drivers/w1/slaves/w1_ds2805.c

   1 /*
   2  * w1_ds2805 - w1 family 0d (DS28E05) driver
   3  *
   4  * Copyright (c) 2016 Andrew Worsley amworsley@gmail.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
  17 #include <linux/w1.h>
  18
  19 #define W1_EEPROM_DS2805       0x0D
  20
  21 #define W1_F0D_EEPROM_SIZE              128
  22 #define W1_F0D_PAGE_BITS                3
  23 #define W1_F0D_PAGE_SIZE                (1<<W1_F0D_PAGE_BITS)
  24 #define W1_F0D_PAGE_MASK                0x0F
  25
  26 #define W1_F0D_SCRATCH_BITS  1
  27 #define W1_F0D_SCRATCH_SIZE  (1<<W1_F0D_SCRATCH_BITS)
  28 #define W1_F0D_SCRATCH_MASK  (W1_F0D_SCRATCH_SIZE-1)
  29
  30 #define W1_F0D_READ_EEPROM      0xF0
  31 #define W1_F0D_WRITE_EEPROM     0x55
  32 #define W1_F0D_RELEASE          0xFF
  33
  34 #define W1_F0D_CS_OK            0xAA /* Chip Status Ok */
  35
  36 #define W1_F0D_TPROG_MS         16
  37
  38 #define W1_F0D_READ_RETRIES             10
  39 #define W1_F0D_READ_MAXLEN              W1_F0D_EEPROM_SIZE
  40
  41 /*
  42  * Check the file size bounds and adjusts count as needed.
  43  * This would not be needed if the file size didn't reset to 0 after a write.
  44  */
  45 static inline size_t w1_f0d_fix_count(loff_t off, size_t count, size_t size)
  46 {
  47         if (off > size)
  48                 return 0;
  49
  50         if ((off + count) > size)
  51                 return size - off;
  52
  53         return count;
  54 }
  55
  56 /*
  57  * Read a block from W1 ROM two times and compares the results.
  58  * If they are equal they are returned, otherwise the read
  59  * is repeated W1_F0D_READ_RETRIES times.
  60  *
  61  * count must not exceed W1_F0D_READ_MAXLEN.
  62  */
  63 static int w1_f0d_readblock(struct w1_slave *sl, int off, int count, char *buf)
  64 {
  65         u8 wrbuf[3];
  66         u8 cmp[W1_F0D_READ_MAXLEN];
  67         int tries = W1_F0D_READ_RETRIES;
  68
  69         do {
  70                 wrbuf[0] = W1_F0D_READ_EEPROM;
  71                 wrbuf[1] = off & 0x7f;
  72                 wrbuf[2] = 0;
  73
  74                 if (w1_reset_select_slave(sl))
  75                         return -1;
  76
  77                 w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
  78                 w1_read_block(sl->master, buf, count);
  79
  80                 if (w1_reset_select_slave(sl))
  81                         return -1;
  82
  83                 w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
  84                 w1_read_block(sl->master, cmp, count);
  85
  86                 if (!memcmp(cmp, buf, count))
  87                         return 0;
  88         } while (--tries);
  89
  90         dev_err(&sl->dev, "proof reading failed %d times\n",
  91                         W1_F0D_READ_RETRIES);
  92
  93         return -1;
  94 }
  95
  96 static ssize_t w1_f0d_read_bin(struct file *filp, struct kobject *kobj,
  97                                struct bin_attribute *bin_attr,
  98                                char *buf, loff_t off, size_t count)
  99 {
 100         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 101         int todo = count;
 102
 103         count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
 104         if (count == 0)
 105                 return 0;
 106
 107         mutex_lock(&sl->master->mutex);
 108
 109         /* read directly from the EEPROM in chunks of W1_F0D_READ_MAXLEN */
 110         while (todo > 0) {
 111                 int block_read;
 112
 113                 if (todo >= W1_F0D_READ_MAXLEN)
 114                         block_read = W1_F0D_READ_MAXLEN;
 115                 else
 116                         block_read = todo;
 117
 118                 if (w1_f0d_readblock(sl, off, block_read, buf) < 0) {
 119                         count = -EIO;
 120                         break;
 121                 }
 122
 123                 todo -= W1_F0D_READ_MAXLEN;
 124                 buf += W1_F0D_READ_MAXLEN;
 125                 off += W1_F0D_READ_MAXLEN;
 126         }
 127
 128         mutex_unlock(&sl->master->mutex);
 129
 130         return count;
 131 }
 132
 133 /*
 134  * Writes to the scratchpad and reads it back for verification.
 135  * Then copies the scratchpad to EEPROM.
 136  * The data must be aligned at W1_F0D_SCRATCH_SIZE bytes and
 137  * must be W1_F0D_SCRATCH_SIZE bytes long.
 138  * The master must be locked.
