1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * drivers/rtc/rtc-pcf8583.c 4 * 5 * Copyright (C) 2000 Russell King 6 * Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix 7 * 8 * Driver for PCF8583 RTC & RAM chip 9 * 10 * Converted to the generic RTC susbsystem by G. Liakhovetski (2006) 11 */ 12 #include <linux/module.h> 13 #include <linux/i2c.h> 14 #include <linux/slab.h> 15 #include <linux/rtc.h> 16 #include <linux/init.h> 17 #include <linux/err.h> 18 #include <linux/errno.h> 19 #include <linux/bcd.h> 20 21 struct rtc_mem { 22 unsigned int loc; 23 unsigned int nr; 24 unsigned char *data; 25 }; 26 27 struct pcf8583 { 28 struct rtc_device *rtc; 29 unsigned char ctrl; 30 }; 31 32 #define CTRL_STOP 0x80 33 #define CTRL_HOLD 0x40 34 #define CTRL_32KHZ 0x00 35 #define CTRL_MASK 0x08 36 #define CTRL_ALARMEN 0x04 37 #define CTRL_ALARM 0x02 38 #define CTRL_TIMER 0x01 39 40 41 static struct i2c_driver pcf8583_driver; 42 43 #define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl 44 #define set_ctrl(x, v) get_ctrl(x) = v 45 46 #define CMOS_YEAR (64 + 128) 47 #define CMOS_CHECKSUM (63) 48 49 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt) 50 { 51 unsigned char buf[8], addr[1] = { 1 }; 52 struct i2c_msg msgs[2] = { 53 { 54 .addr = client->addr, 55 .flags = 0, 56 .len = 1, 57 .buf = addr, 58 }, { 59 .addr = client->addr, 60 .flags = I2C_M_RD, 61 .len = 6, 62 .buf = buf, 63 } 64 }; 65 int ret; 66 67 memset(buf, 0, sizeof(buf)); 68 69 ret = i2c_transfer(client->adapter, msgs, 2); 70 if (ret == 2) { 71 dt->tm_year = buf[4] >> 6; 72 dt->tm_wday = buf[5] >> 5; 73 74 buf[4] &= 0x3f; 75 buf[5] &= 0x1f; 76 77 dt->tm_sec = bcd2bin(buf[1]); 78 dt->tm_min = bcd2bin(buf[2]); 79 dt->tm_hour = bcd2bin(buf[3]); 80 dt->tm_mday = bcd2bin(buf[4]); 81 dt->tm_mon = bcd2bin(buf[5]) - 1; 82 } 83 84 return ret == 2 ? 0 : -EIO; 85 } 86 87 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo) 88 { 89 unsigned char buf[8]; 90 int ret, len = 6; 91 92 buf[0] = 0; 93 buf[1] = get_ctrl(client) | 0x80; 94 buf[2] = 0; 95 buf[3] = bin2bcd(dt->tm_sec); 96 buf[4] = bin2bcd(dt->tm_min); 97 buf[5] = bin2bcd(dt->tm_hour); 98 99 if (datetoo) { 100 len = 8; 101 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6); 102 buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5); 103 } 104 105 ret = i2c_master_send(client, (char *)buf, len); 106 if (ret != len) 107 return -EIO; 108 109 buf[1] = get_ctrl(client); 110 ret = i2c_master_send(client, (char *)buf, 2); 111 112 return ret == 2 ? 0 : -EIO; 113 } 114 115 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl) 116 { 117 *ctrl = get_ctrl(client); 118 return 0; 119 } 120 121 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl) 122 { 123 unsigned char buf[2]; 124 125 buf[0] = 0; 126 buf[1] = *ctrl; 127 set_ctrl(client, *ctrl); 128 129 return i2c_master_send(client, (char *)buf, 2); 130 } 131 132 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem) 133 { 134 unsigned char addr[1]; 135 struct i2c_msg msgs[2] = { 136 { 137 .addr = client->addr, 138 .flags = 0, 139 .len = 1, 140 .buf = addr, 141 }, { 142 .addr = client->addr, 143 .flags = I2C_M_RD, 144 .len = mem->nr, 145 .buf = mem->data, 146 } 147 }; 148 149 if (mem->loc < 8) 150 return -EINVAL; 151 152 addr[0] = mem->loc; 153 154 return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO; 155 } 156 157 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem) 158 { 159 unsigned char buf[9]; 160 int ret; 161 162 if (mem->loc < 8 || mem->nr > 8) 163 return -EINVAL; 164 165 buf[0] = mem->loc; 166 memcpy(buf + 1, mem->data, mem->nr); 167 168 ret = i2c_master_send(client, buf, mem->nr + 1); 169 return ret == mem->nr + 1 ? 