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 return 0; 176 } 177 178 static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm) 179 { 180 struct spi_device *spi = to_spi_device(dev); 181 int err; 182 unsigned char buf[8], data; 183 184 dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, " 185 "mday=%d, mon=%d, year=%d, wday=%d\n", 186 __func__, 187 tm->tm_sec, tm->tm_min, tm->tm_hour, 188 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 189 190 buf[0] = 0x00; 191 /* hours, minutes and seconds */ 192 buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec); 193 buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min); 194 buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour); 195 196 buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday); 197 198 /* month, 1 - 12 */ 199 buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1); 200 201 /* year and century */ 202 buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100); 203 buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday); 204 205 /* Stop the clock */ 206 err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data); 207 if (err != 0) { 208 dev_err(dev, "Unable to read control register\n"); 209 return -EIO; 210 } 211 212 err = rx4581_set_reg(dev, RX4581_REG_CTRL, 213 (data | RX4581_CTRL_STOP)); 214 if (err != 0) { 215 dev_err(dev, "Unable to write control register\n"); 216 return -EIO; 217 } 218 219 /* write register's data */ 220 err = spi_write_then_read(spi, buf, 8, NULL, 0); 221 if (err != 0) { 222 dev_err(dev, "Unable to write to date registers\n"); 223 return -EIO; 224 } 225 226 /* get VLF and clear it */ 227 err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data); 228 if (err != 0) { 229 dev_err(dev, "Unable to read flag register\n"); 230 return -EIO; 231 } 232 233 err = rx4581_set_reg(dev, RX4581_REG_FLAG, 234 (data & ~(RX4581_FLAG_VLF))); 235 if (err != 0) { 236 dev_err(dev, "Unable to write flag register\n"); 237 return -EIO; 238 } 239 240 /* Restart the clock */ 241 err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data); 242 if (err != 0) { 243 dev_err(dev, "Unable to read control register\n"); 244 return -EIO; 245 } 246 247 err = rx4581_set_reg(dev, RX4581_REG_CTRL, 248 (data & ~(RX4581_CTRL_STOP))); 249 if (err != 0) { 250 dev_err(dev, "Unable to write control register\n"); 251 return -EIO; 252 } 253 254 return 0; 255 } 256 257 static const struct rtc_class_ops rx4581_rtc_ops = { 258 .read_time = rx4581_get_datetime, 259 .set_time = rx4581_set_datetime, 260 }; 261 262 static int rx4581_probe(struct spi_device *spi) 263 { 264 struct rtc_device *rtc; 265 unsigned char tmp; 266 int res; 267 268 res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp); 269 if (res != 0) 270 return res; 271 272 rtc = devm_rtc_device_register(&spi->dev, "rx4581", 273 &rx4581_rtc_ops, THIS_MODULE); 274 if (IS_ERR(rtc)) 275 return PTR_ERR(rtc); 276 277 spi_set_drvdata(spi, rtc); 278 return 0; 279 } 280 281 static const struct spi_device_id rx4581_id[] = { 282 { "rx4581", 0 }, 283 { } 284 }; 285 MODULE_DEVICE_TABLE(spi, rx4581_id); 286 287 static struct spi_driver rx4581_driver = { 288 .driver = { 289 .name = "rtc-rx4581", 290 }, 291 .probe = rx4581_probe, 292 .id_table = rx4581_id, 293 }; 294 295 module_spi_driver(rx4581_driver); 296 297 MODULE_DESCRIPTION("rx4581 spi RTC driver"); 298 MODULE_AUTHOR("Torben Hohn"); 299 MODULE_LICENSE("GPL"); 300 MODULE_ALIAS("spi:rtc-rx4581"); 301