/* * (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> #include <asm/io.h> #endif #if defined(CONFIG_AT91FAMILY) #include <asm/io.h> #include <asm/arch/hardware.h> #include <asm/arch/at91_pio.h> #ifdef CONFIG_AT91_LEGACY #include <asm/arch/gpio.h> #endif #endif #ifdef CONFIG_IXP425 /* only valid for IXP425 */ #include <asm/arch/ixp425.h> #endif #ifdef CONFIG_LPC2292 #include <asm/arch/hardware.h> #endif #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866) #include <asm/io.h> #endif #include <i2c.h> #if defined(CONFIG_SOFT_I2C_GPIO_SCL) # include <asm/gpio.h> # ifndef I2C_GPIO_SYNC # define I2C_GPIO_SYNC # endif # ifndef I2C_INIT # define I2C_INIT \ do { \ gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \ gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \ } while (0) # endif # ifndef I2C_ACTIVE # define I2C_ACTIVE do { } while (0) # endif # ifndef I2C_TRISTATE # define I2C_TRISTATE do { } while (0) # endif # ifndef I2C_READ # define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA) # endif # ifndef I2C_SDA # define I2C_SDA(bit) \ do { \ if (bit) \ gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \ else \ gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \ I2C_GPIO_SYNC; \ } while (0) # endif # ifndef I2C_SCL # define I2C_SCL(bit) \ do { \ gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \ I2C_GPIO_SYNC; \ } while (0) # endif # ifndef I2C_DELAY # define I2C_DELAY udelay(5) /* 1/4 I2C clock duration */ # endif #endif /* #define DEBUG_I2C */ #ifdef DEBUG_I2C DECLARE_GLOBAL_DATA_PTR; #endif /*----------------------------------------------------------------------- * 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 { \ printf (fmt ,##args); \ } while (0) #else #define PRINTD(fmt,args...) #endif #if defined(CONFIG_I2C_MULTI_BUS) static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0; #endif /* CONFIG_I2C_MULTI_BUS */ /*----------------------------------------------------------------------- * Local functions */ #if !defined(CONFIG_SYS_I2C_INIT_BOARD) static void send_reset (void); #endif 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); #if !defined(CONFIG_SYS_I2C_INIT_BOARD) /*----------------------------------------------------------------------- * 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) { I2C_SOFT_DECLARATIONS /* intentional without ';' */ 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; } #endif /*----------------------------------------------------------------------- * START: High -> Low on SDA while SCL is High */ static void send_start(void) { I2C_SOFT_DECLARATIONS /* intentional without ';' */ 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) { I2C_SOFT_DECLARATIONS /* intentional without ';' */ 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) { I2C_SOFT_DECLARATIONS /* intentional without ';' */ I2C_SCL(0); I2C_DELAY; I2C_ACTIVE; I2C_SDA(ack); 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) { I2C_SOFT_DECLARATIONS /* intentional without ';' */ 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 defined(CONFIG_I2C_MULTI_BUS) /* * Functions for multiple I2C bus handling */ unsigned int i2c_get_bus_num(void) { return i2c_bus_num; } int i2c_set_bus_num(unsigned int bus) { #if defined(CONFIG_I2C_MUX) if (bus < CONFIG_SYS_MAX_I2C_BUS) { i2c_bus_num = bus; } else { int ret; ret = i2x_mux_select_mux(bus); i2c_init_board(); if (ret == 0) i2c_bus_num = bus; else return ret; } #else if (bus >= CONFIG_SYS_MAX_I2C_BUS) return -1; i2c_bus_num = bus; #endif return 0; } #endif /*----------------------------------------------------------------------- * 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) { I2C_SOFT_DECLARATIONS /* intentional without ';' */ int data; int j; /* * Read 8 bits, MSB first. */ I2C_TRISTATE; I2C_SDA(1); 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) { #if defined(CONFIG_SYS_I2C_INIT_BOARD) /* call board specific i2c bus reset routine before accessing the */ /* environment, which might be in a chip on that bus. For details */ /* about this problem see doc/I2C_Edge_Conditions. */ i2c_init_board(); #else /* * 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 (); #endif } /*----------------------------------------------------------------------- * 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 write transaction with just address byte * (fake write) */ 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 CONFIG_SYS_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)) & CONFIG_SYS_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; } /* Some I2C chips need a stop/start sequence here, * other chips don't work with a full stop and need * only a start. Default behaviour is to send the * stop/start sequence. */ #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START send_start(); #else send_stop(); send_start(); #endif } /* * 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); }