1 /* 2 * An I2C driver for the Epson RX8581 RTC 3 * 4 * Author: Martyn Welch <martyn.welch@ge.com> 5 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc. 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC) 12 * Copyright 2005-06 Tower Technologies 13 */ 14 15 #include <linux/module.h> 16 #include <linux/i2c.h> 17 #include <linux/bcd.h> 18 #include <linux/rtc.h> 19 #include <linux/log2.h> 20 21 #define DRV_VERSION "0.1" 22 23 #define RX8581_REG_SC 0x00 /* Second in BCD */ 24 #define RX8581_REG_MN 0x01 /* Minute in BCD */ 25 #define RX8581_REG_HR 0x02 /* Hour in BCD */ 26 #define RX8581_REG_DW 0x03 /* Day of Week */ 27 #define RX8581_REG_DM 0x04 /* Day of Month in BCD */ 28 #define RX8581_REG_MO 0x05 /* Month in BCD */ 29 #define RX8581_REG_YR 0x06 /* Year in BCD */ 30 #define RX8581_REG_RAM 0x07 /* RAM */ 31 #define RX8581_REG_AMN 0x08 /* Alarm Min in BCD*/ 32 #define RX8581_REG_AHR 0x09 /* Alarm Hour in BCD */ 33 #define RX8581_REG_ADM 0x0A 34 #define RX8581_REG_ADW 0x0A 35 #define RX8581_REG_TMR0 0x0B 36 #define RX8581_REG_TMR1 0x0C 37 #define RX8581_REG_EXT 0x0D /* Extension Register */ 38 #define RX8581_REG_FLAG 0x0E /* Flag Register */ 39 #define RX8581_REG_CTRL 0x0F /* Control Register */ 40 41 42 /* Flag Register bit definitions */ 43 #define RX8581_FLAG_UF 0x20 /* Update */ 44 #define RX8581_FLAG_TF 0x10 /* Timer */ 45 #define RX8581_FLAG_AF 0x08 /* Alarm */ 46 #define RX8581_FLAG_VLF 0x02 /* Voltage Low */ 47 48 /* Control Register bit definitions */ 49 #define RX8581_CTRL_UIE 0x20 /* Update Interrupt Enable */ 50 #define RX8581_CTRL_TIE 0x10 /* Timer Interrupt Enable */ 51 #define RX8581_CTRL_AIE 0x08 /* Alarm Interrupt Enable */ 52 #define RX8581_CTRL_STOP 0x02 /* STOP bit */ 53 #define RX8581_CTRL_RESET 0x01 /* RESET bit */ 54 55 static struct i2c_driver rx8581_driver; 56 57 /* 58 * In the routines that deal directly with the rx8581 hardware, we use 59 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. 60 */ 61 static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm) 62 { 63 unsigned char date[7]; 64 int data, err; 65 66 /* First we ensure that the "update flag" is not set, we read the 67 * time and date then re-read the "update flag". If the update flag 68 * has been set, we know that the time has changed during the read so 69 * we repeat the whole process again. 70 */ 71 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG); 72 if (data < 0) { 73 dev_err(&client->dev, "Unable to read device flags\n"); 74 return -EIO; 75 } 76 77 do { 78 /* If update flag set, clear it */ 79 if (data & RX8581_FLAG_UF) { 80 err = i2c_smbus_write_byte_data(client, 81 RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF)); 82 if (err != 0) { 83 dev_err(&client->dev, "Unable to write device " 84 "flags\n"); 85 return -EIO; 86 } 87 } 88 89 /* Now read time and date */ 90 err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC, 91 7, date); 92 if (err < 0) { 93 dev_err(&client->dev, "Unable to read date\n"); 94 return -EIO; 95 } 96 97 /* Check flag register */ 98 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG); 99 if (data < 0) { 100 dev_err(&client->dev, "Unable to read device flags\n"); 101 return -EIO; 102 } 103 } while (data & RX8581_FLAG_UF); 104 105 if (data & RX8581_FLAG_VLF) 106 dev_info(&client->dev, 107 "low voltage detected, date/time is not reliable.\n"); 108 109 dev_dbg(&client->dev, 110 "%s: raw data is sec=%02x, min=%02x, hr=%02x, " 111 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n", 112 __func__, 113 date[0], date[1], date[2], date[3], date[4], date[5], date[6]); 114 115 tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F); 116 tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F); 117 tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */ 118 tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F); 119 tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F); 120 tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */ 121 tm->tm_year = bcd2bin(date[RX8581_REG_YR]); 122 if (tm->tm_year < 70) 123 tm->tm_year += 100; /* assume we are in 1970...2069 */ 124 125 126 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 127 "mday=%d, mon=%d, year=%d, wday=%d\n", 128 __func__, 129 tm->tm_sec, tm->tm_min, tm->tm_hour, 130 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 131 132 err = rtc_valid_tm(tm); 133 if (err < 0) 134 dev_err(&client->dev, "retrieved date/time is not valid.