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-/*!***************************************************************************
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-*!
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-*! FILE NAME : i2c.c
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-*!
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-*! DESCRIPTION: implements an interface for IIC/I2C, both directly from other
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-*! kernel modules (i2c_writereg/readreg) and from userspace using
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-*! ioctl()'s
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-*!
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-*! Nov 30 1998 Torbjorn Eliasson Initial version.
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-*! Bjorn Wesen Elinux kernel version.
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-*! Jan 14 2000 Johan Adolfsson Fixed PB shadow register stuff -
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-*! don't use PB_I2C if DS1302 uses same bits,
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-*! use PB.
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-*| June 23 2003 Pieter Grimmerink Added 'i2c_sendnack'. i2c_readreg now
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-*| generates nack on last received byte,
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-*| instead of ack.
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-*| i2c_getack changed data level while clock
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-*| was high, causing DS75 to see a stop condition
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-*!
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-*! ---------------------------------------------------------------------------
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-*!
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-*! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
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-*!
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-*!***************************************************************************/
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-
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-/****************** INCLUDE FILES SECTION ***********************************/
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-
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-#include <linux/module.h>
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-#include <linux/sched.h>
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-#include <linux/errno.h>
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-#include <linux/kernel.h>
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-#include <linux/fs.h>
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-#include <linux/string.h>
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-#include <linux/init.h>
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-#include <linux/mutex.h>
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-
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-#include <asm/etraxi2c.h>
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-
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-#include <asm/io.h>
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-#include <asm/delay.h>
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-
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-#include "i2c.h"
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-
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-/****************** I2C DEFINITION SECTION *************************/
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-
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-#define D(x)
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-
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-#define I2C_MAJOR 123 /* LOCAL/EXPERIMENTAL */
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-static DEFINE_MUTEX(i2c_mutex);
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-static const char i2c_name[] = "i2c";
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-
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-#define CLOCK_LOW_TIME 8
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-#define CLOCK_HIGH_TIME 8
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-#define START_CONDITION_HOLD_TIME 8
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-#define STOP_CONDITION_HOLD_TIME 8
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-#define ENABLE_OUTPUT 0x01
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-#define ENABLE_INPUT 0x00
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-#define I2C_CLOCK_HIGH 1
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-#define I2C_CLOCK_LOW 0
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-#define I2C_DATA_HIGH 1
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-#define I2C_DATA_LOW 0
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-
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-#define i2c_enable()
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-#define i2c_disable()
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-
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-/* enable or disable output-enable, to select output or input on the i2c bus */
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-
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-#define i2c_dir_out() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_out)
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-#define i2c_dir_in() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_in)
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-
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-/* control the i2c clock and data signals */
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-
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-#define i2c_clk(x) crisv32_io_set(&cris_i2c_clk, x)
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-#define i2c_data(x) crisv32_io_set(&cris_i2c_data, x)
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-
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-/* read a bit from the i2c interface */
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-
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-#define i2c_getbit() crisv32_io_rd(&cris_i2c_data)
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-
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-#define i2c_delay(usecs) udelay(usecs)
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-
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-static DEFINE_SPINLOCK(i2c_lock); /* Protect directions etc */
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-
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-/****************** VARIABLE SECTION ************************************/
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-
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-static struct crisv32_iopin cris_i2c_clk;
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-static struct crisv32_iopin cris_i2c_data;
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-
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-/****************** FUNCTION DEFINITION SECTION *************************/
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-
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-
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-/* generate i2c start condition */
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-
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-void
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-i2c_start(void)
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-{
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- /*
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- * SCL=1 SDA=1
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- */
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- i2c_dir_out();
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- i2c_delay(CLOCK_HIGH_TIME/6);
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- i2c_data(I2C_DATA_HIGH);
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- i2c_clk(I2C_CLOCK_HIGH);
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- i2c_delay(CLOCK_HIGH_TIME);
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- /*
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- * SCL=1 SDA=0
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- */
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- i2c_data(I2C_DATA_LOW);
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- i2c_delay(START_CONDITION_HOLD_TIME);
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- /*
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- * SCL=0 SDA=0
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- */
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- i2c_clk(I2C_CLOCK_LOW);
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- i2c_delay(CLOCK_LOW_TIME);
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-}
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-
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-/* generate i2c stop condition */
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-
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-void
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-i2c_stop(void)
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-{
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- i2c_dir_out();
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-
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- /*
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- * SCL=0 SDA=0
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- */
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- i2c_clk(I2C_CLOCK_LOW);
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- i2c_data(I2C_DATA_LOW);
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- i2c_delay(CLOCK_LOW_TIME*2);
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- /*
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- * SCL=1 SDA=0
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- */
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- i2c_clk(I2C_CLOCK_HIGH);
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- i2c_delay(CLOCK_HIGH_TIME*2);
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- /*
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- * SCL=1 SDA=1
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- */
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- i2c_data(I2C_DATA_HIGH);
