ds2482.c

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#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <asm/delay.h>

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

#define DS2482_CMD_RESET        0xF0    /* No param */
#define DS2482_CMD_SET_READ_PTR     0xE1    /* Param: DS2482_PTR_CODE_xxx */
#define DS2482_CMD_CHANNEL_SELECT   0xC3    /* Param: Channel byte - DS2482-800 only */
#define DS2482_CMD_WRITE_CONFIG     0xD2    /* Param: Config byte */
#define DS2482_CMD_1WIRE_RESET      0xB4    /* Param: None */
#define DS2482_CMD_1WIRE_SINGLE_BIT 0x87    /* Param: Bit byte (bit7) */
#define DS2482_CMD_1WIRE_WRITE_BYTE 0xA5    /* Param: Data byte */
#define DS2482_CMD_1WIRE_READ_BYTE  0x96    /* Param: None */
/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
#define DS2482_CMD_1WIRE_TRIPLET    0x78    /* Param: Dir byte (bit7) */

/* Values for DS2482_CMD_SET_READ_PTR */
#define DS2482_PTR_CODE_STATUS      0xF0
#define DS2482_PTR_CODE_DATA        0xE1
#define DS2482_PTR_CODE_CHANNEL     0xD2    /* DS2482-800 only */
#define DS2482_PTR_CODE_CONFIG      0xC3

#define DS2482_REG_CFG_1WS      0x08
#define DS2482_REG_CFG_SPU      0x04
#define DS2482_REG_CFG_PPM      0x02
#define DS2482_REG_CFG_APU      0x01


static const u8 ds2482_chan_wr[8] =
    { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
static const u8 ds2482_chan_rd[8] =
    { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };


#define DS2482_REG_STS_DIR      0x80
#define DS2482_REG_STS_TSB      0x40
#define DS2482_REG_STS_SBR      0x20
#define DS2482_REG_STS_RST      0x10
#define DS2482_REG_STS_LL       0x08
#define DS2482_REG_STS_SD       0x04
#define DS2482_REG_STS_PPD      0x02
#define DS2482_REG_STS_1WB      0x01


static int ds2482_probe(struct i2c_client *client,
            const struct i2c_device_id *id);
static int ds2482_remove(struct i2c_client *client);


static const struct i2c_device_id ds2482_id[] = {
    { "ds2482", 0 },
    { }
};

static struct i2c_driver ds2482_driver = {
    .driver = {
        .owner  = THIS_MODULE,
        .name   = "ds2482",
    },
    .probe      = ds2482_probe,
    .remove     = ds2482_remove,
    .id_table   = ds2482_id,
};

/*
 * Client data (each client gets its own)
 */

struct ds2482_data;

struct ds2482_w1_chan {
    struct ds2482_data  *pdev;
    u8          channel;
    struct w1_bus_master    w1_bm;
};

struct ds2482_data {
    struct i2c_client   *client;
    struct mutex        access_lock;

    /* 1-wire interface(s) */
    int         w1_count;   /* 1 or 8 */
    struct ds2482_w1_chan   w1_ch[8];

    /* per-device values */
    u8          channel;
    u8          read_prt;   /* see DS2482_PTR_CODE_xxx */
    u8          reg_config;
};


static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
{
    if (pdev->read_prt != read_ptr) {
        if (i2c_smbus_write_byte_data(pdev->client,
                          DS2482_CMD_SET_READ_PTR,
                          read_ptr) < 0)
            return -1;

        pdev->read_prt = read_ptr;
    }
    return 0;
}

static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
{
    if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
        return -1;

    pdev->read_prt = DS2482_PTR_CODE_STATUS;
    return 0;
}

static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
                       u8 cmd, u8 byte)
{
    if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
        return -1;

    /* all cmds leave in STATUS, except CONFIG */
    pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
             DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
    return 0;
}


/*
 * 1-Wire interface code
 */

#define DS2482_WAIT_IDLE_TIMEOUT    100

static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
{
    int temp = -1;
    int retries = 0;

    if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
        do {
            temp = i2c_smbus_read_byte(pdev->client);
        } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
             (++retries < DS2482_WAIT_IDLE_TIMEOUT));
    }

    if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
        printk(KERN_ERR "%s: timeout on channel %d\n",
               __func__, pdev->channel);

    return temp;
}

static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
{
    if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
                      ds2482_chan_wr[channel]) < 0)
        return -1;

    pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
    pdev->channel = -1;
    if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
        pdev->channel = channel;
        return 0;
    }
    return -1;
}


static u8 ds2482_w1_touch_bit(void *data, u8 bit)
{
    struct ds2482_w1_chan *pchan = data;
    struct ds2482_data    *pdev = pchan->pdev;
    int status = -1;

    mutex_lock(&pdev->access_lock);

    /* Select the channel */
    ds2482_wait_1wire_idle(pdev);
    if (pdev->w1_count > 1)
        ds2482_set_channel(pdev, pchan->channel);

    /* Send the touch command, wait until 1WB == 0, return the status */
    if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
                  bit ? 0xFF : 0))
        status = ds2482_wait_1wire_idle(pdev);

    mutex_unlock(&pdev->access_lock);

    return (status & DS2482_REG_STS_SBR) ? 1 : 0;
}

static u8 ds2482_w1_triplet(void *data, u8 dbit)
{
    struct ds2482_w1_chan *pchan = data;
    struct ds2482_data    *pdev = pchan->pdev;
    int status = (3 << 5);

    mutex_lock(&pdev->access_lock);

