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 #include <linux/of.h> 21 #include <linux/of_device.h> 22 23 #define DRV_VERSION "0.1" 24 25 /* ISL register offsets */ 26 #define ISL12022_REG_SC 0x00 27 #define ISL12022_REG_MN 0x01 28 #define ISL12022_REG_HR 0x02 29 #define ISL12022_REG_DT 0x03 30 #define ISL12022_REG_MO 0x04 31 #define ISL12022_REG_YR 0x05 32 #define ISL12022_REG_DW 0x06 33 34 #define ISL12022_REG_SR 0x07 35 #define ISL12022_REG_INT 0x08 36 37 /* ISL register bits */ 38 #define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */ 39 40 #define ISL12022_SR_LBAT85 (1 << 2) 41 #define ISL12022_SR_LBAT75 (1 << 1) 42 43 #define ISL12022_INT_WRTC (1 << 6) 44 45 46 static struct i2c_driver isl12022_driver; 47 48 struct isl12022 { 49 struct rtc_device *rtc; 50 51 bool write_enabled; /* true if write enable is set */ 52 }; 53 54 55 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg, 56 uint8_t *data, size_t n) 57 { 58 struct i2c_msg msgs[] = { 59 { 60 .addr = client->addr, 61 .flags = 0, 62 .len = 1, 63 .buf = data 64 }, /* setup read ptr */ 65 { 66 .addr = client->addr, 67 .flags = I2C_M_RD, 68 .len = n, 69 .buf = data 70 } 71 }; 72 73 int ret; 74 75 data[0] = reg; 76 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); 77 if (ret != ARRAY_SIZE(msgs)) { 78 dev_err(&client->dev, "%s: read error, ret=%d\n", 79 __func__, ret); 80 return -EIO; 81 } 82 83 return 0; 84 } 85 86 87 static int isl12022_write_reg(struct i2c_client *client, 88 uint8_t reg, uint8_t val) 89 { 90 uint8_t data[2] = { reg, val }; 91 int err; 92 93 err = i2c_master_send(client, data, sizeof(data)); 94 if (err != sizeof(data)) { 95 dev_err(&client->dev, 96 "%s: err=%d addr=%02x, data=%02x\n", 97 __func__, err, data[0], data[1]); 98 return -EIO; 99 } 100 101 return 0; 102 } 103 104 105 /* 106 * In the routines that deal directly with the isl12022 hardware, we use 107 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. 108 */ 109 static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm) 110 { 111 uint8_t buf[ISL12022_REG_INT + 1]; 112 int ret; 113 114 ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf)); 115 if (ret) 116 return ret; 117 118 if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) { 119 dev_warn(&client->dev, 120 "voltage dropped below %u%%, " 121 "date and time is not reliable.\n", 122 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75); 123 } 124 125 dev_dbg(&client->dev, 126 "%s: raw data is sec=%02x, min=%02x, hr=%02x, " 127 "mday=%02x, mon=%02x, year=%02x, wday=%02x, " 128 "sr=%02x, int=%02x", 129 __func__, 130 buf[ISL12022_REG_SC], 131 buf[ISL12022_REG_MN], 132 buf[ISL12022_REG_HR], 133 buf[ISL12022_REG_DT], 134 buf[ISL12022_REG_MO], 135 buf[ISL12022_REG_YR], 136 buf[ISL12022_REG_DW], 137 buf[ISL12022_REG_SR], 138 buf[ISL12022_REG_INT]); 139 140 tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F); 141 tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F); 142 tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F); 143 tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F); 144 tm->tm_wday = buf[ISL12022_REG_DW] & 0x07; 145 tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1; 146 tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100; 147 148 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, " 149 "mday=%d, mon=%d, year=%d, wday=%d\n", 150 __func__, 151 tm->tm_sec, tm->tm_min, tm->tm_hour, 152 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 153 154 /* The clock can give out invalid datetime, but we cannot return 155 * -EINVAL otherwise hwclock will refuse to set the time on bootup. */ 156 if (rtc_valid_tm(tm) < 0) 157 dev_err(&client->dev, "retrieved date and time is invalid.