Viewing file:  i2c.c (14.12 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/*!***************************************************************************
*!
*! FILE NAME : i2c.c
*!
*! DESCRIPTION: implements an interface for IIC/I2C, both directly from other
*! kernel modules (i2c_writereg/readreg) and from userspace using
*! ioctl()'s
*!
*! Nov 30 1998 Torbjorn Eliasson Initial version.
*! Bjorn Wesen Elinux kernel version.
*! Jan 14 2000 Johan Adolfsson Fixed PB shadow register stuff -
*! don't use PB_I2C if DS1302 uses same bits,
*! use PB.
*! $Log: i2c.c,v $
*! Revision 1.7 2001/04/04 13:11:36 markusl
*! Updated according to review remarks
*!
*! Revision 1.6 2001/03/19 12:43:00 markusl
*! Made some symbols unstatic (used by the eeprom driver)
*!
*! Revision 1.5 2001/02/27 13:52:48 bjornw
*! malloc.h -> slab.h
*!
*! Revision 1.4 2001/02/15 07:17:40 starvik
*! Corrected usage if port_pb_i2c_shadow
*!
*! Revision 1.3 2001/01/26 17:55:13 bjornw
*! * Made I2C_USES_PB_NOT_PB_I2C a CONFIG option instead of assigning it
*! magically. Config.in needs to set it for the options that need it, like
*! Dallas 1302 support. Actually, it should be default since it screws up
*! the PB bits even if you don't use I2C..
*! * Include linux/config.h to get the above
*!
*! Revision 1.2 2001/01/18 15:49:30 bjornw
*! 2.4 port of I2C including some cleanups (untested of course)
*!
*! Revision 1.1 2001/01/18 15:35:25 bjornw
*! Verbatim copy of the Etrax i2c driver, 2.0 elinux version
*!
*!
*! ---------------------------------------------------------------------------
*!
*! (C) Copyright 1999, 2000, 2001 Axis Communications AB, LUND, SWEDEN
*!
*!***************************************************************************/
/* $Id: i2c.c,v 1.7 2001/04/04 13:11:36 markusl Exp $ */
/****************** INCLUDE FILES SECTION ***********************************/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/config.h>
#include <asm/etraxi2c.h>
#include <asm/system.h>
#include <asm/svinto.h>
#include <asm/io.h>
#include <asm/delay.h>
#include "i2c.h"
/****************** I2C DEFINITION SECTION *************************/
#define D(x)
#define I2C_MAJOR 123 /* LOCAL/EXPERIMENTAL */
static const char i2c_name[] = "i2c";
#define CLOCK_LOW_TIME 8
#define CLOCK_HIGH_TIME 8
#define START_CONDITION_HOLD_TIME 8
#define STOP_CONDITION_HOLD_TIME 8
#define ENABLE_OUTPUT 0x01
#define ENABLE_INPUT 0x00
#define I2C_CLOCK_HIGH 1
#define I2C_CLOCK_LOW 0
#define I2C_DATA_HIGH 1
#define I2C_DATA_LOW 0
#if 0
/* TODO: fix this so the CONFIG_ETRAX_I2C_USES... is set in Config.in instead */
#if defined(CONFIG_DS1302) && (CONFIG_DS1302_SDABIT==0) && \
(CONFIG_DS1302_SCLBIT == 1)
#define CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
#endif
#endif
#ifdef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
/* Use PB and not PB_I2C */
#define SDABIT 0
#define SCLBIT 1
#define i2c_enable()
#define i2c_disable()
/* enable or disable output-enable, to select output or input on the i2c bus */
#define i2c_dir_out() \
REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 1)
#define i2c_dir_in() \
REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 0)
/* control the i2c clock and data signals */
#define i2c_clk(x) \
REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SCLBIT, x)
#define i2c_data(x) \
REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SDABIT, x)
/* read a bit from the i2c interface */
#define i2c_getbit() (*R_PORT_PB_READ & (1 << SDABIT))
#else
/* enable or disable the i2c interface */
#define i2c_enable() *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_en))
#define i2c_disable() *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_en))
/* enable or disable output-enable, to select output or input on the i2c bus */
#define i2c_dir_out() *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_oe_))
#define i2c_dir_in() *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_oe_))
/* control the i2c clock and data signals */
#define i2c_clk(x) *R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
~IO_MASK(R_PORT_PB_I2C, i2c_clk)) | IO_FIELD(R_PORT_PB_I2C, i2c_clk, (x)))
#define i2c_data(x) *R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
~IO_MASK(R_PORT_PB_I2C, i2c_d)) | IO_FIELD(R_PORT_PB_I2C, i2c_d, (x)))
/* read a bit from the i2c interface */
#define i2c_getbit() (*R_PORT_PB_READ & 0x1)
#endif
/* use the kernels delay routine */
#define i2c_delay(usecs) udelay(usecs)
/****************** FUNCTION DEFINITION SECTION *************************/
/* generate i2c start condition */
void
i2c_start(void)
{
/*
* SCL=1 SDA=1
*/
i2c_dir_out();
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_data(I2C_DATA_HIGH);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
/*
* SCL=1 SDA=0
*/
i2c_data(I2C_DATA_LOW);
i2c_delay(START_CONDITION_HOLD_TIME);
