rtc-ds1347.c 4.2 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /* rtc-ds1347.c
  3. *
  4. * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
  5. * Real Time Clock
  6. *
  7. * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
  8. */
  9. #include <linux/init.h>
  10. #include <linux/module.h>
  11. #include <linux/device.h>
  12. #include <linux/platform_device.h>
  13. #include <linux/rtc.h>
  14. #include <linux/spi/spi.h>
  15. #include <linux/bcd.h>
  16. #include <linux/regmap.h>
  17. /* Registers in ds1347 rtc */
  18. #define DS1347_SECONDS_REG 0x01
  19. #define DS1347_MINUTES_REG 0x03
  20. #define DS1347_HOURS_REG 0x05
  21. #define DS1347_DATE_REG 0x07
  22. #define DS1347_MONTH_REG 0x09
  23. #define DS1347_DAY_REG 0x0B
  24. #define DS1347_YEAR_REG 0x0D
  25. #define DS1347_CONTROL_REG 0x0F
  26. #define DS1347_CENTURY_REG 0x13
  27. #define DS1347_STATUS_REG 0x17
  28. #define DS1347_CLOCK_BURST 0x3F
  29. #define DS1347_WP_BIT BIT(7)
  30. #define DS1347_NEOSC_BIT BIT(7)
  31. #define DS1347_OSF_BIT BIT(2)
  32. static const struct regmap_range ds1347_ranges[] = {
  33. {
  34. .range_min = DS1347_SECONDS_REG,
  35. .range_max = DS1347_STATUS_REG,
  36. },
  37. };
  38. static const struct regmap_access_table ds1347_access_table = {
  39. .yes_ranges = ds1347_ranges,
  40. .n_yes_ranges = ARRAY_SIZE(ds1347_ranges),
  41. };
  42. static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
  43. {
  44. struct regmap *map = dev_get_drvdata(dev);
  45. unsigned int status, century, secs;
  46. unsigned char buf[8];
  47. int err;
  48. err = regmap_read(map, DS1347_STATUS_REG, &status);
  49. if (err)
  50. return err;
  51. if (status & DS1347_OSF_BIT)
  52. return -EINVAL;
  53. do {
  54. err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
  55. if (err)
  56. return err;
  57. err = regmap_read(map, DS1347_CENTURY_REG, &century);
  58. if (err)
  59. return err;
  60. err = regmap_read(map, DS1347_SECONDS_REG, &secs);
  61. if (err)
  62. return err;
  63. } while (buf[0] != secs);
  64. dt->tm_sec = bcd2bin(buf[0]);
  65. dt->tm_min = bcd2bin(buf[1] & 0x7f);
  66. dt->tm_hour = bcd2bin(buf[2] & 0x3F);
  67. dt->tm_mday = bcd2bin(buf[3]);
  68. dt->tm_mon = bcd2bin(buf[4]) - 1;
  69. dt->tm_wday = bcd2bin(buf[5]) - 1;
  70. dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;
  71. return 0;
  72. }
  73. static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
  74. {
  75. struct regmap *map = dev_get_drvdata(dev);
  76. unsigned int century;
  77. unsigned char buf[8];
  78. int err;
  79. err = regmap_update_bits(map, DS1347_STATUS_REG,
  80. DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);
  81. if (err)
  82. return err;
  83. buf[0] = bin2bcd(dt->tm_sec);
  84. buf[1] = bin2bcd(dt->tm_min);
  85. buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
  86. buf[3] = bin2bcd(dt->tm_mday);
  87. buf[4] = bin2bcd(dt->tm_mon + 1);
  88. buf[5] = bin2bcd(dt->tm_wday + 1);
  89. buf[6] = bin2bcd(dt->tm_year % 100);
  90. buf[7] = bin2bcd(0x00);
  91. err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
  92. if (err)
  93. return err;
  94. century = (dt->tm_year / 100) + 19;
  95. err = regmap_write(map, DS1347_CENTURY_REG, century);
  96. if (err)
  97. return err;
  98. return regmap_update_bits(map, DS1347_STATUS_REG,
  99. DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
  100. }
  101. static const struct rtc_class_ops ds1347_rtc_ops = {
  102. .read_time = ds1347_read_time,
  103. .set_time = ds1347_set_time,
  104. };
  105. static int ds1347_probe(struct spi_device *spi)
  106. {
  107. struct rtc_device *rtc;
  108. struct regmap_config config;
  109. struct regmap *map;
  110. int err;
  111. memset(&config, 0, sizeof(config));
  112. config.reg_bits = 8;
  113. config.val_bits = 8;
  114. config.read_flag_mask = 0x80;
  115. config.max_register = 0x3F;
  116. config.wr_table = &ds1347_access_table;
  117. /* spi setup with ds1347 in mode 3 and bits per word as 8 */
  118. spi->mode = SPI_MODE_3;
  119. spi->bits_per_word = 8;
  120. spi_setup(spi);
  121. map = devm_regmap_init_spi(spi, &config);
  122. if (IS_ERR(map)) {
  123. dev_err(&spi->dev, "ds1347 regmap init spi failed\n");
  124. return PTR_ERR(map);
  125. }
  126. spi_set_drvdata(spi, map);
  127. /* Disable the write protect of rtc */
  128. err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0);
  129. if (err)
  130. return err;
  131. rtc = devm_rtc_allocate_device(&spi->dev);
  132. if (IS_ERR(rtc))
  133. return PTR_ERR(rtc);
  134. rtc->ops = &ds1347_rtc_ops;
  135. rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
  136. rtc->range_max = RTC_TIMESTAMP_END_9999;
  137. return rtc_register_device(rtc);
  138. }
  139. static struct spi_driver ds1347_driver = {
  140. .driver = {
  141. .name = "ds1347",
  142. },
  143. .probe = ds1347_probe,
  144. };
  145. module_spi_driver(ds1347_driver);
  146. MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
  147. MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
  148. MODULE_LICENSE("GPL v2");