1 /* 2 * drivers/rtc/rtc-pcf8583.c 3 * 4 * Copyright (C) 2000 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Driver for PCF8583 RTC & RAM chip 11 * 12 * Converted to the generic RTC susbsystem by G. Liakhovetski (2006) 13 */ 14 #include <linux/module.h> 15 #include <linux/i2c.h> 16 #include <linux/slab.h> 17 #include <linux/string.h> 18 #include <linux/mc146818rtc.h> 19 #include <linux/init.h> 20 #include <linux/errno.h> 21 #include <linux/bcd.h> 22 23 struct rtc_mem { 24 unsigned int loc; 25 unsigned int nr; 26 unsigned char *data; 27 }; 28 29 struct pcf8583 { 30 struct i2c_client client; 31 struct rtc_device *rtc; 32 unsigned char ctrl; 33 }; 34 35 #define CTRL_STOP 0x80 36 #define CTRL_HOLD 0x40 37 #define CTRL_32KHZ 0x00 38 #define CTRL_MASK 0x08 39 #define CTRL_ALARMEN 0x04 40 #define CTRL_ALARM 0x02 41 #define CTRL_TIMER 0x01 42 43 static unsigned short normal_i2c[] = { 0x50, I2C_CLIENT_END }; 44 45 /* Module parameters */ 46 I2C_CLIENT_INSMOD; 47 48 static struct i2c_driver pcf8583_driver; 49 50 #define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl 51 #define set_ctrl(x, v) get_ctrl(x) = v 52 53 #define CMOS_YEAR (64 + 128) 54 #define CMOS_CHECKSUM (63) 55 56 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt) 57 { 58 unsigned char buf[8], addr[1] = { 1 }; 59 struct i2c_msg msgs[2] = { 60 { 61 .addr = client->addr, 62 .flags = 0, 63 .len = 1, 64 .buf = addr, 65 }, { 66 .addr = client->addr, 67 .flags = I2C_M_RD, 68 .len = 6, 69 .buf = buf, 70 } 71 }; 72 int ret; 73 74 memset(buf, 0, sizeof(buf)); 75 76 ret = i2c_transfer(client->adapter, msgs, 2); 77 if (ret == 2) { 78 dt->tm_year = buf[4] >> 6; 79 dt->tm_wday = buf[5] >> 5; 80 81 buf[4] &= 0x3f; 82 buf[5] &= 0x1f; 83 84 dt->tm_sec = BCD2BIN(buf[1]); 85 dt->tm_min = BCD2BIN(buf[2]); 86 dt->tm_hour = BCD2BIN(buf[3]); 87 dt->tm_mday = BCD2BIN(buf[4]); 88 dt->tm_mon = BCD2BIN(buf[5]) - 1; 89 } 90 91 return ret == 2 ? 0 : -EIO; 92 } 93 94 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo) 95 { 96 unsigned char buf[8]; 97 int ret, len = 6; 98 99 buf[0] = 0; 100 buf[1] = get_ctrl(client) | 0x80; 101 buf[2] = 0; 102 buf[3] = BIN2BCD(dt->tm_sec); 103 buf[4] = BIN2BCD(dt->tm_min); 104 buf[5] = BIN2BCD(dt->tm_hour); 105 106 if (datetoo) { 107 len = 8; 108 buf[6] = BIN2BCD(dt->tm_mday) | (dt->tm_year << 6); 109 buf[7] = BIN2BCD(dt->tm_mon + 1) | (dt->tm_wday << 5); 110 } 111 112 ret = i2c_master_send(client, (char *)buf, len); 113 if (ret != len) 114 return -EIO; 115 116 buf[1] = get_ctrl(client); 117 ret = i2c_master_send(client, (char *)buf, 2); 118 119 return ret == 2 ? 0 : -EIO; 120 } 121 122 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl) 123 { 124 *ctrl = get_ctrl(client); 125 return 0; 126 } 127 128 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl) 129 { 130 unsigned char buf[2]; 131 132 buf[0] = 0; 133 buf[1] = *ctrl; 134 set_ctrl(client, *ctrl); 135 136 return i2c_master_send(client, (char *)buf, 2); 137 } 138 139 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem) 140 { 141 unsigned char addr[1]; 142 struct i2c_msg msgs[2] = { 143 { 144 .addr = client->addr, 145 .flags = 0, 146 .len = 1, 147 .buf = addr, 148 }, { 149 .addr = client->addr, 150 .flags = I2C_M_RD, 151 .len = mem->nr, 152 .buf = mem->data, 153 } 154 }; 155 156 if (mem->loc < 8) 157 return -EINVAL; 158 159 addr[0] = mem->loc; 160 161 return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO; 162 } 163 164 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem) 165 { 166 unsigned char addr[1]; 167 struct i2c_msg msgs[2] = { 168 { 169 .addr = client->addr, 170 .flags = 0, 171 .len = 1, 172 .buf = addr, 173 }, { 174 .addr = client->addr, 175 .flags = I2C_M_NOSTART, 176 .len = mem->nr, 177 .buf = mem->data, 178 } 179 }; 180 181 if (mem->loc < 8) 182 return -EINVAL; 183 184 addr[0] = mem->loc; 185 186 return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO; 187 } 188 189 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm) 190 { 191 struct i2c_client *client = to_i2c_client(dev); 192 unsigned char ctrl, year[2]; 193 struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year }; 194 int real_year, year_offset, err; 195 196 /* 197 * Ensure that the RTC is running. 