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- i2c_delay(STOP_CONDITION_HOLD_TIME);
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-
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- i2c_dir_in();
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-}
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-
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-/* write a byte to the i2c interface */
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-
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-void
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-i2c_outbyte(unsigned char x)
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-{
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- int i;
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-
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- i2c_dir_out();
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-
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- for (i = 0; i < 8; i++) {
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- if (x & 0x80) {
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- i2c_data(I2C_DATA_HIGH);
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- } else {
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- i2c_data(I2C_DATA_LOW);
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- }
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-
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- i2c_delay(CLOCK_LOW_TIME/2);
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- i2c_clk(I2C_CLOCK_HIGH);
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- i2c_delay(CLOCK_HIGH_TIME);
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- i2c_clk(I2C_CLOCK_LOW);
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- i2c_delay(CLOCK_LOW_TIME/2);
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- x <<= 1;
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- }
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- i2c_data(I2C_DATA_LOW);
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- i2c_delay(CLOCK_LOW_TIME/2);
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-
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- /*
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- * enable input
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- */
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- i2c_dir_in();
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-}
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-
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-/* read a byte from the i2c interface */
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-
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-unsigned char
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-i2c_inbyte(void)
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-{
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- unsigned char aBitByte = 0;
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- int i;
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-
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- /* Switch off I2C to get bit */
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- i2c_disable();
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- i2c_dir_in();
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- i2c_delay(CLOCK_HIGH_TIME/2);
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-
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- /* Get bit */
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- aBitByte |= i2c_getbit();
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-
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- /* Enable I2C */
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- i2c_enable();
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- i2c_delay(CLOCK_LOW_TIME/2);
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-
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- for (i = 1; i < 8; i++) {
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- aBitByte <<= 1;
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- /* Clock pulse */
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- i2c_clk(I2C_CLOCK_HIGH);
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- i2c_delay(CLOCK_HIGH_TIME);
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- i2c_clk(I2C_CLOCK_LOW);
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- i2c_delay(CLOCK_LOW_TIME);
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-
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- /* Switch off I2C to get bit */
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- i2c_disable();
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- i2c_dir_in();
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- i2c_delay(CLOCK_HIGH_TIME/2);
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-
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- /* Get bit */
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- aBitByte |= i2c_getbit();
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-
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- /* Enable I2C */
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- i2c_enable();
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- i2c_delay(CLOCK_LOW_TIME/2);
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- }
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- i2c_clk(I2C_CLOCK_HIGH);
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- i2c_delay(CLOCK_HIGH_TIME);
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-
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- /*
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- * we leave the clock low, getbyte is usually followed
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- * by sendack/nack, they assume the clock to be low
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- */
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- i2c_clk(I2C_CLOCK_LOW);
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- return aBitByte;
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-}
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-
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-/*#---------------------------------------------------------------------------
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-*#
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-*# FUNCTION NAME: i2c_getack
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-*#
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-*# DESCRIPTION : checks if ack was received from ic2
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-*#
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-*#--------------------------------------------------------------------------*/
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-
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-int
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-i2c_getack(void)
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-{
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- int ack = 1;
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- /*
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- * enable output
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- */
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- i2c_dir_out();
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- /*
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- * Release data bus by setting
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- * data high
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- */
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- i2c_data(I2C_DATA_HIGH);
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- /*
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- * enable input
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- */
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- i2c_dir_in();
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- i2c_delay(CLOCK_HIGH_TIME/4);
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- /*
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- * generate ACK clock pulse
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- */
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- i2c_clk(I2C_CLOCK_HIGH);
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-#if 0
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- /*
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- * Use PORT PB instead of I2C
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- * for input. (I2C not working)
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- */
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- i2c_clk(1);
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- i2c_data(1);
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- /*
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- * switch off I2C
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- */
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- i2c_data(1);
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- i2c_disable();
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- i2c_dir_in();
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-#endif
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-
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- /*
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- * now wait for ack
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- */
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- i2c_delay(CLOCK_HIGH_TIME/2);
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- /*
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- * check for ack
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- */
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- if (i2c_getbit())
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- ack = 0;
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- i2c_delay(CLOCK_HIGH_TIME/2);
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- if (!ack) {
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- if (!i2c_getbit()) /* receiver pulld SDA low */
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- ack = 1;
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- i2c_delay(CLOCK_HIGH_TIME/2);
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- }
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-
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- /*
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- * our clock is high now, make sure data is low
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- * before we enable our output. If we keep data high
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- * and enable output, we would generate a stop condition.
