549 lines
14 KiB
C
549 lines
14 KiB
C
/**
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* ds2482.c - provides i2c to w1-master bridge(s)
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* Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
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*
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* The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim).
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* It is a I2C to 1-wire bridge.
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* There are two variations: -100 and -800, which have 1 or 8 1-wire ports.
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* The complete datasheet can be obtained from MAXIM's website at:
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* http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/delay.h>
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#include <asm/delay.h>
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#include "../w1.h"
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#include "../w1_int.h"
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/**
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* Address is selected using 2 pins, resulting in 4 possible addresses.
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* 0x18, 0x19, 0x1a, 0x1b
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* However, the chip cannot be detected without doing an i2c write,
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* so use the force module parameter.
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*/
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static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
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/**
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* Insmod parameters
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*/
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I2C_CLIENT_INSMOD_1(ds2482);
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/**
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* The DS2482 registers - there are 3 registers that are addressed by a read
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* pointer. The read pointer is set by the last command executed.
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*
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* To read the data, issue a register read for any address
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*/
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#define DS2482_CMD_RESET 0xF0 /* No param */
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#define DS2482_CMD_SET_READ_PTR 0xE1 /* Param: DS2482_PTR_CODE_xxx */
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#define DS2482_CMD_CHANNEL_SELECT 0xC3 /* Param: Channel byte - DS2482-800 only */
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#define DS2482_CMD_WRITE_CONFIG 0xD2 /* Param: Config byte */
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#define DS2482_CMD_1WIRE_RESET 0xB4 /* Param: None */
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#define DS2482_CMD_1WIRE_SINGLE_BIT 0x87 /* Param: Bit byte (bit7) */
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#define DS2482_CMD_1WIRE_WRITE_BYTE 0xA5 /* Param: Data byte */
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#define DS2482_CMD_1WIRE_READ_BYTE 0x96 /* Param: None */
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/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
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#define DS2482_CMD_1WIRE_TRIPLET 0x78 /* Param: Dir byte (bit7) */
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/* Values for DS2482_CMD_SET_READ_PTR */
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#define DS2482_PTR_CODE_STATUS 0xF0
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#define DS2482_PTR_CODE_DATA 0xE1
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#define DS2482_PTR_CODE_CHANNEL 0xD2 /* DS2482-800 only */
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#define DS2482_PTR_CODE_CONFIG 0xC3
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/**
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* Configure Register bit definitions
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* The top 4 bits always read 0.
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* To write, the top nibble must be the 1's compl. of the low nibble.
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*/
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#define DS2482_REG_CFG_1WS 0x08
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#define DS2482_REG_CFG_SPU 0x04
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#define DS2482_REG_CFG_PPM 0x02
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#define DS2482_REG_CFG_APU 0x01
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/**
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* Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
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* To set the channel, write the value at the index of the channel.
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* Read and compare against the corresponding value to verify the change.
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*/
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static const u8 ds2482_chan_wr[8] =
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{ 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
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static const u8 ds2482_chan_rd[8] =
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{ 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };
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/**
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* Status Register bit definitions (read only)
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*/
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#define DS2482_REG_STS_DIR 0x80
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#define DS2482_REG_STS_TSB 0x40
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#define DS2482_REG_STS_SBR 0x20
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#define DS2482_REG_STS_RST 0x10
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#define DS2482_REG_STS_LL 0x08
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#define DS2482_REG_STS_SD 0x04
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#define DS2482_REG_STS_PPD 0x02
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#define DS2482_REG_STS_1WB 0x01
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static int ds2482_probe(struct i2c_client *client,
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const struct i2c_device_id *id);
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static int ds2482_detect(struct i2c_client *client, int kind,
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struct i2c_board_info *info);
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static int ds2482_remove(struct i2c_client *client);
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/**
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* Driver data (common to all clients)
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*/
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static const struct i2c_device_id ds2482_id[] = {
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{ "ds2482", 0 },
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{ }
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};
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static struct i2c_driver ds2482_driver = {
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.driver = {
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.owner = THIS_MODULE,
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.name = "ds2482",
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},
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.probe = ds2482_probe,
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.remove = ds2482_remove,
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.id_table = ds2482_id,
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.detect = ds2482_detect,
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.address_data = &addr_data,
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};
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/*
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* Client data (each client gets its own)
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*/
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struct ds2482_data;
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struct ds2482_w1_chan {
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struct ds2482_data *pdev;
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u8 channel;
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struct w1_bus_master w1_bm;
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};
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struct ds2482_data {
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struct i2c_client *client;
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struct mutex access_lock;
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/* 1-wire interface(s) */
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int w1_count; /* 1 or 8 */
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struct ds2482_w1_chan w1_ch[8];
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/* per-device values */
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u8 channel;
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u8 read_prt; /* see DS2482_PTR_CODE_xxx */
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u8 reg_config;
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};
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/**
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* Sets the read pointer.