    /* Select the channel */
    ds2482_wait_1wire_idle(pdev);
    if (pdev->w1_count > 1)
        ds2482_set_channel(pdev, pchan->channel);

    /* Send the triplet command, wait until 1WB == 0, return the status */
    if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
                  dbit ? 0xFF : 0))
        status = ds2482_wait_1wire_idle(pdev);

    mutex_unlock(&pdev->access_lock);

    /* Decode the status */
    return (status >> 5);
}

static void ds2482_w1_write_byte(void *data, u8 byte)
{
    struct ds2482_w1_chan *pchan = data;
    struct ds2482_data    *pdev = pchan->pdev;

    mutex_lock(&pdev->access_lock);

    /* Select the channel */
    ds2482_wait_1wire_idle(pdev);
    if (pdev->w1_count > 1)
        ds2482_set_channel(pdev, pchan->channel);

    /* Send the write byte command */
    ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);

    mutex_unlock(&pdev->access_lock);
}

static u8 ds2482_w1_read_byte(void *data)
{
    struct ds2482_w1_chan *pchan = data;
    struct ds2482_data    *pdev = pchan->pdev;
    int result;

    mutex_lock(&pdev->access_lock);

    /* Select the channel */
    ds2482_wait_1wire_idle(pdev);
    if (pdev->w1_count > 1)
        ds2482_set_channel(pdev, pchan->channel);

    /* Send the read byte command */
    ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);

    /* Wait until 1WB == 0 */
    ds2482_wait_1wire_idle(pdev);

    /* Select the data register */
    ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);

    /* Read the data byte */
    result = i2c_smbus_read_byte(pdev->client);

    mutex_unlock(&pdev->access_lock);

    return result;
}


static u8 ds2482_w1_reset_bus(void *data)
{
    struct ds2482_w1_chan *pchan = data;
    struct ds2482_data    *pdev = pchan->pdev;
    int err;
    u8 retval = 1;

    mutex_lock(&pdev->access_lock);

    /* Select the channel */
    ds2482_wait_1wire_idle(pdev);
    if (pdev->w1_count > 1)
        ds2482_set_channel(pdev, pchan->channel);

    /* Send the reset command */
    err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
    if (err >= 0) {
        /* Wait until the reset is complete */
        err = ds2482_wait_1wire_idle(pdev);
        retval = !(err & DS2482_REG_STS_PPD);

        /* If the chip did reset since detect, re-config it */
        if (err & DS2482_REG_STS_RST)
            ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
                         0xF0);
    }

    mutex_unlock(&pdev->access_lock);

    return retval;
}


static int ds2482_probe(struct i2c_client *client,
            const struct i2c_device_id *id)
{
    struct ds2482_data *data;
    int err = -ENODEV;
    int temp1;
    int idx;

    if (!i2c_check_functionality(client->adapter,
                     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
                     I2C_FUNC_SMBUS_BYTE))
        return -ENODEV;

    if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
        err = -ENOMEM;
        goto exit;
    }

    data->client = client;
    i2c_set_clientdata(client, data);

    /* Reset the device (sets the read_ptr to status) */
    if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
        dev_warn(&client->dev, "DS2482 reset failed.\n");
        goto exit_free;
    }

    /* Sleep at least 525ns to allow the reset to complete */
    ndelay(525);

    /* Read the status byte - only reset bit and line should be set */
    temp1 = i2c_smbus_read_byte(client);
    if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
        dev_warn(&client->dev, "DS2482 reset status "
             "0x%02X - not a DS2482\n", temp1);
        goto exit_free;
    }

    /* Detect the 8-port version */
    data->w1_count = 1;
    if (ds2482_set_channel(data, 7) == 0)
        data->w1_count = 8;

    /* Set all config items to 0 (off) */
    ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 0xF0);

    mutex_init(&data->access_lock);

    /* Register 1-wire interface(s) */
    for (idx = 0; idx < data->w1_count; idx++) {
        data->w1_ch[idx].pdev = data;
        data->w1_ch[idx].channel = idx;

        /* Populate all the w1 bus master stuff */
        data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
        data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
        data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
        data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
        data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
        data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;

        err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
        if (err) {
            data->w1_ch[idx].pdev = NULL;
            goto exit_w1_remove;
        }
    }

    return 0;

exit_w1_remove:
    for (idx = 0; idx < data->w1_count; idx++) {
        if (data->w1_ch[idx].pdev != NULL)
            w1_remove_master_device(&data->w1_ch[idx].w1_bm);
    }
exit_free:
    kfree(data);
exit:
    return err;
}

static int ds2482_remove(struct i2c_client *client)
{
    struct ds2482_data   *data = i2c_get_clientdata(client);
    int idx;

    /* Unregister the 1-wire bridge(s) */
    for (idx = 0; idx < data->w1_count; idx++) {
        if (data->w1_ch[idx].pdev != NULL)
            w1_remove_master_device(&data->w1_ch[idx].w1_bm);
    }

    /* Free the memory */
    kfree(data);
    return 0;
}

static int __init sensors_ds2482_init(void)
{
    return i2c_add_driver(&ds2482_driver);
}

static void __exit sensors_ds2482_exit(void)
{
    i2c_del_driver(&ds2482_driver);
}

MODULE_AUTHOR("Ben Gardner <[email protected]>");
MODULE_DESCRIPTION("DS2482 driver");
MODULE_LICENSE("GPL");

module_init(sensors_ds2482_init);
module_exit(sensors_ds2482_exit);