pandora_bl.c 4.2 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * Backlight driver for Pandora handheld.
  4. * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
  5. * Based on pwm_bl.c
  6. *
  7. * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
  8. */
  9. #include <linux/module.h>
  10. #include <linux/kernel.h>
  11. #include <linux/platform_device.h>
  12. #include <linux/delay.h>
  13. #include <linux/fb.h>
  14. #include <linux/backlight.h>
  15. #include <linux/mfd/twl.h>
  16. #include <linux/err.h>
  17. #define TWL_PWM0_ON 0x00
  18. #define TWL_PWM0_OFF 0x01
  19. #define TWL_INTBR_GPBR1 0x0c
  20. #define TWL_INTBR_PMBR1 0x0d
  21. #define TWL_PMBR1_PWM0_MUXMASK 0x0c
  22. #define TWL_PMBR1_PWM0 0x04
  23. #define PWM0_CLK_ENABLE BIT(0)
  24. #define PWM0_ENABLE BIT(2)
  25. /* range accepted by hardware */
  26. #define MIN_VALUE 9
  27. #define MAX_VALUE 63
  28. #define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
  29. struct pandora_private {
  30. unsigned old_state;
  31. #define PANDORABL_WAS_OFF 1
  32. };
  33. static int pandora_backlight_update_status(struct backlight_device *bl)
  34. {
  35. int brightness = bl->props.brightness;
  36. struct pandora_private *priv = bl_get_data(bl);
  37. u8 r;
  38. if (bl->props.power != FB_BLANK_UNBLANK)
  39. brightness = 0;
  40. if (bl->props.state & BL_CORE_FBBLANK)
  41. brightness = 0;
  42. if (bl->props.state & BL_CORE_SUSPENDED)
  43. brightness = 0;
  44. if ((unsigned int)brightness > MAX_USER_VALUE)
  45. brightness = MAX_USER_VALUE;
  46. if (brightness == 0) {
  47. if (priv->old_state == PANDORABL_WAS_OFF)
  48. goto done;
  49. /* first disable PWM0 output, then clock */
  50. twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  51. r &= ~PWM0_ENABLE;
  52. twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  53. r &= ~PWM0_CLK_ENABLE;
  54. twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  55. goto done;
  56. }
  57. if (priv->old_state == PANDORABL_WAS_OFF) {
  58. /*
  59. * set PWM duty cycle to max. TPS61161 seems to use this
  60. * to calibrate it's PWM sensitivity when it starts.
  61. */
  62. twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
  63. /* first enable clock, then PWM0 out */
  64. twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
  65. r &= ~PWM0_ENABLE;
  66. r |= PWM0_CLK_ENABLE;
  67. twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  68. r |= PWM0_ENABLE;
  69. twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
  70. /*
  71. * TI made it very easy to enable digital control, so easy that
  72. * it often triggers unintentionally and disabes PWM control,
  73. * so wait until 1 wire mode detection window ends.
  74. */
  75. usleep_range(2000, 10000);
  76. }
  77. twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
  78. done:
  79. if (brightness != 0)
  80. priv->old_state = 0;
  81. else
  82. priv->old_state = PANDORABL_WAS_OFF;
  83. return 0;
  84. }
  85. static const struct backlight_ops pandora_backlight_ops = {
  86. .options = BL_CORE_SUSPENDRESUME,
  87. .update_status = pandora_backlight_update_status,
  88. };
  89. static int pandora_backlight_probe(struct platform_device *pdev)
  90. {
  91. struct backlight_properties props;
  92. struct backlight_device *bl;
  93. struct pandora_private *priv;
  94. u8 r;
  95. priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  96. if (!priv) {
  97. dev_err(&pdev->dev, "failed to allocate driver private data\n");
  98. return -ENOMEM;
  99. }
  100. memset(&props, 0, sizeof(props));
  101. props.max_brightness = MAX_USER_VALUE;
  102. props.type = BACKLIGHT_RAW;
  103. bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
  104. priv, &pandora_backlight_ops, &props);
  105. if (IS_ERR(bl)) {
  106. dev_err(&pdev->dev, "failed to register backlight\n");
  107. return PTR_ERR(bl);
  108. }
  109. platform_set_drvdata(pdev, bl);
  110. /* 64 cycle period, ON position 0 */
  111. twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
  112. priv->old_state = PANDORABL_WAS_OFF;
  113. bl->props.brightness = MAX_USER_VALUE;
  114. backlight_update_status(bl);
  115. /* enable PWM function in pin mux */
  116. twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
  117. r &= ~TWL_PMBR1_PWM0_MUXMASK;
  118. r |= TWL_PMBR1_PWM0;
  119. twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
  120. return 0;
  121. }
  122. static struct platform_driver pandora_backlight_driver = {
  123. .driver = {
  124. .name = "pandora-backlight",
  125. },
  126. .probe = pandora_backlight_probe,
  127. };
  128. module_platform_driver(pandora_backlight_driver);
  129. MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
  130. MODULE_DESCRIPTION("Pandora Backlight Driver");
  131. MODULE_LICENSE("GPL");
  132. MODULE_ALIAS("platform:pandora-backlight");