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* @param pdev The ds2482 client pointer
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* @param read_ptr see DS2482_PTR_CODE_xxx above
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* @return -1 on failure, 0 on success
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*/
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static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
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{
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if (pdev->read_prt != read_ptr) {
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if (i2c_smbus_write_byte_data(pdev->client,
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DS2482_CMD_SET_READ_PTR,
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read_ptr) < 0)
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return -1;
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pdev->read_prt = read_ptr;
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}
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return 0;
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}
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/**
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* Sends a command without a parameter
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* @param pdev The ds2482 client pointer
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* @param cmd DS2482_CMD_RESET,
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* DS2482_CMD_1WIRE_RESET,
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* DS2482_CMD_1WIRE_READ_BYTE
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* @return -1 on failure, 0 on success
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*/
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static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
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{
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if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
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return -1;
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pdev->read_prt = DS2482_PTR_CODE_STATUS;
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return 0;
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}
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/**
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* Sends a command with a parameter
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* @param pdev The ds2482 client pointer
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* @param cmd DS2482_CMD_WRITE_CONFIG,
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* DS2482_CMD_1WIRE_SINGLE_BIT,
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* DS2482_CMD_1WIRE_WRITE_BYTE,
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* DS2482_CMD_1WIRE_TRIPLET
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* @param byte The data to send
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* @return -1 on failure, 0 on success
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*/
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static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
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u8 cmd, u8 byte)
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{
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if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
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return -1;
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/* all cmds leave in STATUS, except CONFIG */
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pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
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DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
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return 0;
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}
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/*
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* 1-Wire interface code
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*/
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#define DS2482_WAIT_IDLE_TIMEOUT 100
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/**
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* Waits until the 1-wire interface is idle (not busy)
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*
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* @param pdev Pointer to the device structure
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* @return the last value read from status or -1 (failure)
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*/
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static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
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{
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int temp = -1;
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int retries = 0;
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if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
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do {
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temp = i2c_smbus_read_byte(pdev->client);
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} while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
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(++retries < DS2482_WAIT_IDLE_TIMEOUT));
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}
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if (retries > DS2482_WAIT_IDLE_TIMEOUT)
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printk(KERN_ERR "%s: timeout on channel %d\n",
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__func__, pdev->channel);
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return temp;
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}
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/**
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* Selects a w1 channel.
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* The 1-wire interface must be idle before calling this function.
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*
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* @param pdev The ds2482 client pointer
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* @param channel 0-7
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* @return -1 (failure) or 0 (success)
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*/
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static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
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{
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if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
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ds2482_chan_wr[channel]) < 0)
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return -1;
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pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
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pdev->channel = -1;
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if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
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pdev->channel = channel;
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return 0;
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}
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return -1;
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}
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/**
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* Performs the touch-bit function, which writes a 0 or 1 and reads the level.
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*
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* @param data The ds2482 channel pointer
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* @param bit The level to write: 0 or non-zero
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* @return The level read: 0 or 1
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*/
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static u8 ds2482_w1_touch_bit(void *data, u8 bit)
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{
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struct ds2482_w1_chan *pchan = data;
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struct ds2482_data *pdev = pchan->pdev;
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int status = -1;
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mutex_lock(&pdev->access_lock);
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/* Select the channel */
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ds2482_wait_1wire_idle(pdev);
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if (pdev->w1_count > 1)
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ds2482_set_channel(pdev, pchan->channel);
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/* Send the touch command, wait until 1WB == 0, return the status */
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if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
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bit ? 0xFF : 0))
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status = ds2482_wait_1wire_idle(pdev);
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mutex_unlock(&pdev->access_lock);
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return (status & DS2482_REG_STS_SBR) ? 1 : 0;
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}
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/**
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* Performs the triplet function, which reads two bits and writes a bit.
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* The bit written is determined by the two reads:
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* 00 => dbit, 01 => 0, 10 => 1
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*
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* @param data The ds2482 channel pointer
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* @param dbit The direction to choose if both branches are valid
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* @return b0=read1 b1=read2 b3=bit written
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*/
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static u8 ds2482_w1_triplet(void *data, u8 dbit)
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{
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struct ds2482_w1_chan *pchan = data;
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struct ds2482_data *pdev = pchan->pdev;
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int status = (3 << 5);
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mutex_lock(&pdev->access_lock);
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/* Select the channel */
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ds2482_wait_1wire_idle(pdev);
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if (pdev->w1_count > 1)
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ds2482_set_channel(pdev, pchan->channel);
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/* Send the triplet command, wait until 1WB == 0, return the status */
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if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
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dbit ? 0xFF : 0))
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status = ds2482_wait_1wire_idle(pdev);
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mutex_unlock(&pdev->access_lock);
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/* Decode the status */
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return (status >> 5);
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}
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/**
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* Performs the write byte function.
