drivers/w1/slaves/w1_ds2431.c

   1 /*
   2  * w1_ds2431.c - w1 family 2d (DS2431) driver
   3  *
   4  * Copyright (c) 2008 Bernhard Weirich <bernhard.weirich@riedel.net>
   5  *
   6  * Heavily inspired by w1_DS2433 driver from Ben Gardner <bgardner@wabtec.com>
   7  *
   8  * This source code is licensed under the GNU General Public License,
   9  * Version 2. See the file COPYING for more details.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/device.h>
  16 #include <linux/types.h>
  17 #include <linux/delay.h>
  18
  19 #include <linux/w1.h>
  20
  21 #define W1_EEPROM_DS2431        0x2D
  22
  23 #define W1_F2D_EEPROM_SIZE              128
  24 #define W1_F2D_PAGE_COUNT               4
  25 #define W1_F2D_PAGE_BITS                5
  26 #define W1_F2D_PAGE_SIZE                (1<<W1_F2D_PAGE_BITS)
  27 #define W1_F2D_PAGE_MASK                0x1F
  28
  29 #define W1_F2D_SCRATCH_BITS  3
  30 #define W1_F2D_SCRATCH_SIZE  (1<<W1_F2D_SCRATCH_BITS)
  31 #define W1_F2D_SCRATCH_MASK  (W1_F2D_SCRATCH_SIZE-1)
  32
  33 #define W1_F2D_READ_EEPROM      0xF0
  34 #define W1_F2D_WRITE_SCRATCH    0x0F
  35 #define W1_F2D_READ_SCRATCH     0xAA
  36 #define W1_F2D_COPY_SCRATCH     0x55
  37
  38
  39 #define W1_F2D_TPROG_MS         11
  40
  41 #define W1_F2D_READ_RETRIES             10
  42 #define W1_F2D_READ_MAXLEN              8
  43
  44 /*
  45  * Check the file size bounds and adjusts count as needed.
  46  * This would not be needed if the file size didn't reset to 0 after a write.
  47  */
  48 static inline size_t w1_f2d_fix_count(loff_t off, size_t count, size_t size)
  49 {
  50         if (off > size)
  51                 return 0;
  52
  53         if ((off + count) > size)
  54                 return size - off;
  55
  56         return count;
  57 }
  58
  59 /*
  60  * Read a block from W1 ROM two times and compares the results.
  61  * If they are equal they are returned, otherwise the read
  62  * is repeated W1_F2D_READ_RETRIES times.
  63  *
  64  * count must not exceed W1_F2D_READ_MAXLEN.
  65  */
  66 static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)
  67 {
  68         u8 wrbuf[3];
  69         u8 cmp[W1_F2D_READ_MAXLEN];
  70         int tries = W1_F2D_READ_RETRIES;
  71
  72         do {
  73                 wrbuf[0] = W1_F2D_READ_EEPROM;
  74                 wrbuf[1] = off & 0xff;
  75                 wrbuf[2] = off >> 8;
  76
  77                 if (w1_reset_select_slave(sl))
  78                         return -1;
  79
  80                 w1_write_block(sl->master, wrbuf, 3);
  81                 w1_read_block(sl->master, buf, count);
  82
  83                 if (w1_reset_select_slave(sl))
  84                         return -1;
  85
  86                 w1_write_block(sl->master, wrbuf, 3);
  87                 w1_read_block(sl->master, cmp, count);
  88
  89                 if (!memcmp(cmp, buf, count))
  90                         return 0;
  91         } while (--tries);
  92
  93         dev_err(&sl->dev, "proof reading failed %d times\n",
  94                         W1_F2D_READ_RETRIES);
  95
  96         return -1;
  97 }
  98
  99 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 100                            struct bin_attribute *bin_attr, char *buf,
 101                            loff_t off, size_t count)
 102 {
 103         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 104         int todo = count;
 105
 106         count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
 107         if (count == 0)
 108                 return 0;
 109
 110         mutex_lock(&sl->master->bus_mutex);
 111
 112         /* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */
 113         while (todo > 0) {
 114                 int block_read;
 115
 116                 if (todo >= W1_F2D_READ_MAXLEN)
 117                         block_read = W1_F2D_READ_MAXLEN;
 118                 else
 119                         block_read = todo;
 120
 121                 if (w1_f2d_readblock(sl, off, block_read, buf) < 0)
 122                         count = -EIO;
 123
 124                 todo -= W1_F2D_READ_MAXLEN;
 125                 buf += W1_F2D_READ_MAXLEN;
 126                 off += W1_F2D_READ_MAXLEN;
 127         }
 128
 129         mutex_unlock(&sl->master->bus_mutex);
 130
 131         return count;
 132 }
 133
 134 /*
 135  * Writes to the scratchpad and reads it back for verification.
 136  * Then copies the scratchpad to EEPROM.
 137  * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and
 138  * must be W1_F2D_SCRATCH_SIZE bytes long.
 139  * The master must be locked.
