w1_ds2431.c

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/*
 * w1_ds2431.c - w1 family 2d (DS2431) driver
 *
 * Copyright (c) 2008 Bernhard Weirich <[email protected]>
 *
 * Heavily inspired by w1_DS2433 driver from 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 "../w1.h"
#include "../w1_int.h"
#include "../w1_family.h"

#define W1_F2D_EEPROM_SIZE      128
#define W1_F2D_PAGE_COUNT       4
#define W1_F2D_PAGE_BITS        5
#define W1_F2D_PAGE_SIZE        (1<<W1_F2D_PAGE_BITS)
#define W1_F2D_PAGE_MASK        0x1F

#define W1_F2D_SCRATCH_BITS  3
#define W1_F2D_SCRATCH_SIZE  (1<<W1_F2D_SCRATCH_BITS)
#define W1_F2D_SCRATCH_MASK  (W1_F2D_SCRATCH_SIZE-1)

#define W1_F2D_READ_EEPROM  0xF0
#define W1_F2D_WRITE_SCRATCH    0x0F
#define W1_F2D_READ_SCRATCH 0xAA
#define W1_F2D_COPY_SCRATCH 0x55


#define W1_F2D_TPROG_MS     11

#define W1_F2D_READ_RETRIES     10
#define W1_F2D_READ_MAXLEN      8

/*
 * Check the file size bounds and adjusts count as needed.
 * This would not be needed if the file size didn't reset to 0 after a write.
 */
static inline size_t w1_f2d_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;
}

/*
 * Read a block from W1 ROM two times and compares the results.
 * If they are equal they are returned, otherwise the read
 * is repeated W1_F2D_READ_RETRIES times.
 *
 * count must not exceed W1_F2D_READ_MAXLEN.
 */
static int w1_f2d_readblock(struct w1_slave *sl, int off, int count, char *buf)
{
    u8 wrbuf[3];
    u8 cmp[W1_F2D_READ_MAXLEN];
    int tries = W1_F2D_READ_RETRIES;

    do {
        wrbuf[0] = W1_F2D_READ_EEPROM;
        wrbuf[1] = off & 0xff;
        wrbuf[2] = off >> 8;

        if (w1_reset_select_slave(sl))
            return -1;

        w1_write_block(sl->master, wrbuf, 3);
        w1_read_block(sl->master, buf, count);

        if (w1_reset_select_slave(sl))
            return -1;

        w1_write_block(sl->master, wrbuf, 3);
        w1_read_block(sl->master, cmp, count);

        if (!memcmp(cmp, buf, count))
            return 0;
    } while (--tries);

    dev_err(&sl->dev, "proof reading failed %d times\n",
            W1_F2D_READ_RETRIES);

    return -1;
}

static ssize_t w1_f2d_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);
    int todo = count;

    count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
    if (count == 0)
        return 0;

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

    /* read directly from the EEPROM in chunks of W1_F2D_READ_MAXLEN */
    while (todo > 0) {
        int block_read;

        if (todo >= W1_F2D_READ_MAXLEN)
            block_read = W1_F2D_READ_MAXLEN;
        else
            block_read = todo;

        if (w1_f2d_readblock(sl, off, block_read, buf) < 0)
            count = -EIO;

        todo -= W1_F2D_READ_MAXLEN;
        buf += W1_F2D_READ_MAXLEN;
        off += W1_F2D_READ_MAXLEN;
    }

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

    return count;
}

/*
 * Writes to the scratchpad and reads it back for verification.
 * Then copies the scratchpad to EEPROM.
 * The data must be aligned at W1_F2D_SCRATCH_SIZE bytes and
 * must be W1_F2D_SCRATCH_SIZE bytes long.
 * The master must be locked.
 *
 * @param sl    The slave structure
 * @param addr  Address for the write
 * @param len   length must be <= (W1_F2D_PAGE_SIZE - (addr & W1_F2D_PAGE_MASK))
 * @param data  The data to write
 * @return  0=Success -1=failure
 */
static int w1_f2d_write(struct w1_slave *sl, int addr, int len, const u8 *data)
{
    int tries = W1_F2D_READ_RETRIES;
    u8 wrbuf[4];
    u8 rdbuf[W1_F2D_SCRATCH_SIZE + 3];
    u8 es = (addr + len - 1) % W1_F2D_SCRATCH_SIZE;

retry:

