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
  19 #define CRC16_INIT              0
  20 #define CRC16_VALID             0xb001
  21
  22 #endif
  23
  24 #include "w1.h"
  25 #include "w1_io.h"
  26 #include "w1_int.h"
  27 #include "w1_family.h"
  28
  29 MODULE_LICENSE("GPL");
  30 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
  31 MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");
  32
  33 #define W1_EEPROM_SIZE          512
  34 #define W1_PAGE_COUNT           16
  35 #define W1_PAGE_SIZE            32
  36 #define W1_PAGE_BITS            5
  37 #define W1_PAGE_MASK            0x1F
  38
  39 #define W1_F23_TIME             300
  40
  41 #define W1_F23_READ_EEPROM      0xF0
  42 #define W1_F23_WRITE_SCRATCH    0x0F
  43 #define W1_F23_READ_SCRATCH     0xAA
  44 #define W1_F23_COPY_SCRATCH     0x55
  45
  46 struct w1_f23_data {
  47         u8      memory[W1_EEPROM_SIZE];
  48         u32     validcrc;
  49 };
  50
  51 /**
  52  * Check the file size bounds and adjusts count as needed.
  53  * This would not be needed if the file size didn't reset to 0 after a write.
  54  */
  55 static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
  56 {
  57         if (off > size)
  58                 return 0;
  59
  60         if ((off + count) > size)
  61                 return (size - off);
  62
  63         return count;
  64 }
  65
  66 #ifdef CONFIG_W1_F23_CRC
  67 static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
  68                                 int block)
  69 {
  70         u8      wrbuf[3];
  71         int     off = block * W1_PAGE_SIZE;
  72
  73         if (data->validcrc & (1 << block))
  74                 return 0;
  75
  76         if (w1_reset_select_slave(sl)) {
  77                 data->validcrc = 0;
  78                 return -EIO;
  79         }
  80
  81         wrbuf[0] = W1_F23_READ_EEPROM;
  82         wrbuf[1] = off & 0xff;
  83         wrbuf[2] = off >> 8;
  84         w1_write_block(sl->master, wrbuf, 3);
  85         w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
  86
  87         /* cache the block if the CRC is valid */
  88         if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
  89                 data->validcrc |= (1 << block);
  90
  91         return 0;
  92 }
  93 #endif  /* CONFIG_W1_F23_CRC */
  94
  95 static ssize_t w1_f23_read_bin(struct kobject *kobj, char *buf, loff_t off,
  96                                size_t count)
  97 {
  98         struct w1_slave *sl = kobj_to_w1_slave(kobj);
  99 #ifdef CONFIG_W1_F23_CRC
 100         struct w1_f23_data *data = sl->family_data;
 101         int i, min_page, max_page;
 102 #else
 103         u8 wrbuf[3];
 104 #endif
 105
 106         if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
 107                 return 0;
 108
 109         atomic_inc(&sl->refcnt);
 110         if (down_interruptible(&sl->master->mutex)) {
 111                 count = 0;
 112                 goto out_dec;
 113         }
 114
 115 #ifdef CONFIG_W1_F23_CRC
 116
 117         min_page = (off >> W1_PAGE_BITS);
 118         max_page = (off + count - 1) >> W1_PAGE_BITS;
 119         for (i = min_page; i <= max_page; i++) {
 120                 if (w1_f23_refresh_block(sl, data, i)) {
 121                         count = -EIO;
 122                         goto out_up;
 123                 }
 124         }
 125         memcpy(buf, &data->memory[off], count);
 126
 127 #else   /* CONFIG_W1_F23_CRC */
 128
 129         /* read directly from the EEPROM */
 130         if (w1_reset_select_slave(sl)) {
 131                 count = -EIO;
 132                 goto out_up;
 133         }
 134
 135         wrbuf[0] = W1_F23_READ_EEPROM;
 136         wrbuf[1] = off & 0xff;
 137         wrbuf[2] = off >> 8;
 138         w1_write_block(sl->master, wrbuf, 3);
 139         w1_read_block(sl->master, buf, count);
 140
 141 #endif  /* CONFIG_W1_F23_CRC */
 142
 143 out_up:
 144         up(&sl->master->mutex);
 145 out_dec:
 146         atomic_dec(&sl->refcnt);
 147
 148         return count;
 149 }
 150
 151 /**
 152  * Writes to the scratchpad and reads it back for verification.
 153  * Then copies the scratchpad to EEPROM.
 154  * The data must be on one page.
 155  * The master must be locked.
