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 struct rx8581 { 56 struct i2c_client *client; 57 struct rtc_device *rtc; 58 s32 (*read_block_data)(const struct i2c_client *client, u8 command, 59 u8 length, u8 *values); 60 s32 (*write_block_data)(const struct i2c_client *client, u8 command, 61 u8 length, const u8 *values); 62 }; 63 64 static struct i2c_driver rx8581_driver; 65 66 static int rx8581_read_block_data(const struct i2c_client *client, u8 command, 67 u8 length, u8 *values) 68 { 69 s32 i, data; 70 71 for (i = 0; i < length; i++) { 72 data = i2c_smbus_read_byte_data(client, command + i); 73 if (data < 0) 74 return data; 75 values[i] = data; 76 } 77 return i; 78 } 79 80 static int rx8581_write_block_data(const struct i2c_client *client, u8 command, 81 u8 length, const u8 *values) 82 { 83 s32 i, ret; 84 85 for (i = 0; i < length; i++) { 86 ret = i2c_smbus_write_byte_data(client, command + i, 87 values[i]); 88 if (ret < 0) 89 return ret; 90 } 91 return length; 92 } 93 94 /* 95 * In the routines that deal directly with the rx8581 hardware, we use 96 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. 97 */ 98 static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm) 99 { 100 unsigned char date[7]; 101 int data, err; 102 struct rx8581 *rx8581 = i2c_get_clientdata(client); 103 104 /* First we ensure that the "update flag" is not set, we read the 105 * time and date then re-read the "update flag". If the update flag 106 * has been set, we know that the time has changed during the read so 107 * we repeat the whole process again. 108 */ 109 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG); 110 if (data < 0) { 111 dev_err(&client->dev, "Unable to read device flags\n"); 112 return -EIO; 113 } 114 115 do { 116 /* If update flag set, clear it */ 117 if (data & RX8581_FLAG_UF) { 118 err = i2c_smbus_write_byte_data(client, 119 RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF)); 120 if (err != 0) { 121 dev_err(&client->dev, "Unable to write device flags\n"); 122 return -EIO; 123 } 124 } 125 126 /* Now read time and date */ 127 err = rx8581->read_block_data(client, RX8581_REG_SC, 128 7, date); 129 if (err < 0) { 130 dev_err(&client->dev, "Unable to read date\n"); 131 return -EIO; 132 } 133 134 /* Check flag register */ 135 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG); 136 if (data < 0) { 137 dev_err(&client->dev, "Unable to read device flags\n"); 138 return -EIO; 139 } 140 } while (data & RX8581_FLAG_UF); 141 142 if (data & RX8581_FLAG_VLF) 143 dev_info(&client->dev, 144 "low voltage detected, date/time is not reliable.\n"); 145 146 dev_dbg(&client->dev, 147 "%s: raw data is sec=%02x, min=%02x, hr=%02x, " 148 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n", 149 __func__, 150 date[0], date[1], date[2], date[3], date[4], date[5], date[6]); 151 152 tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F); 153 tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F); 154 tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */ 155 tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F); 156 tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F); 157 tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */ 158 tm->tm_year = bcd2bin(date[RX8581_REG_YR]); 159 if (tm->tm_year < 70) 160 tm->tm_year += 100; /* assume we are in 1970...2069 */ 161 162 163 dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, " 164 "mday=%d, mon=%d, year=%d, wday=%d\n", 165 __func__, 166 tm->tm_sec, tm->tm_min, tm->tm_hour, 167 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 168 169 err = rtc_valid_tm(tm); 170 if (err < 0) 171 dev_err(&client->dev, "retrieved date/time is not valid.