 140  *
 141  * @param sl    The slave structure
 142  * @param addr  Address for the write
 143  * @param len   length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
 144  * @param data  The data to write
 145  * @return      0=Success -1=failure
 146  */
 147 static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 148 {
 149         int tries = W1_F2D_READ_RETRIES;
 150         u8 wrbuf[4];
 151         u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
 152         u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;
 153
 154 retry:
 155
 156         /* Write the data to the scratchpad */
 157         if (w1_reset_select_slave(sl))
 158                 return -1;
 159
 160         wrbuf[0] = W1_F2D_WRITE_SCRATCH;
 161         wrbuf[1] = addr & 0xff;
 162         wrbuf[2] = addr >> 8;
 163
 164         w1_write_block(sl->master, wrbuf, 3);
 165         w1_write_block(sl->master, data, len);
 166
 167         /* Read the scratchpad and verify */
 168         if (w1_reset_select_slave(sl))
 169                 return -1;
 170
 171         w1_write_8(sl->master, W1_F2D_READ_SCRATCH);
 172         w1_read_block(sl->master, rdbuf, len + 3);
 173
 174         /* Compare what was read against the data written */
 175         if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
 176             (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0)) {
 177
 178                 if (--tries)
 179                         goto retry;
 180
 181                 dev_err(&sl->dev,
 182                         "could not write to eeprom, scratchpad compare failed %d times\n",
 183                         W1_F2D_READ_RETRIES);
 184
 185                 return -1;
 186         }
 187
 188         /* Copy the scratchpad to EEPROM */
 189         if (w1_reset_select_slave(sl))
 190                 return -1;
 191
 192         wrbuf[0] = W1_F2D_COPY_SCRATCH;
 193         wrbuf[3] = es;
 194         w1_write_block(sl->master, wrbuf, 4);
 195
 196         /* Sleep for tprog ms to wait for the write to complete */
 197         msleep(W1_F2D_TPROG_MS);
 198
 199         /* Reset the bus to wake up the EEPROM  */
 200         w1_reset_bus(sl->master);
 201
 202         return 0;
 203 }
 204
 205 static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
 206                             struct bin_attribute *bin_attr, char *buf,
 207                             loff_t off, size_t count)
 208 {
 209         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 210         int addr, len;
 211         int copy;
 212
 213         count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
 214         if (count == 0)
 215                 return 0;
 216
 217         mutex_lock(&sl->master->bus_mutex);
 218
 219         /* Can only write data in blocks of the size of the scratchpad */
 220         addr = off;
 221         len = count;
 222         while (len > 0) {
 223
 224                 /* if len too short or addr not aligned */
 225                 if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
 226                         char tmp[W1_F2D_SCRATCH_SIZE];
 227
 228                         /* read the block and update the parts to be written */
 229                         if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,
 230                                         W1_F2D_SCRATCH_SIZE, tmp)) {
 231                                 count = -EIO;
 232                                 goto out_up;
 233                         }
 234
 235                         /* copy at most to the boundary of the PAGE or len */
 236                         copy = W1_F2D_SCRATCH_SIZE -
 237                                 (addr & W1_F2D_SCRATCH_MASK);
 238
 239                         if (copy > len)
 240                                 copy = len;
 241
 242                         memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
 243                         if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,
 244                                         W1_F2D_SCRATCH_SIZE, tmp) < 0) {
 245                                 count = -EIO;
 246                                 goto out_up;
 247                         }
 248                 } else {
 249
 250                         copy = W1_F2D_SCRATCH_SIZE;
 251                         if (w1_f2d_write(sl, addr, copy, buf) < 0) {
 252                                 count = -EIO;
 253                                 goto out_up;
 254                         }
 255                 }
 256                 buf += copy;
 257                 addr += copy;
 258                 len -= copy;
 259         }
 260
 261 out_up:
 262         mutex_unlock(&sl->master->bus_mutex);
 263
 264         return count;
 265 }
 266
 267 static BIN_ATTR_RW(eeprom, W1_F2D_EEPROM_SIZE);
 268
 269 static struct bin_attribute *w1_f2d_bin_attrs[] = {
 270         &bin_attr_eeprom,
 271         NULL,
 272 };
 273
 274 static const struct attribute_group w1_f2d_group = {
 275         .bin_attrs = w1_f2d_bin_attrs,
 276 };
 277
 278 static const struct attribute_group *w1_f2d_groups[] = {
 279         &w1_f2d_group,
 280         NULL,
 281 };
 282
 283 static struct w1_family_ops w1_f2d_fops = {
 284         .groups         = w1_f2d_groups,
 285 };
 286
 287 static struct w1_family w1_family_2d = {
 288         .fid = W1_EEPROM_DS2431,
 289         .fops = &w1_f2d_fops,
 290 };
 291 module_w1_family(w1_family_2d);
 292
 293 MODULE_AUTHOR("Bernhard Weirich <bernhard.weirich@riedel.net>");
 294 MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");
 295 MODULE_LICENSE("GPL");
 296 MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2431));