drivers/w1/w1_ds2433.c

   1 /*
   2  *      w1_ds2433.c - w1 family 23 (DS2433) driver
   3  *
   4  * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.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 #ifdef CONFIG_W1_F23_CRC
  17 #include <linux/crc16.h>
  18 #endif
  19
  20 #include "w1.h"
  21 #include "w1_io.h"
  22 #include "w1_int.h"
  23 #include "w1_family.h"
  24
  25 MODULE_LICENSE("GPL");
  26 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
  27 MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");
  28
  29 #define W1_EEPROM_SIZE          512
  30 #define W1_PAGE_COUNT           16
  31 #define W1_PAGE_SIZE            32
  32 #define W1_PAGE_BITS            5
  33 #define W1_PAGE_MASK            0x1F
  34
  35 #define W1_F23_TIME             300
  36
  37 #define W1_F23_READ_EEPROM      0xF0
  38 #define W1_F23_WRITE_SCRATCH    0x0F
  39 #define W1_F23_READ_SCRATCH     0xAA
  40 #define W1_F23_COPY_SCRATCH     0x55
  41
  42 struct w1_f23_data {
  43         u8      memory[W1_EEPROM_SIZE];
  44         u32     validcrc;
  45 };
  46
  47 /**
  48  * Check the file size bounds and adjusts count as needed.
  49  * This would not be needed if the file size didn't reset to 0 after a write.
  50  */
  51 static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
  52 {
  53         if (off > size)
  54                 return 0;
  55
  56         if ((off + count) > size)
  57                 return (size - off);
  58
  59         return count;
  60 }
  61
  62 #ifdef CONFIG_W1_F23_CRC
  63 static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
  64                                 int block)
  65 {
  66         u8      wrbuf[3];
  67         int     off = block * W1_PAGE_SIZE;
  68
  69         if (data->validcrc & (1 << block))
  70                 return 0;
  71
  72         if (w1_reset_select_slave(sl)) {
  73                 data->validcrc = 0;
  74                 return -EIO;
  75         }
  76
  77         wrbuf[0] = W1_F23_READ_EEPROM;
  78         wrbuf[1] = off & 0xff;
  79         wrbuf[2] = off >> 8;
  80         w1_write_block(sl->master, wrbuf, 3);
  81         w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
  82
  83         /* cache the block if the CRC is valid */
  84         if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
  85                 data->validcrc |= (1 << block);
  86
  87         return 0;
  88 }
  89 #endif  /* CONFIG_W1_F23_CRC */
  90
  91 static ssize_t w1_f23_read_bin(struct kobject *kobj, char *buf, loff_t off,
  92                                size_t count)
  93 {
  94         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  95 #ifdef CONFIG_W1_F23_CRC
  96         struct w1_f23_data *data = sl->family_data;
  97         int i, min_page, max_page;
  98 #else
  99         u8 wrbuf[3];
 100 #endif
 101
 102         if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
 103                 return 0;
 104
 105         atomic_inc(&sl->refcnt);
 106         if (down_interruptible(&sl->master->mutex)) {
 107                 count = 0;
 108                 goto out_dec;
 109         }
 110
 111 #ifdef CONFIG_W1_F23_CRC
 112
 113         min_page = (off >> W1_PAGE_BITS);
 114         max_page = (off + count - 1) >> W1_PAGE_BITS;
 115         for (i = min_page; i <= max_page; i++) {
 116                 if (w1_f23_refresh_block(sl, data, i)) {
 117                         count = -EIO;
 118                         goto out_up;
 119                 }
 120         }
 121         memcpy(buf, &data->memory[off], count);
 122
 123 #else   /* CONFIG_W1_F23_CRC */
 124
 125         /* read directly from the EEPROM */
 126         if (w1_reset_select_slave(sl)) {
 127                 count = -EIO;
 128                 goto out_up;
 129         }
 130
 131         wrbuf[0] = W1_F23_READ_EEPROM;
 132         wrbuf[1] = off & 0xff;
 133         wrbuf[2] = off >> 8;
 134         w1_write_block(sl->master, wrbuf, 3);
 135         w1_read_block(sl->master, buf, count);
 136
 137 #endif  /* CONFIG_W1_F23_CRC */
 138
 139 out_up:
 140         up(&sl->master->mutex);
 141 out_dec:
 142         atomic_dec(&sl->refcnt);
 143
 144         return count;
 145 }
 146
 147 /**
 148  * Writes to the scratchpad and reads it back for verification.
 149  * Then copies the scratchpad to EEPROM.
 150  * The data must be on one page.
 151  * The master must be locked.
