drivers/w1/slaves/w1_ds2805.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * w1_ds2805 - w1 family 0d (DS28E05) driver
   4  *
   5  * Copyright (c) 2016 Andrew Worsley amworsley@gmail.com
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/device.h>
  12 #include <linux/types.h>
  13 #include <linux/delay.h>
  14
  15 #include <linux/w1.h>
  16
  17 #define W1_EEPROM_DS2805       0x0D
  18
  19 #define W1_F0D_EEPROM_SIZE              128
  20 #define W1_F0D_PAGE_BITS                3
  21 #define W1_F0D_PAGE_SIZE                (1<<W1_F0D_PAGE_BITS)
  22 #define W1_F0D_PAGE_MASK                0x0F
  23
  24 #define W1_F0D_SCRATCH_BITS  1
  25 #define W1_F0D_SCRATCH_SIZE  (1<<W1_F0D_SCRATCH_BITS)
  26 #define W1_F0D_SCRATCH_MASK  (W1_F0D_SCRATCH_SIZE-1)
  27
  28 #define W1_F0D_READ_EEPROM      0xF0
  29 #define W1_F0D_WRITE_EEPROM     0x55
  30 #define W1_F0D_RELEASE          0xFF
  31
  32 #define W1_F0D_CS_OK            0xAA /* Chip Status Ok */
  33
  34 #define W1_F0D_TPROG_MS         16
  35
  36 #define W1_F0D_READ_RETRIES             10
  37 #define W1_F0D_READ_MAXLEN              W1_F0D_EEPROM_SIZE
  38
  39 /*
  40  * Check the file size bounds and adjusts count as needed.
  41  * This would not be needed if the file size didn't reset to 0 after a write.
  42  */
  43 static inline size_t w1_f0d_fix_count(loff_t off, size_t count, size_t size)
  44 {
  45         if (off > size)
  46                 return 0;
  47
  48         if ((off + count) > size)
  49                 return size - off;
  50
  51         return count;
  52 }
  53
  54 /*
  55  * Read a block from W1 ROM two times and compares the results.
  56  * If they are equal they are returned, otherwise the read
  57  * is repeated W1_F0D_READ_RETRIES times.
  58  *
  59  * count must not exceed W1_F0D_READ_MAXLEN.
  60  */
  61 static int w1_f0d_readblock(struct w1_slave *sl, int off, int count, char *buf)
  62 {
  63         u8 wrbuf[3];
  64         u8 cmp[W1_F0D_READ_MAXLEN];
  65         int tries = W1_F0D_READ_RETRIES;
  66
  67         do {
  68                 wrbuf[0] = W1_F0D_READ_EEPROM;
  69                 wrbuf[1] = off & 0x7f;
  70                 wrbuf[2] = 0;
  71
  72                 if (w1_reset_select_slave(sl))
  73                         return -1;
  74
  75                 w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
  76                 w1_read_block(sl->master, buf, count);
  77
  78                 if (w1_reset_select_slave(sl))
  79                         return -1;
  80
  81                 w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
  82                 w1_read_block(sl->master, cmp, count);
  83
  84                 if (!memcmp(cmp, buf, count))
  85                         return 0;
  86         } while (--tries);
  87
  88         dev_err(&sl->dev, "proof reading failed %d times\n",
  89                         W1_F0D_READ_RETRIES);
  90
  91         return -1;
  92 }
  93
  94 static ssize_t w1_f0d_read_bin(struct file *filp, struct kobject *kobj,
  95                                struct bin_attribute *bin_attr,
  96                                char *buf, loff_t off, size_t count)
  97 {
  98         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  99         int todo = count;
 100
 101         count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
 102         if (count == 0)
 103                 return 0;
 104
 105         mutex_lock(&sl->master->mutex);
 106
 107         /* read directly from the EEPROM in chunks of W1_F0D_READ_MAXLEN */
 108         while (todo > 0) {
 109                 int block_read;
 110
 111                 if (todo >= W1_F0D_READ_MAXLEN)
 112                         block_read = W1_F0D_READ_MAXLEN;
 113                 else
 114                         block_read = todo;
 115
 116                 if (w1_f0d_readblock(sl, off, block_read, buf) < 0) {
 117                         count = -EIO;
 118                         break;
 119                 }
 120
 121                 todo -= W1_F0D_READ_MAXLEN;
 122                 buf += W1_F0D_READ_MAXLEN;
 123                 off += W1_F0D_READ_MAXLEN;
 124         }
 125
 126         mutex_unlock(&sl->master->mutex);
 127
 128         return count;
 129 }
 130
 131 /*
 132  * Writes to the scratchpad and reads it back for verification.
