linux-imx

/**

 * 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 <linux/w1.h>

​

/**

 * Allow the active pullup to be disabled, default is enabled.

 *

 * Note from the DS2482 datasheet:

 * The APU bit controls whether an active pullup (controlled slew-rate

 * transistor) or a passive pullup (Rwpu resistor) will be used to drive

 * a 1-Wire line from low to high. When APU = 0, active pullup is disabled

 * (resistor mode). Active Pullup should always be selected unless there is

 * only a single slave on the 1-Wire line.

 */

static int ds2482_active_pullup = 1;

module_param_named(active_pullup, ds2482_active_pullup, int, 0644);

MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \

                "0-disable, 1-enable (default)");

​

/**

 * 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

​

/**