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https://github.com/AsahiLinux/u-boot
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2ac6985a74
This patch adds a #define to optionally change the behaviour of i2c_read() in soft_i2c.c to send an I2C repeated start instead of a stop-start between sending the device address pointer write and reading back the data. The current behaviour is retained as the default. While most devices will work either way, I have a smart battery(*) that requires repeated start, and someone at some point found a device that required a stop-start. (*) http://www.inspired-energy.com/Standard_Products/NL2054/NL2054%20Rev1.0%20Data%20Sheet.pdf Signed-off-by: Andrew Dyer <adyer@righthandtech.com>
446 lines
9.9 KiB
C
446 lines
9.9 KiB
C
/*
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* (C) Copyright 2001, 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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* This has been changed substantially by Gerald Van Baren, Custom IDEAS,
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* vanbaren@cideas.com. It was heavily influenced by LiMon, written by
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* Neil Russell.
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*/
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#include <common.h>
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#ifdef CONFIG_MPC8260 /* only valid for MPC8260 */
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#include <ioports.h>
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#include <asm/io.h>
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#endif
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#ifdef CONFIG_AT91RM9200 /* need this for the at91rm9200 */
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#include <asm/io.h>
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#include <asm/arch/hardware.h>
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#endif
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#ifdef CONFIG_IXP425 /* only valid for IXP425 */
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#include <asm/arch/ixp425.h>
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#endif
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#ifdef CONFIG_LPC2292
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#include <asm/arch/hardware.h>
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#endif
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#ifdef CONFIG_MPC866 /* only valid for MPC866 */
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#include <asm/io.h>
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#endif
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#include <i2c.h>
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/* #define DEBUG_I2C */
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#ifdef DEBUG_I2C
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DECLARE_GLOBAL_DATA_PTR;
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#endif
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/*-----------------------------------------------------------------------
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* Definitions
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*/
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#define RETRIES 0
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#define I2C_ACK 0 /* PD_SDA level to ack a byte */
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#define I2C_NOACK 1 /* PD_SDA level to noack a byte */
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#ifdef DEBUG_I2C
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#define PRINTD(fmt,args...) do { \
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if (gd->have_console) \
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printf (fmt ,##args); \
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} while (0)
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#else
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#define PRINTD(fmt,args...)
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#endif
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#if defined(CONFIG_I2C_MULTI_BUS)
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static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
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#endif /* CONFIG_I2C_MULTI_BUS */
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/*-----------------------------------------------------------------------
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* Local functions
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*/
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#if !defined(CONFIG_SYS_I2C_INIT_BOARD)
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static void send_reset (void);
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#endif
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static void send_start (void);
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static void send_stop (void);
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static void send_ack (int);
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static int write_byte (uchar byte);
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static uchar read_byte (int);
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#if !defined(CONFIG_SYS_I2C_INIT_BOARD)
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/*-----------------------------------------------------------------------
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* Send a reset sequence consisting of 9 clocks with the data signal high
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* to clock any confused device back into an idle state. Also send a
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* <stop> at the end of the sequence for belts & suspenders.
