LXR linux/drivers/w1/slaves/w1

   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#include <linux/slab.h>
  17#ifdef CONFIG_W1_SLAVE_DS2433_CRC
  18#include <linux/crc16.h>
  19
  20#define CRC16_INIT              0
  21#define CRC16_VALID             0xb001
  22
  23#endif
  24
  25#include <linux/w1.h>
  26
  27#define W1_EEPROM_DS2433        0x23
  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
  42struct 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 */
  51static 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_SLAVE_DS2433_CRC
  63static 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_SLAVE_DS2433_CRC */
  90
  91static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
  92                           struct bin_attribute *bin_attr, char *buf,
  93                           loff_t off, size_t count)
  94{
  95        struct w1_slave *sl = kobj_to_w1_slave(kobj);
  96#ifdef CONFIG_W1_SLAVE_DS2433_CRC
  97        struct w1_f23_data *data = sl->family_data;
  98        int i, min_page, max_page;
  99#else
 100        u8 wrbuf[3];
 101#endif
 102
 103        if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
 104                return 0;
 105
 106        mutex_lock(&sl->master->bus_mutex);
 107
 108#ifdef CONFIG_W1_SLAVE_DS2433_CRC
 109
 110        min_page = (off >> W1_PAGE_BITS);
 111        max_page = (off + count - 1) >> W1_PAGE_BITS;
 112        for (i = min_page; i <= max_page; i++) {
 113                if (w1_f23_refresh_block(sl, data, i)) {
 114                        count = -EIO;
 115                        goto out_up;
 116                }
 117        }
 118        memcpy(buf, &data->memory[off], count);
 119
 120#else   /* CONFIG_W1_SLAVE_DS2433_CRC */
 121
 122        /* read directly from the EEPROM */
 123        if (w1_reset_select_slave(sl)) {
 124                count = -EIO;
 125                goto out_up;
 126        }
 127
 128        wrbuf[0] = W1_F23_READ_EEPROM;
 129        wrbuf[1] = off & 0xff;
 130        wrbuf[2] = off >> 8;
 131        w1_write_block(sl->master, wrbuf, 3);
 132        w1_read_block(sl->master, buf, count);
 133
 134#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 135
 136out_up:
 137        mutex_unlock(&sl->master->bus_mutex);
 138
 139        return count;
 140}
 141
 142/**
 143 * Writes to the scratchpad and reads it back for verification.
 144 * Then copies the scratchpad to EEPROM.
 145 * The data must be on one page.
 146 * The master must be locked.
 147 *
 148 * @param sl    The slave structure
 149 * @param addr  Address for the write
 150 * @param len   length must be <= (W1_PAGE_SIZE - (addr & W1_PAGE_MASK))
 151 * @param data  The data to write
 152 * @return      0=Success -1=failure
 153 */
 154static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
 155{
 156#ifdef CONFIG_W1_SLAVE_DS2433_CRC
 157        struct w1_f23_data *f23 = sl->family_data;
 158#endif
 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#ifdef CONFIG_W1_SLAVE_DS2433_CRC
 200        f23->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
 201#endif
 202        return 0;
 203}
 204
 205static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
 206                            struct bin_attribute *bin_attr, char *buf,
 207                            loff_t off, size_t count)
 208{
 209        struct w1_slave *sl = kobj_to_w1_slave(kobj);
 210        int addr, len, idx;
 211
 212        if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
 213                return 0;
 214
 215#ifdef CONFIG_W1_SLAVE_DS2433_CRC
 216        /* can only write full blocks in cached mode */
 217        if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
 218                dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
 219                        (int)off, count);
 220                return -EINVAL;
 221        }
 222
 223        /* make sure the block CRCs are valid */
 224        for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
 225                if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
 226                        dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
 227                        return -EINVAL;
 228                }
 229        }
 230#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 231
 232        mutex_lock(&sl->master->bus_mutex);
 233
 234        /* Can only write data to one page at a time */
 235        idx = 0;
 236        while (idx < count) {
 237                addr = off + idx;
 238                len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
 239                if (len > (count - idx))
 240                        len = count - idx;
 241
 242                if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
 243                        count = -EIO;
 244                        goto out_up;
 245                }
 246                idx += len;
 247        }
 248
 249out_up:
 250        mutex_unlock(&sl->master->bus_mutex);
 251
 252        return count;
 253}
 254
 255static BIN_ATTR_RW(eeprom, W1_EEPROM_SIZE);
 256
 257static struct bin_attribute *w1_f23_bin_attributes[] = {
 258        &bin_attr_eeprom,
 259        NULL,
 260};
 261
 262static const struct attribute_group w1_f23_group = {
 263        .bin_attrs = w1_f23_bin_attributes,
 264};
 265
 266static const struct attribute_group *w1_f23_groups[] = {
 267        &w1_f23_group,
 268        NULL,
 269};
 270
 271static int w1_f23_add_slave(struct w1_slave *sl)
 272{
 273#ifdef CONFIG_W1_SLAVE_DS2433_CRC
 274        struct w1_f23_data *data;
 275
 276        data = kzalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
 277        if (!data)
 278                return -ENOMEM;
 279        sl->family_data = data;
 280
 281#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 282        return 0;
 283}
 284
 285static void w1_f23_remove_slave(struct w1_slave *sl)
 286{
 287#ifdef CONFIG_W1_SLAVE_DS2433_CRC
 288        kfree(sl->family_data);
 289        sl->family_data = NULL;
 290#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
 291}
 292
 293static struct w1_family_ops w1_f23_fops = {
 294        .add_slave      = w1_f23_add_slave,
 295        .remove_slave   = w1_f23_remove_slave,
 296        .groups         = w1_f23_groups,
 297};
 298
 299static struct w1_family w1_family_23 = {
 300        .fid = W1_EEPROM_DS2433,
 301        .fops = &w1_f23_fops,
 302};
 303module_w1_family(w1_family_23);
 304
 305MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
 306MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");
 307MODULE_LICENSE("GPL");
 308MODULE_ALIAS("w1-family-" __stringify(W1_EEPROM_DS2433));
 309