diff options
Diffstat (limited to 'u-boot/drivers/i2c/soft_i2c.c')
| -rw-r--r-- | u-boot/drivers/i2c/soft_i2c.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/u-boot/drivers/i2c/soft_i2c.c b/u-boot/drivers/i2c/soft_i2c.c new file mode 100644 index 0000000..69b5f42 --- /dev/null +++ b/u-boot/drivers/i2c/soft_i2c.c @@ -0,0 +1,484 @@ +/* + * (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 { \ + if (gd->have_console) \ + 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); + 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); +} |