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*
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* @param data The ds2482 channel pointer
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* @param byte The value to write
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*/
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static void ds2482_w1_write_byte(void *data, u8 byte)
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{
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struct ds2482_w1_chan *pchan = data;
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struct ds2482_data *pdev = pchan->pdev;
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mutex_lock(&pdev->access_lock);
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/* Select the channel */
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ds2482_wait_1wire_idle(pdev);
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if (pdev->w1_count > 1)
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ds2482_set_channel(pdev, pchan->channel);
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/* Send the write byte command */
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ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
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mutex_unlock(&pdev->access_lock);
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}
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/**
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* Performs the read byte function.
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*
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* @param data The ds2482 channel pointer
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* @return The value read
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*/
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static u8 ds2482_w1_read_byte(void *data)
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{
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struct ds2482_w1_chan *pchan = data;
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struct ds2482_data *pdev = pchan->pdev;
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int result;
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mutex_lock(&pdev->access_lock);
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/* Select the channel */
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ds2482_wait_1wire_idle(pdev);
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if (pdev->w1_count > 1)
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ds2482_set_channel(pdev, pchan->channel);
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/* Send the read byte command */
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ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
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/* Wait until 1WB == 0 */
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ds2482_wait_1wire_idle(pdev);
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/* Select the data register */
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ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
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/* Read the data byte */
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result = i2c_smbus_read_byte(pdev->client);
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mutex_unlock(&pdev->access_lock);
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return result;
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}
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/**
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* Sends a reset on the 1-wire interface
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*
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* @param data The ds2482 channel pointer
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* @return 0=Device present, 1=No device present or error
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*/
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static u8 ds2482_w1_reset_bus(void *data)
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{
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struct ds2482_w1_chan *pchan = data;
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struct ds2482_data *pdev = pchan->pdev;
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int err;
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u8 retval = 1;
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mutex_lock(&pdev->access_lock);
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/* Select the channel */
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ds2482_wait_1wire_idle(pdev);
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if (pdev->w1_count > 1)
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ds2482_set_channel(pdev, pchan->channel);
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/* Send the reset command */
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err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
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if (err >= 0) {
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/* Wait until the reset is complete */
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err = ds2482_wait_1wire_idle(pdev);
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retval = !(err & DS2482_REG_STS_PPD);
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/* If the chip did reset since detect, re-config it */
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if (err & DS2482_REG_STS_RST)
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ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
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0xF0);
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}
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mutex_unlock(&pdev->access_lock);
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return retval;
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}
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static int ds2482_detect(struct i2c_client *client, int kind,
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struct i2c_board_info *info)
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{
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if (!i2c_check_functionality(client->adapter,
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I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
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I2C_FUNC_SMBUS_BYTE))
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return -ENODEV;
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strlcpy(info->type, "ds2482", I2C_NAME_SIZE);
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return 0;
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}
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static int ds2482_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct ds2482_data *data;
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int err = -ENODEV;
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int temp1;
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int idx;
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if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
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err = -ENOMEM;
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goto exit;
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}
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data->client = client;
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i2c_set_clientdata(client, data);
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/* Reset the device (sets the read_ptr to status) */
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if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
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dev_warn(&client->dev, "DS2482 reset failed.\n");
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goto exit_free;
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}
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/* Sleep at least 525ns to allow the reset to complete */
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ndelay(525);
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/* Read the status byte - only reset bit and line should be set */
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temp1 = i2c_smbus_read_byte(client);
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if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
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dev_warn(&client->dev, "DS2482 reset status "
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"0x%02X - not a DS2482\n", temp1);
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goto exit_free;
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}
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/* Detect the 8-port version */
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data->w1_count = 1;
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if (ds2482_set_channel(data, 7) == 0)
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data->w1_count = 8;
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/* Set all config items to 0 (off) */
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ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 0xF0);
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mutex_init(&data->access_lock);
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/* Register 1-wire interface(s) */
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for (idx = 0; idx < data->w1_count; idx++) {
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data->w1_ch[idx].pdev = data;
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data->w1_ch[idx].channel = idx;
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/* Populate all the w1 bus master stuff */
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data->w1_ch[idx].w1_bm.data = &data->w1_ch[idx];
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data->w1_ch[idx].w1_bm.read_byte = ds2482_w1_read_byte;
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data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
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data->w1_ch[idx].w1_bm.touch_bit = ds2482_w1_touch_bit;
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data->w1_ch[idx].w1_bm.triplet = ds2482_w1_triplet;
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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 <bgardner@wabtec.com>");
|
|
MODULE_DESCRIPTION("DS2482 driver");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
module_init(sensors_ds2482_init);
|
|
module_exit(sensors_ds2482_exit);
|