/**
* 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"
/**
* 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_probe(struct i2c_client *client,
const struct i2c_device_id *id);
static int ds2482_remove(struct i2c_client *client);
/**
* Driver data (common to all clients)
*/
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;
};
/**
* 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;
}
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;
}
module_i2c_driver(ds2482_driver);
MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
MODULE_DESCRIPTION("DS2482 driver");
MODULE_LICENSE("GPL");
