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