drivers/i2c/chips/ds1337.c

   1 /*
   2  *  linux/drivers/i2c/chips/ds1337.c
   3  *
   4  *  Copyright (C) 2005 James Chapman <jchapman@katalix.com>
   5  *
   6  *      based on linux/drivers/acorn/char/pcf8583.c
   7  *  Copyright (C) 2000 Russell King
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  *
  13  * Driver for Dallas Semiconductor DS1337 and DS1339 real time clock chip
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <linux/i2c.h>
  20 #include <linux/string.h>
  21 #include <linux/rtc.h>          /* get the user-level API */
  22 #include <linux/bcd.h>
  23 #include <linux/list.h>
  24
  25 /* Device registers */
  26 #define DS1337_REG_HOUR         2
  27 #define DS1337_REG_DAY          3
  28 #define DS1337_REG_DATE         4
  29 #define DS1337_REG_MONTH        5
  30 #define DS1337_REG_CONTROL      14
  31 #define DS1337_REG_STATUS       15
  32
  33 /* FIXME - how do we export these interface constants? */
  34 #define DS1337_GET_DATE         0
  35 #define DS1337_SET_DATE         1
  36
  37 /*
  38  * Functions declaration
  39  */
  40 static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };
  41
  42 I2C_CLIENT_INSMOD_1(ds1337);
  43
  44 static int ds1337_attach_adapter(struct i2c_adapter *adapter);
  45 static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
  46 static void ds1337_init_client(struct i2c_client *client);
  47 static int ds1337_detach_client(struct i2c_client *client);
  48 static int ds1337_command(struct i2c_client *client, unsigned int cmd,
  49                           void *arg);
  50
  51 /*
  52  * Driver data (common to all clients)
  53  */
  54 static struct i2c_driver ds1337_driver = {
  55         .driver = {
  56                 .name   = "ds1337",
  57         },
  58         .attach_adapter = ds1337_attach_adapter,
  59         .detach_client  = ds1337_detach_client,
  60         .command        = ds1337_command,
  61 };
  62
  63 /*
  64  * Client data (each client gets its own)
  65  */
  66 struct ds1337_data {
  67         struct i2c_client client;
  68         struct list_head list;
  69 };
  70
  71 /*
  72  * Internal variables
  73  */
  74 static LIST_HEAD(ds1337_clients);
  75
  76 static inline int ds1337_read(struct i2c_client *client, u8 reg, u8 *value)
  77 {
  78         s32 tmp = i2c_smbus_read_byte_data(client, reg);
  79
  80         if (tmp < 0)
  81                 return -EIO;
  82
  83         *value = tmp;
  84
  85         return 0;
  86 }
  87
  88 /*
  89  * Chip access functions
  90  */
  91 static int ds1337_get_datetime(struct i2c_client *client, struct rtc_time *dt)
  92 {
  93         int result;
  94         u8 buf[7];
  95         u8 val;
  96         struct i2c_msg msg[2];
  97         u8 offs = 0;
  98
  99         if (!dt) {
 100                 dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
 101                 return -EINVAL;
 102         }
 103
 104         msg[0].addr = client->addr;
 105         msg[0].flags = 0;
 106         msg[0].len = 1;
 107         msg[0].buf = &offs;
 108
 109         msg[1].addr = client->addr;
 110         msg[1].flags = I2C_M_RD;
 111         msg[1].len = sizeof(buf);
 112         msg[1].buf = &buf[0];
 113
 114         result = i2c_transfer(client->adapter, msg, 2);
 115
 116         dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
 117                 __FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
 118                 buf[4], buf[5], buf[6]);
 119
 120         if (result == 2) {
 121                 dt->tm_sec = BCD2BIN(buf[0]);
 122                 dt->tm_min = BCD2BIN(buf[1]);
 123                 val = buf[2] & 0x3f;
 124                 dt->tm_hour = BCD2BIN(val);
 125                 dt->tm_wday = BCD2BIN(buf[3]) - 1;
 126                 dt->tm_mday = BCD2BIN(buf[4]);
 127                 val = buf[5] & 0x7f;
 128                 dt->tm_mon = BCD2BIN(val) - 1;
 129                 dt->tm_year = BCD2BIN(buf[6]);
 130                 if (buf[5] & 0x80)
 131                         dt->tm_year += 100;
 132
 133                 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, "
 134                         "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 135                         __FUNCTION__, dt->tm_sec, dt->tm_min,
 136                         dt->tm_hour, dt->tm_mday,
 137                         dt->tm_mon, dt->tm_year, dt->tm_wday);
 138
 139                 return 0;
 140         }
 141
 142         dev_err(&client->dev, "error reading data! %d\n", result);
 143         return -EIO;
 144 }
