2 * (C) Copyright 2001, 2002
3 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 * See file CREDITS for list of people who contributed to this
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
23 * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
24 * vanbaren@cideas.com. It was heavily influenced by LiMon, written by
29 #ifdef CONFIG_MPC8260 /* only valid for MPC8260 */
33 #if defined(CONFIG_AT91FAMILY)
35 #include <asm/arch/hardware.h>
36 #include <asm/arch/at91_pio.h>
37 #ifdef CONFIG_AT91_LEGACY
38 #include <asm/arch/gpio.h>
41 #ifdef CONFIG_IXP425 /* only valid for IXP425 */
42 #include <asm/arch/ixp425.h>
44 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
49 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
50 # include <asm/gpio.h>
52 # ifndef I2C_GPIO_SYNC
53 # define I2C_GPIO_SYNC
59 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
60 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
65 # define I2C_ACTIVE do { } while (0)
69 # define I2C_TRISTATE do { } while (0)
73 # define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
77 # define I2C_SDA(bit) \
80 gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
82 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
88 # define I2C_SCL(bit) \
90 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
96 # define I2C_DELAY udelay(5) /* 1/4 I2C clock duration */
101 /* #define DEBUG_I2C */
104 DECLARE_GLOBAL_DATA_PTR;
107 /*-----------------------------------------------------------------------
113 #define I2C_ACK 0 /* PD_SDA level to ack a byte */
114 #define I2C_NOACK 1 /* PD_SDA level to noack a byte */
118 #define PRINTD(fmt,args...) do { \
119 printf (fmt ,##args); \
122 #define PRINTD(fmt,args...)
125 #if defined(CONFIG_I2C_MULTI_BUS)
126 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
127 #endif /* CONFIG_I2C_MULTI_BUS */
129 /*-----------------------------------------------------------------------
132 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
133 static void send_reset (void);
135 static void send_start (void);
136 static void send_stop (void);
137 static void send_ack (int);
138 static int write_byte (uchar byte);
139 static uchar read_byte (int);
141 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
142 /*-----------------------------------------------------------------------
143 * Send a reset sequence consisting of 9 clocks with the data signal high
144 * to clock any confused device back into an idle state. Also send a
145 * <stop> at the end of the sequence for belts & suspenders.
147 static void send_reset(void)
149 I2C_SOFT_DECLARATIONS /* intentional without ';' */
158 for(j = 0; j < 9; j++) {
171 /*-----------------------------------------------------------------------
172 * START: High -> Low on SDA while SCL is High
174 static void send_start(void)
176 I2C_SOFT_DECLARATIONS /* intentional without ';' */
188 /*-----------------------------------------------------------------------
189 * STOP: Low -> High on SDA while SCL is High
191 static void send_stop(void)
193 I2C_SOFT_DECLARATIONS /* intentional without ';' */
207 /*-----------------------------------------------------------------------
208 * ack should be I2C_ACK or I2C_NOACK
210 static void send_ack(int ack)
212 I2C_SOFT_DECLARATIONS /* intentional without ';' */
226 /*-----------------------------------------------------------------------
227 * Send 8 bits and look for an acknowledgement.
229 static int write_byte(uchar data)
231 I2C_SOFT_DECLARATIONS /* intentional without ';' */
236 for(j = 0; j < 8; j++) {
239 I2C_SDA(data & 0x80);
249 * Look for an <ACK>(negative logic) and return it.
264 return(nack); /* not a nack is an ack */
267 #if defined(CONFIG_I2C_MULTI_BUS)
269 * Functions for multiple I2C bus handling
271 unsigned int i2c_get_bus_num(void)
276 int i2c_set_bus_num(unsigned int bus)
278 #if defined(CONFIG_I2C_MUX)
279 if (bus < CONFIG_SYS_MAX_I2C_BUS) {
284 ret = i2x_mux_select_mux(bus);
292 if (bus >= CONFIG_SYS_MAX_I2C_BUS)
300 /*-----------------------------------------------------------------------
301 * if ack == I2C_ACK, ACK the byte so can continue reading, else
302 * send I2C_NOACK to end the read.
304 static uchar read_byte(int ack)
306 I2C_SOFT_DECLARATIONS /* intentional without ';' */
311 * Read 8 bits, MSB first.
316 for(j = 0; j < 8; j++) {
330 /*=====================================================================*/
331 /* Public Functions */
332 /*=====================================================================*/
334 /*-----------------------------------------------------------------------
337 void i2c_init (int speed, int slaveaddr)
339 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
340 /* call board specific i2c bus reset routine before accessing the */
341 /* environment, which might be in a chip on that bus. For details */
342 /* about this problem see doc/I2C_Edge_Conditions. */
346 * WARNING: Do NOT save speed in a static variable: if the
347 * I2C routines are called before RAM is initialized (to read
348 * the DIMM SPD, for instance), RAM won't be usable and your
355 /*-----------------------------------------------------------------------
356 * Probe to see if a chip is present. Also good for checking for the
357 * completion of EEPROM writes since the chip stops responding until
358 * the write completes (typically 10mSec).
360 int i2c_probe(uchar addr)
365 * perform 1 byte write transaction with just address byte
369 rc = write_byte ((addr << 1) | 0);
375 /*-----------------------------------------------------------------------
378 int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
381 PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
382 chip, addr, alen, buffer, len);
384 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
386 * EEPROM chips that implement "address overflow" are ones
387 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
388 * address and the extra bits end up in the "chip address"
389 * bit slots. This makes a 24WC08 (1Kbyte) chip look like
390 * four 256 byte chips.
392 * Note that we consider the length of the address field to
393 * still be one byte because the extra address bits are
394 * hidden in the chip address.
396 chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
398 PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
403 * Do the addressing portion of a write cycle to set the
404 * chip's address pointer. If the address length is zero,
405 * don't do the normal write cycle to set the address pointer,
406 * there is no address pointer in this chip.
410 if(write_byte(chip << 1)) { /* write cycle */
412 PRINTD("i2c_read, no chip responded %02X\n", chip);
415 shift = (alen-1) * 8;
417 if(write_byte(addr >> shift)) {
418 PRINTD("i2c_read, address not <ACK>ed\n");
424 /* Some I2C chips need a stop/start sequence here,
425 * other chips don't work with a full stop and need
426 * only a start. Default behaviour is to send the
427 * stop/start sequence.
429 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
437 * Send the chip address again, this time for a read cycle.
438 * Then read the data. On the last byte, we do a NACK instead
439 * of an ACK(len == 0) to terminate the read.
441 write_byte((chip << 1) | 1); /* read cycle */
443 *buffer++ = read_byte(len == 0);
449 /*-----------------------------------------------------------------------
452 int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
454 int shift, failures = 0;
456 PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
457 chip, addr, alen, buffer, len);
460 if(write_byte(chip << 1)) { /* write cycle */
462 PRINTD("i2c_write, no chip responded %02X\n", chip);
465 shift = (alen-1) * 8;
467 if(write_byte(addr >> shift)) {
468 PRINTD("i2c_write, address not <ACK>ed\n");
475 if(write_byte(*buffer++)) {