gpio-raspberrypi-exp.c 6.3 KB

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  1. // SPDX-License-Identifier: GPL-2.0+
  2. /*
  3. * Raspberry Pi 3 expander GPIO driver
  4. *
  5. * Uses the firmware mailbox service to communicate with the
  6. * GPIO expander on the VPU.
  7. *
  8. * Copyright (C) 2017 Raspberry Pi Trading Ltd.
  9. */
  10. #include <linux/err.h>
  11. #include <linux/gpio/driver.h>
  12. #include <linux/module.h>
  13. #include <linux/platform_device.h>
  14. #include <soc/bcm2835/raspberrypi-firmware.h>
  15. #define MODULE_NAME "raspberrypi-exp-gpio"
  16. #define NUM_GPIO 8
  17. #define RPI_EXP_GPIO_BASE 128
  18. #define RPI_EXP_GPIO_DIR_IN 0
  19. #define RPI_EXP_GPIO_DIR_OUT 1
  20. struct rpi_exp_gpio {
  21. struct gpio_chip gc;
  22. struct rpi_firmware *fw;
  23. };
  24. /* VC4 firmware mailbox interface data structures */
  25. struct gpio_set_config {
  26. u32 gpio;
  27. u32 direction;
  28. u32 polarity;
  29. u32 term_en;
  30. u32 term_pull_up;
  31. u32 state;
  32. };
  33. struct gpio_get_config {
  34. u32 gpio;
  35. u32 direction;
  36. u32 polarity;
  37. u32 term_en;
  38. u32 term_pull_up;
  39. };
  40. struct gpio_get_set_state {
  41. u32 gpio;
  42. u32 state;
  43. };
  44. static int rpi_exp_gpio_get_polarity(struct gpio_chip *gc, unsigned int off)
  45. {
  46. struct rpi_exp_gpio *gpio;
  47. struct gpio_get_config get;
  48. int ret;
  49. gpio = gpiochip_get_data(gc);
  50. get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
  51. ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
  52. &get, sizeof(get));
  53. if (ret || get.gpio != 0) {
  54. dev_err(gc->parent, "Failed to get GPIO %u config (%d %x)\n",
  55. off, ret, get.gpio);
  56. return ret ? ret : -EIO;
  57. }
  58. return get.polarity;
  59. }
  60. static int rpi_exp_gpio_dir_in(struct gpio_chip *gc, unsigned int off)
  61. {
  62. struct rpi_exp_gpio *gpio;
  63. struct gpio_set_config set_in;
  64. int ret;
  65. gpio = gpiochip_get_data(gc);
  66. set_in.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
  67. set_in.direction = RPI_EXP_GPIO_DIR_IN;
  68. set_in.term_en = 0; /* termination disabled */
  69. set_in.term_pull_up = 0; /* n/a as termination disabled */
  70. set_in.state = 0; /* n/a as configured as an input */
  71. ret = rpi_exp_gpio_get_polarity(gc, off);
  72. if (ret < 0)
  73. return ret;
  74. set_in.polarity = ret; /* Retain existing setting */
  75. ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
  76. &set_in, sizeof(set_in));
  77. if (ret || set_in.gpio != 0) {
  78. dev_err(gc->parent, "Failed to set GPIO %u to input (%d %x)\n",
  79. off, ret, set_in.gpio);
  80. return ret ? ret : -EIO;
  81. }
  82. return 0;
  83. }
  84. static int rpi_exp_gpio_dir_out(struct gpio_chip *gc, unsigned int off, int val)
  85. {
  86. struct rpi_exp_gpio *gpio;
  87. struct gpio_set_config set_out;
  88. int ret;
  89. gpio = gpiochip_get_data(gc);
  90. set_out.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
  91. set_out.direction = RPI_EXP_GPIO_DIR_OUT;
  92. set_out.term_en = 0; /* n/a as an output */
  93. set_out.term_pull_up = 0; /* n/a as termination disabled */
  94. set_out.state = val; /* Output state */
  95. ret = rpi_exp_gpio_get_polarity(gc, off);
  96. if (ret < 0)
  97. return ret;
  98. set_out.polarity = ret; /* Retain existing setting */
  99. ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
  100. &set_out, sizeof(set_out));
  101. if (ret || set_out.gpio != 0) {
  102. dev_err(gc->parent, "Failed to set GPIO %u to output (%d %x)\n",
  103. off, ret, set_out.gpio);
  104. return ret ? ret : -EIO;
  105. }
  106. return 0;
  107. }
  108. static int rpi_exp_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
