/** * 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		0x01static 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);