w1_ds2433.c

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/*
 *  w1_ds2433.c - w1 family 23 (DS2433) driver
 *
 * Copyright (c) 2005 Ben Gardner <[email protected]>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2. See the file COPYING for more details.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/slab.h>
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
#include <linux/crc16.h>

#define CRC16_INIT      0
#define CRC16_VALID     0xb001

#endif

#include "../w1.h"
#include "../w1_int.h"
#include "../w1_family.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ben Gardner <[email protected]>");
MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");

#define W1_EEPROM_SIZE      512
#define W1_PAGE_COUNT       16
#define W1_PAGE_SIZE        32
#define W1_PAGE_BITS        5
#define W1_PAGE_MASK        0x1F

#define W1_F23_TIME     300

#define W1_F23_READ_EEPROM  0xF0
#define W1_F23_WRITE_SCRATCH    0x0F
#define W1_F23_READ_SCRATCH 0xAA
#define W1_F23_COPY_SCRATCH 0x55

struct w1_f23_data {
    u8  memory[W1_EEPROM_SIZE];
    u32 validcrc;
};

static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)
{
    if (off > size)
        return 0;

    if ((off + count) > size)
        return (size - off);

    return count;
}

#ifdef CONFIG_W1_SLAVE_DS2433_CRC
static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,
                int block)
{
    u8  wrbuf[3];
    int off = block * W1_PAGE_SIZE;

    if (data->validcrc & (1 << block))
        return 0;

    if (w1_reset_select_slave(sl)) {
        data->validcrc = 0;
        return -EIO;
    }

    wrbuf[0] = W1_F23_READ_EEPROM;
    wrbuf[1] = off & 0xff;
    wrbuf[2] = off >> 8;
    w1_write_block(sl->master, wrbuf, 3);
    w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);

    /* cache the block if the CRC is valid */
    if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)
        data->validcrc |= (1 << block);

    return 0;
}
#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

static ssize_t w1_f23_read_bin(struct file *filp, struct kobject *kobj,
                   struct bin_attribute *bin_attr,
                   char *buf, loff_t off, size_t count)
{
    struct w1_slave *sl = kobj_to_w1_slave(kobj);
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
    struct w1_f23_data *data = sl->family_data;
    int i, min_page, max_page;
#else
    u8 wrbuf[3];
#endif

    if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
        return 0;

    mutex_lock(&sl->master->bus_mutex);

#ifdef CONFIG_W1_SLAVE_DS2433_CRC

    min_page = (off >> W1_PAGE_BITS);
    max_page = (off + count - 1) >> W1_PAGE_BITS;
    for (i = min_page; i <= max_page; i++) {
        if (w1_f23_refresh_block(sl, data, i)) {
            count = -EIO;
            goto out_up;
        }
    }
    memcpy(buf, &data->memory[off], count);

#else   /* CONFIG_W1_SLAVE_DS2433_CRC */

    /* read directly from the EEPROM */
    if (w1_reset_select_slave(sl)) {
        count = -EIO;
        goto out_up;
    }

    wrbuf[0] = W1_F23_READ_EEPROM;
    wrbuf[1] = off & 0xff;
    wrbuf[2] = off >> 8;
    w1_write_block(sl->master, wrbuf, 3);
    w1_read_block(sl->master, buf, count);

#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

out_up:
    mutex_unlock(&sl->master->bus_mutex);

    return count;
}

static int w1_f23_write(struct w1_slave *sl, int addr, int len, const u8 *data)
{
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
    struct w1_f23_data *f23 = sl->family_data;
#endif
    u8 wrbuf[4];
    u8 rdbuf[W1_PAGE_SIZE + 3];
    u8 es = (addr + len - 1) & 0x1f;

    /* Write the data to the scratchpad */
    if (w1_reset_select_slave(sl))
        return -1;

    wrbuf[0] = W1_F23_WRITE_SCRATCH;
    wrbuf[1] = addr & 0xff;
    wrbuf[2] = addr >> 8;

    w1_write_block(sl->master, wrbuf, 3);
    w1_write_block(sl->master, data, len);