 139  *
 140  * @param sl    The slave structure
 141  * @param addr  Address for the write
 142  * @param len   length must be <= (W1_F0D_PAGE_SIZE - (addr & W1_F0D_PAGE_MASK))
 143  * @param data  The data to write
 144  * @return      0=Success -1=failure
 145  */
 146 static int w1_f0d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 147 {
 148         int tries = W1_F0D_READ_RETRIES;
 149         u8 wrbuf[3];
 150         u8 rdbuf[W1_F0D_SCRATCH_SIZE];
 151         u8 cs;
 152
 153         if ((addr & 1) || (len != 2)) {
 154                 dev_err(&sl->dev, "%s: bad addr/len -  addr=%#x len=%d\n",
 155                     __func__, addr, len);
 156                 return -1;
 157         }
 158
 159 retry:
 160
 161         /* Write the data to the scratchpad */
 162         if (w1_reset_select_slave(sl))
 163                 return -1;
 164
 165         wrbuf[0] = W1_F0D_WRITE_EEPROM;
 166         wrbuf[1] = addr & 0xff;
 167         wrbuf[2] = 0xff; /* ?? from Example */
 168
 169         w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
 170         w1_write_block(sl->master, data, len);
 171
 172         w1_read_block(sl->master, rdbuf, sizeof(rdbuf));
 173         /* Compare what was read against the data written */
 174         if ((rdbuf[0] != data[0]) || (rdbuf[1] != data[1])) {
 175
 176                 if (--tries)
 177                         goto retry;
 178
 179                 dev_err(&sl->dev,
 180                         "could not write to eeprom, scratchpad compare failed %d times\n",
 181                         W1_F0D_READ_RETRIES);
 182                 pr_info("%s: rdbuf = %#x %#x data = %#x %#x\n",
 183                     __func__, rdbuf[0], rdbuf[1], data[0], data[1]);
 184
 185                 return -1;
 186         }
 187
 188         /* Trigger write out to EEPROM */
 189         w1_write_8(sl->master, W1_F0D_RELEASE);
 190
 191         /* Sleep for tprog ms to wait for the write to complete */
 192         msleep(W1_F0D_TPROG_MS);
 193
 194         /* Check CS (Command Status) == 0xAA ? */
 195         cs = w1_read_8(sl->master);
 196         if (cs != W1_F0D_CS_OK) {
 197                 dev_err(&sl->dev, "save to eeprom failed = CS=%#x\n", cs);
 198                 return -1;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static ssize_t w1_f0d_write_bin(struct file *filp, struct kobject *kobj,
 205                                 struct bin_attribute *bin_attr,
 206                                 char *buf, loff_t off, size_t count)
 207 {
 208         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 209         int addr, len;
 210         int copy;
 211
 212         count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
 213         if (count == 0)
 214                 return 0;
 215
 216         mutex_lock(&sl->master->mutex);
 217
 218         /* Can only write data in blocks of the size of the scratchpad */
 219         addr = off;
 220         len = count;
 221         while (len > 0) {
 222
 223                 /* if len too short or addr not aligned */
 224                 if (len < W1_F0D_SCRATCH_SIZE || addr & W1_F0D_SCRATCH_MASK) {
 225                         char tmp[W1_F0D_SCRATCH_SIZE];
 226
 227                         /* read the block and update the parts to be written */
 228                         if (w1_f0d_readblock(sl, addr & ~W1_F0D_SCRATCH_MASK,
 229                                         W1_F0D_SCRATCH_SIZE, tmp)) {
 230                                 count = -EIO;
 231                                 goto out_up;
 232                         }
 233
 234                         /* copy at most to the boundary of the PAGE or len */
 235                         copy = W1_F0D_SCRATCH_SIZE -
 236                                 (addr & W1_F0D_SCRATCH_MASK);
 237
 238                         if (copy > len)
 239                                 copy = len;
 240
 241                         memcpy(&tmp[addr & W1_F0D_SCRATCH_MASK], buf, copy);
 242                         if (w1_f0d_write(sl, addr & ~W1_F0D_SCRATCH_MASK,
 243                                         W1_F0D_SCRATCH_SIZE, tmp) < 0) {
 244                                 count = -EIO;
 245                                 goto out_up;
 246                         }
 247                 } else {
 248
 249                         copy = W1_F0D_SCRATCH_SIZE;
 250                         if (w1_f0d_write(sl, addr, copy, buf) < 0) {
 251                                 count = -EIO;
 252                                 goto out_up;
 253                         }
 254                 }
 255                 buf += copy;
 256                 addr += copy;
 257                 len -= copy;
 258         }
 259
 260 out_up:
 261         mutex_unlock(&sl->master->mutex);
 262
 263         return count;
 264 }
 265
 266 static struct bin_attribute w1_f0d_bin_attr = {
 267         .attr = {
 268                 .name = "eeprom",
 269                 .mode = S_IRUGO | S_IWUSR,
 270         },
 271         .size = W1_F0D_EEPROM_SIZE,
 272         .read = w1_f0d_read_bin,
 273         .write = w1_f0d_write_bin,
 274 };
 275
 276 static int w1_f0d_add_slave(struct w1_slave *sl)
 277 {
 278         return sysfs_create_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
 279 }
 280
 281 static void w1_f0d_remove_slave(struct w1_slave *sl)
 282 {
 283         sysfs_remove_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
 284 }
 285
 286 static struct w1_family_ops w1_f0d_fops = {
 287         .add_slave      = w1_f0d_add_slave,
 288         .remove_slave   = w1_f0d_remove_slave,
 289 };
 290
 291 static struct w1_family w1_family_2d = {
 292         .fid = W1_EEPROM_DS2805,
 293         .fops = &w1_f0d_fops,
 294 };
 295
 296 static int __init w1_f0d_init(void)
 297 {
 298         pr_info("%s()\n", __func__);
 299         return w1_register_family(&w1_family_2d);
 300 }
 301
 302 static void __exit w1_f0d_fini(void)
 303 {
 304         pr_info("%s()\n", __func__);
 305         w1_unregister_family(&w1_family_2d);
 306 }
 307
 308 module_init(w1_f0d_init);
 309 module_exit(w1_f0d_fini);
 310
 311 MODULE_LICENSE("GPL");
 312 MODULE_AUTHOR("Andrew Worsley amworsley@gmail.com");
 313 MODULE_DESCRIPTION("w1 family 0d driver for DS2805, 1kb EEPROM");