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 = { CMOS_YEAR, sizeof(year), year }; 180 int real_year, year_offset, err; 181 182 /* 183 * Ensure that the RTC is running. 184 */ 185 pcf8583_get_ctrl(client, &ctrl); 186 if (ctrl & (CTRL_STOP | CTRL_HOLD)) { 187 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD); 188 189 dev_warn(dev, "resetting control %02x -> %02x\n", 190 ctrl, new_ctrl); 191 192 err = pcf8583_set_ctrl(client, &new_ctrl); 193 if (err < 0) 194 return err; 195 } 196 197 if (pcf8583_get_datetime(client, tm) || 198 pcf8583_read_mem(client, &mem)) 199 return -EIO; 200 201 real_year = year[0]; 202 203 /* 204 * The RTC year holds the LSB two bits of the current 205 * year, which should reflect the LSB two bits of the 206 * CMOS copy of the year. Any difference indicates 207 * that we have to correct the CMOS version. 208 */ 209 year_offset = tm->tm_year - (real_year & 3); 210 if (year_offset < 0) 211 /* 212 * RTC year wrapped. Adjust it appropriately. 213 */ 214 year_offset += 4; 215 216 tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900; 217 218 return 0; 219 } 220 221 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm) 222 { 223 struct i2c_client *client = to_i2c_client(dev); 224 unsigned char year[2], chk; 225 struct rtc_mem cmos_year = { CMOS_YEAR, sizeof(year), year }; 226 struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk }; 227 unsigned int proper_year = tm->tm_year + 1900; 228 int ret; 229 230 /* 231 * The RTC's own 2-bit year must reflect the least 232 * significant two bits of the CMOS year. 233 */ 234 235 ret = pcf8583_set_datetime(client, tm, 1); 236 if (ret) 237 return ret; 238 239 ret = pcf8583_read_mem(client, &cmos_check); 240 if (ret) 241 return ret; 242 243 ret = pcf8583_read_mem(client, &cmos_year); 244 if (ret) 245 return ret; 246 247 chk -= year[1] + year[0]; 248 249 year[1] = proper_year / 100; 250 year[0] = proper_year % 100; 251 252 chk += year[1] + year[0]; 253 254 ret = pcf8583_write_mem(client, &cmos_year); 255 256 if (ret) 257 return ret; 258 259 ret = pcf8583_write_mem(client, &cmos_check); 260 261 return ret; 262 } 263 264 static const struct rtc_class_ops pcf8583_rtc_ops = { 265 .read_time = pcf8583_rtc_read_time, 266 .set_time = pcf8583_rtc_set_time, 267 }; 268 269 static int pcf8583_probe(struct i2c_client *client, 270 const struct i2c_device_id *id) 271 { 272 struct pcf8583 *pcf8583; 273 274 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 275 return -ENODEV; 276 277 pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583), 278 GFP_KERNEL); 279 if (!pcf8583) 280 return -ENOMEM; 281 282 i2c_set_clientdata(client, pcf8583); 283 284 pcf8583->rtc = devm_rtc_device_register(&client->dev, 285 pcf8583_driver.driver.name, 286 &pcf8583_rtc_ops, THIS_MODULE); 287 288 return PTR_ERR_OR_ZERO(pcf8583->rtc); 289 } 290 291 static const struct i2c_device_id pcf8583_id[] = { 292 { "pcf8583", 0 }, 293 { } 294 }; 295 MODULE_DEVICE_TABLE(i2c, pcf8583_id); 296 297 static struct i2c_driver pcf8583_driver = { 298 .driver = { 299 .name = "pcf8583", 300 .owner = THIS_MODULE, 301 }, 302 .probe = pcf8583_probe, 303 .id_table = pcf8583_id, 304 }; 305 306 module_i2c_driver(pcf8583_driver); 307 308 MODULE_AUTHOR("Russell King"); 309 MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); 310 MODULE_LICENSE("GPL"); 311