drivers/w1/slaves/w1_ds28e04.c

   1 /*
   2  *      w1_ds28e04.c - w1 family 1C (DS28E04) driver
   3  *
   4  * Copyright (c) 2012 Markus Franke <franke.m@sebakmt.com>
   5  *
   6  * This source code is licensed under the GNU General Public License,
   7  * Version 2. See the file COPYING for more details.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/moduleparam.h>
  13 #include <linux/device.h>
  14 #include <linux/types.h>
  15 #include <linux/delay.h>
  16 #include <linux/slab.h>
  17 #include <linux/crc16.h>
  18 #include <linux/uaccess.h>
  19
  20 #define CRC16_INIT              0
  21 #define CRC16_VALID             0xb001
  22
  23 #include <linux/w1.h>
  24
  25 #define W1_FAMILY_DS28E04       0x1C
  26
  27 /* Allow the strong pullup to be disabled, but default to enabled.
  28  * If it was disabled a parasite powered device might not get the required
  29  * current to copy the data from the scratchpad to EEPROM.  If it is enabled
  30  * parasite powered devices have a better chance of getting the current
  31  * required.
  32  */
  33 static int w1_strong_pullup = 1;
  34 module_param_named(strong_pullup, w1_strong_pullup, int, 0);
  35
  36 /* enable/disable CRC checking on DS28E04-100 memory accesses */
  37 static char w1_enable_crccheck = 1;
  38
  39 #define W1_EEPROM_SIZE          512
  40 #define W1_PAGE_COUNT           16
  41 #define W1_PAGE_SIZE            32
  42 #define W1_PAGE_BITS            5
  43 #define W1_PAGE_MASK            0x1F
  44
  45 #define W1_F1C_READ_EEPROM      0xF0
  46 #define W1_F1C_WRITE_SCRATCH    0x0F
  47 #define W1_F1C_READ_SCRATCH     0xAA
  48 #define W1_F1C_COPY_SCRATCH     0x55
  49 #define W1_F1C_ACCESS_WRITE     0x5A
  50
  51 #define W1_1C_REG_LOGIC_STATE   0x220
  52
  53 struct w1_f1C_data {
  54         u8      memory[W1_EEPROM_SIZE];
  55         u32     validcrc;
  56 };
  57
  58 /**
  59  * Check the file size bounds and adjusts count as needed.
  60  * This would not be needed if the file size didn't reset to 0 after a write.
  61  */
  62 static inline size_t w1_f1C_fix_count(loff_t off, size_t count, size_t size)
  63 {
  64         if (off > size)
  65                 return 0;
  66
  67         if ((off + count) > size)
  68                 return size - off;
  69
  70         return count;
  71 }
  72
  73 static int w1_f1C_refresh_block(struct w1_slave *sl, struct w1_f1C_data *data,
  74                                 int block)
  75 {
  76         u8      wrbuf[3];
  77         int     off = block * W1_PAGE_SIZE;
  78
  79         if (data->validcrc & (1 << block))
  80                 return 0;
  81
  82         if (w1_reset_select_slave(sl)) {
  83                 data->validcrc = 0;
  84                 return -EIO;
  85         }
  86
  87         wrbuf[0] = W1_F1C_READ_EEPROM;
  88         wrbuf[1] = off & 0xff;
  89         wrbuf[2] = off >> 8;
  90         w1_write_block(sl->master, wrbuf, 3);
  91         w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
  92
  93         /* cache the block if the CRC is valid */
  94         if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
  95                 data->validcrc |= (1 << block);
  96
  97         return 0;
  98 }
  99
 100 static int w1_f1C_read(struct w1_slave *sl, int addr, int len, char *data)
 101 {
 102         u8 wrbuf[3];
 103
 104         /* read directly from the EEPROM */
 105         if (w1_reset_select_slave(sl))
 106                 return -EIO;
 107
 108         wrbuf[0] = W1_F1C_READ_EEPROM;
 109         wrbuf[1] = addr & 0xff;
 110         wrbuf[2] = addr >> 8;
 111
 112         w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
 113         return w1_read_block(sl->master, data, len);
 114 }
 115
 116 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 117                            struct bin_attribute *bin_attr, char *buf,
 118                            loff_t off, size_t count)
 119 {
 120         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 121         struct w1_f1C_data *data = sl->family_data;
 122         int i, min_page, max_page;
 123
 124         count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
 125         if (count == 0)
 126                 return 0;
 127
 128         mutex_lock(&sl->master->mutex);
 129
 130         if (w1_enable_crccheck) {
 131                 min_page = (off >> W1_PAGE_BITS);
 132                 max_page = (off + count - 1) >> W1_PAGE_BITS;
 133                 for (i = min_page; i <= max_page; i++) {
 134                         if (w1_f1C_refresh_block(sl, data, i)) {
 135                                 count = -EIO;
 136                                 goto out_up;
 137                         }
 138                 }
 139                 memcpy(buf, &data->memory[off], count);
 140         } else {
 141                 count = w1_f1C_read(sl, off, count, buf);
 142         }
 143
 144 out_up:
 145         mutex_unlock(&sl->master->mutex);
 146
 147         return count;
 148 }
 149
 150 /**
 151  * Writes to the scratchpad and reads it back for verification.
