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