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/err.h> 21 #include <linux/errno.h> 22 #include <linux/bcd.h> 23 24 struct rtc_mem { 25 unsigned int loc; 26 unsigned int nr; 27 unsigned char *data; 28 }; 29 30 struct pcf8583 { 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 44 static struct i2c_driver pcf8583_driver; 45 46 #define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl 47 #define set_ctrl(x, v) get_ctrl(x) = v 48 49 #define CMOS_YEAR (64 + 128) 50 #define CMOS_CHECKSUM (63) 51 52 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt) 53 { 54 unsigned char buf[8], addr[1] = { 1 }; 55 struct i2c_msg msgs[2] = { 56 { 57 .addr = client->addr, 58 .flags = 0, 59 .len = 1, 60 .buf = addr, 61 }, { 62 .addr = client->addr, 63 .flags = I2C_M_RD, 64 .len = 6, 65 .buf = buf, 66 } 67 }; 68 int ret; 69 70 memset(buf, 0, sizeof(buf)); 71 72 ret = i2c_transfer(client->adapter, msgs, 2); 73 if (ret == 2) { 74 dt->tm_year = buf[4] >> 6; 75 dt->tm_wday = buf[5] >> 5; 76 77 buf[4] &= 0x3f; 78 buf[5] &= 0x1f; 79 80 dt->tm_sec = bcd2bin(buf[1]); 81 dt->tm_min = bcd2bin(buf[2]); 82 dt->tm_hour = bcd2bin(buf[3]); 83 dt->tm_mday = bcd2bin(buf[4]); 84 dt->tm_mon = bcd2bin(buf[5]) - 1; 85 } 86 87 return ret == 2 ? 0 : -EIO; 88 } 89 90 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo) 91 { 92 unsigned char buf[8]; 93 int ret, len = 6; 94 95 buf[0] = 0; 96 buf[1] = get_ctrl(client) | 0x80; 97 buf[2] = 0; 98 buf[3] = bin2bcd(dt->tm_sec); 99 buf[4] = bin2bcd(dt->tm_min); 100 buf[5] = bin2bcd(dt->tm_hour); 101 102 if (datetoo) { 103 len = 8; 104 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6); 105 buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5); 106 } 107 108 ret = i2c_master_send(client, (char *)buf, len); 109 if (ret != len) 110 return -EIO; 111 112 buf[1] = get_ctrl(client); 113 ret = i2c_master_send(client, (char *)buf, 2); 114 115 return ret == 2 ? 0 : -EIO; 116 } 117 118 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl) 119 { 120 *ctrl = get_ctrl(client); 121 return 0; 122 } 123 124 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl) 125 { 126 unsigned char buf[2]; 127 128 buf[0] = 0; 129 buf[1] = *ctrl; 130 set_ctrl(client, *ctrl); 131 132 return i2c_master_send(client, (char *)buf, 2); 133 } 134 135 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem) 136 { 137 unsigned char addr[1]; 138 struct i2c_msg msgs[2] = { 139 { 140 .addr = client->addr, 141 .flags = 0, 142 .len = 1, 143 .buf = addr, 144 }, { 145 .addr = client->addr, 146 .flags = I2C_M_RD, 147 .len = mem->nr, 148 .buf = mem->data, 149 } 150 }; 151 152 if (mem->loc < 8) 153 return -EINVAL; 154 155 addr[0] = mem->loc; 156 157 return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO; 158 } 159 160 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem) 161 { 162 unsigned char buf[9]; 163 int ret; 164 165 if (mem->loc < 8 || mem->nr > 8) 166 return -EINVAL; 167 168 buf[0] = mem->loc; 169 memcpy(buf + 1, mem->data, mem->nr); 170 171 ret = i2c_master_send(client, buf, mem->nr + 1); 172 return ret == mem->nr + 1 ? 0 : -EIO; 173 } 174 175 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm) 176 { 177 struct i2c_client *client = to_i2c_client(dev); 178 unsigned char ctrl, year[2]; 179 struct rtc_mem mem = { 180 .loc = CMOS_YEAR, 181 .nr = sizeof(year), 182 .data = year 183 }; 184 int real_year, year_offset, err; 185 186 /* 187 * Ensure that the RTC is running. 