 145
 146 static int ds1337_set_datetime(struct i2c_client *client, struct rtc_time *dt)
 147 {
 148         int result;
 149         u8 buf[8];
 150         u8 val;
 151         struct i2c_msg msg[1];
 152
 153         if (!dt) {
 154                 dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
 155                 return -EINVAL;
 156         }
 157
 158         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 159                 "mday=%d, mon=%d, year=%d, wday=%d\n", __FUNCTION__,
 160                 dt->tm_sec, dt->tm_min, dt->tm_hour,
 161                 dt->tm_mday, dt->tm_mon, dt->tm_year, dt->tm_wday);
 162
 163         buf[0] = 0;             /* reg offset */
 164         buf[1] = BIN2BCD(dt->tm_sec);
 165         buf[2] = BIN2BCD(dt->tm_min);
 166         buf[3] = BIN2BCD(dt->tm_hour);
 167         buf[4] = BIN2BCD(dt->tm_wday + 1);
 168         buf[5] = BIN2BCD(dt->tm_mday);
 169         buf[6] = BIN2BCD(dt->tm_mon + 1);
 170         val = dt->tm_year;
 171         if (val >= 100) {
 172                 val -= 100;
 173                 buf[6] |= (1 << 7);
 174         }
 175         buf[7] = BIN2BCD(val);
 176
 177         msg[0].addr = client->addr;
 178         msg[0].flags = 0;
 179         msg[0].len = sizeof(buf);
 180         msg[0].buf = &buf[0];
 181
 182         result = i2c_transfer(client->adapter, msg, 1);
 183         if (result == 1)
 184                 return 0;
 185
 186         dev_err(&client->dev, "error writing data! %d\n", result);
 187         return -EIO;
 188 }
 189
 190 static int ds1337_command(struct i2c_client *client, unsigned int cmd,
 191                           void *arg)
 192 {
 193         dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);
 194
 195         switch (cmd) {
 196         case DS1337_GET_DATE:
 197                 return ds1337_get_datetime(client, arg);
 198
 199         case DS1337_SET_DATE:
 200                 return ds1337_set_datetime(client, arg);
 201
 202         default:
 203                 return -EINVAL;
 204         }
 205 }
 206
 207 /*
 208  * Public API for access to specific device. Useful for low-level
 209  * RTC access from kernel code.
 210  */
 211 int ds1337_do_command(int bus, int cmd, void *arg)
 212 {
 213         struct list_head *walk;
 214         struct list_head *tmp;
 215         struct ds1337_data *data;
 216
 217         list_for_each_safe(walk, tmp, &ds1337_clients) {
 218                 data = list_entry(walk, struct ds1337_data, list);
 219                 if (data->client.adapter->nr == bus)
 220                         return ds1337_command(&data->client, cmd, arg);
 221         }
 222
 223         return -ENODEV;
 224 }
 225
 226 static int ds1337_attach_adapter(struct i2c_adapter *adapter)
 227 {
 228         return i2c_probe(adapter, &addr_data, ds1337_detect);
 229 }
 230
 231 /*
 232  * The following function does more than just detection. If detection
 233  * succeeds, it also registers the new chip.
 234  */
 235 static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
 236 {
 237         struct i2c_client *new_client;
 238         struct ds1337_data *data;
 239         int err = 0;
 240         const char *name = "";
 241
 242         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 243                                      I2C_FUNC_I2C))
 244                 goto exit;
 245
 246         if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
 247                 err = -ENOMEM;
 248                 goto exit;
 249         }
 250         INIT_LIST_HEAD(&data->list);
 251
 252         /* The common I2C client data is placed right before the
 253          * DS1337-specific data.
 254          */
 255         new_client = &data->client;
 256         i2c_set_clientdata(new_client, data);
 257         new_client->addr = address;
 258         new_client->adapter = adapter;
 259         new_client->driver = &ds1337_driver;
 260         new_client->flags = 0;
 261
 262         /*
 263          * Now we do the remaining detection. A negative kind means that
 264          * the driver was loaded with no force parameter (default), so we
 265          * must both detect and identify the chip. A zero kind means that
 266          * the driver was loaded with the force parameter, the detection
 267          * step shall be skipped. A positive kind means that the driver
 268          * was loaded with the force parameter and a given kind of chip is
 269          * requested, so both the detection and the identification steps
 270          * are skipped.