\n"); 158 159 return 0; 160 } 161 162 static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm) 163 { 164 struct isl12022 *isl12022 = i2c_get_clientdata(client); 165 size_t i; 166 int ret; 167 uint8_t buf[ISL12022_REG_DW + 1]; 168 169 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, " 170 "mday=%d, mon=%d, year=%d, wday=%d\n", 171 __func__, 172 tm->tm_sec, tm->tm_min, tm->tm_hour, 173 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 174 175 if (!isl12022->write_enabled) { 176 177 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1); 178 if (ret) 179 return ret; 180 181 /* Check if WRTC (write rtc enable) is set factory default is 182 * 0 (not set) */ 183 if (!(buf[0] & ISL12022_INT_WRTC)) { 184 dev_info(&client->dev, 185 "init write enable and 24 hour format\n"); 186 187 /* Set the write enable bit. */ 188 ret = isl12022_write_reg(client, 189 ISL12022_REG_INT, 190 buf[0] | ISL12022_INT_WRTC); 191 if (ret) 192 return ret; 193 194 /* Write to any RTC register to start RTC, we use the 195 * HR register, setting the MIL bit to use the 24 hour 196 * format. */ 197 ret = isl12022_read_regs(client, ISL12022_REG_HR, 198 buf, 1); 199 if (ret) 200 return ret; 201 202 ret = isl12022_write_reg(client, 203 ISL12022_REG_HR, 204 buf[0] | ISL12022_HR_MIL); 205 if (ret) 206 return ret; 207 } 208 209 isl12022->write_enabled = 1; 210 } 211 212 /* hours, minutes and seconds */ 213 buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec); 214 buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min); 215 buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL; 216 217 buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday); 218 219 /* month, 1 - 12 */ 220 buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1); 221 222 /* year and century */ 223 buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100); 224 225 buf[ISL12022_REG_DW] = tm->tm_wday & 0x07; 226 227 /* write register's data */ 228 for (i = 0; i < ARRAY_SIZE(buf); i++) { 229 ret = isl12022_write_reg(client, ISL12022_REG_SC + i, 230 buf[ISL12022_REG_SC + i]); 231 if (ret) 232 return -EIO; 233 } 234 235 return 0; 236 } 237 238 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm) 239 { 240 return isl12022_get_datetime(to_i2c_client(dev), tm); 241 } 242 243 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm) 244 { 245 return isl12022_set_datetime(to_i2c_client(dev), tm); 246 } 247 248 static const struct rtc_class_ops isl12022_rtc_ops = { 249 .read_time = isl12022_rtc_read_time, 250 .set_time = isl12022_rtc_set_time, 251 }; 252 253 static int isl12022_probe(struct i2c_client *client, 254 const struct i2c_device_id *id) 255 { 256 struct isl12022 *isl12022; 257 258 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 259 return -ENODEV; 260 261 isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022), 262 GFP_KERNEL); 263 if (!isl12022) 264 return -ENOMEM; 265 266 dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n"); 267 268 i2c_set_clientdata(client, isl12022); 269 270 isl12022->rtc = devm_rtc_device_register(&client->dev, 271 isl12022_driver.driver.name, 272 &isl12022_rtc_ops, THIS_MODULE); 273 return PTR_ERR_OR_ZERO(isl12022->rtc); 274 } 275 276 #ifdef CONFIG_OF 277 static const struct of_device_id isl12022_dt_match[] = { 278 { .compatible = "isl,isl12022" }, 279 { }, 280 }; 281 #endif 282 283 static const struct i2c_device_id isl12022_id[] = { 284 { "isl12022", 0 }, 285 { } 286 }; 287 MODULE_DEVICE_TABLE(i2c, isl12022_id); 288 289 static struct i2c_driver isl12022_driver = { 290 .driver = { 291 .name = "rtc-isl12022", 292 #ifdef CONFIG_OF 293 .of_match_table = of_match_ptr(isl12022_dt_match), 294 #endif 295 }, 296 .probe = isl12022_probe, 297 .id_table = isl12022_id, 298 }; 299 300 module_i2c_driver(isl12022_driver); 301 302 MODULE_AUTHOR("roman.fietze@telemotive.de"); 303 MODULE_DESCRIPTION("ISL 12022 RTC driver"); 304 MODULE_LICENSE("GPL"); 305 MODULE_VERSION(DRV_VERSION); 306