2 * i2c Support for Atmel's AT91RM9200 Two-Wire Interface
6 * Borrowed heavily from original work by:
7 * Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
9 * Modified to work with u-boot by (C) 2004 Gary Jennejohn garyj@denx.de
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
28 #ifdef CONFIG_HARD_I2C
32 #include <asm/arch/hardware.h>
34 #include <at91rm9200_i2c.h>
39 * Poll the i2c status register until the specified bit is set.
40 * Returns 0 if timed out (100 msec)
42 static short at91_poll_status(AT91PS_TWI twi, unsigned long bit) {
43 int loop_cntr = 10000;
46 } while (!(twi->TWI_SR & bit) && (--loop_cntr > 0));
48 return (loop_cntr > 0);
52 * Generic i2c master transfer entrypoint
54 * rw == 1 means that this is a read
57 at91_xfer(unsigned char chip, unsigned int addr, int alen,
58 unsigned char *buffer, int len, int rw)
60 AT91PS_TWI twi = (AT91PS_TWI) AT91_TWI_BASE;
63 /* Set the TWI Master Mode Register */
64 twi->TWI_MMR = (chip << 16) | (alen << 8)
65 | ((rw == 1) ? AT91C_TWI_MREAD : 0);
67 /* Set TWI Internal Address Register with first messages data field */
68 /* only one address byte is supported */
70 twi->TWI_IADR = addr & 0xff;
74 if (length && buf) { /* sanity check */
76 twi->TWI_CR = AT91C_TWI_START;
79 twi->TWI_CR = AT91C_TWI_STOP;
80 /* Wait until transfer is finished */
81 if (!at91_poll_status(twi, AT91C_TWI_RXRDY)) {
82 debug ("at91_i2c: timeout 1\n");
85 *buf++ = twi->TWI_RHR;
87 if (!at91_poll_status(twi, AT91C_TWI_TXCOMP)) {
88 debug ("at91_i2c: timeout 2\n");
92 twi->TWI_CR = AT91C_TWI_START;
94 twi->TWI_THR = *buf++;
96 twi->TWI_CR = AT91C_TWI_STOP;
97 if (!at91_poll_status(twi, AT91C_TWI_TXRDY)) {
98 debug ("at91_i2c: timeout 3\n");
102 /* Wait until transfer is finished */
103 if (!at91_poll_status(twi, AT91C_TWI_TXCOMP)) {
104 debug ("at91_i2c: timeout 4\n");
113 i2c_probe(unsigned char chip)
117 return at91_xfer(chip, 0, 0, buffer, 1, 1);
121 i2c_read (unsigned char chip, unsigned int addr, int alen,
122 unsigned char *buffer, int len)
124 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
125 /* we only allow one address byte */
128 /* XXX assume an ATMEL AT24C16 */
130 #if 0 /* EEPROM code already sets this correctly */
131 chip |= (addr >> 8) & 0xff;
136 return at91_xfer(chip, addr, alen, buffer, len, 1);
140 i2c_write(unsigned char chip, unsigned int addr, int alen,
141 unsigned char *buffer, int len)
146 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
147 /* we only allow one address byte */
150 /* XXX assume an ATMEL AT24C16 */
153 /* do single byte writes */
154 for (i = 0; i < len; i++) {
155 #if 0 /* EEPROM code already sets this correctly */
156 chip |= (addr >> 8) & 0xff;
159 if (at91_xfer(chip, addr, alen, buf++, 1, 0))
166 return at91_xfer(chip, addr, alen, buffer, len, 0);
170 * Main initialization routine
173 i2c_init(int speed, int slaveaddr)
175 AT91PS_TWI twi = (AT91PS_TWI) AT91_TWI_BASE;
177 *AT91C_PIOA_PDR = AT91C_PA25_TWD | AT91C_PA26_TWCK;
178 *AT91C_PIOA_ASR = AT91C_PA25_TWD | AT91C_PA26_TWCK;
179 *AT91C_PIOA_MDER = AT91C_PA25_TWD | AT91C_PA26_TWCK;
180 *AT91C_PMC_PCER = 1 << AT91C_ID_TWI; /* enable peripheral clock */
182 twi->TWI_IDR = 0x3ff; /* Disable all interrupts */
183 twi->TWI_CR = AT91C_TWI_SWRST; /* Reset peripheral */
184 twi->TWI_CR = AT91C_TWI_MSEN | AT91C_TWI_SVDIS; /* Set Master mode */
186 /* Here, CKDIV = 1 and CHDIV=CLDIV ==> CLDIV = CHDIV = 1/4*((Fmclk/FTWI) -6) */
187 twi->TWI_CWGR = AT91C_TWI_CKDIV1 | AT91C_TWI_CLDIV3 | (AT91C_TWI_CLDIV3 << 8);
189 debug ("Found AT91 i2c\n");
192 #endif /* CONFIG_HARD_I2C */