mirror of
https://github.com/AsahiLinux/u-boot
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414 lines
9.3 KiB
C
414 lines
9.3 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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#endif
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#include <i2c.h>
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#if defined(CONFIG_SOFT_I2C)
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/* #define DEBUG_I2C */
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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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DECLARE_GLOBAL_DATA_PTR; \
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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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/*-----------------------------------------------------------------------
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* Local functions
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*/
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static void send_reset (void);
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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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/*-----------------------------------------------------------------------
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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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#ifdef CONFIG_MPC8260
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volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
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#endif
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#ifdef CONFIG_8xx
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volatile immap_t *immr = (immap_t *)CFG_IMMR;
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#endif
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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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/*-----------------------------------------------------------------------
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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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#ifdef CONFIG_MPC8260
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volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
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#endif
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#ifdef CONFIG_8xx
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volatile immap_t *immr = (immap_t *)CFG_IMMR;
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#endif
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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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#ifdef CONFIG_MPC8260
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volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
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#endif
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#ifdef CONFIG_8xx
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volatile immap_t *immr = (immap_t *)CFG_IMMR;
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#endif
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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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#ifdef CONFIG_MPC8260
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volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
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#endif
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#ifdef CONFIG_8xx
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volatile immap_t *immr = (immap_t *)CFG_IMMR;
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#endif
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I2C_ACTIVE;
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I2C_SCL(0);
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I2C_DELAY;
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I2C_SDA(ack);
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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_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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#ifdef CONFIG_MPC8260
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volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
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#endif
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#ifdef CONFIG_8xx
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volatile immap_t *immr = (immap_t *)CFG_IMMR;
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#endif
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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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/*-----------------------------------------------------------------------
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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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#ifdef CONFIG_MPC8260
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volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
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#endif
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#ifdef CONFIG_8xx
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volatile immap_t *immr = (immap_t *)CFG_IMMR;
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#endif
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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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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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/*
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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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}
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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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/* perform 1 byte read transaction */
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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 CFG_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)) & CFG_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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send_stop(); /* reportedly some chips need a full stop */
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send_start();
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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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/*-----------------------------------------------------------------------
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* Read a register
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*/
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uchar i2c_reg_read(uchar i2c_addr, uchar reg)
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{
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char buf;
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i2c_read(i2c_addr, reg, 1, &buf, 1);
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return(buf);
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}
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/*-----------------------------------------------------------------------
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* Write a register
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*/
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void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
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{
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i2c_write(i2c_addr, reg, 1, &val, 1);
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}
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#endif /* CONFIG_SOFT_I2C */
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