rtc-rx4581.c 7.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /* drivers/rtc/rtc-rx4581.c
  3. *
  4. * written by Torben Hohn <torbenh@linutronix.de>
  5. *
  6. * Based on:
  7. * drivers/rtc/rtc-max6902.c
  8. *
  9. * Copyright (C) 2006 8D Technologies inc.
  10. * Copyright (C) 2004 Compulab Ltd.
  11. *
  12. * Driver for MAX6902 spi RTC
  13. *
  14. * and based on:
  15. * drivers/rtc/rtc-rx8581.c
  16. *
  17. * An I2C driver for the Epson RX8581 RTC
  18. *
  19. * Author: Martyn Welch <martyn.welch@ge.com>
  20. * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
  21. *
  22. * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
  23. * Copyright 2005-06 Tower Technologies
  24. */
  25. #include <linux/module.h>
  26. #include <linux/kernel.h>
  27. #include <linux/platform_device.h>
  28. #include <linux/init.h>
  29. #include <linux/rtc.h>
  30. #include <linux/spi/spi.h>
  31. #include <linux/bcd.h>
  32. #define RX4581_REG_SC 0x00 /* Second in BCD */
  33. #define RX4581_REG_MN 0x01 /* Minute in BCD */
  34. #define RX4581_REG_HR 0x02 /* Hour in BCD */
  35. #define RX4581_REG_DW 0x03 /* Day of Week */
  36. #define RX4581_REG_DM 0x04 /* Day of Month in BCD */
  37. #define RX4581_REG_MO 0x05 /* Month in BCD */
  38. #define RX4581_REG_YR 0x06 /* Year in BCD */
  39. #define RX4581_REG_RAM 0x07 /* RAM */
  40. #define RX4581_REG_AMN 0x08 /* Alarm Min in BCD*/
  41. #define RX4581_REG_AHR 0x09 /* Alarm Hour in BCD */
  42. #define RX4581_REG_ADM 0x0A
  43. #define RX4581_REG_ADW 0x0A
  44. #define RX4581_REG_TMR0 0x0B
  45. #define RX4581_REG_TMR1 0x0C
  46. #define RX4581_REG_EXT 0x0D /* Extension Register */
  47. #define RX4581_REG_FLAG 0x0E /* Flag Register */
  48. #define RX4581_REG_CTRL 0x0F /* Control Register */
  49. /* Flag Register bit definitions */
  50. #define RX4581_FLAG_UF 0x20 /* Update */
  51. #define RX4581_FLAG_TF 0x10 /* Timer */
  52. #define RX4581_FLAG_AF 0x08 /* Alarm */
  53. #define RX4581_FLAG_VLF 0x02 /* Voltage Low */
  54. /* Control Register bit definitions */
  55. #define RX4581_CTRL_UIE 0x20 /* Update Interrupt Enable */
  56. #define RX4581_CTRL_TIE 0x10 /* Timer Interrupt Enable */
  57. #define RX4581_CTRL_AIE 0x08 /* Alarm Interrupt Enable */
  58. #define RX4581_CTRL_STOP 0x02 /* STOP bit */
  59. #define RX4581_CTRL_RESET 0x01 /* RESET bit */
  60. static int rx4581_set_reg(struct device *dev, unsigned char address,
  61. unsigned char data)
  62. {
  63. struct spi_device *spi = to_spi_device(dev);
  64. unsigned char buf[2];
  65. /* high nibble must be '0' to write */
  66. buf[0] = address & 0x0f;
  67. buf[1] = data;
  68. return spi_write_then_read(spi, buf, 2, NULL, 0);
  69. }
  70. static int rx4581_get_reg(struct device *dev, unsigned char address,
  71. unsigned char *data)
  72. {
  73. struct spi_device *spi = to_spi_device(dev);
  74. /* Set MSB to indicate read */
  75. *data = address | 0x80;
  76. return spi_write_then_read(spi, data, 1, data, 1);
  77. }
  78. /*
  79. * In the routines that deal directly with the rx8581 hardware, we use
  80. * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  81. */
  82. static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
  83. {
  84. struct spi_device *spi = to_spi_device(dev);
  85. unsigned char date[7];
  86. unsigned char data;
  87. int err;
  88. /* First we ensure that the "update flag" is not set, we read the
  89. * time and date then re-read the "update flag". If the update flag
  90. * has been set, we know that the time has changed during the read so
  91. * we repeat the whole process again.