 133  * Then copies the scratchpad to EEPROM.
 134  * The data must be aligned at W1_F0D_SCRATCH_SIZE bytes and
 135  * must be W1_F0D_SCRATCH_SIZE bytes long.
 136  * The master must be locked.
 137  *
 138  * @param sl    The slave structure
 139  * @param addr  Address for the write
 140  * @param len   length must be <= (W1_F0D_PAGE_SIZE - (addr & W1_F0D_PAGE_MASK))
 141  * @param data  The data to write
 142  * @return      0=Success -1=failure
 143  */
 144 static int w1_f0d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 145 {
 146         int tries = W1_F0D_READ_RETRIES;
 147         u8 wrbuf[3];
 148         u8 rdbuf[W1_F0D_SCRATCH_SIZE];
 149         u8 cs;
 150
 151         if ((addr & 1) || (len != 2)) {
 152                 dev_err(&sl->dev, "%s: bad addr/len -  addr=%#x len=%d\n",
 153                     __func__, addr, len);
 154                 return -1;
 155         }
 156
 157 retry:
 158
 159         /* Write the data to the scratchpad */
 160         if (w1_reset_select_slave(sl))
 161                 return -1;
 162
 163         wrbuf[0] = W1_F0D_WRITE_EEPROM;
 164         wrbuf[1] = addr & 0xff;
 165         wrbuf[2] = 0xff; /* ?? from Example */
 166
 167         w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
 168         w1_write_block(sl->master, data, len);
 169
 170         w1_read_block(sl->master, rdbuf, sizeof(rdbuf));
 171         /* Compare what was read against the data written */
 172         if ((rdbuf[0] != data[0]) || (rdbuf[1] != data[1])) {
 173
 174                 if (--tries)
 175                         goto retry;
 176
 177                 dev_err(&sl->dev,
 178                         "could not write to eeprom, scratchpad compare failed %d times\n",
 179                         W1_F0D_READ_RETRIES);
 180                 pr_info("%s: rdbuf = %#x %#x data = %#x %#x\n",
 181                     __func__, rdbuf[0], rdbuf[1], data[0], data[1]);
 182
 183                 return -1;
 184         }
 185
 186         /* Trigger write out to EEPROM */
 187         w1_write_8(sl->master, W1_F0D_RELEASE);
 188
 189         /* Sleep for tprog ms to wait for the write to complete */
 190         msleep(W1_F0D_TPROG_MS);
 191
 192         /* Check CS (Command Status) == 0xAA ? */
 193         cs = w1_read_8(sl->master);
 194         if (cs != W1_F0D_CS_OK) {
 195                 dev_err(&sl->dev, "save to eeprom failed = CS=%#x\n", cs);
 196                 return -1;
 197         }
 198
 199         return 0;
 200 }
 201
 202 static ssize_t w1_f0d_write_bin(struct file *filp, struct kobject *kobj,
 203                                 struct bin_attribute *bin_attr,
 204                                 char *buf, loff_t off, size_t count)
 205 {
 206         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 207         int addr, len;
 208         int copy;
 209
 210         count = w1_f0d_fix_count(off, count, W1_F0D_EEPROM_SIZE);
 211         if (count == 0)
 212                 return 0;
 213
 214         mutex_lock(&sl->master->mutex);
 215
 216         /* Can only write data in blocks of the size of the scratchpad */
 217         addr = off;
 218         len = count;
 219         while (len > 0) {
 220
