powernv-op-panel.c 5.1 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224
  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * OPAL Operator Panel Display Driver
  4. *
  5. * Copyright 2016, Suraj Jitindar Singh, IBM Corporation.
  6. */
  7. #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  8. #include <linux/init.h>
  9. #include <linux/module.h>
  10. #include <linux/kernel.h>
  11. #include <linux/fs.h>
  12. #include <linux/device.h>
  13. #include <linux/errno.h>
  14. #include <linux/mutex.h>
  15. #include <linux/of.h>
  16. #include <linux/slab.h>
  17. #include <linux/platform_device.h>
  18. #include <linux/miscdevice.h>
  19. #include <asm/opal.h>
  20. /*
  21. * This driver creates a character device (/dev/op_panel) which exposes the
  22. * operator panel (character LCD display) on IBM Power Systems machines
  23. * with FSPs.
  24. * A character buffer written to the device will be displayed on the
  25. * operator panel.
  26. */
  27. static DEFINE_MUTEX(oppanel_mutex);
  28. static u32 num_lines, oppanel_size;
  29. static oppanel_line_t *oppanel_lines;
  30. static char *oppanel_data;
  31. static loff_t oppanel_llseek(struct file *filp, loff_t offset, int whence)
  32. {
  33. return fixed_size_llseek(filp, offset, whence, oppanel_size);
  34. }
  35. static ssize_t oppanel_read(struct file *filp, char __user *userbuf, size_t len,
  36. loff_t *f_pos)
  37. {
  38. return simple_read_from_buffer(userbuf, len, f_pos, oppanel_data,
  39. oppanel_size);
  40. }
  41. static int __op_panel_update_display(void)
  42. {
  43. struct opal_msg msg;
  44. int rc, token;
  45. token = opal_async_get_token_interruptible();
  46. if (token < 0) {
  47. if (token != -ERESTARTSYS)
  48. pr_debug("Couldn't get OPAL async token [token=%d]\n",
  49. token);
  50. return token;
  51. }
  52. rc = opal_write_oppanel_async(token, oppanel_lines, num_lines);
  53. switch (rc) {
  54. case OPAL_ASYNC_COMPLETION:
  55. rc = opal_async_wait_response(token, &msg);
  56. if (rc) {
  57. pr_debug("Failed to wait for async response [rc=%d]\n",
  58. rc);
  59. break;
  60. }
  61. rc = opal_get_async_rc(msg);
  62. if (rc != OPAL_SUCCESS) {
  63. pr_debug("OPAL async call returned failed [rc=%d]\n",
  64. rc);
  65. break;
  66. }
  67. case OPAL_SUCCESS:
  68. break;
  69. default:
  70. pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc);
  71. }
  72. opal_async_release_token(token);
  73. return rc;
  74. }
  75. static ssize_t oppanel_write(struct file *filp, const char __user *userbuf,
  76. size_t len, loff_t *f_pos)
  77. {
  78. loff_t f_pos_prev = *f_pos;
  79. ssize_t ret;
  80. int rc;
  81. if (!*f_pos)
  82. memset(oppanel_data, ' ', oppanel_size);
  83. else if (*f_pos >= oppanel_size)
  84. return -EFBIG;
  85. ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf,
  86. len);
  87. if (ret > 0) {
  88. rc = __op_panel_update_display();
  89. if (rc != OPAL_SUCCESS) {
  90. pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n",
  91. rc);
  92. *f_pos = f_pos_prev;
  93. return -EIO;
  94. }
  95. }
  96. return ret;
  97. }
  98. static int oppanel_open(struct inode *inode, struct file *filp)
  99. {
  100. if (!mutex_trylock(&oppanel_mutex)) {
  101. pr_debug("Device Busy\n");
  102. return -EBUSY;
  103. }
  104. return 0;
  105. }
  106. static int oppanel_release(struct inode *inode, struct file *filp)
  107. {
  108. mutex_unlock(&oppanel_mutex);
  109. return 0;
  110. }
  111. static const struct file_operations oppanel_fops = {
  112. .owner = THIS_MODULE,
  113. .llseek = oppanel_llseek,
  114. .read = oppanel_read,
  115. .write = oppanel_write,
  116. .open = oppanel_open,
  117. .release = oppanel_release
  118. };
  119. static struct miscdevice oppanel_dev = {
  120. .minor = MISC_DYNAMIC_MINOR,
  121. .name = "op_panel",
  122. .fops = &oppanel_fops
  123. };
  124. static int oppanel_probe(struct platform_device *pdev)
  125. {
  126. struct device_node *np = pdev->dev.of_node;
  127. u32 line_len;
  128. int rc, i;
  129. rc = of_property_read_u32(np, "#length", &line_len);
  130. if (rc) {
  131. pr_err_ratelimited("Operator panel length property not found\n");
  132. return rc;
  133. }
  134. rc = of_property_read_u32(np, "#lines", &num_lines);
  135. if (rc) {
  136. pr_err_ratelimited("Operator panel lines property not found\n");
  137. return rc;
  138. }
  139. oppanel_size = line_len * num_lines;
  140. pr_devel("Operator panel of size %u found with %u lines of length %u\n",
  141. oppanel_size, num_lines, line_len);
  142. oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL);
  143. if (!oppanel_data)
  144. return -ENOMEM;
  145. oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL);
  146. if (!oppanel_lines) {
  147. rc = -ENOMEM;
  148. goto free_oppanel_data;
  149. }
  150. memset(oppanel_data, ' ', oppanel_size);
  151. for (i = 0; i < num_lines; i++) {
  152. oppanel_lines[i].line_len = cpu_to_be64(line_len);
  153. oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i *
  154. line_len]));
  155. }
  156. rc = misc_register(&oppanel_dev);
  157. if (rc) {
  158. pr_err_ratelimited("Failed to register as misc device\n");
  159. goto free_oppanel;
  160. }
  161. return 0;
  162. free_oppanel:
  163. kfree(oppanel_lines);
  164. free_oppanel_data:
  165. kfree(oppanel_data);
  166. return rc;
  167. }
  168. static int oppanel_remove(struct platform_device *pdev)
  169. {
  170. misc_deregister(&oppanel_dev);
  171. kfree(oppanel_lines);
  172. kfree(oppanel_data);
  173. return 0;
  174. }
  175. static const struct of_device_id oppanel_match[] = {
  176. { .compatible = "ibm,opal-oppanel" },
  177. { },
  178. };
  179. static struct platform_driver oppanel_driver = {
  180. .driver = {
  181. .name = "powernv-op-panel",
  182. .of_match_table = oppanel_match,
  183. },
  184. .probe = oppanel_probe,
  185. .remove = oppanel_remove,
  186. };
  187. module_platform_driver(oppanel_driver);
  188. MODULE_DEVICE_TABLE(of, oppanel_match);
  189. MODULE_LICENSE("GPL v2");
  190. MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver");
  191. MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>");