1 /* 2 * drivers/rtc/rtc-pcf8583.c 3 * 4 * Copyright (C) 2000 Russell King 5 * Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * Driver for PCF8583 RTC & RAM chip 12 * 13 * Converted to the generic RTC susbsystem by G. Liakhovetski (2006) 14 */ 15 #include <linux/module.h> 16 #include <linux/i2c.h> 17 #include <linux/slab.h> 18 #include <linux/rtc.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 rtc_device *rtc; 31 unsigned char ctrl; 32 }; 33 34 #define CTRL_STOP 0x80 35 #define CTRL_HOLD 0x40 36 #define CTRL_32KHZ 0x00 37 #define CTRL_MASK 0x08 38 #define CTRL_ALARMEN 0x04 39 #define CTRL_ALARM 0x02 40 #define CTRL_TIMER 0x01 41 42 43 static struct i2c_driver pcf8583_driver; 44 45 #define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl 46 #define set_ctrl(x, v) get_ctrl(x) = v 47 48 #define CMOS_YEAR (64 + 128) 49 #define CMOS_CHECKSUM (63) 50 51 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt) 52 { 53 unsigned char buf[8], addr[1] = { 1 }; 54 struct i2c_msg msgs[2] = { 55 { 56 .addr = client->addr, 57 .flags = 0, 58 .len = 1, 59 .buf = addr, 60 }, { 61 .addr = client->addr, 62 .flags = I2C_M_RD, 63 .len = 6, 64 .buf = buf, 65 } 66 }; 67 int ret; 68 69 memset(buf, 0, sizeof(buf)); 70 71 ret = i2c_transfer(client->adapter, msgs, 2); 72 if (ret == 2) { 73 dt->tm_year = buf[4] >> 6; 74 dt->tm_wday = buf[5] >> 5; 75 76 buf[4] &= 0x3f; 77 buf[5] &= 0x1f; 78 79 dt->tm_sec = bcd2bin(buf[1]); 80 dt->tm_min = bcd2bin(buf[2]); 81 dt->tm_hour = bcd2bin(buf[3]); 82 dt->tm_mday = bcd2bin(buf[4]); 83 dt->tm_mon = bcd2bin(buf[5]) - 1; 84 } 85 86 return ret == 2 ? 0 : -EIO; 87 } 88 89 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo) 90 { 91 unsigned char buf[8]; 92 int ret, len = 6; 93 94 buf[0] = 0; 95 buf[1] = get_ctrl(client) | 0x80; 96 buf[2] = 0; 97 buf[3] = bin2bcd(dt->tm_sec); 98 buf[4] = bin2bcd(dt->tm_min); 99 buf[5] = bin2bcd(dt->tm_hour); 100 101 if (datetoo) { 102 len = 8; 103 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6); 104 buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5); 105 } 106 107 ret = i2c_master_send(client, (char *)buf, len); 108 if (ret != len) 109 return -EIO; 110 111 buf[1] = get_ctrl(client); 112 ret = i2c_master_send(client, (char *)buf, 2); 113 114 return ret == 2 ? 0 : -EIO; 115 } 116 117 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl) 118 { 119 *ctrl = get_ctrl(client); 120 return 0; 121 } 122 123 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl) 124 { 125 unsigned char buf[2]; 126 127 buf[0] = 0; 128 buf[1] = *ctrl; 129 set_ctrl(client, *ctrl); 130 131 return i2c_master_send(client, (char *)buf, 2); 132 } 133 134 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem) 135 { 136 unsigned char addr[1]; 137 struct i2c_msg msgs[2] = { 138 { 139 .addr = client->addr, 140 .flags = 0, 141 .len = 1, 142 .buf = addr, 143 }, { 144 .addr = client->addr, 145 .flags = I2C_M_RD, 146 .len = mem->nr, 147 .buf = mem->data, 148 } 149 }; 150 151 if (mem->loc < 8) 152 return -EINVAL; 153 154 addr[0] = mem->loc; 155 156 return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO; 157 } 158 159 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem) 160 { 161 unsigned char buf[9]; 162 int ret; 163 164 if (mem->loc < 8 || mem->nr > 8) 165 return -EINVAL; 166 167 buf[0] = mem->loc; 168 memcpy(buf + 1, mem->data, mem->nr); 169 170 ret = i2c_master_send(client, buf, mem->nr + 1); 171 return ret == mem->nr + 1 ? 0 : -EIO; 172 } 173 174 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm) 175 { 176 struct i2c_client *client = to_i2c_client(dev); 177 unsigned char ctrl, year[2]; 178 struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year }; 179 int real_year, year_offset, err; 180 181 /* 182 * Ensure that the RTC is running. 