1 /* drivers/rtc/rtc-rx4581.c 2 * 3 * written by Torben Hohn <torbenh@linutronix.de> 4 * 5 * Based on: 6 * drivers/rtc/rtc-max6902.c 7 * 8 * Copyright (C) 2006 8D Technologies inc. 9 * Copyright (C) 2004 Compulab Ltd. 10 * 11 * This program is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License version 2 as 13 * published by the Free Software Foundation. 14 * 15 * Driver for MAX6902 spi RTC 16 * 17 * and based on: 18 * drivers/rtc/rtc-rx8581.c 19 * 20 * An I2C driver for the Epson RX8581 RTC 21 * 22 * Author: Martyn Welch <martyn.welch@ge.com> 23 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc. 24 * 25 * This program is free software; you can redistribute it and/or modify 26 * it under the terms of the GNU General Public License version 2 as 27 * published by the Free Software Foundation. 28 * 29 * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC) 30 * Copyright 2005-06 Tower Technologies 31 * 32 */ 33 34 #include <linux/module.h> 35 #include <linux/kernel.h> 36 #include <linux/platform_device.h> 37 #include <linux/init.h> 38 #include <linux/rtc.h> 39 #include <linux/spi/spi.h> 40 #include <linux/bcd.h> 41 42 #define RX4581_REG_SC 0x00 /* Second in BCD */ 43 #define RX4581_REG_MN 0x01 /* Minute in BCD */ 44 #define RX4581_REG_HR 0x02 /* Hour in BCD */ 45 #define RX4581_REG_DW 0x03 /* Day of Week */ 46 #define RX4581_REG_DM 0x04 /* Day of Month in BCD */ 47 #define RX4581_REG_MO 0x05 /* Month in BCD */ 48 #define RX4581_REG_YR 0x06 /* Year in BCD */ 49 #define RX4581_REG_RAM 0x07 /* RAM */ 50 #define RX4581_REG_AMN 0x08 /* Alarm Min in BCD*/ 51 #define RX4581_REG_AHR 0x09 /* Alarm Hour in BCD */ 52 #define RX4581_REG_ADM 0x0A 53 #define RX4581_REG_ADW 0x0A 54 #define RX4581_REG_TMR0 0x0B 55 #define RX4581_REG_TMR1 0x0C 56 #define RX4581_REG_EXT 0x0D /* Extension Register */ 57 #define RX4581_REG_FLAG 0x0E /* Flag Register */ 58 #define RX4581_REG_CTRL 0x0F /* Control Register */ 59 60 61 /* Flag Register bit definitions */ 62 #define RX4581_FLAG_UF 0x20 /* Update */ 63 #define RX4581_FLAG_TF 0x10 /* Timer */ 64 #define RX4581_FLAG_AF 0x08 /* Alarm */ 65 #define RX4581_FLAG_VLF 0x02 /* Voltage Low */ 66 67 /* Control Register bit definitions */ 68 #define RX4581_CTRL_UIE 0x20 /* Update Interrupt Enable */ 69 #define RX4581_CTRL_TIE 0x10 /* Timer Interrupt Enable */ 70 #define RX4581_CTRL_AIE 0x08 /* Alarm Interrupt Enable */ 71 #define RX4581_CTRL_STOP 0x02 /* STOP bit */ 72 #define RX4581_CTRL_RESET 0x01 /* RESET bit */ 73 74 static int rx4581_set_reg(struct device *dev, unsigned char address, 75 unsigned char data) 76 { 77 struct spi_device *spi = to_spi_device(dev); 78 unsigned char buf[2]; 79 80 /* high nibble must be '0' to write */ 81 buf[0] = address & 0x0f; 82 buf[1] = data; 83 84 return spi_write_then_read(spi, buf, 2, NULL, 0); 85 } 86 87 static int rx4581_get_reg(struct device *dev, unsigned char address, 88 unsigned char *data) 89 { 90 struct spi_device *spi = to_spi_device(dev); 91 92 /* Set MSB to indicate read */ 93 *data = address | 0x80; 94 95 return spi_write_then_read(spi, data, 1, data, 1); 96 } 97 98 /* 99 * In the routines that deal directly with the rx8581 hardware, we use 100 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. 101 */ 102 static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm) 103 { 104 struct spi_device *spi = to_spi_device(dev); 105 unsigned char date[7]; 106 unsigned char data; 107 int err; 108 109 /* First we ensure that the "update flag" is not set, we read the 110 * time and date then re-read the "update flag". If the update flag 111 * has been set, we know that the time has changed during the read so 112 * we repeat the whole process again. 113 */ 114 err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data); 115 if (err != 0) { 116 dev_err(dev, "Unable to read device flags\n"); 117 return -EIO; 118 } 119 120 do { 121 /* If update flag set, clear it */ 122 if (data & RX4581_FLAG_UF) { 123 err = rx4581_set_reg(dev, 124 RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF)); 125 if (err != 0) { 126 dev_err(dev, "Unable to write device " 127 "flags\n"); 128 return -EIO; 129 } 130 } 131 132 /* Now read time and date */ 133 date[0] = 0x80; 134 err = spi_write_then_read(spi, date, 1, date, 7); 135 if (err < 0) { 136 dev_err(dev, "Unable to read date\n"); 137 return -EIO; 138 } 139 140 /* Check flag register */ 141 err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data); 142 if (err != 0) { 143 dev_err(dev, "Unable to read device flags\n"); 144 return -EIO; 145 } 146 } while (data & RX4581_FLAG_UF); 147 148 if (data & RX4581_FLAG_VLF) 149 dev_info(dev, 150 "low voltage detected, date/time is not reliable.