w1_ds28e04.c

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/*
 *  w1_ds28e04.c - w1 family 1C (DS28E04) driver
 *
 * Copyright (c) 2012 Markus Franke <[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>
#include <linux/crc16.h>
#include <linux/uaccess.h>

#define CRC16_INIT      0
#define CRC16_VALID     0xb001

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

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Markus Franke <[email protected]>, <[email protected]>");
MODULE_DESCRIPTION("w1 family 1C driver for DS28E04, 4kb EEPROM and PIO");

/* Allow the strong pullup to be disabled, but default to enabled.
 * If it was disabled a parasite powered device might not get the required
 * current to copy the data from the scratchpad to EEPROM.  If it is enabled
 * parasite powered devices have a better chance of getting the current
 * required.
 */
static int w1_strong_pullup = 1;
module_param_named(strong_pullup, w1_strong_pullup, int, 0);

/* enable/disable CRC checking on DS28E04-100 memory accesses */
static char w1_enable_crccheck = 1;

#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_F1C_READ_EEPROM  0xF0
#define W1_F1C_WRITE_SCRATCH    0x0F
#define W1_F1C_READ_SCRATCH 0xAA
#define W1_F1C_COPY_SCRATCH 0x55
#define W1_F1C_ACCESS_WRITE 0x5A

#define W1_1C_REG_LOGIC_STATE   0x220

struct w1_f1C_data {
    u8  memory[W1_EEPROM_SIZE];
    u32 validcrc;
};

static inline size_t w1_f1C_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;
}

static int w1_f1C_refresh_block(struct w1_slave *sl, struct w1_f1C_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_F1C_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;
}

static int w1_f1C_read(struct w1_slave *sl, int addr, int len, char *data)
{
    u8 wrbuf[3];

    /* read directly from the EEPROM */
    if (w1_reset_select_slave(sl))
        return -EIO;

    wrbuf[0] = W1_F1C_READ_EEPROM;
    wrbuf[1] = addr & 0xff;
    wrbuf[2] = addr >> 8;

    w1_write_block(sl->master, wrbuf, sizeof(wrbuf));
    return w1_read_block(sl->master, data, len);
}

static ssize_t w1_f1C_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);
    struct w1_f1C_data *data = sl->family_data;
    int i, min_page, max_page;

    count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
    if (count == 0)
        return 0;

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

    if (w1_enable_crccheck) {
        min_page = (off >> W1_PAGE_BITS);
        max_page = (off + count - 1) >> W1_PAGE_BITS;
        for (i = min_page; i <= max_page; i++) {
            if (w1_f1C_refresh_block(sl, data, i)) {
                count = -EIO;
                goto out_up;
            }
        }
        memcpy(buf, &data->memory[off], count);
    } else {
        count = w1_f1C_read(sl, off, count, buf);
    }

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

    return count;
}

static int w1_f1C_write(struct w1_slave *sl, int addr, int len, const u8 *data)
{
    u8 wrbuf[4];
    u8 rdbuf[W1_PAGE_SIZE + 3];
    u8 es = (addr + len - 1) & 0x1f;
    unsigned int tm = 10;
    int i;
    struct w1_f1C_data *f1C = sl->family_data;

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

    wrbuf[0] = W1_F1C_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_F1C_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_F1C_COPY_SCRATCH;
    wrbuf[3] = es;

    for (i = 0; i < sizeof(wrbuf); ++i) {
        /* issue 10ms strong pullup (or delay) on the last byte
           for writing the data from the scratchpad to EEPROM */
        if (w1_strong_pullup && i == sizeof(wrbuf)-1)
            w1_next_pullup(sl->master, tm);

        w1_write_8(sl->master, wrbuf[i]);
    }

    if (!w1_strong_pullup)
        msleep(tm);

    if (w1_enable_crccheck) {
        /* invalidate cached data */
        f1C->validcrc &= ~(1 << (addr >> W1_PAGE_BITS));
    }

    /* Reset the bus to wake up the EEPROM (this may not be needed) */
    w1_reset_bus(sl->master);

    return 0;
}

static ssize_t w1_f1C_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;

    count = w1_f1C_fix_count(off, count, W1_EEPROM_SIZE);
    if (count == 0)
        return 0;

    if (w1_enable_crccheck) {
        /* 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;
            }
        }
    }

    mutex_lock(&sl->master->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_f1C_write(sl, addr, len, &buf[idx]) < 0) {
            count = -EIO;
            goto out_up;
        }
        idx += len;
    }

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

    return count;
}

static ssize_t w1_f1C_read_pio(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 ret;