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*/
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static void send_reset(void)
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{
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I2C_SOFT_DECLARATIONS /* intentional without ';' */
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int j;
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I2C_SCL(1);
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I2C_SDA(1);
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#ifdef I2C_INIT
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I2C_INIT;
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#endif
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I2C_TRISTATE;
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for(j = 0; j < 9; j++) {
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I2C_SCL(0);
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I2C_DELAY;
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I2C_DELAY;
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I2C_SCL(1);
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I2C_DELAY;
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I2C_DELAY;
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}
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send_stop();
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I2C_TRISTATE;
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}
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#endif
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/*-----------------------------------------------------------------------
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* START: High -> Low on SDA while SCL is High
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*/
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static void send_start(void)
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{
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I2C_SOFT_DECLARATIONS /* intentional without ';' */
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I2C_DELAY;
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I2C_SDA(1);
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I2C_ACTIVE;
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I2C_DELAY;
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I2C_SCL(1);
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I2C_DELAY;
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I2C_SDA(0);
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I2C_DELAY;
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}
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/*-----------------------------------------------------------------------
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* STOP: Low -> High on SDA while SCL is High
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*/
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static void send_stop(void)
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{
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I2C_SOFT_DECLARATIONS /* intentional without ';' */
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I2C_SCL(0);
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I2C_DELAY;
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I2C_SDA(0);
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I2C_ACTIVE;
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I2C_DELAY;
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I2C_SCL(1);
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I2C_DELAY;
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I2C_SDA(1);
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I2C_DELAY;
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I2C_TRISTATE;
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}
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/*-----------------------------------------------------------------------
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* ack should be I2C_ACK or I2C_NOACK
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*/
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static void send_ack(int ack)
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{
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I2C_SOFT_DECLARATIONS /* intentional without ';' */
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I2C_SCL(0);
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I2C_DELAY;
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I2C_ACTIVE;
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I2C_SDA(ack);
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I2C_DELAY;
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I2C_SCL(1);
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I2C_DELAY;
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I2C_DELAY;
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I2C_SCL(0);
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I2C_DELAY;
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}
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/*-----------------------------------------------------------------------
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* Send 8 bits and look for an acknowledgement.
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*/
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static int write_byte(uchar data)
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{
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I2C_SOFT_DECLARATIONS /* intentional without ';' */
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int j;
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int nack;
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I2C_ACTIVE;
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for(j = 0; j < 8; j++) {
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I2C_SCL(0);
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I2C_DELAY;
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I2C_SDA(data & 0x80);
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I2C_DELAY;
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I2C_SCL(1);
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I2C_DELAY;
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I2C_DELAY;
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data <<= 1;
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}
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/*
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* Look for an <ACK>(negative logic) and return it.
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*/
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I2C_SCL(0);
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I2C_DELAY;
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I2C_SDA(1);
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I2C_TRISTATE;
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I2C_DELAY;
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I2C_SCL(1);
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I2C_DELAY;
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I2C_DELAY;
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nack = I2C_READ;
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I2C_SCL(0);
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I2C_DELAY;
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I2C_ACTIVE;
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return(nack); /* not a nack is an ack */
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}
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#if defined(CONFIG_I2C_MULTI_BUS)
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/*
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* Functions for multiple I2C bus handling
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*/
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unsigned int i2c_get_bus_num(void)
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{
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return i2c_bus_num;
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}
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int i2c_set_bus_num(unsigned int bus)
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{
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#if defined(CONFIG_I2C_MUX)
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if (bus < CONFIG_SYS_MAX_I2C_BUS) {
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i2c_bus_num = bus;
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} else {
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int ret;
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ret = i2x_mux_select_mux(bus);
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if (ret == 0)
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i2c_bus_num = bus;
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else
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return ret;
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}
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#else
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if (bus >= CONFIG_SYS_MAX_I2C_BUS)
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return -1;
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i2c_bus_num = bus;
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#endif
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return 0;
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}
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/* TODO: add 100/400k switching */
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unsigned int i2c_get_bus_speed(void)
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{
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return CONFIG_SYS_I2C_SPEED;
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}
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int i2c_set_bus_speed(unsigned int speed)
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{
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if (speed != CONFIG_SYS_I2C_SPEED)
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return -1;
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return 0;
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}
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#endif
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/*-----------------------------------------------------------------------
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* if ack == I2C_ACK, ACK the byte so can continue reading, else
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* send I2C_NOACK to end the read.
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*/
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static uchar read_byte(int ack)
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{
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I2C_SOFT_DECLARATIONS /* intentional without ';' */
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int data;
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int j;
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/*
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* Read 8 bits, MSB first.