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- */
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-#if 0
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- i2c_data(I2C_DATA_LOW);
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-
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- /*
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- * end clock pulse
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- */
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- i2c_enable();
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- i2c_dir_out();
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-#endif
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- i2c_clk(I2C_CLOCK_LOW);
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- i2c_delay(CLOCK_HIGH_TIME/4);
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- /*
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- * enable output
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- */
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- i2c_dir_out();
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- /*
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- * remove ACK clock pulse
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- */
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- i2c_data(I2C_DATA_HIGH);
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- i2c_delay(CLOCK_LOW_TIME/2);
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- return ack;
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-}
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-
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-/*#---------------------------------------------------------------------------
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-*#
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-*# FUNCTION NAME: I2C::sendAck
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-*#
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-*# DESCRIPTION : Send ACK on received data
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-*#
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-*#--------------------------------------------------------------------------*/
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-void
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-i2c_sendack(void)
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-{
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- /*
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- * enable output
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- */
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- i2c_delay(CLOCK_LOW_TIME);
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- i2c_dir_out();
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- /*
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- * set ack pulse high
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- */
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- i2c_data(I2C_DATA_LOW);
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- /*
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- * generate clock pulse
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- */
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- i2c_delay(CLOCK_HIGH_TIME/6);
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- i2c_clk(I2C_CLOCK_HIGH);
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- i2c_delay(CLOCK_HIGH_TIME);
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- i2c_clk(I2C_CLOCK_LOW);
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- i2c_delay(CLOCK_LOW_TIME/6);
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- /*
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- * reset data out
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- */
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- i2c_data(I2C_DATA_HIGH);
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- i2c_delay(CLOCK_LOW_TIME);
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-
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- i2c_dir_in();
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-}
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-
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-/*#---------------------------------------------------------------------------
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-*#
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-*# FUNCTION NAME: i2c_sendnack
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-*#
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-*# DESCRIPTION : Sends NACK on received data
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-*#
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-*#--------------------------------------------------------------------------*/
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-void
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-i2c_sendnack(void)
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-{
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- /*
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- * enable output
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- */
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- i2c_delay(CLOCK_LOW_TIME);
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- i2c_dir_out();
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- /*
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- * set data high
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- */
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- i2c_data(I2C_DATA_HIGH);
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- /*
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- * generate clock pulse
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- */
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- i2c_delay(CLOCK_HIGH_TIME/6);
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- i2c_clk(I2C_CLOCK_HIGH);
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- i2c_delay(CLOCK_HIGH_TIME);
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- i2c_clk(I2C_CLOCK_LOW);
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- i2c_delay(CLOCK_LOW_TIME);
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-
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- i2c_dir_in();
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-}
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-
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-/*#---------------------------------------------------------------------------
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-*#
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-*# FUNCTION NAME: i2c_write
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-*#
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-*# DESCRIPTION : Writes a value to an I2C device
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-*#
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-*#--------------------------------------------------------------------------*/
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-int
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-i2c_write(unsigned char theSlave, void *data, size_t nbytes)
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-{
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- int error, cntr = 3;
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- unsigned char bytes_wrote = 0;
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- unsigned char value;
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- unsigned long flags;
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-
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- spin_lock_irqsave(&i2c_lock, flags);
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-
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- do {
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- error = 0;
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-
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- i2c_start();
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- /*
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- * send slave address
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- */
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- i2c_outbyte((theSlave & 0xfe));
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- /*
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- * wait for ack
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- */
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- if (!i2c_getack())
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- error = 1;
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- /*
