+++ /dev/null
-/*!***************************************************************************
-*!
-*! 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.
-*| June 23 2003 Pieter Grimmerink Added 'i2c_sendnack'. i2c_readreg now
-*| generates nack on last received byte,
-*| instead of ack.
-*| i2c_getack changed data level while clock
-*| was high, causing DS75 to see a stop condition
-*!
-*! ---------------------------------------------------------------------------
-*!
-*! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
-*!
-*!***************************************************************************/
-
-/****************** INCLUDE FILES SECTION ***********************************/
-
-#include <linux/module.h>
-#include <linux/sched.h>
-#include <linux/errno.h>
-#include <linux/kernel.h>
-#include <linux/fs.h>
-#include <linux/string.h>
-#include <linux/init.h>
-#include <linux/mutex.h>
-
-#include <asm/etraxi2c.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 DEFINE_MUTEX(i2c_mutex);
-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
-
-#define i2c_enable()
-#define i2c_disable()
-
-/* enable or disable output-enable, to select output or input on the i2c bus */
-
-#define i2c_dir_out() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_out)
-#define i2c_dir_in() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_in)
-
-/* control the i2c clock and data signals */
-
-#define i2c_clk(x) crisv32_io_set(&cris_i2c_clk, x)
-#define i2c_data(x) crisv32_io_set(&cris_i2c_data, x)
-
-/* read a bit from the i2c interface */
-
-#define i2c_getbit() crisv32_io_rd(&cris_i2c_data)
-
-#define i2c_delay(usecs) udelay(usecs)
-
-static DEFINE_SPINLOCK(i2c_lock); /* Protect directions etc */
-
-/****************** VARIABLE SECTION ************************************/
-
-static struct crisv32_iopin cris_i2c_clk;
-static struct crisv32_iopin cris_i2c_data;
-
-/****************** 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;
-
- /* Switch off I2C to get bit */
- i2c_disable();
- i2c_dir_in();
- i2c_delay(CLOCK_HIGH_TIME/2);
-
- /* Get bit */
- aBitByte |= i2c_getbit();
-
- /* Enable I2C */
- i2c_enable();
- i2c_delay(CLOCK_LOW_TIME/2);
-
- for (i = 1; i < 8; i++) {
- aBitByte <<= 1;
- /* Clock pulse */
- i2c_clk(I2C_CLOCK_HIGH);
- i2c_delay(CLOCK_HIGH_TIME);
- i2c_clk(I2C_CLOCK_LOW);
- i2c_delay(CLOCK_LOW_TIME);
-
- /* Switch off I2C to get bit */
- i2c_disable();
- i2c_dir_in();
- i2c_delay(CLOCK_HIGH_TIME/2);
-
- /* Get bit */
- aBitByte |= i2c_getbit();
-
- /* Enable I2C */
- i2c_enable();
- i2c_delay(CLOCK_LOW_TIME/2);
- }
- i2c_clk(I2C_CLOCK_HIGH);
- i2c_delay(CLOCK_HIGH_TIME);
-
- /*
- * we leave the clock low, getbyte is usually followed
- * by sendack/nack, they assume the clock to be low
- */
- i2c_clk(I2C_CLOCK_LOW);
- 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);
-#if 0
- /*
- * 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();
-#endif
-
- /*
- * 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);
- }
-
- /*
- * our clock is high now, make sure data is low
- * before we enable our output. If we keep data high
- * and enable output, we would generate a stop condition.
- */
-#if 0
- i2c_data(I2C_DATA_LOW);
-
- /*
- * end clock pulse
- */
- i2c_enable();
- i2c_dir_out();
-#endif
- 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_sendnack
-*#
-*# DESCRIPTION : Sends NACK on received data
-*#
-*#--------------------------------------------------------------------------*/
-void
-i2c_sendnack(void)
-{
- /*
- * enable output
- */
- i2c_delay(CLOCK_LOW_TIME);
- i2c_dir_out();
- /*
- * set data high
- */
- i2c_data(I2C_DATA_HIGH);
- /*
- * 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);
-
- i2c_dir_in();
-}
-
-/*#---------------------------------------------------------------------------
-*#
-*# FUNCTION NAME: i2c_write
-*#
-*# DESCRIPTION : Writes a value to an I2C device
-*#
-*#--------------------------------------------------------------------------*/
-int
-i2c_write(unsigned char theSlave, void *data, size_t nbytes)
-{
- int error, cntr = 3;
- unsigned char bytes_wrote = 0;
- unsigned char value;
- unsigned long flags;
-
- spin_lock_irqsave(&i2c_lock, flags);
-
- do {
- error = 0;
-
- i2c_start();
- /*
- * send slave address
- */
- i2c_outbyte((theSlave & 0xfe));
- /*
- * wait for ack
- */
- if (!i2c_getack())
- error = 1;
- /*
- * send data
- */
- for (bytes_wrote = 0; bytes_wrote < nbytes; bytes_wrote++) {
- memcpy(&value, data + bytes_wrote, sizeof value);
