  162. .name = "kirkwood-cpufreq",
  163. },
  164. };
  165. module_platform_driver(kirkwood_cpufreq_platform_driver);
  166. MODULE_LICENSE("GPL v2");
  167. MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
  168. MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
  169. MODULE_ALIAS("platform:kirkwood-cpufreq");