rtc-aspeed.c 3.1 KB

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  1. // SPDX-License-Identifier: GPL-2.0+
  2. // Copyright 2015 IBM Corp.
  3. #include <linux/module.h>
  4. #include <linux/of.h>
  5. #include <linux/platform_device.h>
  6. #include <linux/rtc.h>
  7. #include <linux/io.h>
  8. struct aspeed_rtc {
  9. struct rtc_device *rtc_dev;
  10. void __iomem *base;
  11. };
  12. #define RTC_TIME 0x00
  13. #define RTC_YEAR 0x04
  14. #define RTC_CTRL 0x10
  15. #define RTC_UNLOCK BIT(1)
  16. #define RTC_ENABLE BIT(0)
  17. static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm)
  18. {
  19. struct aspeed_rtc *rtc = dev_get_drvdata(dev);
  20. unsigned int cent, year;
  21. u32 reg1, reg2;
  22. if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) {
  23. dev_dbg(dev, "%s failing as rtc disabled\n", __func__);
  24. return -EINVAL;
  25. }
  26. do {
  27. reg2 = readl(rtc->base + RTC_YEAR);
  28. reg1 = readl(rtc->base + RTC_TIME);
  29. } while (reg2 != readl(rtc->base + RTC_YEAR));
  30. tm->tm_mday = (reg1 >> 24) & 0x1f;
  31. tm->tm_hour = (reg1 >> 16) & 0x1f;
  32. tm->tm_min = (reg1 >> 8) & 0x3f;
  33. tm->tm_sec = (reg1 >> 0) & 0x3f;
  34. cent = (reg2 >> 16) & 0x1f;
  35. year = (reg2 >> 8) & 0x7f;
  36. tm->tm_mon = ((reg2 >> 0) & 0x0f) - 1;
  37. tm->tm_year = year + (cent * 100) - 1900;
  38. dev_dbg(dev, "%s %ptR", __func__, tm);
  39. return 0;
  40. }
  41. static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm)
  42. {
  43. struct aspeed_rtc *rtc = dev_get_drvdata(dev);
  44. u32 reg1, reg2, ctrl;
  45. int year, cent;
  46. cent = (tm->tm_year + 1900) / 100;
  47. year = tm->tm_year % 100;
  48. reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) |
  49. tm->tm_sec;
  50. reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) |
  51. ((tm->tm_mon + 1) & 0xf);
  52. ctrl = readl(rtc->base + RTC_CTRL);
  53. writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL);
  54. writel(reg1, rtc->base + RTC_TIME);
  55. writel(reg2, rtc->base + RTC_YEAR);
  56. /* Re-lock and ensure enable is set now that a time is programmed */
  57. writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL);
  58. return 0;
  59. }
  60. static const struct rtc_class_ops aspeed_rtc_ops = {
  61. .read_time = aspeed_rtc_read_time,
  62. .set_time = aspeed_rtc_set_time,
  63. };
  64. static int aspeed_rtc_probe(struct platform_device *pdev)
  65. {
  66. struct aspeed_rtc *rtc;
  67. rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
  68. if (!rtc)
  69. return -ENOMEM;
  70. rtc->base = devm_platform_ioremap_resource(pdev, 0);
  71. if (IS_ERR(rtc->base))
  72. return PTR_ERR(rtc->base);
  73. rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
  74. if (IS_ERR(rtc->rtc_dev))
  75. return PTR_ERR(rtc->rtc_dev);
  76. platform_set_drvdata(pdev, rtc);
  77. rtc->rtc_dev->ops = &aspeed_rtc_ops;
  78. rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
  79. rtc->rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */
  80. return rtc_register_device(rtc->rtc_dev);
  81. }
  82. static const struct of_device_id aspeed_rtc_match[] = {
  83. { .compatible = "aspeed,ast2400-rtc", },
  84. { .compatible = "aspeed,ast2500-rtc", },
  85. { .compatible = "aspeed,ast2600-rtc", },
  86. {}
  87. };
  88. MODULE_DEVICE_TABLE(of, aspeed_rtc_match);
  89. static struct platform_driver aspeed_rtc_driver = {
  90. .driver = {
  91. .name = "aspeed-rtc",
  92. .of_match_table = of_match_ptr(aspeed_rtc_match),
  93. },
  94. };
  95. module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe);
  96. MODULE_DESCRIPTION("ASPEED RTC driver");
  97. MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
  98. MODULE_LICENSE("GPL");