 271          *
 272          * For detection, we read registers that are most likely to cause
 273          * detection failure, i.e. those that have more bits with fixed
 274          * or reserved values.
 275          */
 276
 277         /* Default to an DS1337 if forced */
 278         if (kind == 0)
 279                 kind = ds1337;
 280
 281         if (kind < 0) {         /* detection and identification */
 282                 u8 data;
 283
 284                 /* Check that status register bits 6-2 are zero */
 285                 if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) ||
 286                     (data & 0x7c))
 287                         goto exit_free;
 288
 289                 /* Check for a valid day register value */
 290                 if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) ||
 291                     (data == 0) || (data & 0xf8))
 292                         goto exit_free;
 293
 294                 /* Check for a valid date register value */
 295                 if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) ||
 296                     (data == 0) || (data & 0xc0) || ((data & 0x0f) > 9) ||
 297                     (data >= 0x32))
 298                         goto exit_free;
 299
 300                 /* Check for a valid month register value */
 301                 if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) ||
 302                     (data == 0) || (data & 0x60) || ((data & 0x0f) > 9) ||
 303                     ((data >= 0x13) && (data <= 0x19)))
 304                         goto exit_free;
 305
 306                 /* Check that control register bits 6-5 are zero */
 307                 if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) ||
 308                     (data & 0x60))
 309                         goto exit_free;
 310
 311                 kind = ds1337;
 312         }
 313
 314         if (kind == ds1337)
 315                 name = "ds1337";
 316
 317         /* We can fill in the remaining client fields */
 318         strlcpy(new_client->name, name, I2C_NAME_SIZE);
 319
 320         /* Tell the I2C layer a new client has arrived */
 321         if ((err = i2c_attach_client(new_client)))
 322                 goto exit_free;
 323
 324         /* Initialize the DS1337 chip */
 325         ds1337_init_client(new_client);
 326
 327         /* Add client to local list */
 328         list_add(&data->list, &ds1337_clients);
 329
 330         return 0;
 331
 332 exit_free:
 333         kfree(data);
 334 exit:
 335         return err;
 336 }
 337
 338 static void ds1337_init_client(struct i2c_client *client)
 339 {
 340         u8 status, control;
 341
 342         /* On some boards, the RTC isn't configured by boot firmware.
 343          * Handle that case by starting/configuring the RTC now.
 344          */
 345         status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
 346         control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
 347
 348         if ((status & 0x80) || (control & 0x80)) {
 349                 /* RTC not running */
 350                 u8 buf[16];
 351                 struct i2c_msg msg[1];
 352
 353                 dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);
 354
 355                 /* Initialize all, including STATUS and CONTROL to zero */
 356                 memset(buf, 0, sizeof(buf));
 357                 msg[0].addr = client->addr;
 358                 msg[0].flags = 0;
 359                 msg[0].len = sizeof(buf);
 360                 msg[0].buf = &buf[0];
 361
 362                 i2c_transfer(client->adapter, msg, 1);
 363         } else {
 364                 /* Running: ensure that device is set in 24-hour mode */
 365                 s32 val;
 366
 367                 val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
 368                 if ((val >= 0) && (val & (1 << 6)))
 369                         i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
 370                                                   val & 0x3f);
 371         }
 372 }
 373
 374 static int ds1337_detach_client(struct i2c_client *client)
 375 {
 376         int err;
 377         struct ds1337_data *data = i2c_get_clientdata(client);
 378
 379         if ((err = i2c_detach_client(client)))
 380                 return err;
 381
 382         list_del(&data->list);
 383         kfree(data);
 384         return 0;
 385 }
 386
 387 static int __init ds1337_init(void)
 388 {
 389         return i2c_add_driver(&ds1337_driver);
 390 }
 391
 392 static void __exit ds1337_exit(void)
 393 {
 394         i2c_del_driver(&ds1337_driver);
 395 }
 396
 397 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 398 MODULE_DESCRIPTION("DS1337 RTC driver");
 399 MODULE_LICENSE("GPL");
 400
 401 EXPORT_SYMBOL_GPL(ds1337_do_command);
 402
 403 module_init(ds1337_init);
 404 module_exit(ds1337_exit);