1 /* 2 * Copyright (C) 2012 Avionic Design GmbH 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9 #include <linux/bcd.h> 10 #include <linux/i2c.h> 11 #include <linux/module.h> 12 #include <linux/rtc.h> 13 #include <linux/of.h> 14 15 #define DRIVER_NAME "rtc-pcf8523" 16 17 #define REG_CONTROL1 0x00 18 #define REG_CONTROL1_CAP_SEL (1 << 7) 19 #define REG_CONTROL1_STOP (1 << 5) 20 21 #define REG_CONTROL3 0x02 22 #define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */ 23 #define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */ 24 #define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */ 25 #define REG_CONTROL3_PM_MASK 0xe0 26 #define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */ 27 28 #define REG_SECONDS 0x03 29 #define REG_SECONDS_OS (1 << 7) 30 31 #define REG_MINUTES 0x04 32 #define REG_HOURS 0x05 33 #define REG_DAYS 0x06 34 #define REG_WEEKDAYS 0x07 35 #define REG_MONTHS 0x08 36 #define REG_YEARS 0x09 37 38 struct pcf8523 { 39 struct rtc_device *rtc; 40 }; 41 42 static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep) 43 { 44 struct i2c_msg msgs[2]; 45 u8 value = 0; 46 int err; 47 48 msgs[0].addr = client->addr; 49 msgs[0].flags = 0; 50 msgs[0].len = sizeof(reg); 51 msgs[0].buf = ® 52 53 msgs[1].addr = client->addr; 54 msgs[1].flags = I2C_M_RD; 55 msgs[1].len = sizeof(value); 56 msgs[1].buf = &value; 57 58 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); 59 if (err < 0) 60 return err; 61 62 *valuep = value; 63 64 return 0; 65 } 66 67 static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value) 68 { 69 u8 buffer[2] = { reg, value }; 70 struct i2c_msg msg; 71 int err; 72 73 msg.addr = client->addr; 74 msg.flags = 0; 75 msg.len = sizeof(buffer); 76 msg.buf = buffer; 77 78 err = i2c_transfer(client->adapter, &msg, 1); 79 if (err < 0) 80 return err; 81 82 return 0; 83 } 84 85 static int pcf8523_select_capacitance(struct i2c_client *client, bool high) 86 { 87 u8 value; 88 int err; 89 90 err = pcf8523_read(client, REG_CONTROL1, &value); 91 if (err < 0) 92 return err; 93 94 if (!high) 95 value &= ~REG_CONTROL1_CAP_SEL; 96 else 97 value |= REG_CONTROL1_CAP_SEL; 98 99 err = pcf8523_write(client, REG_CONTROL1, value); 100 if (err < 0) 101 return err; 102 103 return err; 104 } 105 106 static int pcf8523_set_pm(struct i2c_client *client, u8 pm) 107 { 108 u8 value; 109 int err; 110 111 err = pcf8523_read(client, REG_CONTROL3, &value); 112 if (err < 0) 113 return err; 114 115 value = (value & ~REG_CONTROL3_PM_MASK) | pm; 116 117 err = pcf8523_write(client, REG_CONTROL3, value); 118 if (err < 0) 119 return err; 120 121 return 0; 122 } 123 124 static int pcf8523_stop_rtc(struct i2c_client *client) 125 { 126 u8 value; 127 int err; 128 129 err = pcf8523_read(client, REG_CONTROL1, &value); 130 if (err < 0) 131 return err; 132 133 value |= REG_CONTROL1_STOP; 134 135 err = pcf8523_write(client, REG_CONTROL1, value); 136 if (err < 0) 137 return err; 138 139 return 0; 140 } 141 142 static int pcf8523_start_rtc(struct i2c_client *client) 143 { 144 u8 value; 145 int err; 146 147 err = pcf8523_read(client, REG_CONTROL1, &value); 148 if (err < 0) 149 return err; 150 151 value &= ~REG_CONTROL1_STOP; 152 153 err = pcf8523_write(client, REG_CONTROL1, value); 154 if (err < 0) 155 return err; 156 157 return 0; 158 } 159 160 static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm) 161 { 162 struct i2c_client *client = to_i2c_client(dev); 163 u8 start = REG_SECONDS, regs[7]; 164 struct i2c_msg msgs[2]; 165 int err; 166 167 msgs[0].addr = client->addr; 168 msgs[0].flags = 0; 169 msgs[0].len = 1; 170 msgs[0].buf = &start; 171 172 msgs[1].addr = client->addr; 173 msgs[1].flags = I2C_M_RD; 174 msgs[1].len = sizeof(regs); 175 msgs[1].buf = regs; 176 177 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); 178 if (err < 0) 179 return err; 180 181 if (regs[0] & REG_SECONDS_OS) { 182 /* 183 * If the oscillator was stopped, try to clear the flag. Upon 184 * power-up the flag is always set, but if we cannot clear it 185 * the oscillator isn't running properly for some reason. The 186 * sensible thing therefore is to return an error, signalling 187 * that the clock cannot be assumed to be correct. 