drivers/w1/slaves/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_SLAVE_DS2433_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_int.h"
  26 #include "../w1_family.h"
  27
  28 MODULE_LICENSE("GPL");
  29 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
  30 MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");
  31
  32 #define W1_EEPROM_SIZE          512
  33 #define W1_PAGE_COUNT           16
  34 #define W1_PAGE_SIZE            32
  35 #define W1_PAGE_BITS            5
  36 #define W1_PAGE_MASK            0x1F
  37
  38 #define W1_F23_TIME             300
  39
  40 #define W1_F23_READ_EEPROM      0xF0
  41 #define W1_F23_WRITE_SCRATCH    0x0F
  42 #define W1_F23_READ_SCRATCH     0xAA
  43 #define W1_F23_COPY_SCRATCH     0x55
  44
  45 struct w1_f23_data {
  46         u8      memory[W1_EEPROM_SIZE];
  47         u32     validcrc;
  48 };
  49
  50 /**
  51  * Check the file size bounds and adjusts count as needed.
  52  * This would not be needed if the file size didn't reset to 0 after a write.
  53  */
  54 static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
  55 {
  56         if (off > size)
  57                 return 0;
  58
  59         if ((off + count) > size)
  60                 return (size - off);
  61
  62         return count;
  63 }
  64
  65 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
  66 static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
  67                                 int block)
  68 {
  69         u8      wrbuf[3];
  70         int     off = block * W1_PAGE_SIZE;
  71
  72         if (data->validcrc & (1 << block))
  73                 return 0;
  74
  75         if (w1_reset_select_slave(sl)) {
  76                 data->validcrc = 0;
  77                 return -EIO;
  78         }
  79
  80         wrbuf[0] = W1_F23_READ_EEPROM;
  81         wrbuf[1] = off & 0xff;
  82         wrbuf[2] = off >> 8;
  83         w1_write_block(sl->master, wrbuf, 3);
  84         w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);
  85
  86         /* cache the block if the CRC is valid */
  87         if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
  88                 data->validcrc |= (1 << block);
  89
  90         return 0;
  91 }
  92 #endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
  93
  94 static ssize_t w1_f23_read_bin(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 #ifdef CONFIG_W1_SLAVE_DS2433_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         mutex_lock(&sl->master->mutex);
 110
 111 #ifdef CONFIG_W1_SLAVE_DS2433_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_SLAVE_DS2433_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_SLAVE_DS2433_CRC */
 138
 139 out_up:
 140         mutex_unlock(&sl->master->mutex);
 141
 142         return count;
 143 }
 144
 145 /**
 146  * Writes to the scratchpad and reads it back for verification.
 147  * Then copies the scratchpad to EEPROM.
 148  * The data must be on one page.
 149  * The master must be locked.
 150  *
 151  * @param sl    The slave structure
 152  * @param addr  Address for the write
 153  * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
 154  * @param data  The data to write
 155  * @return      0=Success -1=failure
 156  */
 157 static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 158 {
 159         u8 wrbuf[4];
 160         u8 rdbuf[W1_PAGE_SIZE + 3];
 161         u8 es = (addr + len - 1) & 0x1f;
 162
 163         /* Write the data to the scratchpad */
 164         if (w1_reset_select_slave(sl))
 165                 return -1;
 166
 167         wrbuf[0] = W1_F23_WRITE_SCRATCH;
 168         wrbuf[1] = addr & 0xff;
 169         wrbuf[2] = addr >> 8;
 170
 171         w1_write_block(sl->master, wrbuf, 3);
 172         w1_write_block(sl->master, data, len);
 173
 174         /* Read the scratchpad and verify */
 175         if (w1_reset_select_slave(sl))
 176                 return -1;
 177
 178         w1_write_8(sl->master, W1_F23_READ_SCRATCH);
 179         w1_read_block(sl->master, rdbuf, len + 3);
 180
 181         /* Compare what was read against the data written */
 182         if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
 183             (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
 184                 return -1;
 185
 186         /* Copy the scratchpad to EEPROM */
 187         if (w1_reset_select_slave(sl))
 188                 return -1;
 189
 190         wrbuf[0] = W1_F23_COPY_SCRATCH;
 191         wrbuf[3] = es;
 192         w1_write_block(sl->master, wrbuf, 4);
 193
 194         /* Sleep for 5 ms to wait for the write to complete */
 195         msleep(5);
 196
 197         /* Reset the bus to wake up the EEPROM (this may not be needed) */
 198         w1_reset_bus(sl->master);
 199
 200         return 0;
 201 }
 202
 203 static ssize_t w1_f23_write_bin(struct kobject *kobj,
 204                                 struct bin_attribute *bin_attr,
 205                                 char *buf, loff_t off, size_t count)
 206 {
 207         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 208         int addr, len, idx;
 209
 210         if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
 211                 return 0;
 212
 213 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
 214         /* can only write full blocks in cached mode */
 215         if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
 216                 dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
 217                         (int)off, count);
 218                 return -EINVAL;
 219         }
 220
 221         /* make sure the block CRCs are valid */
 222         for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
 223                 if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
 224                         dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
 225                         return -EINVAL;
 226                 }
 227         }
 228 #endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 229
 230         mutex_lock(&sl->master->mutex);
 231
 232         /* Can only write data to one page at a time */
 233         idx = 0;
 234         while (idx < count) {
 235                 addr = off + idx;
 236                 len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
 237                 if (len > (count - idx))
 238                         len = count - idx;
 239
 240                 if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
 241                         count = -EIO;
 242                         goto out_up;
 243                 }
 244                 idx += len;
 245         }
 246
 247 out_up:
 248         mutex_unlock(&sl->master->mutex);
 249
 250         return count;
 251 }
 252
 253 static struct bin_attribute w1_f23_bin_attr = {
 254         .attr = {
 255                 .name = "eeprom",
 256                 .mode = S_IRUGO | S_IWUSR,
 257         },
 258         .size = W1_EEPROM_SIZE,
 259         .read = w1_f23_read_bin,
 260         .write = w1_f23_write_bin,
 261 };
 262
 263 static int w1_f23_add_slave(struct w1_slave *sl)
 264 {
 265         int err;
 266 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
 267         struct w1_f23_data *data;
 268
 269         data = kzalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
 270         if (!data)
 271                 return -ENOMEM;
 272         sl->family_data = data;
 273
 274 #endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 275
 276         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
 277
 278 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
 279         if (err)
 280                 kfree(data);
 281 #endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 282
 283         return err;
 284 }
 285
 286 static void w1_f23_remove_slave(struct w1_slave *sl)
 287 {
 288 #ifdef CONFIG_W1_SLAVE_DS2433_CRC
 289         kfree(sl->family_data);
 290         sl->family_data = NULL;
 291 #endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 292         sysfs_remove_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
 293 }
 294
 295 static struct w1_family_ops w1_f23_fops = {
 296         .add_slave      = w1_f23_add_slave,
 297         .remove_slave   = w1_f23_remove_slave,
 298 };
 299
 300 static struct w1_family w1_family_23 = {
 301         .fid = W1_EEPROM_DS2433,
 302         .fops = &w1_f23_fops,
 303 };
 304
 305 static int __init w1_f23_init(void)
 306 {
 307         return w1_register_family(&w1_family_23);
 308 }
 309
 310 static void __exit w1_f23_fini(void)
 311 {
 312         w1_unregister_family(&w1_family_23);
 313 }
 314
 315 module_init(w1_f23_init);
 316 module_exit(w1_f23_fini);