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*/
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I2C_TRISTATE;
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I2C_SDA(1);
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data = 0;
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for(j = 0; j < 8; j++) {
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I2C_SCL(0);
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I2C_DELAY;
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I2C_SCL(1);
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I2C_DELAY;
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data <<= 1;
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data |= I2C_READ;
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I2C_DELAY;
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}
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send_ack(ack);
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return(data);
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}
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/*=====================================================================*/
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/* Public Functions */
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/*=====================================================================*/
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/*-----------------------------------------------------------------------
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* Initialization
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*/
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void i2c_init (int speed, int slaveaddr)
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{
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#if defined(CONFIG_SYS_I2C_INIT_BOARD)
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/* call board specific i2c bus reset routine before accessing the */
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/* environment, which might be in a chip on that bus. For details */
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/* about this problem see doc/I2C_Edge_Conditions. */
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i2c_init_board();
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#else
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/*
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* WARNING: Do NOT save speed in a static variable: if the
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* I2C routines are called before RAM is initialized (to read
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* the DIMM SPD, for instance), RAM won't be usable and your
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* system will crash.
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*/
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send_reset ();
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#endif
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}
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/*-----------------------------------------------------------------------
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* Probe to see if a chip is present. Also good for checking for the
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* completion of EEPROM writes since the chip stops responding until
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* the write completes (typically 10mSec).
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*/
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int i2c_probe(uchar addr)
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{
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int rc;
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/*
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* perform 1 byte write transaction with just address byte
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* (fake write)
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*/
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send_start();
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rc = write_byte ((addr << 1) | 0);
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send_stop();
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return (rc ? 1 : 0);
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}
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/*-----------------------------------------------------------------------
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* Read bytes
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*/
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int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
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{
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int shift;
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PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
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chip, addr, alen, buffer, len);
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#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
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/*
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* EEPROM chips that implement "address overflow" are ones
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* like Catalyst 24WC04/08/16 which has 9/10/11 bits of
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* address and the extra bits end up in the "chip address"
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* bit slots. This makes a 24WC08 (1Kbyte) chip look like
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* four 256 byte chips.
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*
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* Note that we consider the length of the address field to
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* still be one byte because the extra address bits are
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* hidden in the chip address.
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*/
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chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
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PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
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chip, addr);
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#endif
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/*
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* Do the addressing portion of a write cycle to set the
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* chip's address pointer. If the address length is zero,
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* don't do the normal write cycle to set the address pointer,
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* there is no address pointer in this chip.
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*/
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send_start();
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if(alen > 0) {
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if(write_byte(chip << 1)) { /* write cycle */
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send_stop();
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PRINTD("i2c_read, no chip responded %02X\n", chip);
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return(1);
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}
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shift = (alen-1) * 8;
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while(alen-- > 0) {
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if(write_byte(addr >> shift)) {
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PRINTD("i2c_read, address not <ACK>ed\n");
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return(1);
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}
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shift -= 8;
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}
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/* Some I2C chips need a stop/start sequence here,
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* other chips don't work with a full stop and need
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* only a start. Default behaviour is to send the
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* stop/start sequence.
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*/
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#ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
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send_start();
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#else
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send_stop();
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send_start();
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#endif
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}
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/*
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* Send the chip address again, this time for a read cycle.
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* Then read the data. On the last byte, we do a NACK instead
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* of an ACK(len == 0) to terminate the read.
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*/
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write_byte((chip << 1) | 1); /* read cycle */
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while(len-- > 0) {
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*buffer++ = read_byte(len == 0);
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}
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send_stop();
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return(0);
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}
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/*-----------------------------------------------------------------------
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* Write bytes
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*/
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int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
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{
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int shift, failures = 0;
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PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
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chip, addr, alen, buffer, len);
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send_start();
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if(write_byte(chip << 1)) { /* write cycle */
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send_stop();
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PRINTD("i2c_write, no chip responded %02X\n", chip);
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return(1);
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}
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shift = (alen-1) * 8;
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while(alen-- > 0) {
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if(write_byte(addr >> shift)) {
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PRINTD("i2c_write, address not <ACK>ed\n");
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return(1);
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}
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shift -= 8;
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}
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while(len-- > 0) {
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if(write_byte(*buffer++)) {
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failures++;
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}
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}
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send_stop();
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return(failures);
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}
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