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- * send data
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- */
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- for (bytes_wrote = 0; bytes_wrote < nbytes; bytes_wrote++) {
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- memcpy(&value, data + bytes_wrote, sizeof value);
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- i2c_outbyte(value);
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- /*
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- * now it's time to wait for ack
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- */
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- if (!i2c_getack())
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- error |= 4;
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- }
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- /*
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- * end byte stream
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- */
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- i2c_stop();
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-
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- } while (error && cntr--);
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-
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- i2c_delay(CLOCK_LOW_TIME);
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-
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- spin_unlock_irqrestore(&i2c_lock, flags);
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-
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- return -error;
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-}
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-
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-/*#---------------------------------------------------------------------------
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-*#
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-*# FUNCTION NAME: i2c_read
|
|
|
-*#
|
|
|
-*# DESCRIPTION : Reads a value from an I2C device
|
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|
-*#
|
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|
-*#--------------------------------------------------------------------------*/
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|
-int
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|
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-i2c_read(unsigned char theSlave, void *data, size_t nbytes)
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|
-{
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- unsigned char b = 0;
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- unsigned char bytes_read = 0;
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- int error, cntr = 3;
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- unsigned long flags;
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|
-
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|
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- spin_lock_irqsave(&i2c_lock, flags);
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|
|
-
|
|
|
- do {
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|
- error = 0;
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|
|
- memset(data, 0, nbytes);
|
|
|
- /*
|
|
|
- * generate start condition
|
|
|
- */
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|
|
- i2c_start();
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|
|
- /*
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- * send slave address
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|
- */
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- i2c_outbyte((theSlave | 0x01));
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|
- /*
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|
- * wait for ack
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|
|
- */
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|
|
- if (!i2c_getack())
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|
|
- error = 1;
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|
|
- /*
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|
|
- * fetch data
|
|
|
- */
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|
- for (bytes_read = 0; bytes_read < nbytes; bytes_read++) {
|
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|
- b = i2c_inbyte();
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- memcpy(data + bytes_read, &b, sizeof b);
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-
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|
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- if (bytes_read < (nbytes - 1))
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|
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- i2c_sendack();
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|
|
- }
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|
|
- /*
|
|
|
- * last received byte needs to be nacked
|
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|
- * instead of acked
|
|
|
- */
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|
- i2c_sendnack();
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|
|
- /*
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|
|
- * end sequence
|
|
|
- */
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|
|
- i2c_stop();
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|
|
- } while (error && cntr--);
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|
|
-
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|
|
- spin_unlock_irqrestore(&i2c_lock, flags);
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|
-
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|
|
- return -error;
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|
|
-}
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|
|
-
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|
|
-/*#---------------------------------------------------------------------------
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|
-*#
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|
|
-*# FUNCTION NAME: i2c_writereg
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|
-*#
|
|
|
-*# DESCRIPTION : Writes a value to an I2C device
|
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|
-*#
|
|
|
-*#--------------------------------------------------------------------------*/
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|
-int
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|
-i2c_writereg(unsigned char theSlave, unsigned char theReg,
|
|
|
- unsigned char theValue)
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|
-{
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|
|
- int error, cntr = 3;
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|
- unsigned long flags;
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|
|
-
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|
|
- spin_lock_irqsave(&i2c_lock, flags);
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|
|
-
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|
|
- do {
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|
|
- error = 0;
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|
|
-
|
|
|
- i2c_start();
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|
|
- /*
|
|
|
- * send slave address
|
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|
- */
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|
- i2c_outbyte((theSlave & 0xfe));
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|
- /*
|
|
|
- * wait for ack
|
|
|
- */
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|
|
- if(!i2c_getack())
|
|
|
- error = 1;
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|
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- /*
|
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|
- * now select register
|
|
|
- */
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|
|
- i2c_dir_out();
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|
|
- i2c_outbyte(theReg);
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|
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- /*
|
|
|
- * now it's time to wait for ack
|
|
|
- */
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|
|
- if(!i2c_getack())
|
|
|
- error |= 2;
|
|
|
- /*
|
|
|
- * send register register data
|
|
|
- */
|
|
|
- i2c_outbyte(theValue);
|
|
|
- /*
|
|
|
- * now it's time to wait for ack
|
|
|
- */
|
|
|
- if(!i2c_getack())
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|
|
- error |= 4;
|
|
|
- /*
|
|
|
- * end byte stream
|
|
|
- */
|
|
|
- i2c_stop();
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|
|
- } 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 ********************************/
|