\n"); 135 136 return err; 137 } 138 139 static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm) 140 { 141 int data, err; 142 unsigned char buf[7]; 143 144 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, " 145 "mday=%d, mon=%d, year=%d, wday=%d\n", 146 __func__, 147 tm->tm_sec, tm->tm_min, tm->tm_hour, 148 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 149 150 /* hours, minutes and seconds */ 151 buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec); 152 buf[RX8581_REG_MN] = bin2bcd(tm->tm_min); 153 buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour); 154 155 buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday); 156 157 /* month, 1 - 12 */ 158 buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1); 159 160 /* year and century */ 161 buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100); 162 buf[RX8581_REG_DW] = (0x1 << tm->tm_wday); 163 164 /* Stop the clock */ 165 data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL); 166 if (data < 0) { 167 dev_err(&client->dev, "Unable to read control register\n"); 168 return -EIO; 169 } 170 171 err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL, 172 (data | RX8581_CTRL_STOP)); 173 if (err < 0) { 174 dev_err(&client->dev, "Unable to write control register\n"); 175 return -EIO; 176 } 177 178 /* write register's data */ 179 err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf); 180 if (err < 0) { 181 dev_err(&client->dev, "Unable to write to date registers\n"); 182 return -EIO; 183 } 184 185 /* get VLF and clear it */ 186 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG); 187 if (data < 0) { 188 dev_err(&client->dev, "Unable to read flag register\n"); 189 return -EIO; 190 } 191 192 err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG, 193 (data & ~(RX8581_FLAG_VLF))); 194 if (err != 0) { 195 dev_err(&client->dev, "Unable to write flag register\n"); 196 return -EIO; 197 } 198 199 /* Restart the clock */ 200 data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL); 201 if (data < 0) { 202 dev_err(&client->dev, "Unable to read control register\n"); 203 return -EIO; 204 } 205 206 err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL, 207 (data & ~(RX8581_CTRL_STOP))); 208 if (err != 0) { 209 dev_err(&client->dev, "Unable to write control register\n"); 210 return -EIO; 211 } 212 213 return 0; 214 } 215 216 static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm) 217 { 218 return rx8581_get_datetime(to_i2c_client(dev), tm); 219 } 220 221 static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm) 222 { 223 return rx8581_set_datetime(to_i2c_client(dev), tm); 224 } 225 226 static const struct rtc_class_ops rx8581_rtc_ops = { 227 .read_time = rx8581_rtc_read_time, 228 .set_time = rx8581_rtc_set_time, 229 }; 230 231 static int rx8581_probe(struct i2c_client *client, 232 const struct i2c_device_id *id) 233 { 234 struct rtc_device *rtc; 235 236 dev_dbg(&client->dev, "%s\n", __func__); 237 238 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 239 return -ENODEV; 240 241 dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n"); 242 243 rtc = devm_rtc_device_register(&client->dev, rx8581_driver.driver.name, 244 &rx8581_rtc_ops, THIS_MODULE); 245 246 if (IS_ERR(rtc)) 247 return PTR_ERR(rtc); 248 249 i2c_set_clientdata(client, rtc); 250 251 return 0; 252 } 253 254 static int rx8581_remove(struct i2c_client *client) 255 { 256 return 0; 257 } 258 259 static const struct i2c_device_id rx8581_id[] = { 260 { "rx8581", 0 }, 261 { } 262 }; 263 MODULE_DEVICE_TABLE(i2c, rx8581_id); 264 265 static struct i2c_driver rx8581_driver = { 266 .driver = { 267 .name = "rtc-rx8581", 268 .owner = THIS_MODULE, 269 }, 270 .probe = rx8581_probe, 271 .remove = rx8581_remove, 272 .id_table = rx8581_id, 273 }; 274 275 module_i2c_driver(rx8581_driver); 276 277 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>"); 278 MODULE_DESCRIPTION("Epson RX-8581 RTC driver"); 279 MODULE_LICENSE("GPL"); 280 MODULE_VERSION(DRV_VERSION); 281