/* * (C) Copyright 2001, 2002 * Wolfgang Denk, DENX Software Engineering, wd@denx.de. * * See file CREDITS for list of people who contributed to this * project. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, * MA 02111-1307 USA * * This has been changed substantially by Gerald Van Baren, Custom IDEAS, * vanbaren@cideas.com. It was heavily influenced by LiMon, written by * Neil Russell. */ #include <common.h> #ifdef CONFIG_MPC8260 /* only valid for MPC8260 */ #include <ioports.h> #endif #ifdef CONFIG_AT91RM9200DK /* need this for the at91rm9200dk */ #include <asm/io.h> #include <asm/arch/hardware.h> #endif #include <i2c.h> #if defined(CONFIG_SOFT_I2C) /* #define DEBUG_I2C */ /*----------------------------------------------------------------------- * Definitions */ #define RETRIES 0 #define I2C_ACK 0 /* PD_SDA level to ack a byte */ #define I2C_NOACK 1 /* PD_SDA level to noack a byte */ #ifdef DEBUG_I2C #define PRINTD(fmt,args...) do { \ DECLARE_GLOBAL_DATA_PTR; \ if (gd->have_console) \ printf (fmt ,##args); \ } while (0) #else #define PRINTD(fmt,args...) #endif /*----------------------------------------------------------------------- * Local functions */ static void send_reset (void); static void send_start (void); static void send_stop (void); static void send_ack (int); static int write_byte (uchar byte); static uchar read_byte (int); /*----------------------------------------------------------------------- * Send a reset sequence consisting of 9 clocks with the data signal high * to clock any confused device back into an idle state. Also send a * <stop> at the end of the sequence for belts & suspenders. */ static void send_reset(void) { #ifdef CONFIG_MPC8260 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); #endif #ifdef CONFIG_8xx volatile immap_t *immr = (immap_t *)CFG_IMMR; #endif int j; I2C_SCL(1); I2C_SDA(1); #ifdef I2C_INIT I2C_INIT; #endif I2C_TRISTATE; for(j = 0; j < 9; j++) { I2C_SCL(0); I2C_DELAY; I2C_DELAY; I2C_SCL(1); I2C_DELAY; I2C_DELAY; } send_stop(); I2C_TRISTATE; } /*----------------------------------------------------------------------- * START: High -> Low on SDA while SCL is High */ static void send_start(void) { #ifdef CONFIG_MPC8260 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); #endif #ifdef CONFIG_8xx volatile immap_t *immr = (immap_t *)CFG_IMMR; #endif I2C_DELAY; I2C_SDA(1); I2C_ACTIVE; I2C_DELAY; I2C_SCL(1); I2C_DELAY; I2C_SDA(0); I2C_DELAY; } /*----------------------------------------------------------------------- * STOP: Low -> High on SDA while SCL is High */ static void send_stop(void) { #ifdef CONFIG_MPC8260 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); #endif #ifdef CONFIG_8xx volatile immap_t *immr = (immap_t *)CFG_IMMR; #endif I2C_SCL(0); I2C_DELAY; I2C_SDA(0); I2C_ACTIVE; I2C_DELAY; I2C_SCL(1); I2C_DELAY; I2C_SDA(1); I2C_DELAY; I2C_TRISTATE; } /*----------------------------------------------------------------------- * ack should be I2C_ACK or I2C_NOACK */ static void send_ack(int ack) { #ifdef CONFIG_MPC8260 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); #endif #ifdef CONFIG_8xx volatile immap_t *immr = (immap_t *)CFG_IMMR; #endif I2C_ACTIVE; I2C_SCL(0); I2C_DELAY; I2C_SDA(ack); I2C_ACTIVE; I2C_DELAY; I2C_SCL(1); I2C_DELAY; I2C_DELAY; I2C_SCL(0); I2C_DELAY; } /*----------------------------------------------------------------------- * Send 8 bits and look for an acknowledgement. */ static int write_byte(uchar data) { #ifdef CONFIG_MPC8260 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); #endif #ifdef CONFIG_8xx volatile immap_t *immr = (immap_t *)CFG_IMMR; #endif int j; int nack; I2C_ACTIVE; for(j = 0; j < 8; j++) { I2C_SCL(0); I2C_DELAY; I2C_SDA(data & 0x80); I2C_DELAY; I2C_SCL(1); I2C_DELAY; I2C_DELAY; data <<= 1; } /* * Look for an <ACK>(negative logic) and return it. */ I2C_SCL(0); I2C_DELAY; I2C_SDA(1); I2C_TRISTATE; I2C_DELAY; I2C_SCL(1); I2C_DELAY; I2C_DELAY; nack = I2C_READ; I2C_SCL(0); I2C_DELAY; I2C_ACTIVE; return(nack); /* not a nack is an ack */ } /*----------------------------------------------------------------------- * if ack == I2C_ACK, ACK the byte so can continue reading, else * send I2C_NOACK to end the