 152  * Then copies the scratchpad to EEPROM.
 153  * The data must be on one page.
 154  * The master must be locked.
 155  *
 156  * @param sl    The slave structure
 157  * @param addr  Address for the write
 158  * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
 159  * @param data  The data to write
 160  * @return      0=Success -1=failure
 161  */
 162 static int w1_f1C_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 163 {
 164         u8 wrbuf[4];
 165         u8 rdbuf[W1_PAGE_SIZE + 3];
 166         u8 es = (addr + len - 1) & 0x1f;
 167         unsigned int tm = 10;
 168         int i;
 169         struct w1_f1C_data *f1C = sl->family_data;
 170
 171         /* Write the data to the scratchpad */
 172         if (w1_reset_select_slave(sl))
 173                 return -1;
 174
 175         wrbuf[0] = W1_F1C_WRITE_SCRATCH;
 176         wrbuf[1] = addr & 0xff;
 177         wrbuf[2] = addr >> 8;
 178
 179         w1_write_block(sl->master, wrbuf, 3);
 180         w1_write_block(sl->master, data, len);
 181
 182         /* Read the scratchpad and verify */
 183         if (w1_reset_select_slave(sl))
 184                 return -1;
 185
 186         w1_write_8(sl->master, W1_F1C_READ_SCRATCH);
 187         w1_read_block(sl->master, rdbuf, len + 3);
 188
 189         /* Compare what was read against the data written */
 190         if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
 191             (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
 192                 return -1;
 193
 194         /* Copy the scratchpad to EEPROM */
 195         if (w1_reset_select_slave(sl))
 196                 return -1;
 197
 198         wrbuf[0] = W1_F1C_COPY_SCRATCH;
 199         wrbuf[3] = es;
 200
 201         for (i = 0; i < sizeof(wrbuf); ++i) {
 202                 /* issue 10ms strong pullup (or delay) on the last byte
 203                    for writing the data from the scratchpad to EEPROM */
 204                 if (w1_strong_pullup && i == sizeof(wrbuf)-1)
 205                         w1_next_pullup(sl->master, tm);
 206
 207                 w1_write_8(sl->master, wrbuf[i]);
 208         }
 209
 210         if (!w1_strong_pullup)
 211                 msleep(tm);
 212
 213         if (w1_enable_crccheck) {
 214                 /* invalidate cached data */
 215                 f1C->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
 216         }
 217
 218         /* Reset the bus to wake up the EEPROM (this may not be needed) */
 219         w1_reset_bus(sl->master);
 220
 221         return 0;
 222 }
 223
 224 static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
 225                             struct bin_attribute *bin_attr, char *buf,
 226                             loff_t off, size_t count)
 227
 228 {
 229         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 230         int addr, len, idx;
 231
 232         count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
 233         if (count == 0)
 234                 return 0;
 235
 236         if (w1_enable_crccheck) {
 237                 /* can only write full blocks in cached mode */
 238                 if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
 239                         dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
 240                                 (int)off, count);
 241                         return -EINVAL;
 242                 }
 243
 244                 /* make sure the block CRCs are valid */
 245                 for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
 246                         if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE)
 247                                 != CRC16_VALID) {
 248                                 dev_err(&sl->dev, "bad CRC at offset %d\n",
 249                                         (int)off);
 250                                 return -EINVAL;
 251                         }
 252                 }
 253         }
 254
 255         mutex_lock(&sl->master->mutex);
 256
 257         /* Can only write data to one page at a time */
 258         idx = 0;
 259         while (idx < count) {
 260                 addr = off + idx;
 261                 len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
 262                 if (len > (count - idx))
 263                         len = count - idx;
 264
 265                 if (w1_f1C_write(sl, addr, len, &buf[idx]) < 0) {
 266                         count = -EIO;
 267                         goto out_up;
 268                 }
 269                 idx += len;
 270         }
 271
 272 out_up:
 273         mutex_unlock(&sl->master->mutex);
 274
 275         return count;
 276 }