183 */ 184 pcf8583_get_ctrl(client, &ctrl); 185 if (ctrl & (CTRL_STOP | CTRL_HOLD)) { 186 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD); 187 188 dev_warn(dev, "resetting control %02x -> %02x\n", 189 ctrl, new_ctrl); 190 191 if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 0) 192 return err; 193 } 194 195 if (pcf8583_get_datetime(client, tm) || 196 pcf8583_read_mem(client, &mem)) 197 return -EIO; 198 199 real_year = year[0]; 200 201 /* 202 * The RTC year holds the LSB two bits of the current 203 * year, which should reflect the LSB two bits of the 204 * CMOS copy of the year. Any difference indicates 205 * that we have to correct the CMOS version. 206 */ 207 year_offset = tm->tm_year - (real_year & 3); 208 if (year_offset < 0) 209 /* 210 * RTC year wrapped. Adjust it appropriately. 211 */ 212 year_offset += 4; 213 214 tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900; 215 216 return 0; 217 } 218 219 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm) 220 { 221 struct i2c_client *client = to_i2c_client(dev); 222 unsigned char year[2], chk; 223 struct rtc_mem cmos_year = { CMOS_YEAR, sizeof(year), year }; 224 struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk }; 225 unsigned int proper_year = tm->tm_year + 1900; 226 int ret; 227 228 /* 229 * The RTC's own 2-bit year must reflect the least 230 * significant two bits of the CMOS year. 231 */ 232 233 ret = pcf8583_set_datetime(client, tm, 1); 234 if (ret) 235 return ret; 236 237 ret = pcf8583_read_mem(client, &cmos_check); 238 if (ret) 239 return ret; 240 241 ret = pcf8583_read_mem(client, &cmos_year); 242 if (ret) 243 return ret; 244 245 chk -= year[1] + year[0]; 246 247 year[1] = proper_year / 100; 248 year[0] = proper_year % 100; 249 250 chk += year[1] + year[0]; 251 252 ret = pcf8583_write_mem(client, &cmos_year); 253 254 if (ret) 255 return ret; 256 257 ret = pcf8583_write_mem(client, &cmos_check); 258 259 return ret; 260 } 261 262 static const struct rtc_class_ops pcf8583_rtc_ops = { 263 .read_time = pcf8583_rtc_read_time, 264 .set_time = pcf8583_rtc_set_time, 265 }; 266 267 static int pcf8583_probe(struct i2c_client *client, 268 const struct i2c_device_id *id) 269 { 270 struct pcf8583 *pcf8583; 271 int err; 272 273 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 274 return -ENODEV; 275 276 pcf8583 = kzalloc(sizeof(struct pcf8583), GFP_KERNEL); 277 if (!pcf8583) 278 return -ENOMEM; 279 280 i2c_set_clientdata(client, pcf8583); 281 282 pcf8583->rtc = rtc_device_register(pcf8583_driver.driver.name, 283 &client->dev, &pcf8583_rtc_ops, THIS_MODULE); 284 285 if (IS_ERR(pcf8583->rtc)) { 286 err = PTR_ERR(pcf8583->rtc); 287 goto exit_kfree; 288 } 289 290 return 0; 291 292 exit_kfree: 293 kfree(pcf8583); 294 return err; 295 } 296 297 static int pcf8583_remove(struct i2c_client *client) 298 { 299 struct pcf8583 *pcf8583 = i2c_get_clientdata(client); 300 301 if (pcf8583->rtc) 302 rtc_device_unregister(pcf8583->rtc); 303 kfree(pcf8583); 304 return 0; 305 } 306 307 static const struct i2c_device_id pcf8583_id[] = { 308 { "pcf8583", 0 }, 309 { } 310 }; 311 MODULE_DEVICE_TABLE(i2c, pcf8583_id); 312 313 static struct i2c_driver pcf8583_driver = { 314 .driver = { 315 .name = "pcf8583", 316 .owner = THIS_MODULE, 317 }, 318 .probe = pcf8583_probe, 319 .remove = pcf8583_remove, 320 .id_table = pcf8583_id, 321 }; 322 323 module_i2c_driver(pcf8583_driver); 324 325 MODULE_AUTHOR("Russell King"); 326 MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); 327 MODULE_LICENSE("GPL"); 328