188 */ 189 190 regs[0] &= ~REG_SECONDS_OS; 191 192 err = pcf8523_write(client, REG_SECONDS, regs[0]); 193 if (err < 0) 194 return err; 195 196 err = pcf8523_read(client, REG_SECONDS, ®s[0]); 197 if (err < 0) 198 return err; 199 200 if (regs[0] & REG_SECONDS_OS) 201 return -EAGAIN; 202 } 203 204 tm->tm_sec = bcd2bin(regs[0] & 0x7f); 205 tm->tm_min = bcd2bin(regs[1] & 0x7f); 206 tm->tm_hour = bcd2bin(regs[2] & 0x3f); 207 tm->tm_mday = bcd2bin(regs[3] & 0x3f); 208 tm->tm_wday = regs[4] & 0x7; 209 tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1; 210 tm->tm_year = bcd2bin(regs[6]) + 100; 211 212 return rtc_valid_tm(tm); 213 } 214 215 static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm) 216 { 217 struct i2c_client *client = to_i2c_client(dev); 218 struct i2c_msg msg; 219 u8 regs[8]; 220 int err; 221 222 /* 223 * The hardware can only store values between 0 and 99 in it's YEAR 224 * register (with 99 overflowing to 0 on increment). 225 * After 2100-02-28 we could start interpreting the year to be in the 226 * interval [2100, 2199], but there is no path to switch in a smooth way 227 * because the chip handles YEAR=0x00 (and the out-of-spec 228 * YEAR=0xa0) as a leap year, but 2100 isn't. 229 */ 230 if (tm->tm_year < 100 || tm->tm_year >= 200) 231 return -EINVAL; 232 233 err = pcf8523_stop_rtc(client); 234 if (err < 0) 235 return err; 236 237 regs[0] = REG_SECONDS; 238 regs[1] = bin2bcd(tm->tm_sec); 239 regs[2] = bin2bcd(tm->tm_min); 240 regs[3] = bin2bcd(tm->tm_hour); 241 regs[4] = bin2bcd(tm->tm_mday); 242 regs[5] = tm->tm_wday; 243 regs[6] = bin2bcd(tm->tm_mon + 1); 244 regs[7] = bin2bcd(tm->tm_year - 100); 245 246 msg.addr = client->addr; 247 msg.flags = 0; 248 msg.len = sizeof(regs); 249 msg.buf = regs; 250 251 err = i2c_transfer(client->adapter, &msg, 1); 252 if (err < 0) { 253 /* 254 * If the time cannot be set, restart the RTC anyway. Note 255 * that errors are ignored if the RTC cannot be started so 256 * that we have a chance to propagate the original error. 257 */ 258 pcf8523_start_rtc(client); 259 return err; 260 } 261 262 return pcf8523_start_rtc(client); 263 } 264 265 #ifdef CONFIG_RTC_INTF_DEV 266 static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd, 267 unsigned long arg) 268 { 269 struct i2c_client *client = to_i2c_client(dev); 270 u8 value; 271 int ret = 0, err; 272 273 switch (cmd) { 274 case RTC_VL_READ: 275 err = pcf8523_read(client, REG_CONTROL3, &value); 276 if (err < 0) 277 return err; 278 279 if (value & REG_CONTROL3_BLF) 280 ret = 1; 281 282 if (copy_to_user((void __user *)arg, &ret, sizeof(int))) 283 return -EFAULT; 284 285 return 0; 286 default: 287 return -ENOIOCTLCMD; 288 } 289 } 290 #else 291 #define pcf8523_rtc_ioctl NULL 292 #endif 293 294 static const struct rtc_class_ops pcf8523_rtc_ops = { 295 .read_time = pcf8523_rtc_read_time, 296 .set_time = pcf8523_rtc_set_time, 297 .ioctl = pcf8523_rtc_ioctl, 298 }; 299 300 static int pcf8523_probe(struct i2c_client *client, 301 const struct i2c_device_id *id) 302 { 303 struct pcf8523 *pcf; 304 int err; 305 306 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 307 return -ENODEV; 308 309 pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL); 310 if (!pcf) 311 return -ENOMEM; 312 313 err = pcf8523_select_capacitance(client, true); 314 if (err < 0) 315 return err; 316 317 err = pcf8523_set_pm(client, 0); 318 if (err < 0) 319 return err; 320 321 pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME, 322 &pcf8523_rtc_ops, THIS_MODULE); 323 if (IS_ERR(pcf->rtc)) 324 return PTR_ERR(pcf->rtc); 325 326 i2c_set_clientdata(client, pcf); 327 328 return 0; 329 } 330 331 static const struct i2c_device_id pcf8523_id[] = { 332 { "pcf8523", 0 }, 333 { } 334 }; 335 MODULE_DEVICE_TABLE(i2c, pcf8523_id); 336 337 #ifdef CONFIG_OF 338 static const struct of_device_id pcf8523_of_match[] = { 339 { .compatible = "nxp,pcf8523" }, 340 { } 341 }; 342 MODULE_DEVICE_TABLE(of, pcf8523_of_match); 343 #endif 344 345 static struct i2c_driver pcf8523_driver = { 346 .driver = { 347 .name = DRIVER_NAME, 348 .of_match_table = of_match_ptr(pcf8523_of_match), 349 }, 350 .probe = pcf8523_probe, 351 .id_table = pcf8523_id, 352 }; 353 module_i2c_driver(pcf8523_driver); 354 355 MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>"); 356 MODULE_DESCRIPTION("NXP PCF8523 RTC driver"); 357 MODULE_LICENSE("GPL v2"); 358