  92. */
  93. err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
  94. if (err != 0) {
  95. dev_err(dev, "Unable to read device flags\n");
  96. return -EIO;
  97. }
  98. do {
  99. /* If update flag set, clear it */
  100. if (data & RX4581_FLAG_UF) {
  101. err = rx4581_set_reg(dev,
  102. RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
  103. if (err != 0) {
  104. dev_err(dev, "Unable to write device "
  105. "flags\n");
  106. return -EIO;
  107. }
  108. }
  109. /* Now read time and date */
  110. date[0] = 0x80;
  111. err = spi_write_then_read(spi, date, 1, date, 7);
  112. if (err < 0) {
  113. dev_err(dev, "Unable to read date\n");
  114. return -EIO;
  115. }
  116. /* Check flag register */
  117. err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
  118. if (err != 0) {
  119. dev_err(dev, "Unable to read device flags\n");
  120. return -EIO;
  121. }
  122. } while (data & RX4581_FLAG_UF);
  123. if (data & RX4581_FLAG_VLF)
  124. dev_info(dev,
  125. "low voltage detected, date/time is not reliable.\n");
  126. dev_dbg(dev,
  127. "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
  128. "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
  129. __func__,
  130. date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
  131. tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F);
  132. tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
  133. tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */
  134. tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F);
  135. tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F);
  136. tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
  137. tm->tm_year = bcd2bin(date[RX4581_REG_YR]);
  138. if (tm->tm_year < 70)
  139. tm->tm_year += 100; /* assume we are in 1970...2069 */
  140. dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  141. "mday=%d, mon=%d, year=%d, wday=%d\n",
  142. __func__,
  143. tm->tm_sec, tm->tm_min, tm->tm_hour,
  144. tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  145. return 0;
  146. }
  147. static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
  148. {
  149. struct spi_device *spi = to_spi_device(dev);
  150. int err;
  151. unsigned char buf[8], data;
  152. dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
  153. "mday=%d, mon=%d, year=%d, wday=%d\n",
  154. __func__,
  155. tm->tm_sec, tm->tm_min, tm->tm_hour,
  156. tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  157. buf[0] = 0x00;
  158. /* hours, minutes and seconds */
  159. buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
  160. buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
  161. buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
  162. buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
  163. /* month, 1 - 12 */
  164. buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
  165. /* year and century */
  166. buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
  167. buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
  168. /* Stop the clock */
  169. err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
  170. if (err != 0) {
  171. dev_err(dev, "Unable to read control register\n");
  172. return -EIO;
  173. }
  174. err = rx4581_set_reg(dev, RX4581_REG_CTRL,
  175. (data | RX4581_CTRL_STOP));
  176. if (err != 0) {
  177. dev_err(dev, "Unable to write control register\n");
  178. return -EIO;
  179. }
  180. /* write register's data */
  181. err = spi_write_then_read(spi, buf, 8, NULL, 0);
  182. if (err != 0) {
  183. dev_err(dev, "Unable to write to date registers\n");
  184. return -EIO;
  185. }
  186. /* get VLF and clear it */
  187. err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
  188. if (err != 0) {
  189. dev_err(dev, "Unable to read flag register\n");
  190. return -EIO;
  191. }
  192. err = rx4581_set_reg(dev, RX4581_REG_FLAG,
  193. (data & ~(RX4581_FLAG_VLF)));
  194. if (err != 0) {
  195. dev_err(dev, "Unable to write flag register\n");
  196. return -EIO;
  197. }
  198. /* Restart the clock */
  199. err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
  200. if (err != 0) {
  201. dev_err(dev, "Unable to read control register\n");
  202. return -EIO;
  203. }
  204. err = rx4581_set_reg(dev, RX4581_REG_CTRL,
  205. (data & ~(RX4581_CTRL_STOP)));
  206. if (err != 0) {
  207. dev_err(dev, "Unable to write control register\n");
  208. return -EIO;
  209. }
  210. return 0;
  211. }
  212. static const struct rtc_class_ops rx4581_rtc_ops = {
  213. .read_time = rx4581_get_datetime,
  214. .set_time = rx4581_set_datetime,
  215. };
  216. static int rx4581_probe(struct spi_device *spi)
  217. {
  218. struct rtc_device *rtc;
  219. unsigned char tmp;
  220. int res;
  221. res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
  222. if (res != 0)
  223. return res;
  224. rtc = devm_rtc_device_register(&spi->dev, "rx4581",
  225. &rx4581_rtc_ops, THIS_MODULE);
  226. if (IS_ERR(rtc))
  227. return PTR_ERR(rtc);
  228. spi_set_drvdata(spi, rtc);
  229. return 0;
  230. }
  231. static const struct spi_device_id rx4581_id[] = {
  232. { "rx4581", 0 },
  233. { }
  234. };
  235. MODULE_DEVICE_TABLE(spi, rx4581_id);
  236. static struct spi_driver rx4581_driver = {
  237. .driver = {
  238. .name = "rtc-rx4581",
  239. },
  240. .probe = rx4581_probe,
  241. .id_table = rx4581_id,
  242. };
  243. module_spi_driver(rx4581_driver);
  244. MODULE_DESCRIPTION("rx4581 spi RTC driver");
  245. MODULE_AUTHOR("Torben Hohn");
  246. MODULE_LICENSE("GPL");
  247. MODULE_ALIAS("spi:rtc-rx4581");