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Diffstat (limited to 'common/soft_i2c.c')
| -rw-r--r-- | common/soft_i2c.c | 416 |
1 files changed, 416 insertions, 0 deletions
diff --git a/common/soft_i2c.c b/common/soft_i2c.c new file mode 100644 index 0000000..7777480 --- /dev/null +++ b/common/soft_i2c.c @@ -0,0 +1,416 @@ +/* + * (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 +#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_ACTIVE; + I2C_SDA(1); + 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) +{ +#ifdef CONFIG_8xx + volatile immap_t *immr = (immap_t *)CFG_IMMR; +#endif + +#ifdef I2C_INIT + I2C_INIT; +#endif + /* + * 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; + + send_start(); + rc = write_byte ((addr << 1) | 1); + 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 */ |