/*
* SCL=0 SDA=0
*/
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
}
/* generate i2c stop condition */
void
i2c_stop(void)
{
i2c_dir_out();
/*
* SCL=0 SDA=0
*/
i2c_clk(I2C_CLOCK_LOW);
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_LOW_TIME*2);
/*
* SCL=1 SDA=0
*/
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME*2);
/*
* SCL=1 SDA=1
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(STOP_CONDITION_HOLD_TIME);
i2c_dir_in();
}
/* write a byte to the i2c interface */
void
i2c_outbyte(unsigned char x)
{
int i;
i2c_dir_out();
for (i = 0; i < 8; i++) {
if (x & 0x80)
i2c_data(I2C_DATA_HIGH);
else
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_LOW_TIME/2);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME/2);
x <<= 1;
}
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_LOW_TIME/2);
/*
* enable input
*/
i2c_dir_in();
}
/* read a byte from the i2c interface */
unsigned char
i2c_inbyte(void)
{
unsigned char aBitByte = 0;
int i;
int iaa;
/*
* enable output
*/
i2c_dir_out();
/*
* Release data bus by setting
* data high
*/
i2c_data(I2C_DATA_HIGH);
/*
* enable input
*/
i2c_dir_in();
/*
* Use PORT PB instead of I2C
* for input. (I2C not working)
*/
i2c_clk(1);
i2c_data(1);
/*
* get bits
*/
for (i = 0; i < 8; i++) {
i2c_delay(CLOCK_LOW_TIME/2);
/*
* low clock period
*/
i2c_clk(I2C_CLOCK_HIGH);
/*
* switch off I2C
*/
i2c_data(1);
i2c_disable();
i2c_dir_in();
/*
* wait before getting bit
*/
i2c_delay(CLOCK_HIGH_TIME/2);
aBitByte = (aBitByte << 1);
iaa = i2c_getbit();
aBitByte = aBitByte | iaa ;
/*
* wait
*/
i2c_delay(CLOCK_HIGH_TIME/2);
/*
* end clock puls
*/
i2c_enable();
i2c_dir_out();
i2c_clk(I2C_CLOCK_LOW);
/*
* low clock period
*/
i2c_delay(CLOCK_LOW_TIME/2);
}
i2c_dir_out();
return aBitByte;
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_getack
*#
*# DESCRIPTION : checks if ack was received from ic2
*#
*#--------------------------------------------------------------------------*/
int
i2c_getack(void)
{
int ack = 1;
/*
* enable output
*/
i2c_dir_out();
/*
* Release data bus by setting
* data high
*/
i2c_data(I2C_DATA_HIGH);
/*
* enable input
*/
i2c_dir_in();
i2c_delay(CLOCK_HIGH_TIME/4);
/*
* generate ACK clock pulse
*/
i2c_clk(I2C_CLOCK_HIGH);
/*
* Use PORT PB instead of I2C
* for input. (I2C not working)
*/
i2c_clk(1);
i2c_data(1);
/*
* switch off I2C
*/
i2c_data(1);
i2c_disable();
i2c_dir_in();
/*
* now wait for ack
*/
i2c_delay(CLOCK_HIGH_TIME/2);
/*
* check for ack
*/
if(i2c_getbit())
ack = 0;
i2c_delay(CLOCK_HIGH_TIME/2);
if(!ack){
if(!i2c_getbit()) /* receiver pulld SDA low */
ack = 1;
i2c_delay(CLOCK_HIGH_TIME/2);
}
/*
* end clock pulse
*/
i2c_enable();
i2c_dir_out();
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_HIGH_TIME/4);
/*
* enable output
*/
i2c_dir_out();
/*
* remove ACK clock pulse
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(CLOCK_LOW_TIME/2);
return ack;
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: I2C::sendAck
*#
*# DESCRIPTION : Send ACK on received data
*#
*#--------------------------------------------------------------------------*/
void
i2c_sendack(void)
{
/*
* enable output
*/
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_out();
/*
* set ack pulse high
*/
i2c_data(I2C_DATA_LOW);
/*
* generate clock pulse
*/
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME/6);
/*
* reset data out
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_in();
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_writereg
*#
*# DESCRIPTION : Writes a value to an I2C device
*#
*#--------------------------------------------------------------------------*/
int
i2c_writereg(unsigned char theSlave, unsigned char theReg,
unsigned char theValue)
{
int error, cntr = 3;
unsigned long flags;
do {
error = 0;
/*
* we don't like to be interrupted
*/
save_flags(flags);
cli();
/*
* generate start condition
*/
i2c_start();
/*
* dummy preamble
*/
i2c_outbyte(0x01);
i2c_data(I2C_DATA_HIGH);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME); /* Dummy Acknowledge */
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_LOW_TIME); /* Repeated Start Condition */
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
i2c_start();
/*
* send slave address
*/
i2c_outbyte(theSlave);
/*
* wait for ack
*/
if(!i2c_getack())
error = 1;
/*
* now select register
*/
i2c_dir_out();
i2c_outbyte(theReg);
/*
* now it's time to wait for ack
*/
if(!i2c_getack())
error |= 2;
/*
* send register register data
*/
i2c_outbyte(theValue);
/*
* now it's time to wait for ack
*/
if(!i2c_getack())
error |= 4;
/*
* end byte stream
*/
i2c_stop();
/*
* enable interrupt again
*/
restore_flags(flags);
} while(error && cntr--);
i2c_delay(CLOCK_LOW_TIME);
return -error;
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_readreg
*#
*# DESCRIPTION : Reads a value from the decoder registers.