  109. {
  110. struct rpi_exp_gpio *gpio;
  111. struct gpio_get_config get;
  112. int ret;
  113. gpio = gpiochip_get_data(gc);
  114. get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
  115. ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
  116. &get, sizeof(get));
  117. if (ret || get.gpio != 0) {
  118. dev_err(gc->parent,
  119. "Failed to get GPIO %u config (%d %x)\n", off, ret,
  120. get.gpio);
  121. return ret ? ret : -EIO;
  122. }
  123. if (get.direction)
  124. return GPIO_LINE_DIRECTION_OUT;
  125. return GPIO_LINE_DIRECTION_IN;
  126. }
  127. static int rpi_exp_gpio_get(struct gpio_chip *gc, unsigned int off)
  128. {
  129. struct rpi_exp_gpio *gpio;
  130. struct gpio_get_set_state get;
  131. int ret;
  132. gpio = gpiochip_get_data(gc);
  133. get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
  134. get.state = 0; /* storage for returned value */
  135. ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_STATE,
  136. &get, sizeof(get));
  137. if (ret || get.gpio != 0) {
  138. dev_err(gc->parent,
  139. "Failed to get GPIO %u state (%d %x)\n", off, ret,
  140. get.gpio);
  141. return ret ? ret : -EIO;
  142. }
  143. return !!get.state;
  144. }
  145. static void rpi_exp_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
  146. {
  147. struct rpi_exp_gpio *gpio;
  148. struct gpio_get_set_state set;
  149. int ret;
  150. gpio = gpiochip_get_data(gc);
  151. set.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
  152. set.state = val; /* Output state */
  153. ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_STATE,
  154. &set, sizeof(set));
  155. if (ret || set.gpio != 0)
  156. dev_err(gc->parent,
  157. "Failed to set GPIO %u state (%d %x)\n", off, ret,
  158. set.gpio);
  159. }
  160. static int rpi_exp_gpio_probe(struct platform_device *pdev)
  161. {
  162. struct device *dev = &pdev->dev;
  163. struct device_node *np = dev->of_node;
  164. struct device_node *fw_node;
  165. struct rpi_firmware *fw;
  166. struct rpi_exp_gpio *rpi_gpio;
  167. fw_node = of_get_parent(np);
  168. if (!fw_node) {
  169. dev_err(dev, "Missing firmware node\n");
  170. return -ENOENT;
  171. }
  172. fw = rpi_firmware_get(fw_node);
  173. of_node_put(fw_node);
  174. if (!fw)
  175. return -EPROBE_DEFER;
  176. rpi_gpio = devm_kzalloc(dev, sizeof(*rpi_gpio), GFP_KERNEL);
  177. if (!rpi_gpio)
  178. return -ENOMEM;
  179. rpi_gpio->fw = fw;
  180. rpi_gpio->gc.parent = dev;
  181. rpi_gpio->gc.label = MODULE_NAME;
  182. rpi_gpio->gc.owner = THIS_MODULE;
  183. rpi_gpio->gc.of_node = np;
  184. rpi_gpio->gc.base = -1;
  185. rpi_gpio->gc.ngpio = NUM_GPIO;
  186. rpi_gpio->gc.direction_input = rpi_exp_gpio_dir_in;
  187. rpi_gpio->gc.direction_output = rpi_exp_gpio_dir_out;
  188. rpi_gpio->gc.get_direction = rpi_exp_gpio_get_direction;
  189. rpi_gpio->gc.get = rpi_exp_gpio_get;
  190. rpi_gpio->gc.set = rpi_exp_gpio_set;
  191. rpi_gpio->gc.can_sleep = true;
  192. return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
  193. }
  194. static const struct of_device_id rpi_exp_gpio_ids[] = {
  195. { .compatible = "raspberrypi,firmware-gpio" },
  196. { }
  197. };
  198. MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
  199. static struct platform_driver rpi_exp_gpio_driver = {
  200. .driver = {
  201. .name = MODULE_NAME,
  202. .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
  203. },
  204. .probe = rpi_exp_gpio_probe,
  205. };
  206. module_platform_driver(rpi_exp_gpio_driver);
  207. MODULE_LICENSE("GPL");
  208. MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
  209. MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
  210. MODULE_ALIAS("platform:rpi-exp-gpio");