198 */ 199 pcf8583_get_ctrl(client, &ctrl); 200 if (ctrl & (CTRL_STOP | CTRL_HOLD)) { 201 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD); 202 203 printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n", 204 ctrl, new_ctrl); 205 206 if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 0) 207 return err; 208 } 209 210 if (pcf8583_get_datetime(client, tm) || 211 pcf8583_read_mem(client, &mem)) 212 return -EIO; 213 214 real_year = year[0]; 215 216 /* 217 * The RTC year holds the LSB two bits of the current 218 * year, which should reflect the LSB two bits of the 219 * CMOS copy of the year. Any difference indicates 220 * that we have to correct the CMOS version. 221 */ 222 year_offset = tm->tm_year - (real_year & 3); 223 if (year_offset < 0) 224 /* 225 * RTC year wrapped. Adjust it appropriately. 226 */ 227 year_offset += 4; 228 229 tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900; 230 231 return 0; 232 } 233 234 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm) 235 { 236 struct i2c_client *client = to_i2c_client(dev); 237 unsigned char year[2], chk; 238 struct rtc_mem cmos_year = { CMOS_YEAR, sizeof(year), year }; 239 struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk }; 240 unsigned int proper_year = tm->tm_year + 1900; 241 int ret; 242 243 /* 244 * The RTC's own 2-bit year must reflect the least 245 * significant two bits of the CMOS year. 246 */ 247 248 ret = pcf8583_set_datetime(client, tm, 1); 249 if (ret) 250 return ret; 251 252 ret = pcf8583_read_mem(client, &cmos_check); 253 if (ret) 254 return ret; 255 256 ret = pcf8583_read_mem(client, &cmos_year); 257 if (ret) 258 return ret; 259 260 chk -= year[1] + year[0]; 261 262 year[1] = proper_year / 100; 263 year[0] = proper_year % 100; 264 265 chk += year[1] + year[0]; 266 267 ret = pcf8583_write_mem(client, &cmos_year); 268 269 if (ret) 270 return ret; 271 272 ret = pcf8583_write_mem(client, &cmos_check); 273 274 return ret; 275 } 276 277 static const struct rtc_class_ops pcf8583_rtc_ops = { 278 .read_time = pcf8583_rtc_read_time, 279 .set_time = pcf8583_rtc_set_time, 280 }; 281 282 static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind); 283 284 static int pcf8583_attach(struct i2c_adapter *adap) 285 { 286 return i2c_probe(adap, &addr_data, pcf8583_probe); 287 } 288 289 static int pcf8583_detach(struct i2c_client *client) 290 { 291 int err; 292 struct pcf8583 *pcf = i2c_get_clientdata(client); 293 struct rtc_device *rtc = pcf->rtc; 294 295 if (rtc) 296 rtc_device_unregister(rtc); 297 298 if ((err = i2c_detach_client(client))) 299 return err; 300 301 kfree(pcf); 302 return 0; 303 } 304 305 static struct i2c_driver pcf8583_driver = { 306 .driver = { 307 .name = "pcf8583", 308 }, 309 .id = I2C_DRIVERID_PCF8583, 310 .attach_adapter = pcf8583_attach, 311 .detach_client = pcf8583_detach, 312 }; 313 314 static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind) 315 { 316 struct pcf8583 *pcf; 317 struct i2c_client *client; 318 struct rtc_device *rtc; 319 unsigned char buf[1], ad[1] = { 0 }; 320 int err; 321 struct i2c_msg msgs[2] = { 322 { 323 .addr = addr, 324 .flags = 0, 325 .len = 1, 326 .buf = ad, 327 }, { 328 .addr = addr, 329 .flags = I2C_M_RD, 330 .len = 1, 331 .buf = buf, 332 } 333 }; 334 335 pcf = kzalloc(sizeof(*pcf), GFP_KERNEL); 336 if (!pcf) 337 return -ENOMEM; 338 339 client = &pcf->client; 340 341 client->addr = addr; 342 client->adapter = adap; 343 client->driver = &pcf8583_driver; 344 345 strlcpy(client->name, pcf8583_driver.driver.name, I2C_NAME_SIZE); 346 347 if (i2c_transfer(client->adapter, msgs, 2) != 2) { 348 err = -EIO; 349 goto exit_kfree; 350 } 351 352 err = i2c_attach_client(client); 353 354 if (err) 355 goto exit_kfree; 356 357 rtc = rtc_device_register(pcf8583_driver.driver.name, &client->dev, 358 &pcf8583_rtc_ops, THIS_MODULE); 359 360 if (IS_ERR(rtc)) { 361 err = PTR_ERR(rtc); 362 goto exit_detach; 363 } 364 365 pcf->rtc = rtc; 366 i2c_set_clientdata(client, pcf); 367 set_ctrl(client, buf[0]); 368 369 return 0; 370 371 exit_detach: 372 i2c_detach_client(client); 373 374 exit_kfree: 375 kfree(pcf); 376 377 return err; 378 } 379 380 static __init int pcf8583_init(void) 381 { 382 return i2c_add_driver(&pcf8583_driver); 383 } 384 385 static __exit void pcf8583_exit(void) 386 { 387 i2c_del_driver(&pcf8583_driver); 388 } 389 390 module_init(pcf8583_init); 391 module_exit(pcf8583_exit); 392 393 MODULE_AUTHOR("Russell King"); 394 MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); 395 MODULE_LICENSE("GPL"); 396