188 */ 189 pcf8583_get_ctrl(client, &ctrl); 190 if (ctrl & (CTRL_STOP | CTRL_HOLD)) { 191 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD); 192 193 dev_warn(dev, "resetting control %02x -> %02x\n", 194 ctrl, new_ctrl); 195 196 err = pcf8583_set_ctrl(client, &new_ctrl); 197 if (err < 0) 198 return err; 199 } 200 201 if (pcf8583_get_datetime(client, tm) || 202 pcf8583_read_mem(client, &mem)) 203 return -EIO; 204 205 real_year = year[0]; 206 207 /* 208 * The RTC year holds the LSB two bits of the current 209 * year, which should reflect the LSB two bits of the 210 * CMOS copy of the year. Any difference indicates 211 * that we have to correct the CMOS version. 212 */ 213 year_offset = tm->tm_year - (real_year & 3); 214 if (year_offset < 0) 215 /* 216 * RTC year wrapped. Adjust it appropriately. 217 */ 218 year_offset += 4; 219 220 tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900; 221 222 return 0; 223 } 224 225 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm) 226 { 227 struct i2c_client *client = to_i2c_client(dev); 228 unsigned char year[2], chk; 229 struct rtc_mem cmos_year = { 230 .loc = CMOS_YEAR, 231 .nr = sizeof(year), 232 .data = year 233 }; 234 struct rtc_mem cmos_check = { 235 .loc = CMOS_CHECKSUM, 236 .nr = 1, 237 .data = &chk 238 }; 239 unsigned int proper_year = tm->tm_year + 1900; 240 int ret; 241 242 /* 243 * The RTC's own 2-bit year must reflect the least 244 * significant two bits of the CMOS year. 245 */ 246 247 ret = pcf8583_set_datetime(client, tm, 1); 248 if (ret) 249 return ret; 250 251 ret = pcf8583_read_mem(client, &cmos_check); 252 if (ret) 253 return ret; 254 255 ret = pcf8583_read_mem(client, &cmos_year); 256 if (ret) 257 return ret; 258 259 chk -= year[1] + year[0]; 260 261 year[1] = proper_year / 100; 262 year[0] = proper_year % 100; 263 264 chk += year[1] + year[0]; 265 266 ret = pcf8583_write_mem(client, &cmos_year); 267 268 if (ret) 269 return ret; 270 271 ret = pcf8583_write_mem(client, &cmos_check); 272 273 return ret; 274 } 275 276 static const struct rtc_class_ops pcf8583_rtc_ops = { 277 .read_time = pcf8583_rtc_read_time, 278 .set_time = pcf8583_rtc_set_time, 279 }; 280 281 static int pcf8583_probe(struct i2c_client *client, 282 const struct i2c_device_id *id) 283 { 284 struct pcf8583 *pcf8583; 285 286 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 287 return -ENODEV; 288 289 pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583), 290 GFP_KERNEL); 291 if (!pcf8583) 292 return -ENOMEM; 293 294 i2c_set_clientdata(client, pcf8583); 295 296 pcf8583->rtc = devm_rtc_device_register(&client->dev, 297 pcf8583_driver.driver.name, 298 &pcf8583_rtc_ops, THIS_MODULE); 299 300 return PTR_ERR_OR_ZERO(pcf8583->rtc); 301 } 302 303 static const struct i2c_device_id pcf8583_id[] = { 304 { "pcf8583", 0 }, 305 { } 306 }; 307 MODULE_DEVICE_TABLE(i2c, pcf8583_id); 308 309 static struct i2c_driver pcf8583_driver = { 310 .driver = { 311 .name = "pcf8583", 312 .owner = THIS_MODULE, 313 }, 314 .probe = pcf8583_probe, 315 .id_table = pcf8583_id, 316 }; 317 318 module_i2c_driver(pcf8583_driver); 319 320 MODULE_AUTHOR("Russell King"); 321 MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); 322 MODULE_LICENSE("GPL"); 323