*#
*#--------------------------------------------------------------------------*/
unsigned char
i2c_readreg(unsigned char theSlave, unsigned char theReg)
{
unsigned char b = 0;
int error, cntr = 3;
unsigned long flags;
do {
error = 0;
/*
* we don't like to be interrupted
*/
save_flags(flags);
cli();
/*
* generate start condition
*/
i2c_start();
/*
* dummy preamble
*/
i2c_outbyte(0x01);
i2c_data(I2C_DATA_HIGH);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME); /* Dummy Acknowledge */
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_LOW_TIME); /* Repeated Start Condition */
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
i2c_start();
/*
* send slave address
*/
i2c_outbyte(theSlave);
/*
* wait for ack
*/
if(!i2c_getack())
error = 1;
/*
* now select register
*/
i2c_dir_out();
i2c_outbyte(theReg);
/*
* now it's time to wait for ack
*/
if(!i2c_getack())
error = 1;
/*
* repeat start condition
*/
i2c_delay(CLOCK_LOW_TIME);
i2c_start();
/*
* send slave address
*/
i2c_outbyte(theSlave | 0x01);
/*
* wait for ack
*/
if(!i2c_getack())
error = 1;
/*
* fetch register
*/
b = i2c_inbyte();
/*
* send Ack
*/
i2c_sendack();
/*
* end sequence
*/
i2c_stop();
/*
* enable interrupt again
*/
restore_flags(flags);
} while(error && cntr--);
return b;
}
static int
i2c_open(struct inode *inode, struct file *filp)
{
return 0;
}
static int
i2c_release(struct inode *inode, struct file *filp)
{
return 0;
}
/* Main device API. ioctl's to write or read to/from i2c registers.
*/
static int
i2c_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
if(_IOC_TYPE(cmd) != ETRAXI2C_IOCTYPE) {
return -EINVAL;
}
switch (_IOC_NR(cmd)) {
case I2C_WRITEREG:
/* write to an i2c slave */
D(printk("i2cw %d %d %d\n",
I2C_ARGSLAVE(arg),
I2C_ARGREG(arg),
I2C_ARGVALUE(arg)));
return i2c_writereg(I2C_ARGSLAVE(arg),
I2C_ARGREG(arg),
I2C_ARGVALUE(arg));
case I2C_READREG:
{
unsigned char val;
/* read from an i2c slave */
D(printk("i2cr %d %d ",
I2C_ARGSLAVE(arg),
I2C_ARGREG(arg)));
val = i2c_readreg(I2C_ARGSLAVE(arg), I2C_ARGREG(arg));
D(printk("= %d\n", val));
return val;
}
default:
return -EINVAL;
}
return 0;
}
static struct file_operations i2c_fops = {
owner: THIS_MODULE,
ioctl: i2c_ioctl,
open: i2c_open,
release: i2c_release,
};
static int __init
i2c_init(void)
{
int res;
/* Setup and enable the Port B I2C interface */
#ifndef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
*R_PORT_PB_I2C = port_pb_i2c_shadow |=
IO_STATE(R_PORT_PB_I2C, i2c_en, on) |
IO_FIELD(R_PORT_PB_I2C, i2c_d, 1) |
IO_FIELD(R_PORT_PB_I2C, i2c_clk, 1) |
IO_STATE(R_PORT_PB_I2C, i2c_oe_, enable);
#endif
port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir0);
port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir1);
*R_PORT_PB_DIR = (port_pb_dir_shadow |=
IO_STATE(R_PORT_PB_DIR, dir0, input) |
IO_STATE(R_PORT_PB_DIR, dir1, output));
/* register char device */
res = register_chrdev(I2C_MAJOR, i2c_name, &i2c_fops);
if(res < 0) {
printk(KERN_ERR "i2c: couldn't get a major number.\n");
return res;
}
printk("I2C driver v2.2, (c) 1999-2001 Axis Communications AB\n");
return 0;
}
/* this makes sure that i2c_init is called during boot */
module_init(i2c_init);
/****************** END OF FILE i2c.c ********************************/
|