1 /* 2 * An I2C driver for the Intersil ISL 12022 3 * 4 * Author: Roman Fietze <roman.fietze@telemotive.de> 5 * 6 * Based on the Philips PCF8563 RTC 7 * by Alessandro Zummo <a.zummo@towertech.it>. 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License version 11 * 2 as published by the Free Software Foundation. 12 */ 13 14 #include <linux/i2c.h> 15 #include <linux/bcd.h> 16 #include <linux/rtc.h> 17 #include <linux/slab.h> 18 #include <linux/module.h> 19 20 #define DRV_VERSION "0.1" 21 22 /* ISL register offsets */ 23 #define ISL12022_REG_SC 0x00 24 #define ISL12022_REG_MN 0x01 25 #define ISL12022_REG_HR 0x02 26 #define ISL12022_REG_DT 0x03 27 #define ISL12022_REG_MO 0x04 28 #define ISL12022_REG_YR 0x05 29 #define ISL12022_REG_DW 0x06 30 31 #define ISL12022_REG_SR 0x07 32 #define ISL12022_REG_INT 0x08 33 34 /* ISL register bits */ 35 #define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */ 36 37 #define ISL12022_SR_LBAT85 (1 << 2) 38 #define ISL12022_SR_LBAT75 (1 << 1) 39 40 #define ISL12022_INT_WRTC (1 << 6) 41 42 43 static struct i2c_driver isl12022_driver; 44 45 struct isl12022 { 46 struct rtc_device *rtc; 47 48 bool write_enabled; /* true if write enable is set */ 49 }; 50 51 52 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg, 53 uint8_t *data, size_t n) 54 { 55 struct i2c_msg msgs[] = { 56 { 57 .addr = client->addr, 58 .flags = 0, 59 .len = 1, 60 .buf = data 61 }, /* setup read ptr */ 62 { 63 .addr = client->addr, 64 .flags = I2C_M_RD, 65 .len = n, 66 .buf = data 67 } 68 }; 69 70 int ret; 71 72 data[0] = reg; 73 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); 74 if (ret != ARRAY_SIZE(msgs)) { 75 dev_err(&client->dev, "%s: read error, ret=%d\n", 76 __func__, ret); 77 return -EIO; 78 } 79 80 return 0; 81 } 82 83 84 static int isl12022_write_reg(struct i2c_client *client, 85 uint8_t reg, uint8_t val) 86 { 87 uint8_t data[2] = { reg, val }; 88 int err; 89 90 err = i2c_master_send(client, data, sizeof(data)); 91 if (err != sizeof(data)) { 92 dev_err(&client->dev, 93 "%s: err=%d addr=%02x, data=%02x\n", 94 __func__, err, data[0], data[1]); 95 return -EIO; 96 } 97 98 return 0; 99 } 100 101 102 /* 103 * In the routines that deal directly with the isl12022 hardware, we use 104 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. 105 */ 106 static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm) 107 { 108 uint8_t buf[ISL12022_REG_INT + 1]; 109 int ret; 110 111 ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf)); 112 if (ret) 113 return ret; 114 115 if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) { 116 dev_warn(&client->dev, 117 "voltage dropped below %u%%, " 118 "date and time is not reliable.\n", 119 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75); 120 } 121 122 dev_dbg(&client->dev, 123 "%s: raw data is sec=%02x, min=%02x, hr=%02x, " 124 "mday=%02x, mon=%02x, year=%02x, wday=%02x, " 125 "sr=%02x, int=%02x", 126 __func__, 127 buf[ISL12022_REG_SC], 128 buf[ISL12022_REG_MN], 129 buf[ISL12022_REG_HR], 130 buf[ISL12022_REG_DT], 131 buf[ISL12022_REG_MO], 132 buf[ISL12022_REG_YR], 133 buf[ISL12022_REG_DW], 134 buf[ISL12022_REG_SR], 135 buf[ISL12022_REG_INT]); 136 137 tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F); 138 tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F); 139 tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F); 140 tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F); 141 tm->tm_wday = buf[ISL12022_REG_DW] & 0x07; 142 tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1; 143 tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100; 144 145 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, " 146 "mday=%d, mon=%d, year=%d, wday=%d\n", 147 __func__, 148 tm->tm_sec, tm->tm_min, tm->tm_hour, 149 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 150 151 /* The clock can give out invalid datetime, but we cannot return 152 * -EINVAL otherwise hwclock will refuse to set the time on bootup. */ 153 if (rtc_valid_tm(tm) < 0) 154 dev_err(&client->dev, "retrieved date and time is invalid.