read. */ static uchar read_byte(int ack) { #ifdef CONFIG_MPC8260 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT); #endif #ifdef CONFIG_8xx volatile immap_t *immr = (immap_t *)CFG_IMMR; #endif int data; int j; /* * Read 8 bits, MSB first. */ I2C_TRISTATE; data = 0; for(j = 0; j < 8; j++) { I2C_SCL(0); I2C_DELAY; I2C_SCL(1); I2C_DELAY; data <<= 1; data |= I2C_READ; I2C_DELAY; } send_ack(ack); return(data); } /*=====================================================================*/ /* Public Functions */ /*=====================================================================*/ /*----------------------------------------------------------------------- * Initialization */ void i2c_init (int speed, int slaveaddr) { /* * WARNING: Do NOT save speed in a static variable: if the * I2C routines are called before RAM is initialized (to read * the DIMM SPD, for instance), RAM won't be usable and your * system will crash. */ send_reset (); } /*----------------------------------------------------------------------- * Probe to see if a chip is present. Also good for checking for the * completion of EEPROM writes since the chip stops responding until * the write completes (typically 10mSec). */ int i2c_probe(uchar addr) { int rc; /* perform 1 byte read transaction */ send_start(); rc = write_byte ((addr << 1) | 0); send_stop(); return (rc ? 1 : 0); } /*----------------------------------------------------------------------- * Read bytes */ int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len) { int shift; PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n", chip, addr, alen, buffer, len); #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW /* * EEPROM chips that implement "address overflow" are ones * like Catalyst 24WC04/08/16 which has 9/10/11 bits of * address and the extra bits end up in the "chip address" * bit slots. This makes a 24WC08 (1Kbyte) chip look like * four 256 byte chips. * * Note that we consider the length of the address field to * still be one byte because the extra address bits are * hidden in the chip address. */ chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW); PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n", chip, addr); #endif /* * Do the addressing portion of a write cycle to set the * chip's address pointer. If the address length is zero, * don't do the normal write cycle to set the address pointer, * there is no address pointer in this chip. */ send_start(); if(alen > 0) { if(write_byte(chip << 1)) { /* write cycle */ send_stop(); PRINTD("i2c_read, no chip responded %02X\n", chip); return(1); } shift = (alen-1) * 8; while(alen-- > 0) { if(write_byte(addr >> shift)) { PRINTD("i2c_read, address not <ACK>ed\n"); return(1); } shift -= 8; } send_stop(); /* reportedly some chips need a full stop */ send_start(); } /* * Send the chip address again, this time for a read cycle. * Then read the data. On the last byte, we do a NACK instead * of an ACK(len == 0) to terminate the read. */ write_byte((chip << 1) | 1); /* read cycle */ while(len-- > 0) { *buffer++ = read_byte(len == 0); } send_stop(); return(0); } /*----------------------------------------------------------------------- * Write bytes */ int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len) { int shift, failures = 0; PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n", chip, addr, alen, buffer, len); send_start(); if(write_byte(chip << 1)) { /* write cycle */ send_stop(); PRINTD("i2c_write, no chip responded %02X\n", chip); return(1); } shift = (alen-1) * 8; while(alen-- > 0) { if(write_byte(addr >> shift)) { PRINTD("i2c_write, address not <ACK>ed\n"); return(1); } shift -= 8; } while(len-- > 0) { if(write_byte(*buffer++)) { failures++; } } send_stop(); return(failures); } /*----------------------------------------------------------------------- * Read a register */ uchar i2c_reg_read(uchar i2c_addr, uchar reg) { char buf; i2c_read(i2c_addr, reg, 1, &buf, 1); return(buf); } /*----------------------------------------------------------------------- * Write a register */ void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val) { i2c_write(i2c_addr, reg, 1, &val, 1); } #endif /* CONFIG_SOFT_I2C */