rtc-r9701.c 3.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * Driver for Epson RTC-9701JE
  4. *
  5. * Copyright (C) 2008 Magnus Damm
  6. *
  7. * Based on rtc-max6902.c
  8. *
  9. * Copyright (C) 2006 8D Technologies inc.
  10. * Copyright (C) 2004 Compulab Ltd.
  11. */
  12. #include <linux/module.h>
  13. #include <linux/kernel.h>
  14. #include <linux/platform_device.h>
  15. #include <linux/device.h>
  16. #include <linux/init.h>
  17. #include <linux/rtc.h>
  18. #include <linux/spi/spi.h>
  19. #include <linux/bcd.h>
  20. #include <linux/delay.h>
  21. #include <linux/bitops.h>
  22. #define RSECCNT 0x00 /* Second Counter */
  23. #define RMINCNT 0x01 /* Minute Counter */
  24. #define RHRCNT 0x02 /* Hour Counter */
  25. #define RWKCNT 0x03 /* Week Counter */
  26. #define RDAYCNT 0x04 /* Day Counter */
  27. #define RMONCNT 0x05 /* Month Counter */
  28. #define RYRCNT 0x06 /* Year Counter */
  29. #define R100CNT 0x07 /* Y100 Counter */
  30. #define RMINAR 0x08 /* Minute Alarm */
  31. #define RHRAR 0x09 /* Hour Alarm */
  32. #define RWKAR 0x0a /* Week/Day Alarm */
  33. #define RTIMCNT 0x0c /* Interval Timer */
  34. #define REXT 0x0d /* Extension Register */
  35. #define RFLAG 0x0e /* RTC Flag Register */
  36. #define RCR 0x0f /* RTC Control Register */
  37. static int write_reg(struct device *dev, int address, unsigned char data)
  38. {
  39. struct spi_device *spi = to_spi_device(dev);
  40. unsigned char buf[2];
  41. buf[0] = address & 0x7f;
  42. buf[1] = data;
  43. return spi_write(spi, buf, ARRAY_SIZE(buf));
  44. }
  45. static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
  46. {
  47. struct spi_device *spi = to_spi_device(dev);
  48. u8 txbuf[1], rxbuf[1];
  49. int k, ret;
  50. ret = 0;
  51. for (k = 0; ret == 0 && k < no_regs; k++) {
  52. txbuf[0] = 0x80 | regs[k];
  53. ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
  54. regs[k] = rxbuf[0];
  55. }
  56. return ret;
  57. }
  58. static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
  59. {
  60. int ret;
  61. unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
  62. RDAYCNT, RMONCNT, RYRCNT };
  63. ret = read_regs(dev, buf, ARRAY_SIZE(buf));
  64. if (ret)
  65. return ret;
  66. dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */
  67. dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */
  68. dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */
  69. dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */
  70. dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */
  71. dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */
  72. return 0;
  73. }
  74. static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
  75. {
  76. int ret;
  77. ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour));
  78. ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min));
  79. ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec));
  80. ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday));
  81. ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1));
  82. ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100));
  83. return ret;
  84. }
  85. static const struct rtc_class_ops r9701_rtc_ops = {
  86. .read_time = r9701_get_datetime,
  87. .set_time = r9701_set_datetime,
  88. };
  89. static int r9701_probe(struct spi_device *spi)
  90. {
  91. struct rtc_device *rtc;
  92. unsigned char tmp;
  93. int res;
  94. tmp = R100CNT;
  95. res = read_regs(&spi->dev, &tmp, 1);
  96. if (res || tmp != 0x20) {
  97. dev_err(&spi->dev, "cannot read RTC register\n");
  98. return -ENODEV;
  99. }
  100. rtc = devm_rtc_allocate_device(&spi->dev);
  101. if (IS_ERR(rtc))
  102. return PTR_ERR(rtc);
  103. spi_set_drvdata(spi, rtc);
  104. rtc->ops = &r9701_rtc_ops;
  105. rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
  106. rtc->range_max = RTC_TIMESTAMP_END_2099;
  107. return rtc_register_device(rtc);
  108. }
  109. static struct spi_driver r9701_driver = {
  110. .driver = {
  111. .name = "rtc-r9701",
  112. },
  113. .probe = r9701_probe,
  114. };
  115. module_spi_driver(r9701_driver);
  116. MODULE_DESCRIPTION("r9701 spi RTC driver");
  117. MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
  118. MODULE_LICENSE("GPL");
  119. MODULE_ALIAS("spi:rtc-r9701");