 156  *
 157  * @param sl    The slave structure
 158  * @param addr  Address for the write
 159  * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
 160  * @param data  The data to write
 161  * @return      0=Success -1=failure
 162  */
 163 static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 164 {
 165         u8 wrbuf[4];
 166         u8 rdbuf[W1_PAGE_SIZE + 3];
 167         u8 es = (addr + len - 1) & 0x1f;
 168
 169         /* Write the data to the scratchpad */
 170         if (w1_reset_select_slave(sl))
 171                 return -1;
 172
 173         wrbuf[0] = W1_F23_WRITE_SCRATCH;
 174         wrbuf[1] = addr & 0xff;
 175         wrbuf[2] = addr >> 8;
 176
 177         w1_write_block(sl->master, wrbuf, 3);
 178         w1_write_block(sl->master, data, len);
 179
 180         /* Read the scratchpad and verify */
 181         if (w1_reset_select_slave(sl))
 182                 return -1;
 183
 184         w1_write_8(sl->master, W1_F23_READ_SCRATCH);
 185         w1_read_block(sl->master, rdbuf, len + 3);
 186
 187         /* Compare what was read against the data written */
 188         if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
 189             (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
 190                 return -1;
 191
 192         /* Copy the scratchpad to EEPROM */
 193         if (w1_reset_select_slave(sl))
 194                 return -1;
 195
 196         wrbuf[0] = W1_F23_COPY_SCRATCH;
 197         wrbuf[3] = es;
 198         w1_write_block(sl->master, wrbuf, 4);
 199
 200         /* Sleep for 5 ms to wait for the write to complete */
 201         msleep(5);
 202
 203         /* Reset the bus to wake up the EEPROM (this may not be needed) */
 204         w1_reset_bus(sl->master);
 205
 206         return 0;
 207 }
 208
 209 static ssize_t w1_f23_write_bin(struct kobject *kobj, char *buf, loff_t off,
 210                                 size_t count)
 211 {
 212         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 213         int addr, len, idx;
 214
 215         if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
 216                 return 0;
 217
 218 #ifdef CONFIG_W1_F23_CRC
 219         /* can only write full blocks in cached mode */
 220         if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
 221                 dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
 222                         (int)off, count);
 223                 return -EINVAL;
 224         }
 225
 226         /* make sure the block CRCs are valid */
 227         for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
 228                 if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
 229                         dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
 230                         return -EINVAL;
 231                 }
 232         }
 233 #endif  /* CONFIG_W1_F23_CRC */
 234
 235         atomic_inc(&sl->refcnt);
 236         if (down_interruptible(&sl->master->mutex)) {
 237                 count = 0;
 238                 goto out_dec;
 239         }
 240
 241         /* Can only write data to one page at a time */
 242         idx = 0;
 243         while (idx < count) {
 244                 addr = off + idx;
 245                 len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
 246                 if (len > (count - idx))
 247                         len = count - idx;
 248
 249                 if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
 250                         count = -EIO;
 251                         goto out_up;
 252                 }
 253                 idx += len;
 254         }
 255
 256 out_up:
 257         up(&sl->master->mutex);
 258 out_dec:
 259         atomic_dec(&sl->refcnt);
 260
 261         return count;
 262 }
 263
 264 static struct bin_attribute w1_f23_bin_attr = {
 265         .attr = {
 266                 .name = "eeprom",
 267                 .mode = S_IRUGO | S_IWUSR,
 268                 .owner = THIS_MODULE,
 269         },
 270         .size = W1_EEPROM_SIZE,
 271         .read = w1_f23_read_bin,
 272         .write = w1_f23_write_bin,
 273 };
 274
 275 static int w1_f23_add_slave(struct w1_slave *sl)
 276 {
 277         int err;
 278 #ifdef CONFIG_W1_F23_CRC
 279         struct w1_f23_data *data;
 280
 281         data = kmalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
 282         if (!data)
 283                 return -ENOMEM;
 284         memset(data, 0, sizeof(struct w1_f23_data));
 285         sl->family_data = data;
 286
 287 #endif  /* CONFIG_W1_F23_CRC */
 288
 289         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
 290
 291 #ifdef CONFIG_W1_F23_CRC
 292         if (err)
 293                 kfree(data);
 294 #endif  /* CONFIG_W1_F23_CRC */
 295
 296         return err;
 297 }
 298
 299 static void w1_f23_remove_slave(struct w1_slave *sl)
 300 {
 301 #ifdef CONFIG_W1_F23_CRC
 302         kfree(sl->family_data);
 303         sl->family_data = NULL;
 304 #endif  /* CONFIG_W1_F23_CRC */
 305         sysfs_remove_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
 306 }
 307
 308 static struct w1_family_ops w1_f23_fops = {
 309         .add_slave      = w1_f23_add_slave,
 310         .remove_slave   = w1_f23_remove_slave,
 311 };
 312
 313 static struct w1_family w1_family_23 = {
 314         .fid = W1_EEPROM_DS2433,
 315         .fops = &w1_f23_fops,
 316 };
 317
 318 static int __init w1_f23_init(void)
 319 {
 320         return w1_register_family(&w1_family_23);
 321 }
 322
 323 static void __exit w1_f23_fini(void)
 324 {
 325         w1_unregister_family(&w1_family_23);
 326 }
 327
 328 module_init(w1_f23_init);
 329 module_exit(w1_f23_fini);