 221                 /* if len too short or addr not aligned */
 222                 if (len < W1_F0D_SCRATCH_SIZE || addr & W1_F0D_SCRATCH_MASK) {
 223                         char tmp[W1_F0D_SCRATCH_SIZE];
 224
 225                         /* read the block and update the parts to be written */
 226                         if (w1_f0d_readblock(sl, addr & ~W1_F0D_SCRATCH_MASK,
 227                                         W1_F0D_SCRATCH_SIZE, tmp)) {
 228                                 count = -EIO;
 229                                 goto out_up;
 230                         }
 231
 232                         /* copy at most to the boundary of the PAGE or len */
 233                         copy = W1_F0D_SCRATCH_SIZE -
 234                                 (addr & W1_F0D_SCRATCH_MASK);
 235
 236                         if (copy > len)
 237                                 copy = len;
 238
 239                         memcpy(&tmp[addr & W1_F0D_SCRATCH_MASK], buf, copy);
 240                         if (w1_f0d_write(sl, addr & ~W1_F0D_SCRATCH_MASK,
 241                                         W1_F0D_SCRATCH_SIZE, tmp) < 0) {
 242                                 count = -EIO;
 243                                 goto out_up;
 244                         }
 245                 } else {
 246
 247                         copy = W1_F0D_SCRATCH_SIZE;
 248                         if (w1_f0d_write(sl, addr, copy, buf) < 0) {
 249                                 count = -EIO;
 250                                 goto out_up;
 251                         }
 252                 }
 253                 buf += copy;
 254                 addr += copy;
 255                 len -= copy;
 256         }
 257
 258 out_up:
 259         mutex_unlock(&sl->master->mutex);
 260
 261         return count;
 262 }
 263
 264 static struct bin_attribute w1_f0d_bin_attr = {
 265         .attr = {
 266                 .name = "eeprom",
 267                 .mode = S_IRUGO | S_IWUSR,
 268         },
 269         .size = W1_F0D_EEPROM_SIZE,
 270         .read = w1_f0d_read_bin,
 271         .write = w1_f0d_write_bin,
 272 };
 273
 274 static int w1_f0d_add_slave(struct w1_slave *sl)
 275 {
 276         return sysfs_create_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
 277 }
 278
 279 static void w1_f0d_remove_slave(struct w1_slave *sl)
 280 {
 281         sysfs_remove_bin_file(&sl->dev.kobj, &w1_f0d_bin_attr);
 282 }
 283
 284 static const struct w1_family_ops w1_f0d_fops = {
 285         .add_slave      = w1_f0d_add_slave,
 286         .remove_slave   = w1_f0d_remove_slave,
 287 };
 288
 289 static struct w1_family w1_family_0d = {
 290         .fid = W1_EEPROM_DS2805,
 291         .fops = &w1_f0d_fops,
 292 };
 293
 294 static int __init w1_f0d_init(void)
 295 {
 296         pr_info("%s()\n", __func__);
 297         return w1_register_family(&w1_family_0d);
 298 }
 299
 300 static void __exit w1_f0d_fini(void)
 301 {
 302         pr_info("%s()\n", __func__);
 303         w1_unregister_family(&w1_family_0d);
 304 }
 305
 306 module_init(w1_f0d_init);
 307 module_exit(w1_f0d_fini);
 308
 309 MODULE_LICENSE("GPL");
 310 MODULE_AUTHOR("Andrew Worsley amworsley@gmail.com");
 311 MODULE_DESCRIPTION("w1 family 0d driver for DS2805, 1kb EEPROM");