mirror of
https://github.com/brain-hackers/u-boot-brain
synced 2024-08-19 00:18:51 +09:00
258 lines
4.3 KiB
C
258 lines
4.3 KiB
C
/*
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* (C) Copyright 2002
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* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#include <config.h>
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#include <common.h>
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#include <asm/io.h>
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#include "hardware.h"
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#include "i2c.h"
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static void i2c_start (void);
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static void i2c_stop (void);
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static int i2c_write (u8 data);
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static void i2c_read (u8 * data);
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static inline void i2c_port_start (void);
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static inline void i2c_clock (unsigned int val);
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static inline void i2c_data (unsigned int val);
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static inline unsigned int
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i2c_in (void);
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static inline void i2c_write_bit (unsigned int val);
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static inline unsigned int
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i2c_read_bit (void);
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static inline void i2c_udelay (unsigned int time);
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int i2c_read_byte (
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u8 * data,
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u8 dev,
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u8 offset)
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{
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int err = 0;
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i2c_start();
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err = ! i2c_write(dev);
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if (! err)
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{
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err = ! i2c_write(offset);
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}
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if (! err)
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{
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i2c_start();
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}
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if (! err)
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{
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err = ! i2c_write(dev | 0x01);
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}
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if (! err)
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{
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i2c_read(data);
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}
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i2c_stop();
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return ! err;
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}
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static inline void i2c_udelay (
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unsigned int time)
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{
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int v;
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asm volatile("mtdec %0" : : "r" (time * ((CONFIG_SYS_BUS_CLK / 4) / 1000000)));
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do
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{
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asm volatile("isync; mfdec %0" : "=r" (v));
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} while (v >= 0);
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}
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/* Low-level hardware access
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*/
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#define BIT_GPDATA 0x80000000
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#define BIT_GPCLK 0x40000000
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static inline void i2c_port_start (void)
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{
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out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~(BIT_GPCLK | BIT_GPDATA));
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out32(REG(CPC0, GPOUT), in32(REG(CPC0, GPOUT)) & ~(BIT_GPCLK | BIT_GPDATA));
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iobarrier_rw();
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i2c_udelay(1);
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}
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static inline void i2c_clock (
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unsigned int val)
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{
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if (val)
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{
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out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~BIT_GPCLK);
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}
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else
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{
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out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) | BIT_GPCLK);
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}
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iobarrier_rw();
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i2c_udelay(1);
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}
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static inline void i2c_data (
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unsigned int val)
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{
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if (val)
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{
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out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) & ~BIT_GPDATA);
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}
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else
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{
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out32(REG(CPC0, GPDIR), in32(REG(CPC0, GPDIR)) | BIT_GPDATA);
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}
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iobarrier_rw();
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i2c_udelay(1);
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}
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static inline unsigned int i2c_in (void)
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{
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unsigned int val = ((in32(REG(CPC0, GPIN)) & BIT_GPDATA) != 0)?1:0;
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iobarrier_rw();
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return val;
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}
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/* Protocol implementation
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*/
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static inline void i2c_write_bit (
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unsigned int val)
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{
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i2c_data(val);
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i2c_udelay(10);
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i2c_clock(1);
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i2c_udelay(10);
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i2c_clock(0);
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i2c_udelay(10);
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}
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static inline unsigned int i2c_read_bit (void)
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{
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unsigned int val;
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i2c_data(1);
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i2c_udelay(10);
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i2c_clock(1);
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i2c_udelay(10);
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val = i2c_in();
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i2c_clock(0);
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i2c_udelay(10);
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return val;
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}
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unsigned int i2c_reset (void)
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{
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unsigned int val;
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int i;
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i2c_port_start();
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i=0;
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do {
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i2c_udelay(10);
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i2c_clock(0);
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i2c_udelay(10);
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i2c_clock(1);
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i2c_udelay(10);
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val = i2c_in();
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i++;
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} while ((i<9)&&(val==0));
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return (val);
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}
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static void i2c_start (void)
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{
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i2c_data(1);
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i2c_clock(1);
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i2c_udelay(10);
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i2c_data(0);
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i2c_udelay(10);
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i2c_clock(0);
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i2c_udelay(10);
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}
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static void i2c_stop (void)
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{
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i2c_data(0);
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i2c_udelay(10);
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i2c_clock(1);
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i2c_udelay(10);
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i2c_data(1);
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i2c_udelay(10);
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}
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static int i2c_write (
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u8 data)
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{
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unsigned int i;
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for (i = 0; i < 8; i++)
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{
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i2c_write_bit(data >> 7);
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data <<= 1;
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}
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return i2c_read_bit() == 0;
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}
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static void i2c_read (
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u8 * data)
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{
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unsigned int i;
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u8 val = 0;
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for (i = 0; i < 8; i++)
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{
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val <<= 1;
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val |= i2c_read_bit();
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}
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*data = val;
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i2c_write_bit(1); /* NoAck */
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}
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