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/**

 * ds2482.c - provides i2c to w1-master bridge(s)

 * Copyright (C) 2005  Ben Gardner <bgardner@wabtec.com>

 *

 * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim).

 * It is a I2C to 1-wire bridge.

 * There are two variations: -100 and -800, which have 1 or 8 1-wire ports.

 * The complete datasheet can be obtained from MAXIM's website at:

 *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; version 2 of the License.

 */

#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"

/**

 * Address is selected using 2 pins, resulting in 4 possible addresses.

 *  0x18, 0x19, 0x1a, 0x1b

 * However, the chip cannot be detected without doing an i2c write,

 * so use the force module parameter.

 */

static unsigned short normal_i2c[] = {I2C_CLIENT_END};

/**

 * Insmod parameters

 */

I2C_CLIENT_INSMOD_1(ds2482);

/**

 * The DS2482 registers - there are 3 registers that are addressed by a read

 * pointer. The read pointer is set by the last command executed.

 *

 * To read the data, issue a register read for any address

 */

#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

/**

 * Configure Register bit definitions

 * The top 4 bits always read 0.

 * To write, the top nibble must be the 1's compl. of the low nibble.

 */

#define DS2482_REG_CFG_1WS              0x08

#define DS2482_REG_CFG_SPU              0x04

#define DS2482_REG_CFG_PPM              0x02

#define DS2482_REG_CFG_APU              0x01

/**

 * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).

 * To set the channel, write the value at the index of the channel.

 * Read and compare against the corresponding value to verify the change.

 */

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 };

/**

 * Status Register bit definitions (read only)

 */

#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_attach_adapter(struct i2c_adapter *adapter);

static int ds2482_detect(struct i2c_adapter *adapter, int address, int kind);

static int ds2482_detach_client(struct i2c_client *client);

/**

 * Driver data (common to all clients)

 */

static struct i2c_driver ds2482_driver = {

        .driver = {

                .owner  = THIS_MODULE,

                .name   = "ds2482",

        },

        .attach_adapter = ds2482_attach_adapter,

        .detach_client  = ds2482_detach_client,

};

/*

 * 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;

};

/**

 * Sets the read pointer.

 * @param pdev          The ds2482 client pointer

 * @param read_ptr      see DS2482_PTR_CODE_xxx above

 * @return -1 on failure, 0 on success

 */

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;

}

/**

 * Sends a command without a parameter

 * @param pdev  The ds2482 client pointer

 * @param cmd   DS2482_CMD_RESET,

 *              DS2482_CMD_1WIRE_RESET,

 *              DS2482_CMD_1WIRE_READ_BYTE

 * @return -1 on failure, 0 on success

 */

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;

}

/**

 * Sends a command with a parameter

 * @param pdev  The ds2482 client pointer

 * @param cmd   DS2482_CMD_WRITE_CONFIG,

 *              DS2482_CMD_1WIRE_SINGLE_BIT,

 *              DS2482_CMD_1WIRE_WRITE_BYTE,

 *              DS2482_CMD_1WIRE_TRIPLET

 * @param byte  The data to send

 * @return -1 on failure, 0 on success

 */

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

/**

 * Waits until the 1-wire interface is idle (not busy)

 *

 * @param pdev Pointer to the device structure

 * @return the last value read from status or -1 (failure)

 */

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;

}

/**

 * Selects a w1 channel.

 * The 1-wire interface must be idle before calling this function.

 *

 * @param pdev          The ds2482 client pointer

 * @param channel       0-7

 * @return              -1 (failure) or 0 (success)

 */

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;

}

/**

 * Performs the touch-bit function, which writes a 0 or 1 and reads the level.

 *

 * @param data  The ds2482 channel pointer

 * @param bit   The level to write: 0 or non-zero

 * @return      The level read: 0 or 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;

}

/**

 * Performs the triplet function, which reads two bits and writes a bit.

 * The bit written is determined by the two reads:

 *   00 => dbit, 01 => 0, 10 => 1

 *

 * @param data  The ds2482 channel pointer

 * @param dbit  The direction to choose if both branches are valid

 * @return      b0=read1 b1=read2 b3=bit written

 */

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);

}

/**

 * Performs the write byte function.

 *

 * @param data  The ds2482 channel pointer

 * @param byte  The value to write

 */

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);

}

/**

 * Performs the read byte function.

 *

 * @param data  The ds2482 channel pointer

 * @return      The value read

 */

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;

}

/**

 * Sends a reset on the 1-wire interface

 *

 * @param data  The ds2482 channel pointer

 * @return      0=Device present, 1=No device present or error

 */

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;

}

/**

 * Called to see if the device exists on an i2c bus.

 */

static int ds2482_attach_adapter(struct i2c_adapter *adapter)

{

        return i2c_probe(adapter, &addr_data, ds2482_detect);

}

/*

 * The following function does more than just detection. If detection

 * succeeds, it also registers the new chip.

 */

static int ds2482_detect(struct i2c_adapter *adapter, int address, int kind)

{

        struct ds2482_data *data;

        struct i2c_client  *new_client;

        int err = 0;

        int temp1;

        int idx;

        if (!i2c_check_functionality(adapter,

                                     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |

                                     I2C_FUNC_SMBUS_BYTE))

                goto exit;

        if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {

                err = -ENOMEM;

                goto exit;

        }

        new_client = &data->client;

        i2c_set_clientdata(new_client, data);

        new_client->addr = address;

        new_client->driver = &ds2482_driver;

        new_client->adapter = adapter;

        /* Reset the device (sets the read_ptr to status) */

        if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {

                dev_dbg(&adapter->dev, "DS2482 reset failed at 0x%02x.\n",

                        address);

                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(new_client);

        if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {

                dev_dbg(&adapter->dev, "DS2482 (0x%02x) reset status "

                        "0x%02X - not a DS2482\n", address, 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);

        /* We can fill in the remaining client fields */

        snprintf(new_client->name, sizeof(new_client->name), "ds2482-%d00",

                 data->w1_count);

        mutex_init(&data->access_lock);

        /* Tell the I2C layer a new client has arrived */

        if ((err = i2c_attach_client(new_client)))

                goto exit_free;

        /* 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:

        i2c_detach_client(new_client);

        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_detach_client(struct i2c_client *client)

{

        struct ds2482_data   *data = i2c_get_clientdata(client);

        int err, 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);

        }

        /* Detach the i2c device */

        if ((err = i2c_detach_client(client))) {

                dev_err(&client->dev,

                        "Deregistration failed, client not detached.\n");

                return err;

        }

        /* 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 <bgardner@wabtec.com>");

MODULE_DESCRIPTION("DS2482 driver");

MODULE_LICENSE("GPL");

module_init(sensors_ds2482_init);

module_exit(sensors_ds2482_exit);