0 : -EIO; 170 } 171 172 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm) 173 { 174 struct i2c_client *client = to_i2c_client(dev); 175 unsigned char ctrl, year[2]; 176 struct rtc_mem mem = { 177 .loc = CMOS_YEAR, 178 .nr = sizeof(year), 179 .data = year 180 }; 181 int real_year, year_offset, err; 182 183 /* 184 * Ensure that the RTC is running. 185 */ 186 pcf8583_get_ctrl(client, &ctrl); 187 if (ctrl & (CTRL_STOP | CTRL_HOLD)) { 188 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD); 189 190 dev_warn(dev, "resetting control %02x -> %02x\n", 191 ctrl, new_ctrl); 192 193 err = pcf8583_set_ctrl(client, &new_ctrl); 194 if (err < 0) 195 return err; 196 } 197 198 if (pcf8583_get_datetime(client, tm) || 199 pcf8583_read_mem(client, &mem)) 200 return -EIO; 201 202 real_year = year[0]; 203 204 /* 205 * The RTC year holds the LSB two bits of the current 206 * year, which should reflect the LSB two bits of the 207 * CMOS copy of the year. Any difference indicates 208 * that we have to correct the CMOS version. 209 */ 210 year_offset = tm->tm_year - (real_year & 3); 211 if (year_offset < 0) 212 /* 213 * RTC year wrapped. Adjust it appropriately. 214 */ 215 year_offset += 4; 216 217 tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900; 218 219 return 0; 220 } 221 222 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm) 223 { 224 struct i2c_client *client = to_i2c_client(dev); 225 unsigned char year[2], chk; 226 struct rtc_mem cmos_year = { 227 .loc = CMOS_YEAR, 228 .nr = sizeof(year), 229 .data = year 230 }; 231 struct rtc_mem cmos_check = { 232 .loc = CMOS_CHECKSUM, 233 .nr = 1, 234 .data = &chk 235 }; 236 unsigned int proper_year = tm->tm_year + 1900; 237 int ret; 238 239 /* 240 * The RTC's own 2-bit year must reflect the least 241 * significant two bits of the CMOS year. 242 */ 243 244 ret = pcf8583_set_datetime(client, tm, 1); 245 if (ret) 246 return ret; 247 248 ret = pcf8583_read_mem(client, &cmos_check); 249 if (ret) 250 return ret; 251 252 ret = pcf8583_read_mem(client, &cmos_year); 253 if (ret) 254 return ret; 255 256 chk -= year[1] + year[0]; 257 258 year[1] = proper_year / 100; 259 year[0] = proper_year % 100; 260 261 chk += year[1] + year[0]; 262 263 ret = pcf8583_write_mem(client, &cmos_year); 264 265 if (ret) 266 return ret; 267 268 ret = pcf8583_write_mem(client, &cmos_check); 269 270 return ret; 271 } 272 273 static const struct rtc_class_ops pcf8583_rtc_ops = { 274 .read_time = pcf8583_rtc_read_time, 275 .set_time = pcf8583_rtc_set_time, 276 }; 277 278 static int pcf8583_probe(struct i2c_client *client) 279 { 280 struct pcf8583 *pcf8583; 281 282 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 283 return -ENODEV; 284 285 pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583), 286 GFP_KERNEL); 287 if (!pcf8583) 288 return -ENOMEM; 289 290 i2c_set_clientdata(client, pcf8583); 291 292 pcf8583->rtc = devm_rtc_device_register(&client->dev, 293 pcf8583_driver.driver.name, 294 &pcf8583_rtc_ops, THIS_MODULE); 295 296 return PTR_ERR_OR_ZERO(pcf8583->rtc); 297 } 298 299 static const struct i2c_device_id pcf8583_id[] = { 300 { "pcf8583", 0 }, 301 { } 302 }; 303 MODULE_DEVICE_TABLE(i2c, pcf8583_id); 304 305 static struct i2c_driver pcf8583_driver = { 306 .driver = { 307 .name = "pcf8583", 308 }, 309 .probe = pcf8583_probe, 310 .id_table = pcf8583_id, 311 }; 312 313 module_i2c_driver(pcf8583_driver); 314 315 MODULE_AUTHOR("Russell King"); 316 MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); 317 MODULE_LICENSE("GPL"); 318