/drivers/staging/iio/trigger/iio-trig-gpio.c

https://bitbucket.org/slukk/jb-tsm-kernel-4.2 · C · 173 lines · 122 code · 26 blank · 25 comment · 11 complexity · 3319f2cd7dd50843a9b8a830c5f4dbf2 MD5 · raw file

  1. /*
  2. * Industrial I/O - gpio based trigger support
  3. *
  4. * Copyright (c) 2008 Jonathan Cameron
  5. *
  6. * This program is free software; you can redistribute it and/or modify it
  7. * under the terms of the GNU General Public License version 2 as published by
  8. * the Free Software Foundation.
  9. *
  10. * Currently this is more of a functioning proof of concept that a fully
  11. * fledged trigger driver.
  12. *
  13. * TODO:
  14. *
  15. * Add board config elements to allow specification of startup settings.
  16. */
  17. #include <linux/kernel.h>
  18. #include <linux/module.h>
  19. #include <linux/platform_device.h>
  20. #include <linux/interrupt.h>
  21. #include <linux/gpio.h>
  22. #include <linux/slab.h>
  23. #include "../iio.h"
  24. #include "../trigger.h"
  25. static LIST_HEAD(iio_gpio_trigger_list);
  26. static DEFINE_MUTEX(iio_gpio_trigger_list_lock);
  27. struct iio_gpio_trigger_info {
  28. struct mutex in_use;
  29. unsigned int irq;
  30. };
  31. /*
  32. * Need to reference count these triggers and only enable gpio interrupts
  33. * as appropriate.
  34. */
  35. /* So what functionality do we want in here?... */
  36. /* set high / low as interrupt type? */
  37. static irqreturn_t iio_gpio_trigger_poll(int irq, void *private)
  38. {
  39. /* Timestamp not currently provided */
  40. iio_trigger_poll(private, 0);
  41. return IRQ_HANDLED;
  42. }
  43. static int iio_gpio_trigger_probe(struct platform_device *pdev)
  44. {
  45. struct iio_gpio_trigger_info *trig_info;
  46. struct iio_trigger *trig, *trig2;
  47. unsigned long irqflags;
  48. struct resource *irq_res;
  49. int irq, ret = 0, irq_res_cnt = 0;
  50. do {
  51. irq_res = platform_get_resource(pdev,
  52. IORESOURCE_IRQ, irq_res_cnt);
  53. if (irq_res == NULL) {
  54. if (irq_res_cnt == 0)
  55. dev_err(&pdev->dev, "No GPIO IRQs specified");
  56. break;
  57. }
  58. irqflags = (irq_res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
  59. for (irq = irq_res->start; irq <= irq_res->end; irq++) {
  60. trig = iio_allocate_trigger("irqtrig%d", irq);
  61. if (!trig) {
  62. ret = -ENOMEM;
  63. goto error_free_completed_registrations;
  64. }
  65. trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
  66. if (!trig_info) {
  67. ret = -ENOMEM;
  68. goto error_put_trigger;
  69. }
  70. trig->private_data = trig_info;
  71. trig_info->irq = irq;
  72. trig->owner = THIS_MODULE;
  73. ret = request_irq(irq, iio_gpio_trigger_poll,
  74. irqflags, trig->name, trig);
  75. if (ret) {
  76. dev_err(&pdev->dev,
  77. "request IRQ-%d failed", irq);
  78. goto error_free_trig_info;
  79. }
  80. ret = iio_trigger_register(trig);
  81. if (ret)
  82. goto error_release_irq;
  83. list_add_tail(&trig->alloc_list,
  84. &iio_gpio_trigger_list);
  85. }
  86. irq_res_cnt++;
  87. } while (irq_res != NULL);
  88. return 0;
  89. /* First clean up the partly allocated trigger */
  90. error_release_irq:
  91. free_irq(irq, trig);
  92. error_free_trig_info:
  93. kfree(trig_info);
  94. error_put_trigger:
  95. iio_put_trigger(trig);
  96. error_free_completed_registrations:
  97. /* The rest should have been added to the iio_gpio_trigger_list */
  98. list_for_each_entry_safe(trig,
  99. trig2,
  100. &iio_gpio_trigger_list,
  101. alloc_list) {
  102. trig_info = trig->private_data;
  103. free_irq(gpio_to_irq(trig_info->irq), trig);
  104. kfree(trig_info);
  105. iio_trigger_unregister(trig);
  106. }
  107. return ret;
  108. }
  109. static int iio_gpio_trigger_remove(struct platform_device *pdev)
  110. {
  111. struct iio_trigger *trig, *trig2;
  112. struct iio_gpio_trigger_info *trig_info;
  113. mutex_lock(&iio_gpio_trigger_list_lock);
  114. list_for_each_entry_safe(trig,
  115. trig2,
  116. &iio_gpio_trigger_list,
  117. alloc_list) {
  118. trig_info = trig->private_data;
  119. iio_trigger_unregister(trig);
  120. free_irq(trig_info->irq, trig);
  121. kfree(trig_info);
  122. iio_put_trigger(trig);
  123. }
  124. mutex_unlock(&iio_gpio_trigger_list_lock);
  125. return 0;
  126. }
  127. static struct platform_driver iio_gpio_trigger_driver = {
  128. .probe = iio_gpio_trigger_probe,
  129. .remove = iio_gpio_trigger_remove,
  130. .driver = {
  131. .name = "iio_gpio_trigger",
  132. .owner = THIS_MODULE,
  133. },
  134. };
  135. static int __init iio_gpio_trig_init(void)
  136. {
  137. return platform_driver_register(&iio_gpio_trigger_driver);
  138. }
  139. module_init(iio_gpio_trig_init);
  140. static void __exit iio_gpio_trig_exit(void)
  141. {
  142. platform_driver_unregister(&iio_gpio_trigger_driver);
  143. }
  144. module_exit(iio_gpio_trig_exit);
  145. MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
  146. MODULE_DESCRIPTION("Example gpio trigger for the iio subsystem");
  147. MODULE_LICENSE("GPL v2");