    /* check arguments */
    if (off != 0 || count != 1 || buf == NULL)
        return -EINVAL;

    mutex_lock(&sl->master->mutex);
    ret = w1_f1C_read(sl, W1_1C_REG_LOGIC_STATE, count, buf);
    mutex_unlock(&sl->master->mutex);

    return ret;
}

static ssize_t w1_f1C_write_pio(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);
    u8 wrbuf[3];
    u8 ack;

    /* check arguments */
    if (off != 0 || count != 1 || buf == NULL)
        return -EINVAL;

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

    /* Write the PIO data */
    if (w1_reset_select_slave(sl)) {
        mutex_unlock(&sl->master->mutex);
        return -1;
    }

    /* set bit 7..2 to value '1' */
    *buf = *buf | 0xFC;

    wrbuf[0] = W1_F1C_ACCESS_WRITE;
    wrbuf[1] = *buf;
    wrbuf[2] = ~(*buf);
    w1_write_block(sl->master, wrbuf, 3);

    w1_read_block(sl->master, &ack, sizeof(ack));

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

    /* check for acknowledgement */
    if (ack != 0xAA)
        return -EIO;

    return count;
}

static ssize_t w1_f1C_show_crccheck(struct device *dev,
                    struct device_attribute *attr, char *buf)
{
    if (put_user(w1_enable_crccheck + 0x30, buf))
        return -EFAULT;

    return sizeof(w1_enable_crccheck);
}

static ssize_t w1_f1C_store_crccheck(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf, size_t count)
{
    char val;

    if (count != 1 || !buf)
        return -EINVAL;

    if (get_user(val, buf))
        return -EFAULT;

    /* convert to decimal */
    val = val - 0x30;
    if (val != 0 && val != 1)
        return -EINVAL;

    /* set the new value */
    w1_enable_crccheck = val;

    return sizeof(w1_enable_crccheck);
}

#define NB_SYSFS_BIN_FILES 2
static struct bin_attribute w1_f1C_bin_attr[NB_SYSFS_BIN_FILES] = {
    {
        .attr = {
            .name = "eeprom",
            .mode = S_IRUGO | S_IWUSR,
        },
        .size = W1_EEPROM_SIZE,
        .read = w1_f1C_read_bin,
        .write = w1_f1C_write_bin,
    },
    {
        .attr = {
            .name = "pio",
            .mode = S_IRUGO | S_IWUSR,
        },
        .size = 1,
        .read = w1_f1C_read_pio,
        .write = w1_f1C_write_pio,
    }
};

static DEVICE_ATTR(crccheck, S_IWUSR | S_IRUGO,
           w1_f1C_show_crccheck, w1_f1C_store_crccheck);

static int w1_f1C_add_slave(struct w1_slave *sl)
{
    int err = 0;
    int i;
    struct w1_f1C_data *data = NULL;

    if (w1_enable_crccheck) {
        data = kzalloc(sizeof(struct w1_f1C_data), GFP_KERNEL);
        if (!data)
            return -ENOMEM;
        sl->family_data = data;
    }

    /* create binary sysfs attributes */
    for (i = 0; i < NB_SYSFS_BIN_FILES && !err; ++i)
        err = sysfs_create_bin_file(
            &sl->dev.kobj, &(w1_f1C_bin_attr[i]));

    if (!err) {
        /* create device attributes */
        err = device_create_file(&sl->dev, &dev_attr_crccheck);
    }

    if (err) {
        /* remove binary sysfs attributes */
        for (i = 0; i < NB_SYSFS_BIN_FILES; ++i)
            sysfs_remove_bin_file(
                &sl->dev.kobj, &(w1_f1C_bin_attr[i]));

        kfree(data);
    }

    return err;
}

static void w1_f1C_remove_slave(struct w1_slave *sl)
{
    int i;

    kfree(sl->family_data);
    sl->family_data = NULL;

    /* remove device attributes */
    device_remove_file(&sl->dev, &dev_attr_crccheck);

    /* remove binary sysfs attributes */
    for (i = 0; i < NB_SYSFS_BIN_FILES; ++i)
        sysfs_remove_bin_file(&sl->dev.kobj, &(w1_f1C_bin_attr[i]));
}

static struct w1_family_ops w1_f1C_fops = {
    .add_slave      = w1_f1C_add_slave,
    .remove_slave   = w1_f1C_remove_slave,
};

static struct w1_family w1_family_1C = {
    .fid = W1_FAMILY_DS28E04,
    .fops = &w1_f1C_fops,
};

static int __init w1_f1C_init(void)
{
    return w1_register_family(&w1_family_1C);
}

static void __exit w1_f1C_fini(void)
{
    w1_unregister_family(&w1_family_1C);
}

module_init(w1_f1C_init);
module_exit(w1_f1C_fini);