pwm-ir-tx.c 2.7 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * Copyright (C) 2017 Sean Young <sean@mess.org>
  4. */
  5. #include <linux/kernel.h>
  6. #include <linux/module.h>
  7. #include <linux/pwm.h>
  8. #include <linux/delay.h>
  9. #include <linux/slab.h>
  10. #include <linux/of.h>
  11. #include <linux/platform_device.h>
  12. #include <media/rc-core.h>
  13. #define DRIVER_NAME "pwm-ir-tx"
  14. #define DEVICE_NAME "PWM IR Transmitter"
  15. struct pwm_ir {
  16. struct pwm_device *pwm;
  17. unsigned int carrier;
  18. unsigned int duty_cycle;
  19. };
  20. static const struct of_device_id pwm_ir_of_match[] = {
  21. { .compatible = "pwm-ir-tx", },
  22. { },
  23. };
  24. MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
  25. static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
  26. {
  27. struct pwm_ir *pwm_ir = dev->priv;
  28. pwm_ir->duty_cycle = duty_cycle;
  29. return 0;
  30. }
  31. static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
  32. {
  33. struct pwm_ir *pwm_ir = dev->priv;
  34. if (!carrier)
  35. return -EINVAL;
  36. pwm_ir->carrier = carrier;
  37. return 0;
  38. }
  39. static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
  40. unsigned int count)
  41. {
  42. struct pwm_ir *pwm_ir = dev->priv;
  43. struct pwm_device *pwm = pwm_ir->pwm;
  44. int i, duty, period;
  45. ktime_t edge;
  46. long delta;
  47. period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
  48. duty = DIV_ROUND_CLOSEST(pwm_ir->duty_cycle * period, 100);
  49. pwm_config(pwm, duty, period);
  50. edge = ktime_get();
  51. for (i = 0; i < count; i++) {
  52. if (i % 2) // space
  53. pwm_disable(pwm);
  54. else
  55. pwm_enable(pwm);
  56. edge = ktime_add_us(edge, txbuf[i]);
  57. delta = ktime_us_delta(edge, ktime_get());
  58. if (delta > 0)
  59. usleep_range(delta, delta + 10);
  60. }
  61. pwm_disable(pwm);
  62. return count;
  63. }
  64. static int pwm_ir_probe(struct platform_device *pdev)
  65. {
  66. struct pwm_ir *pwm_ir;
  67. struct rc_dev *rcdev;
  68. int rc;
  69. pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
  70. if (!pwm_ir)
  71. return -ENOMEM;
  72. pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
  73. if (IS_ERR(pwm_ir->pwm))
  74. return PTR_ERR(pwm_ir->pwm);
  75. pwm_ir->carrier = 38000;
  76. pwm_ir->duty_cycle = 50;
  77. rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
  78. if (!rcdev)
  79. return -ENOMEM;
  80. rcdev->priv = pwm_ir;
  81. rcdev->driver_name = DRIVER_NAME;
  82. rcdev->device_name = DEVICE_NAME;
  83. rcdev->tx_ir = pwm_ir_tx;
  84. rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
  85. rcdev->s_tx_carrier = pwm_ir_set_carrier;
  86. rc = devm_rc_register_device(&pdev->dev, rcdev);
  87. if (rc < 0)
  88. dev_err(&pdev->dev, "failed to register rc device\n");
  89. return rc;
  90. }
  91. static struct platform_driver pwm_ir_driver = {
  92. .probe = pwm_ir_probe,
  93. .driver = {
  94. .name = DRIVER_NAME,
  95. .of_match_table = of_match_ptr(pwm_ir_of_match),
  96. },
  97. };
  98. module_platform_driver(pwm_ir_driver);
  99. MODULE_DESCRIPTION("PWM IR Transmitter");
  100. MODULE_AUTHOR("Sean Young <sean@mess.org>");
  101. MODULE_LICENSE("GPL");