| 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 | printk(KERN_WARNING "RTC: 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 __devexit 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 = __devexit_p(pcf8583_remove), |
| 320 | .id_table = pcf8583_id, |
| 321 | }; |
| 322 | |
| 323 | static __init int pcf8583_init(void) |
| 324 | { |
| 325 | return i2c_add_driver(&pcf8583_driver); |
| 326 | } |
| 327 | |
| 328 | static __exit void pcf8583_exit(void) |
| 329 | { |
| 330 | i2c_del_driver(&pcf8583_driver); |
| 331 | } |
| 332 | |
| 333 | module_init(pcf8583_init); |
| 334 | module_exit(pcf8583_exit); |
| 335 | |
| 336 | MODULE_AUTHOR("Russell King"); |
| 337 | MODULE_DESCRIPTION("PCF8583 I2C RTC driver"); |
| 338 | MODULE_LICENSE("GPL"); |