1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * An I2C driver for the Intersil ISL 12022 4 * 5 * Author: Roman Fietze <roman.fietze@telemotive.de> 6 * 7 * Based on the Philips PCF8563 RTC 8 * by Alessandro Zummo <a.zummo@towertech.it>. 9 */ 10 11 #include <linux/i2c.h> 12 #include <linux/bcd.h> 13 #include <linux/rtc.h> 14 #include <linux/slab.h> 15 #include <linux/module.h> 16 #include <linux/err.h> 17 #include <linux/of.h> 18 #include <linux/of_device.h> 19 20 /* ISL register offsets */ 21 #define ISL12022_REG_SC 0x00 22 #define ISL12022_REG_MN 0x01 23 #define ISL12022_REG_HR 0x02 24 #define ISL12022_REG_DT 0x03 25 #define ISL12022_REG_MO 0x04 26 #define ISL12022_REG_YR 0x05 27 #define ISL12022_REG_DW 0x06 28 29 #define ISL12022_REG_SR 0x07 30 #define ISL12022_REG_INT 0x08 31 32 /* ISL register bits */ 33 #define ISL12022_HR_MIL (1 << 7) /* military or 24 hour time */ 34 35 #define ISL12022_SR_LBAT85 (1 << 2) 36 #define ISL12022_SR_LBAT75 (1 << 1) 37 38 #define ISL12022_INT_WRTC (1 << 6) 39 40 41 static struct i2c_driver isl12022_driver; 42 43 struct isl12022 { 44 struct rtc_device *rtc; 45 46 bool write_enabled; /* true if write enable is set */ 47 }; 48 49 50 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg, 51 uint8_t *data, size_t n) 52 { 53 struct i2c_msg msgs[] = { 54 { 55 .addr = client->addr, 56 .flags = 0, 57 .len = 1, 58 .buf = data 59 }, /* setup read ptr */ 60 { 61 .addr = client->addr, 62 .flags = I2C_M_RD, 63 .len = n, 64 .buf = data 65 } 66 }; 67 68 int ret; 69 70 data[0] = reg; 71 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); 72 if (ret != ARRAY_SIZE(msgs)) { 73 dev_err(&client->dev, "%s: read error, ret=%d\n", 74 __func__, ret); 75 return -EIO; 76 } 77 78 return 0; 79 } 80 81 82 static int isl12022_write_reg(struct i2c_client *client, 83 uint8_t reg, uint8_t val) 84 { 85 uint8_t data[2] = { reg, val }; 86 int err; 87 88 err = i2c_master_send(client, data, sizeof(data)); 89 if (err != sizeof(data)) { 90 dev_err(&client->dev, 91 "%s: err=%d addr=%02x, data=%02x\n", 92 __func__, err, data[0], data[1]); 93 return -EIO; 94 } 95 96 return 0; 97 } 98 99 100 /* 101 * In the routines that deal directly with the isl12022 hardware, we use 102 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. 103 */ 104 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm) 105 { 106 struct i2c_client *client = to_i2c_client(dev); 107 uint8_t buf[ISL12022_REG_INT + 1]; 108 int ret; 109 110 ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf)); 111 if (ret) 112 return ret; 113 114 if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) { 115 dev_warn(&client->dev, 116 "voltage dropped below %u%%, " 117 "date and time is not reliable.\n", 118 buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75); 119 } 120 121 dev_dbg(&client->dev, 122 "%s: raw data is sec=%02x, min=%02x, hr=%02x, " 123 "mday=%02x, mon=%02x, year=%02x, wday=%02x, " 124 "sr=%02x, int=%02x", 125 __func__, 126 buf[ISL12022_REG_SC], 127 buf[ISL12022_REG_MN], 128 buf[ISL12022_REG_HR], 129 buf[ISL12022_REG_DT], 130 buf[ISL12022_REG_MO], 131 buf[ISL12022_REG_YR], 132 buf[ISL12022_REG_DW], 133 buf[ISL12022_REG_SR], 134 buf[ISL12022_REG_INT]); 135 136 tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F); 137 tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F); 138 tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F); 139 tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F); 140 tm->tm_wday = buf[ISL12022_REG_DW] & 0x07; 141 tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1; 142 tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100; 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 return 0; 151 } 