 277
 278 static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
 279
 280 static ssize_t pio_read(struct file *filp, struct kobject *kobj,
 281                         struct bin_attribute *bin_attr, char *buf, loff_t off,
 282                         size_t count)
 283
 284 {
 285         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 286         int ret;
 287
 288         /* check arguments */
 289         if (off != 0 || count != 1 || buf == NULL)
 290                 return -EINVAL;
 291
 292         mutex_lock(&sl->master->mutex);
 293         ret = w1_f1C_read(sl, W1_1C_REG_LOGIC_STATE, count, buf);
 294         mutex_unlock(&sl->master->mutex);
 295
 296         return ret;
 297 }
 298
 299 static ssize_t pio_write(struct file *filp, struct kobject *kobj,
 300                          struct bin_attribute *bin_attr, char *buf, loff_t off,
 301                          size_t count)
 302
 303 {
 304         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 305         u8 wrbuf[3];
 306         u8 ack;
 307
 308         /* check arguments */
 309         if (off != 0 || count != 1 || buf == NULL)
 310                 return -EINVAL;
 311
 312         mutex_lock(&sl->master->mutex);
 313
 314         /* Write the PIO data */
 315         if (w1_reset_select_slave(sl)) {
 316                 mutex_unlock(&sl->master->mutex);
 317                 return -1;
 318         }
 319
 320         /* set bit 7..2 to value '1' */
 321         *buf = *buf | 0xFC;
 322
 323         wrbuf[0] = W1_F1C_ACCESS_WRITE;
 324         wrbuf[1] = *buf;
 325         wrbuf[2] = ~(*buf);
 326         w1_write_block(sl->master, wrbuf, 3);
 327
 328         w1_read_block(sl->master, &ack, sizeof(ack));
 329
 330         mutex_unlock(&sl->master->mutex);
 331
 332         /* check for acknowledgement */
 333         if (ack != 0xAA)
 334                 return -EIO;
 335
 336         return count;
 337 }
 338
 339 static BIN_ATTR_RW(pio, 1);
 340
 341 static ssize_t crccheck_show(struct device *dev, struct device_attribute *attr,
 342                              char *buf)
 343 {
 344         if (put_user(w1_enable_crccheck + 0x30, buf))
 345                 return -EFAULT;
 346
 347         return sizeof(w1_enable_crccheck);
 348 }
 349
 350 static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr,
 351                               const char *buf, size_t count)
 352 {
 353         char val;
 354
 355         if (count != 1 || !buf)
 356                 return -EINVAL;
 357
 358         if (get_user(val, buf))
 359                 return -EFAULT;
 360
 361         /* convert to decimal */
 362         val = val - 0x30;
 363         if (val != 0 && val != 1)
 364                 return -EINVAL;
 365
 366         /* set the new value */
 367         w1_enable_crccheck = val;
 368
 369         return sizeof(w1_enable_crccheck);
 370 }
 371
 372 static DEVICE_ATTR_RW(crccheck);
 373
 374 static struct attribute *w1_f1C_attrs[] = {
 375         &dev_attr_crccheck.attr,
 376         NULL,
 377 };
 378
 379 static struct bin_attribute *w1_f1C_bin_attrs[] = {
 380         &bin_attr_eeprom,
 381         &bin_attr_pio,
 382         NULL,
 383 };
 384
 385 static const struct attribute_group w1_f1C_group = {
 386         .attrs          = w1_f1C_attrs,
 387         .bin_attrs      = w1_f1C_bin_attrs,
 388 };
 389
 390 static const struct attribute_group *w1_f1C_groups[] = {
 391         &w1_f1C_group,
 392         NULL,
 393 };
 394
 395 static int w1_f1C_add_slave(struct w1_slave *sl)
 396 {
 397         struct w1_f1C_data *data = NULL;
 398
 399         if (w1_enable_crccheck) {
 400                 data = kzalloc(sizeof(struct w1_f1C_data), GFP_KERNEL);
 401                 if (!data)
 402                         return -ENOMEM;
 403                 sl->family_data = data;
 404         }
 405
 406         return 0;
 407 }
 408
 409 static void w1_f1C_remove_slave(struct w1_slave *sl)
 410 {
 411         kfree(sl->family_data);
 412         sl->family_data = NULL;
 413 }
 414
 415 static struct w1_family_ops w1_f1C_fops = {
 416         .add_slave      = w1_f1C_add_slave,
 417         .remove_slave   = w1_f1C_remove_slave,
 418         .groups         = w1_f1C_groups,
 419 };
 420
 421 static struct w1_family w1_family_1C = {
 422         .fid = W1_FAMILY_DS28E04,
 423         .fops = &w1_f1C_fops,
 424 };
 425 module_w1_family(w1_family_1C);
 426
 427 MODULE_AUTHOR("Markus Franke <franke.m@sebakmt.com>, <franm@hrz.tu-chemnitz.de>");
 428 MODULE_DESCRIPTION("w1 family 1C driver for DS28E04, 4kb EEPROM and PIO");
 429 MODULE_LICENSE("GPL");
 430 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS28E04));