\n"); 155 156 return 0; 157 } 158 159 static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm) 160 { 161 struct isl12022 *isl12022 = i2c_get_clientdata(client); 162 size_t i; 163 int ret; 164 uint8_t buf[ISL12022_REG_DW + 1]; 165 166 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, " 167 "mday=%d, mon=%d, year=%d, wday=%d\n", 168 __func__, 169 tm->tm_sec, tm->tm_min, tm->tm_hour, 170 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 171 172 if (!isl12022->write_enabled) { 173 174 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1); 175 if (ret) 176 return ret; 177 178 /* Check if WRTC (write rtc enable) is set factory default is 179 * 0 (not set) */ 180 if (!(buf[0] & ISL12022_INT_WRTC)) { 181 dev_info(&client->dev, 182 "init write enable and 24 hour format\n"); 183 184 /* Set the write enable bit. */ 185 ret = isl12022_write_reg(client, 186 ISL12022_REG_INT, 187 buf[0] | ISL12022_INT_WRTC); 188 if (ret) 189 return ret; 190 191 /* Write to any RTC register to start RTC, we use the 192 * HR register, setting the MIL bit to use the 24 hour 193 * format. */ 194 ret = isl12022_read_regs(client, ISL12022_REG_HR, 195 buf, 1); 196 if (ret) 197 return ret; 198 199 ret = isl12022_write_reg(client, 200 ISL12022_REG_HR, 201 buf[0] | ISL12022_HR_MIL); 202 if (ret) 203 return ret; 204 } 205 206 isl12022->write_enabled = 1; 207 } 208 209 /* hours, minutes and seconds */ 210 buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec); 211 buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min); 212 buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL; 213 214 buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday); 215 216 /* month, 1 - 12 */ 217 buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1); 218 219 /* year and century */ 220 buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100); 221 222 buf[ISL12022_REG_DW] = tm->tm_wday & 0x07; 223 224 /* write register's data */ 225 for (i = 0; i < ARRAY_SIZE(buf); i++) { 226 ret = isl12022_write_reg(client, ISL12022_REG_SC + i, 227 buf[ISL12022_REG_SC + i]); 228 if (ret) 229 return -EIO; 230 } 231 232 return 0; 233 } 234 235 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm) 236 { 237 return isl12022_get_datetime(to_i2c_client(dev), tm); 238 } 239 240 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm) 241 { 242 return isl12022_set_datetime(to_i2c_client(dev), tm); 243 } 244 245 static const struct rtc_class_ops isl12022_rtc_ops = { 246 .read_time = isl12022_rtc_read_time, 247 .set_time = isl12022_rtc_set_time, 248 }; 249 250 static int isl12022_probe(struct i2c_client *client, 251 const struct i2c_device_id *id) 252 { 253 struct isl12022 *isl12022; 254 255 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 256 return -ENODEV; 257 258 isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022), 259 GFP_KERNEL); 260 if (!isl12022) 261 return -ENOMEM; 262 263 dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n"); 264 265 i2c_set_clientdata(client, isl12022); 266 267 isl12022->rtc = devm_rtc_device_register(&client->dev, 268 isl12022_driver.driver.name, 269 &isl12022_rtc_ops, THIS_MODULE); 270 if (IS_ERR(isl12022->rtc)) 271 return PTR_ERR(isl12022->rtc); 272 273 return 0; 274 } 275 276 static int isl12022_remove(struct i2c_client *client) 277 { 278 return 0; 279 } 280 281 static const struct i2c_device_id isl12022_id[] = { 282 { "isl12022", 0 }, 283 { } 284 }; 285 MODULE_DEVICE_TABLE(i2c, isl12022_id); 286 287 static struct i2c_driver isl12022_driver = { 288 .driver = { 289 .name = "rtc-isl12022", 290 }, 291 .probe = isl12022_probe, 292 .remove = isl12022_remove, 293 .id_table = isl12022_id, 294 }; 295 296 module_i2c_driver(isl12022_driver); 297 298 MODULE_AUTHOR("roman.fietze@telemotive.de"); 299 MODULE_DESCRIPTION("ISL 12022 RTC driver"); 300 MODULE_LICENSE("GPL"); 301 MODULE_VERSION(DRV_VERSION); 302