- i2c_outbyte(value);
- /*
- * now it's time to wait for ack
- */
- if (!i2c_getack())
- error |= 4;
- }
- /*
- * end byte stream
- */
- i2c_stop();
-
- } while (error && cntr--);
-
- i2c_delay(CLOCK_LOW_TIME);
-
- spin_unlock_irqrestore(&i2c_lock, flags);
-
- return -error;
-}
-
-/*#---------------------------------------------------------------------------
-*#
-*# FUNCTION NAME: i2c_read
-*#
-*# DESCRIPTION : Reads a value from an I2C device
-*#
-*#--------------------------------------------------------------------------*/
-int
-i2c_read(unsigned char theSlave, void *data, size_t nbytes)
-{
- unsigned char b = 0;
- unsigned char bytes_read = 0;
- int error, cntr = 3;
- unsigned long flags;
-
- spin_lock_irqsave(&i2c_lock, flags);
-
- do {
- error = 0;
- memset(data, 0, nbytes);
- /*
- * generate start condition
- */
- i2c_start();
- /*
- * send slave address
- */
- i2c_outbyte((theSlave | 0x01));
- /*
- * wait for ack
- */
- if (!i2c_getack())
- error = 1;
- /*
- * fetch data
- */
- for (bytes_read = 0; bytes_read < nbytes; bytes_read++) {
- b = i2c_inbyte();
- memcpy(data + bytes_read, &b, sizeof b);
-
- if (bytes_read < (nbytes - 1))
- i2c_sendack();
- }
- /*
- * last received byte needs to be nacked
- * instead of acked
- */
- i2c_sendnack();
- /*
- * end sequence
- */
- i2c_stop();
- } while (error && cntr--);
-
- spin_unlock_irqrestore(&i2c_lock, flags);
-
- return -error;
-}
-
-/*#---------------------------------------------------------------------------
-*#
-*# 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;
-
- spin_lock_irqsave(&i2c_lock, flags);
-
- do {
- error = 0;
-
- i2c_start();
- /*
- * send slave address
- */
- i2c_outbyte((theSlave & 0xfe));
- /*
- * 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();
- } while(error && cntr--);
-
- i2c_delay(CLOCK_LOW_TIME);
-
- spin_unlock_irqrestore(&i2c_lock, flags);
-
- 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;
-
- spin_lock_irqsave(&i2c_lock, flags);
-
- do {
- error = 0;
- /*
- * generate start condition
- */
- i2c_start();
-
- /*
- * send slave address
- */
- i2c_outbyte((theSlave & 0xfe));
- /*
- * 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;
- /*
- * repeat start condition
- */
- i2c_delay(CLOCK_LOW_TIME);
- i2c_start();
- /*
- * send slave address
- */
- i2c_outbyte(theSlave | 0x01);
- /*
- * wait for ack
- */
- if(!i2c_getack())
- error |= 4;
- /*
- * fetch register
- */
- b = i2c_inbyte();
- /*
- * last received byte needs to be nacked
- * instead of acked
- */
- i2c_sendnack();
- /*
- * end sequence
- */
- i2c_stop();
-
- } while(error && cntr--);
-
- spin_unlock_irqrestore(&i2c_lock, flags);
-
- 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 long
-i2c_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
-{
- int ret;
- if(_IOC_TYPE(cmd) != ETRAXI2C_IOCTYPE) {
- return -ENOTTY;
- }
-
- 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)));
-
- mutex_lock(&i2c_mutex);
- ret = i2c_writereg(I2C_ARGSLAVE(arg),
- I2C_ARGREG(arg),
- I2C_ARGVALUE(arg));
- mutex_unlock(&i2c_mutex);
- return ret;
-
- case I2C_READREG:
- {
- unsigned char val;
- /* read from an i2c slave */
- D(printk("i2cr %d %d ",
- I2C_ARGSLAVE(arg),
- I2C_ARGREG(arg)));
- mutex_lock(&i2c_mutex);
- val = i2c_readreg(I2C_ARGSLAVE(arg), I2C_ARGREG(arg));
- mutex_unlock(&i2c_mutex);
- D(printk("= %d\n", val));
- return val;
- }
- default:
- return -EINVAL;
-
- }
-
- return 0;
-}
-
-static const struct file_operations i2c_fops = {
- .owner = THIS_MODULE,
- .unlocked_ioctl = i2c_ioctl,
- .open = i2c_open,
- .release = i2c_release,
- .llseek = noop_llseek,
-};
-
-static int __init i2c_init(void)
-{
- static int res;
- static int first = 1;
-
- if (!first)
- return res;
-
- first = 0;
-
- /* Setup and enable the DATA and CLK pins */
-
- res = crisv32_io_get_name(&cris_i2c_data,
- CONFIG_ETRAX_V32_I2C_DATA_PORT);
- if (res < 0)
- return res;
-
- res = crisv32_io_get_name(&cris_i2c_clk, CONFIG_ETRAX_V32_I2C_CLK_PORT);
- crisv32_io_set_dir(&cris_i2c_clk, crisv32_io_dir_out);
-
- return res;
-}
-
-
-static int __init i2c_register(void)
-{
- int res;
-
- res = i2c_init();
- if (res < 0)
- return res;
-
- /* 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(KERN_INFO
- "I2C driver v2.2, (c) 1999-2007 Axis Communications AB\n");
-
- return 0;
-}
-/* this makes sure that i2c_init is called during boot */
-module_init(i2c_register);
-
-/****************** END OF FILE i2c.c ********************************/
projects / karo-tx-linux.git / commitdiff