    /* Read the scratchpad and verify */
    if (w1_reset_select_slave(sl))
        return -1;

    w1_write_8(sl->master, W1_F23_READ_SCRATCH);
    w1_read_block(sl->master, rdbuf, len + 3);

    /* Compare what was read against the data written */
    if ((rdbuf[0] != wrbuf[1]) || (rdbuf[1] != wrbuf[2]) ||
        (rdbuf[2] != es) || (memcmp(data, &rdbuf[3], len) != 0))
        return -1;

    /* Copy the scratchpad to EEPROM */
    if (w1_reset_select_slave(sl))
        return -1;

    wrbuf[0] = W1_F23_COPY_SCRATCH;
    wrbuf[3] = es;
    w1_write_block(sl->master, wrbuf, 4);

    /* Sleep for 5 ms to wait for the write to complete */
    msleep(5);

    /* Reset the bus to wake up the EEPROM (this may not be needed) */
    w1_reset_bus(sl->master);
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
    f23->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
#endif
    return 0;
}

static ssize_t w1_f23_write_bin(struct file *filp, struct kobject *kobj,
                struct bin_attribute *bin_attr,
                char *buf, loff_t off, size_t count)
{
    struct w1_slave *sl = kobj_to_w1_slave(kobj);
    int addr, len, idx;

    if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)
        return 0;

#ifdef CONFIG_W1_SLAVE_DS2433_CRC
    /* can only write full blocks in cached mode */
    if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {
        dev_err(&sl->dev, "invalid offset/count off=%d cnt=%zd\n",
            (int)off, count);
        return -EINVAL;
    }

    /* make sure the block CRCs are valid */
    for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {
        if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {
            dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);
            return -EINVAL;
        }
    }
#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

    mutex_lock(&sl->master->bus_mutex);

    /* Can only write data to one page at a time */
    idx = 0;
    while (idx < count) {
        addr = off + idx;
        len = W1_PAGE_SIZE - (addr & W1_PAGE_MASK);
        if (len > (count - idx))
            len = count - idx;

        if (w1_f23_write(sl, addr, len, &buf[idx]) < 0) {
            count = -EIO;
            goto out_up;
        }
        idx += len;
    }

out_up:
    mutex_unlock(&sl->master->bus_mutex);

    return count;
}

static struct bin_attribute w1_f23_bin_attr = {
    .attr = {
        .name = "eeprom",
        .mode = S_IRUGO | S_IWUSR,
    },
    .size = W1_EEPROM_SIZE,
    .read = w1_f23_read_bin,
    .write = w1_f23_write_bin,
};

static int w1_f23_add_slave(struct w1_slave *sl)
{
    int err;
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
    struct w1_f23_data *data;

    data = kzalloc(sizeof(struct w1_f23_data), GFP_KERNEL);
    if (!data)
        return -ENOMEM;
    sl->family_data = data;

#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

    err = sysfs_create_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);

#ifdef CONFIG_W1_SLAVE_DS2433_CRC
    if (err)
        kfree(data);
#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */

    return err;
}

static void w1_f23_remove_slave(struct w1_slave *sl)
{
#ifdef CONFIG_W1_SLAVE_DS2433_CRC
    kfree(sl->family_data);
    sl->family_data = NULL;
#endif  /* CONFIG_W1_SLAVE_DS2433_CRC */
    sysfs_remove_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);
}

static struct w1_family_ops w1_f23_fops = {
    .add_slave      = w1_f23_add_slave,
    .remove_slave   = w1_f23_remove_slave,
};

static struct w1_family w1_family_23 = {
    .fid = W1_EEPROM_DS2433,
    .fops = &w1_f23_fops,
};

static int __init w1_f23_init(void)
{
    return w1_register_family(&w1_family_23);
}

static void __exit w1_f23_fini(void)
{
    w1_unregister_family(&w1_family_23);
}

module_init(w1_f23_init);
module_exit(w1_f23_fini);