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

    wrbuf[0] = W1_F2D_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_F2D_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)) {

        if (--tries)
            goto retry;

        dev_err(&sl->dev,
            "could not write to eeprom, scratchpad compare failed %d times\n",
            W1_F2D_READ_RETRIES);

        return -1;
    }

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

    wrbuf[0] = W1_F2D_COPY_SCRATCH;
    wrbuf[3] = es;
    w1_write_block(sl->master, wrbuf, 4);

    /* Sleep for tprog ms to wait for the write to complete */
    msleep(W1_F2D_TPROG_MS);

    /* Reset the bus to wake up the EEPROM  */
    w1_reset_bus(sl->master);

    return 0;
}

static ssize_t w1_f2d_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;
    int copy;

    count = w1_f2d_fix_count(off, count, W1_F2D_EEPROM_SIZE);
    if (count == 0)
        return 0;

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

    /* Can only write data in blocks of the size of the scratchpad */
    addr = off;
    len = count;
    while (len > 0) {

        /* if len too short or addr not aligned */
        if (len < W1_F2D_SCRATCH_SIZE || addr & W1_F2D_SCRATCH_MASK) {
            char tmp[W1_F2D_SCRATCH_SIZE];

            /* read the block and update the parts to be written */
            if (w1_f2d_readblock(sl, addr & ~W1_F2D_SCRATCH_MASK,
                    W1_F2D_SCRATCH_SIZE, tmp)) {
                count = -EIO;
                goto out_up;
            }

            /* copy at most to the boundary of the PAGE or len */
            copy = W1_F2D_SCRATCH_SIZE -
                (addr & W1_F2D_SCRATCH_MASK);

            if (copy > len)
                copy = len;

            memcpy(&tmp[addr & W1_F2D_SCRATCH_MASK], buf, copy);
            if (w1_f2d_write(sl, addr & ~W1_F2D_SCRATCH_MASK,
                    W1_F2D_SCRATCH_SIZE, tmp) < 0) {
                count = -EIO;
                goto out_up;
            }
        } else {

            copy = W1_F2D_SCRATCH_SIZE;
            if (w1_f2d_write(sl, addr, copy, buf) < 0) {
                count = -EIO;
                goto out_up;
            }
        }
        buf += copy;
        addr += copy;
        len -= copy;
    }

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

    return count;
}

static struct bin_attribute w1_f2d_bin_attr = {
    .attr = {
        .name = "eeprom",
        .mode = S_IRUGO | S_IWUSR,
    },
    .size = W1_F2D_EEPROM_SIZE,
    .read = w1_f2d_read_bin,
    .write = w1_f2d_write_bin,
};

static int w1_f2d_add_slave(struct w1_slave *sl)
{
    return sysfs_create_bin_file(&sl->dev.kobj, &w1_f2d_bin_attr);
}

static void w1_f2d_remove_slave(struct w1_slave *sl)
{
    sysfs_remove_bin_file(&sl->dev.kobj, &w1_f2d_bin_attr);
}

static struct w1_family_ops w1_f2d_fops = {
    .add_slave      = w1_f2d_add_slave,
    .remove_slave   = w1_f2d_remove_slave,
};

static struct w1_family w1_family_2d = {
    .fid = W1_EEPROM_DS2431,
    .fops = &w1_f2d_fops,
};

static int __init w1_f2d_init(void)
{
    return w1_register_family(&w1_family_2d);
}

static void __exit w1_f2d_fini(void)
{
    w1_unregister_family(&w1_family_2d);
}

module_init(w1_f2d_init);
module_exit(w1_f2d_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Bernhard Weirich <[email protected]>");
MODULE_DESCRIPTION("w1 family 2d driver for DS2431, 1kb EEPROM");