\n"); 172 173 return err; 174 } 175 176 static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm) 177 { 178 int data, err; 179 unsigned char buf[7]; 180 struct rx8581 *rx8581 = i2c_get_clientdata(client); 181 182 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, " 183 "mday=%d, mon=%d, year=%d, wday=%d\n", 184 __func__, 185 tm->tm_sec, tm->tm_min, tm->tm_hour, 186 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 187 188 /* hours, minutes and seconds */ 189 buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec); 190 buf[RX8581_REG_MN] = bin2bcd(tm->tm_min); 191 buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour); 192 193 buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday); 194 195 /* month, 1 - 12 */ 196 buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1); 197 198 /* year and century */ 199 buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100); 200 buf[RX8581_REG_DW] = (0x1 << tm->tm_wday); 201 202 /* Stop the clock */ 203 data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL); 204 if (data < 0) { 205 dev_err(&client->dev, "Unable to read control register\n"); 206 return -EIO; 207 } 208 209 err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL, 210 (data | RX8581_CTRL_STOP)); 211 if (err < 0) { 212 dev_err(&client->dev, "Unable to write control register\n"); 213 return -EIO; 214 } 215 216 /* write register's data */ 217 err = rx8581->write_block_data(client, RX8581_REG_SC, 7, buf); 218 if (err < 0) { 219 dev_err(&client->dev, "Unable to write to date registers\n"); 220 return -EIO; 221 } 222 223 /* get VLF and clear it */ 224 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG); 225 if (data < 0) { 226 dev_err(&client->dev, "Unable to read flag register\n"); 227 return -EIO; 228 } 229 230 err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG, 231 (data & ~(RX8581_FLAG_VLF))); 232 if (err != 0) { 233 dev_err(&client->dev, "Unable to write flag register\n"); 234 return -EIO; 235 } 236 237 /* Restart the clock */ 238 data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL); 239 if (data < 0) { 240 dev_err(&client->dev, "Unable to read control register\n"); 241 return -EIO; 242 } 243 244 err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL, 245 (data & ~(RX8581_CTRL_STOP))); 246 if (err != 0) { 247 dev_err(&client->dev, "Unable to write control register\n"); 248 return -EIO; 249 } 250 251 return 0; 252 } 253 254 static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm) 255 { 256 return rx8581_get_datetime(to_i2c_client(dev), tm); 257 } 258 259 static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm) 260 { 261 return rx8581_set_datetime(to_i2c_client(dev), tm); 262 } 263 264 static const struct rtc_class_ops rx8581_rtc_ops = { 265 .read_time = rx8581_rtc_read_time, 266 .set_time = rx8581_rtc_set_time, 267 }; 268 269 static int rx8581_probe(struct i2c_client *client, 270 const struct i2c_device_id *id) 271 { 272 struct rx8581 *rx8581; 273 274 dev_dbg(&client->dev, "%s\n", __func__); 275 276 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA) 277 && !i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) 278 return -EIO; 279 280 rx8581 = devm_kzalloc(&client->dev, sizeof(struct rx8581), GFP_KERNEL); 281 if (!rx8581) 282 return -ENOMEM; 283 284 i2c_set_clientdata(client, rx8581); 285 rx8581->client = client; 286 287 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) { 288 rx8581->read_block_data = i2c_smbus_read_i2c_block_data; 289 rx8581->write_block_data = i2c_smbus_write_i2c_block_data; 290 } else { 291 rx8581->read_block_data = rx8581_read_block_data; 292 rx8581->write_block_data = rx8581_write_block_data; 293 } 294 295 dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n"); 296 297 rx8581->rtc = devm_rtc_device_register(&client->dev, 298 rx8581_driver.driver.name, &rx8581_rtc_ops, THIS_MODULE); 299 300 if (IS_ERR(rx8581->rtc)) { 301 dev_err(&client->dev, 302 "unable to register the class device\n"); 303 return PTR_ERR(rx8581->rtc); 304 } 305 306 return 0; 307 } 308 309 static const struct i2c_device_id rx8581_id[] = { 310 { "rx8581", 0 }, 311 { } 312 }; 313 MODULE_DEVICE_TABLE(i2c, rx8581_id); 314 315 static struct i2c_driver rx8581_driver = { 316 .driver = { 317 .name = "rtc-rx8581", 318 }, 319 .probe = rx8581_probe, 320 .id_table = rx8581_id, 321 }; 322 323 module_i2c_driver(rx8581_driver); 324 325 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>"); 326 MODULE_DESCRIPTION("Epson RX-8581 RTC driver"); 327 MODULE_LICENSE("GPL"); 328 MODULE_VERSION(DRV_VERSION); 329