\n"); 151 152 dev_dbg(dev, 153 "%s: raw data is sec=%02x, min=%02x, hr=%02x, " 154 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n", 155 __func__, 156 date[0], date[1], date[2], date[3], date[4], date[5], date[6]); 157 158 tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F); 159 tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F); 160 tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */ 161 tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F); 162 tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F); 163 tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */ 164 tm->tm_year = bcd2bin(date[RX4581_REG_YR]); 165 if (tm->tm_year < 70) 166 tm->tm_year += 100; /* assume we are in 1970...2069 */ 167 168 169 dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 170 "mday=%d, mon=%d, year=%d, wday=%d\n", 171 __func__, 172 tm->tm_sec, tm->tm_min, tm->tm_hour, 173 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 174 175 err = rtc_valid_tm(tm); 176 if (err < 0) 177 dev_err(dev, "retrieved date/time is not valid.\n"); 178 179 return err; 180 } 181 182 static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm) 183 { 184 struct spi_device *spi = to_spi_device(dev); 185 int err; 186 unsigned char buf[8], data; 187 188 dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, " 189 "mday=%d, mon=%d, year=%d, wday=%d\n", 190 __func__, 191 tm->tm_sec, tm->tm_min, tm->tm_hour, 192 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 193 194 buf[0] = 0x00; 195 /* hours, minutes and seconds */ 196 buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec); 197 buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min); 198 buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour); 199 200 buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday); 201 202 /* month, 1 - 12 */ 203 buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1); 204 205 /* year and century */ 206 buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100); 207 buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday); 208 209 /* Stop the clock */ 210 err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data); 211 if (err != 0) { 212 dev_err(dev, "Unable to read control register\n"); 213 return -EIO; 214 } 215 216 err = rx4581_set_reg(dev, RX4581_REG_CTRL, 217 (data | RX4581_CTRL_STOP)); 218 if (err != 0) { 219 dev_err(dev, "Unable to write control register\n"); 220 return -EIO; 221 } 222 223 /* write register's data */ 224 err = spi_write_then_read(spi, buf, 8, NULL, 0); 225 if (err != 0) { 226 dev_err(dev, "Unable to write to date registers\n"); 227 return -EIO; 228 } 229 230 /* get VLF and clear it */ 231 err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data); 232 if (err != 0) { 233 dev_err(dev, "Unable to read flag register\n"); 234 return -EIO; 235 } 236 237 err = rx4581_set_reg(dev, RX4581_REG_FLAG, 238 (data & ~(RX4581_FLAG_VLF))); 239 if (err != 0) { 240 dev_err(dev, "Unable to write flag register\n"); 241 return -EIO; 242 } 243 244 /* Restart the clock */ 245 err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data); 246 if (err != 0) { 247 dev_err(dev, "Unable to read control register\n"); 248 return -EIO; 249 } 250 251 err = rx4581_set_reg(dev, RX4581_REG_CTRL, 252 (data & ~(RX4581_CTRL_STOP))); 253 if (err != 0) { 254 dev_err(dev, "Unable to write control register\n"); 255 return -EIO; 256 } 257 258 return 0; 259 } 260 261 static const struct rtc_class_ops rx4581_rtc_ops = { 262 .read_time = rx4581_get_datetime, 263 .set_time = rx4581_set_datetime, 264 }; 265 266 static int rx4581_probe(struct spi_device *spi) 267 { 268 struct rtc_device *rtc; 269 unsigned char tmp; 270 int res; 271 272 res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp); 273 if (res != 0) 274 return res; 275 276 rtc = devm_rtc_device_register(&spi->dev, "rx4581", 277 &rx4581_rtc_ops, THIS_MODULE); 278 if (IS_ERR(rtc)) 279 return PTR_ERR(rtc); 280 281 spi_set_drvdata(spi, rtc); 282 return 0; 283 } 284 285 static const struct spi_device_id rx4581_id[] = { 286 { "rx4581", 0 }, 287 { } 288 }; 289 MODULE_DEVICE_TABLE(spi, rx4581_id); 290 291 static struct spi_driver rx4581_driver = { 292 .driver = { 293 .name = "rtc-rx4581", 294 }, 295 .probe = rx4581_probe, 296 .id_table = rx4581_id, 297 }; 298 299 module_spi_driver(rx4581_driver); 300 301 MODULE_DESCRIPTION("rx4581 spi RTC driver"); 302 MODULE_AUTHOR("Torben Hohn"); 303 MODULE_LICENSE("GPL"); 304 MODULE_ALIAS("spi:rtc-rx4581"); 305