diff options
Diffstat (limited to 'cpu/arm920t/at91rm9200/i2c.c')
| -rw-r--r-- | cpu/arm920t/at91rm9200/i2c.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/cpu/arm920t/at91rm9200/i2c.c b/cpu/arm920t/at91rm9200/i2c.c new file mode 100644 index 0000000..433dd32 --- /dev/null +++ b/cpu/arm920t/at91rm9200/i2c.c @@ -0,0 +1,192 @@ +/* + * i2c Support for Atmel's AT91RM9200 Two-Wire Interface + * + * (c) Rick Bronson + * + * Borrowed heavily from original work by: + * Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com> + * + * Modified to work with u-boot by (C) 2004 Gary Jennejohn garyj@denx.de + * + * 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., 675 Mass Ave, Cambridge, MA 02139, USA. + * +*/ +#include <common.h> + +#ifdef CONFIG_HARD_I2C + +#include <i2c.h> +#include <asm/io.h> +#include <asm/arch/hardware.h> + +#include <at91rm9200_i2c.h> + +/* define DEBUG */ + +/* + * Poll the i2c status register until the specified bit is set. + * Returns 0 if timed out (100 msec) + */ +static short at91_poll_status(AT91PS_TWI twi, unsigned long bit) { + int loop_cntr = 10000; + do { + udelay(10); + } while (!(twi->TWI_SR & bit) && (--loop_cntr > 0)); + + return (loop_cntr > 0); +} + +/* + * Generic i2c master transfer entrypoint + * + * rw == 1 means that this is a read + */ +static int +at91_xfer(unsigned char chip, unsigned int addr, int alen, + unsigned char *buffer, int len, int rw) +{ + AT91PS_TWI twi = (AT91PS_TWI) AT91_TWI_BASE; + int length; + unsigned char *buf; + /* Set the TWI Master Mode Register */ + twi->TWI_MMR = (chip << 16) | (alen << 8) + | ((rw == 1) ? AT91C_TWI_MREAD : 0); + + /* Set TWI Internal Address Register with first messages data field */ + /* only one address byte is supported */ + if (alen > 0) + twi->TWI_IADR = addr & 0xff; + + length = len; + buf = buffer; + if (length && buf) { /* sanity check */ + if (rw) { + twi->TWI_CR = AT91C_TWI_START; + while (length--) { + if (!length) + twi->TWI_CR = AT91C_TWI_STOP; + /* Wait until transfer is finished */ + if (!at91_poll_status(twi, AT91C_TWI_RXRDY)) { + debug ("at91_i2c: timeout 1\n"); + return 1; + } + *buf++ = twi->TWI_RHR; + } + if (!at91_poll_status(twi, AT91C_TWI_TXCOMP)) { + debug ("at91_i2c: timeout 2\n"); + return 1; + } + } else { + twi->TWI_CR = AT91C_TWI_START; + while (length--) { + twi->TWI_THR = *buf++; + if (!length) + twi->TWI_CR = AT91C_TWI_STOP; + if (!at91_poll_status(twi, AT91C_TWI_TXRDY)) { + debug ("at91_i2c: timeout 3\n"); + return 1; + } + } + /* Wait until transfer is finished */ + if (!at91_poll_status(twi, AT91C_TWI_TXCOMP)) { + debug ("at91_i2c: timeout 4\n"); + return 1; + } + } + } + return 0; +} + +int +i2c_probe(unsigned char chip) +{ + char buffer[1]; + + return at91_xfer(chip, 0, 0, buffer, 1, 1); +} + +int +i2c_read (unsigned char chip, unsigned int addr, int alen, + unsigned char *buffer, int len) +{ +#ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW + /* we only allow one address byte */ + if (alen > 1) + return 1; + /* XXX assume an ATMEL AT24C16 */ + if (alen == 1) { +#if 0 /* EEPROM code already sets this correctly */ + chip |= (addr >> 8) & 0xff; +#endif + addr = addr & 0xff; + } +#endif + return at91_xfer(chip, addr, alen, buffer, len, 1); +} + +int +i2c_write(unsigned char chip, unsigned int addr, int alen, + unsigned char *buffer, int len) +{ + int i; + unsigned char *buf; + +#ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW + /* we only allow one address byte */ + if (alen > 1) + return 1; + /* XXX assume an ATMEL AT24C16 */ + if (alen == 1) { + buf = buffer; + /* do single byte writes */ + for (i = 0; i < len; i++) { +#if 0 /* EEPROM code already sets this correctly */ + chip |= (addr >> 8) & 0xff; +#endif + addr = addr & 0xff; + if (at91_xfer(chip, addr, alen, buf++, 1, 0)) + return 1; + addr++; + } + return 0; + } +#endif + return at91_xfer(chip, addr, alen, buffer, len, 0); +} + +/* + * Main initialization routine + */ +void +i2c_init(int speed, int slaveaddr) +{ + AT91PS_TWI twi = (AT91PS_TWI) AT91_TWI_BASE; + + *AT91C_PIOA_PDR = AT91C_PA25_TWD | AT91C_PA26_TWCK; + *AT91C_PIOA_ASR = AT91C_PA25_TWD | AT91C_PA26_TWCK; + *AT91C_PIOA_MDER = AT91C_PA25_TWD | AT91C_PA26_TWCK; + *AT91C_PMC_PCER = 1 << AT91C_ID_TWI; /* enable peripheral clock */ + + twi->TWI_IDR = 0x3ff; /* Disable all interrupts */ + twi->TWI_CR = AT91C_TWI_SWRST; /* Reset peripheral */ + twi->TWI_CR = AT91C_TWI_MSEN | AT91C_TWI_SVDIS; /* Set Master mode */ + + /* Here, CKDIV = 1 and CHDIV=CLDIV ==> CLDIV = CHDIV = 1/4*((Fmclk/FTWI) -6) */ + twi->TWI_CWGR = AT91C_TWI_CKDIV1 | AT91C_TWI_CLDIV3 | (AT91C_TWI_CLDIV3 << 8); + + debug ("Found AT91 i2c\n"); + return; +} +#endif /* CONFIG_HARD_I2C */ |