clk.h 3.2 KB

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  1. /*
  2. * linux/include/linux/clk.h
  3. *
  4. * Copyright (C) 2004 ARM Limited.
  5. * Written by Deep Blue Solutions Limited.
  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. #ifndef __LINUX_CLK_H
  12. #define __LINUX_CLK_H
  13. struct device;
  14. /*
  15. * The base API.
  16. */
  17. /*
  18. * struct clk - an machine class defined object / cookie.
  19. */
  20. struct clk;
  21. /**
  22. * clk_get - lookup and obtain a reference to a clock producer.
  23. * @dev: device for clock "consumer"
  24. * @id: clock comsumer ID
  25. *
  26. * Returns a struct clk corresponding to the clock producer, or
  27. * valid IS_ERR() condition containing errno. The implementation
  28. * uses @dev and @id to determine the clock consumer, and thereby
  29. * the clock producer. (IOW, @id may be identical strings, but
  30. * clk_get may return different clock producers depending on @dev.)
  31. *
  32. * Drivers must assume that the clock source is not enabled.
  33. */
  34. struct clk *clk_get(struct device *dev, const char *id);
  35. /**
  36. * clk_enable - inform the system when the clock source should be running.
  37. * @clk: clock source
  38. *
  39. * If the clock can not be enabled/disabled, this should return success.
  40. *
  41. * Returns success (0) or negative errno.
  42. */
  43. int clk_enable(struct clk *clk);
  44. /**
  45. * clk_disable - inform the system when the clock source is no longer required.
  46. * @clk: clock source
  47. *
  48. * Inform the system that a clock source is no longer required by
  49. * a driver and may be shut down.
  50. *
  51. * Implementation detail: if the clock source is shared between
  52. * multiple drivers, clk_enable() calls must be balanced by the
  53. * same number of clk_disable() calls for the clock source to be
  54. * disabled.
  55. */
  56. void clk_disable(struct clk *clk);
  57. /**
  58. * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
  59. * This is only valid once the clock source has been enabled.
  60. * @clk: clock source
  61. */
  62. unsigned long clk_get_rate(struct clk *clk);
  63. /**
  64. * clk_put - "free" the clock source
  65. * @clk: clock source
  66. *
  67. * Note: drivers must ensure that all clk_enable calls made on this
  68. * clock source are balanced by clk_disable calls prior to calling
  69. * this function.
  70. */
  71. void clk_put(struct clk *clk);
  72. /*
  73. * The remaining APIs are optional for machine class support.
  74. */
  75. /**
  76. * clk_round_rate - adjust a rate to the exact rate a clock can provide
  77. * @clk: clock source
  78. * @rate: desired clock rate in Hz
  79. *
  80. * Returns rounded clock rate in Hz, or negative errno.
  81. */
  82. long clk_round_rate(struct clk *clk, unsigned long rate);
  83. /**
  84. * clk_set_rate - set the clock rate for a clock source
  85. * @clk: clock source
  86. * @rate: desired clock rate in Hz
  87. *
  88. * Returns success (0) or negative errno.
  89. */
  90. int clk_set_rate(struct clk *clk, unsigned long rate);
  91. /**
  92. * clk_set_parent - set the parent clock source for this clock
  93. * @clk: clock source
  94. * @parent: parent clock source
  95. *
  96. * Returns success (0) or negative errno.
  97. */
  98. int clk_set_parent(struct clk *clk, struct clk *parent);
  99. /**
  100. * clk_get_parent - get the parent clock source for this clock
  101. * @clk: clock source
  102. *
  103. * Returns struct clk corresponding to parent clock source, or
  104. * valid IS_ERR() condition containing errno.
  105. */
  106. struct clk *clk_get_parent(struct clk *clk);
  107. #endif