sl28cpld_wdt.c 5.5 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * sl28cpld watchdog driver
  4. *
  5. * Copyright 2020 Kontron Europe GmbH
  6. */
  7. #include <linux/kernel.h>
  8. #include <linux/mod_devicetable.h>
  9. #include <linux/module.h>
  10. #include <linux/platform_device.h>
  11. #include <linux/property.h>
  12. #include <linux/regmap.h>
  13. #include <linux/watchdog.h>
  14. /*
  15. * Watchdog timer block registers.
  16. */
  17. #define WDT_CTRL 0x00
  18. #define WDT_CTRL_EN BIT(0)
  19. #define WDT_CTRL_LOCK BIT(2)
  20. #define WDT_CTRL_ASSERT_SYS_RESET BIT(6)
  21. #define WDT_CTRL_ASSERT_WDT_TIMEOUT BIT(7)
  22. #define WDT_TIMEOUT 0x01
  23. #define WDT_KICK 0x02
  24. #define WDT_KICK_VALUE 0x6b
  25. #define WDT_COUNT 0x03
  26. #define WDT_DEFAULT_TIMEOUT 10
  27. static bool nowayout = WATCHDOG_NOWAYOUT;
  28. module_param(nowayout, bool, 0);
  29. MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  30. __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  31. static int timeout;
  32. module_param(timeout, int, 0);
  33. MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
  34. struct sl28cpld_wdt {
  35. struct watchdog_device wdd;
  36. struct regmap *regmap;
  37. u32 offset;
  38. bool assert_wdt_timeout;
  39. };
  40. static int sl28cpld_wdt_ping(struct watchdog_device *wdd)
  41. {
  42. struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  43. return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,
  44. WDT_KICK_VALUE);
  45. }
  46. static int sl28cpld_wdt_start(struct watchdog_device *wdd)
  47. {
  48. struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  49. unsigned int val;
  50. val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;
  51. if (wdt->assert_wdt_timeout)
  52. val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;
  53. if (nowayout)
  54. val |= WDT_CTRL_LOCK;
  55. return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
  56. val, val);
  57. }
  58. static int sl28cpld_wdt_stop(struct watchdog_device *wdd)
  59. {
  60. struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  61. return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
  62. WDT_CTRL_EN, 0);
  63. }
  64. static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)
  65. {
  66. struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  67. unsigned int val;
  68. int ret;
  69. ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);
  70. if (ret)
  71. return 0;
  72. return val;
  73. }
  74. static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,
  75. unsigned int timeout)
  76. {
  77. struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
  78. int ret;
  79. ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);
  80. if (ret)
  81. return ret;
  82. wdd->timeout = timeout;
  83. return 0;
  84. }
  85. static const struct watchdog_info sl28cpld_wdt_info = {
  86. .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  87. .identity = "sl28cpld watchdog",
  88. };
  89. static struct watchdog_ops sl28cpld_wdt_ops = {
  90. .owner = THIS_MODULE,
  91. .start = sl28cpld_wdt_start,
  92. .stop = sl28cpld_wdt_stop,
  93. .ping = sl28cpld_wdt_ping,
  94. .set_timeout = sl28cpld_wdt_set_timeout,
  95. .get_timeleft = sl28cpld_wdt_get_timeleft,
  96. };
  97. static int sl28cpld_wdt_probe(struct platform_device *pdev)
  98. {
  99. struct watchdog_device *wdd;
  100. struct sl28cpld_wdt *wdt;
  101. unsigned int status;
  102. unsigned int val;
  103. int ret;
  104. if (!pdev->dev.parent)
  105. return -ENODEV;
  106. wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
  107. if (!wdt)
  108. return -ENOMEM;
  109. wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);
  110. if (!wdt->regmap)
  111. return -ENODEV;
  112. ret = device_property_read_u32(&pdev->dev, "reg", &wdt->offset);
  113. if (ret)
  114. return -EINVAL;
  115. wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,
  116. "kontron,assert-wdt-timeout-pin");
  117. /* initialize struct watchdog_device */
  118. wdd = &wdt->wdd;
  119. wdd->parent = &pdev->dev;
  120. wdd->info = &sl28cpld_wdt_info;
  121. wdd->ops = &sl28cpld_wdt_ops;
  122. wdd->min_timeout = 1;
  123. wdd->max_timeout = 255;
  124. watchdog_set_drvdata(wdd, wdt);
  125. watchdog_stop_on_reboot(wdd);
  126. /*
  127. * Read the status early, in case of an error, we haven't modified the
  128. * hardware.
  129. */
  130. ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);
  131. if (ret)
  132. return ret;
  133. /*
  134. * Initial timeout value, may be overwritten by device tree or module
  135. * parmeter in watchdog_init_timeout().
  136. *
  137. * Reading a zero here means that either the hardware has a default
  138. * value of zero (which is very unlikely and definitely a hardware
  139. * bug) or the bootloader set it to zero. In any case, we handle
  140. * this case gracefully and set out own timeout.
  141. */
  142. ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);
  143. if (ret)
  144. return ret;
  145. if (val)
  146. wdd->timeout = val;
  147. else
  148. wdd->timeout = WDT_DEFAULT_TIMEOUT;
  149. watchdog_init_timeout(wdd, timeout, &pdev->dev);
  150. sl28cpld_wdt_set_timeout(wdd, wdd->timeout);
  151. /* if the watchdog is locked, we set nowayout */
  152. if (status & WDT_CTRL_LOCK)
  153. nowayout = true;
  154. watchdog_set_nowayout(wdd, nowayout);
  155. /*
  156. * If watchdog is already running, keep it enabled, but make
  157. * sure its mode is set correctly.
  158. */
  159. if (status & WDT_CTRL_EN) {
  160. sl28cpld_wdt_start(wdd);
  161. set_bit(WDOG_HW_RUNNING, &wdd->status);
  162. }
  163. ret = devm_watchdog_register_device(&pdev->dev, wdd);
  164. if (ret < 0) {
  165. dev_err(&pdev->dev, "failed to register watchdog device\n");
  166. return ret;
  167. }
  168. dev_info(&pdev->dev, "initial timeout %d sec%s\n",
  169. wdd->timeout, nowayout ? ", nowayout" : "");
  170. return 0;
  171. }
  172. static const struct of_device_id sl28cpld_wdt_of_match[] = {
  173. { .compatible = "kontron,sl28cpld-wdt" },
  174. {}
  175. };
  176. MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);
  177. static struct platform_driver sl28cpld_wdt_driver = {
  178. .probe = sl28cpld_wdt_probe,
  179. .driver = {
  180. .name = "sl28cpld-wdt",
  181. .of_match_table = sl28cpld_wdt_of_match,
  182. },
  183. };
  184. module_platform_driver(sl28cpld_wdt_driver);
  185. MODULE_DESCRIPTION("sl28cpld Watchdog Driver");
  186. MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
  187. MODULE_LICENSE("GPL");