152 153 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm) 154 { 155 struct i2c_client *client = to_i2c_client(dev); 156 struct isl12022 *isl12022 = i2c_get_clientdata(client); 157 size_t i; 158 int ret; 159 uint8_t buf[ISL12022_REG_DW + 1]; 160 161 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, " 162 "mday=%d, mon=%d, year=%d, wday=%d\n", 163 __func__, 164 tm->tm_sec, tm->tm_min, tm->tm_hour, 165 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); 166 167 if (!isl12022->write_enabled) { 168 169 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1); 170 if (ret) 171 return ret; 172 173 /* Check if WRTC (write rtc enable) is set factory default is 174 * 0 (not set) */ 175 if (!(buf[0] & ISL12022_INT_WRTC)) { 176 dev_info(&client->dev, 177 "init write enable and 24 hour format\n"); 178 179 /* Set the write enable bit. */ 180 ret = isl12022_write_reg(client, 181 ISL12022_REG_INT, 182 buf[0] | ISL12022_INT_WRTC); 183 if (ret) 184 return ret; 185 186 /* Write to any RTC register to start RTC, we use the 187 * HR register, setting the MIL bit to use the 24 hour 188 * format. */ 189 ret = isl12022_read_regs(client, ISL12022_REG_HR, 190 buf, 1); 191 if (ret) 192 return ret; 193 194 ret = isl12022_write_reg(client, 195 ISL12022_REG_HR, 196 buf[0] | ISL12022_HR_MIL); 197 if (ret) 198 return ret; 199 } 200 201 isl12022->write_enabled = true; 202 } 203 204 /* hours, minutes and seconds */ 205 buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec); 206 buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min); 207 buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL; 208 209 buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday); 210 211 /* month, 1 - 12 */ 212 buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1); 213 214 /* year and century */ 215 buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100); 216 217 buf[ISL12022_REG_DW] = tm->tm_wday & 0x07; 218 219 /* write register's data */ 220 for (i = 0; i < ARRAY_SIZE(buf); i++) { 221 ret = isl12022_write_reg(client, ISL12022_REG_SC + i, 222 buf[ISL12022_REG_SC + i]); 223 if (ret) 224 return -EIO; 225 } 226 227 return 0; 228 } 229 230 static const struct rtc_class_ops isl12022_rtc_ops = { 231 .read_time = isl12022_rtc_read_time, 232 .set_time = isl12022_rtc_set_time, 233 }; 234 235 static int isl12022_probe(struct i2c_client *client) 236 { 237 struct isl12022 *isl12022; 238 239 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 240 return -ENODEV; 241 242 isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022), 243 GFP_KERNEL); 244 if (!isl12022) 245 return -ENOMEM; 246 247 i2c_set_clientdata(client, isl12022); 248 249 isl12022->rtc = devm_rtc_device_register(&client->dev, 250 isl12022_driver.driver.name, 251 &isl12022_rtc_ops, THIS_MODULE); 252 return PTR_ERR_OR_ZERO(isl12022->rtc); 253 } 254 255 #ifdef CONFIG_OF 256 static const struct of_device_id isl12022_dt_match[] = { 257 { .compatible = "isl,isl12022" }, /* for backward compat., don't use */ 258 { .compatible = "isil,isl12022" }, 259 { }, 260 }; 261 MODULE_DEVICE_TABLE(of, isl12022_dt_match); 262 #endif 263 264 static const struct i2c_device_id isl12022_id[] = { 265 { "isl12022", 0 }, 266 { } 267 }; 268 MODULE_DEVICE_TABLE(i2c, isl12022_id); 269 270 static struct i2c_driver isl12022_driver = { 271 .driver = { 272 .name = "rtc-isl12022", 273 #ifdef CONFIG_OF 274 .of_match_table = of_match_ptr(isl12022_dt_match), 275 #endif 276 }, 277 .probe_new = isl12022_probe, 278 .id_table = isl12022_id, 279 }; 280 281 module_i2c_driver(isl12022_driver); 282 283 MODULE_AUTHOR("roman.fietze@telemotive.de"); 284 MODULE_DESCRIPTION("ISL 12022 RTC driver"); 285 MODULE_LICENSE("GPL"); 286