l3.c 2.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * L3 code
  4. *
  5. * Copyright (C) 2008, Christian Pellegrin <chripell@evolware.org>
  6. *
  7. * based on:
  8. *
  9. * L3 bus algorithm module.
  10. *
  11. * Copyright (C) 2001 Russell King, All Rights Reserved.
  12. */
  13. #include <linux/module.h>
  14. #include <linux/kernel.h>
  15. #include <linux/delay.h>
  16. #include <linux/device.h>
  17. #include <linux/gpio.h>
  18. #include <sound/l3.h>
  19. /*
  20. * Send one byte of data to the chip. Data is latched into the chip on
  21. * the rising edge of the clock.
  22. */
  23. static void sendbyte(struct l3_pins *adap, unsigned int byte)
  24. {
  25. int i;
  26. for (i = 0; i < 8; i++) {
  27. adap->setclk(adap, 0);
  28. udelay(adap->data_hold);
  29. adap->setdat(adap, byte & 1);
  30. udelay(adap->data_setup);
  31. adap->setclk(adap, 1);
  32. udelay(adap->clock_high);
  33. byte >>= 1;
  34. }
  35. }
  36. /*
  37. * Send a set of bytes to the chip. We need to pulse the MODE line
  38. * between each byte, but never at the start nor at the end of the
  39. * transfer.
  40. */
  41. static void sendbytes(struct l3_pins *adap, const u8 *buf,
  42. int len)
  43. {
  44. int i;
  45. for (i = 0; i < len; i++) {
  46. if (i) {
  47. udelay(adap->mode_hold);
  48. adap->setmode(adap, 0);
  49. udelay(adap->mode);
  50. }
  51. adap->setmode(adap, 1);
  52. udelay(adap->mode_setup);
  53. sendbyte(adap, buf[i]);
  54. }
  55. }
  56. int l3_write(struct l3_pins *adap, u8 addr, u8 *data, int len)
  57. {
  58. adap->setclk(adap, 1);
  59. adap->setdat(adap, 1);
  60. adap->setmode(adap, 1);
  61. udelay(adap->mode);
  62. adap->setmode(adap, 0);
  63. udelay(adap->mode_setup);
  64. sendbyte(adap, addr);
  65. udelay(adap->mode_hold);
  66. sendbytes(adap, data, len);
  67. adap->setclk(adap, 1);
  68. adap->setdat(adap, 1);
  69. adap->setmode(adap, 0);
  70. return len;
  71. }
  72. EXPORT_SYMBOL_GPL(l3_write);
  73. static void l3_set_clk(struct l3_pins *adap, int val)
  74. {
  75. gpio_set_value(adap->gpio_clk, val);
  76. }
  77. static void l3_set_data(struct l3_pins *adap, int val)
  78. {
  79. gpio_set_value(adap->gpio_data, val);
  80. }
  81. static void l3_set_mode(struct l3_pins *adap, int val)
  82. {
  83. gpio_set_value(adap->gpio_mode, val);
  84. }
  85. int l3_set_gpio_ops(struct device *dev, struct l3_pins *adap)
  86. {
  87. int ret;
  88. if (!adap->use_gpios)
  89. return -EINVAL;
  90. ret = devm_gpio_request_one(dev, adap->gpio_data,
  91. GPIOF_OUT_INIT_LOW, "l3_data");
  92. if (ret < 0)
  93. return ret;
  94. adap->setdat = l3_set_data;
  95. ret = devm_gpio_request_one(dev, adap->gpio_clk,
  96. GPIOF_OUT_INIT_LOW, "l3_clk");
  97. if (ret < 0)
  98. return ret;
  99. adap->setclk = l3_set_clk;
  100. ret = devm_gpio_request_one(dev, adap->gpio_mode,
  101. GPIOF_OUT_INIT_LOW, "l3_mode");
  102. if (ret < 0)
  103. return ret;
  104. adap->setmode = l3_set_mode;
  105. return 0;
  106. }
  107. EXPORT_SYMBOL_GPL(l3_set_gpio_ops);
  108. MODULE_DESCRIPTION("L3 bit-banging driver");
  109. MODULE_AUTHOR("Christian Pellegrin <chripell@evolware.org>");
  110. MODULE_LICENSE("GPL");