 152  *
 153  * @param sl    The slave structure
 154  * @param addr  Address for the write
 155  * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
 156  * @param data  The data to write
 157  * @return      0=Success -1=failure
 158  */
 159 static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 160 {
 161         u8 wrbuf[4];
 162         u8 rdbuf[W1_PAGE_SIZE + 3];
 163         u8 es = (addr + len - 1) & 0x1f;
 164
 165         /* Write the data to the scratchpad */
 166         if (w1_reset_select_slave(sl))
 167                 return -1;
 168
 169         wrbuf[0] = W1_F23_WRITE_SCRATCH;
 170         wrbuf[1] = addr & 0xff;
 171         wrbuf[2] = addr >> 8;
 172
 173         w1_write_block(sl->master, wrbuf, 3);
 174         w1_write_block(sl->master, data, len);
 175
 176         /* Read the scratchpad and verify */
 177         if (w1_reset_select_slave(sl))
 178                 return -1;
 179
 180         w1_write_8(sl->master, W1_F23_READ_SCRATCH);
 181         w1_read_block(sl->master, rdbuf, len + 3);
 182
 183         /* Compare what was read against the data written */
 184         if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
 185             (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
 186                 return -1;
 187
 188         /* Copy the scratchpad to EEPROM */
 189         if (w1_reset_select_slave(sl))
 190                 return -1;
 191
 192         wrbuf[0] = W1_F23_COPY_SCRATCH;
 193         wrbuf[3] = es;
 194         w1_write_block(sl->master, wrbuf, 4);
 195
 196         /* Sleep for 5 ms to wait for the write to complete */
 197         msleep(5);
 198
 199         /* Reset the bus to wake up the EEPROM (this may not be needed) */
 200         w1_reset_bus(sl->master);
 201
 202         return 0;
 203 }
 204
 205 static ssize_t w1_f23_write_bin(struct kobject *kobj, char *buf, loff_t off,
 206                                 size_t count)
 207 {
 208         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 209         int addr, len, idx;
 210
 211         if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
 212                 return 0;
 213
 214 #ifdef CONFIG_W1_F23_CRC
 215         /* can only write full blocks in cached mode */
 216         if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
 217                 dev_err(&sl->dev, "invalid offset/count off=%d cnt=%d\n",
 218                         (int)off, count);
 219                 return -EINVAL;
 220         }
 221
 222         /* make sure the block CRCs are valid */
 223         for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
 224                 if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
 225                         dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
 226                         return -EINVAL;
 227                 }
 228         }
 229 #endif  /* CONFIG_W1_F23_CRC */
 230
 231         atomic_inc(&sl->refcnt);
 232         if (down_interruptible(&sl->master->mutex)) {
 233                 count = 0;
 234                 goto out_dec;
 235         }
 236
 237         /* Can only write data to one page at a time */
 238         idx = 0;
 239         while (idx < count) {
 240                 addr = off + idx;
 241                 len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
 242                 if (len > (count - idx))
 243                         len = count - idx;
 244
 245                 if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
 246                         count = -EIO;
 247                         goto out_up;
 248                 }
 249                 idx += len;
 250         }
 251
 252 out_up:
 253         up(&sl->master->mutex);
 254 out_dec:
 255         atomic_dec(&sl->refcnt);
 256
 257         return count;
 258 }
 259
 260 static struct bin_attribute w1_f23_bin_attr = {
 261         .attr = {
 262                 .name = "eeprom",
 263                 .mode = S_IRUGO | S_IWUSR,
 264                 .owner = THIS_MODULE,
 265         },
 266         .size = W1_EEPROM_SIZE,
 267         .read = w1_f23_read_bin,
 268         .write = w1_f23_write_bin,
 269 };
 270
 271 static int w1_f23_add_slave(struct w1_slave *sl)
 272 {
 273         int err;
 274 #ifdef CONFIG_W1_F23_CRC
 275         struct w1_f23_data *data;
 276
 277         data = kmalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
 278         if (!data)
 279                 return -ENOMEM;
 280         memset(data, 0, sizeof(struct w1_f23_data));
 281         sl->family_data = data;
 282
 283 #endif  /* CONFIG_W1_F23_CRC */
 284
 285         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
 286
 287 #ifdef CONFIG_W1_F23_CRC
 288         if (err)
 289                 kfree(data);
 290 #endif  /* CONFIG_W1_F23_CRC */
 291
 292         return err;
 293 }
 294
 295 static void w1_f23_remove_slave(struct w1_slave *sl)
 296 {
 297 #ifdef CONFIG_W1_F23_CRC
 298         if (sl->family_data) {
 299                 kfree(sl->family_data);
 300                 sl->family_data = NULL;
 301         }
 302 #endif  /* CONFIG_W1_F23_CRC */
 303         sysfs_remove_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
 304 }
 305
 306 static struct w1_family_ops w1_f23_fops = {
 307         .add_slave      = w1_f23_add_slave,
 308         .remove_slave   = w1_f23_remove_slave,
 309 };
 310
 311 static struct w1_family w1_family_23 = {
 312         .fid = W1_EEPROM_DS2433,
 313         .fops = &w1_f23_fops,
 314 };
 315
 316 static int __init w1_f23_init(void)
 317 {
 318         return w1_register_family(&w1_family_23);
 319 }
 320
 321 static void __exit w1_f23_fini(void)
 322 {
 323         w1_unregister_family(&w1_family_23);
 324 }
 325
 326 module_init(w1_f23_init);
 327 module_exit(w1_f23_fini);