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sam7fc/src/at91_twi.c

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/***************************************************************************
* Copyright (C) 02/2008 by Olaf Rempel *
* razzor@kopf-tisch.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; version 2 of the License *
* *
* 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. *
***************************************************************************/
#include <stdint.h>
#include <stdio.h>
#include "AT91SAM7S256.h"
#include "board.h"
#include "at91_twi.h"
#include "at91_pio.h"
/*
* undocumented TWI_SR flags, at least OVRE seems to be present on a sam7s256
* taken from linux-2.6.24/include/asm-arm/arch-at91/at91_twi.h
*/
#define AT91_TWI_OVRE (1<<6) /* Overrun */
#define AT91_TWI_UNRE (1<<7) /* Underrun */
/*
* while ((cldiv = ((MCK / (2 * TWI)) -3) / (1 << ckdiv)) > 255)
* ckdiv++ ;
*
* works for TWI >= 100kHz
*/
#define TWI_CLK(x) (((MCK / (2 * (x))) -3)<<8 | ((MCK / (2 * (x))) -3))
enum twi_states {
TWI_IDLE = 0x00,
TWI_ERROR,
TWI_GENERIC_CMD = 0x10,
TWI_BLMC_UPDATE = 0x20,
};
static volatile uint32_t twi_state = TWI_IDLE;
static uint8_t *twi_data;
static uint32_t twi_size;
static uint32_t twi_count;
static void twi_isr(void)
{
/* get status */
uint32_t status = *AT91C_TWI_SR;
status &= *AT91C_TWI_IMR;
/* NACK - disable all interrupts and go to state TWI_ERROR */
if (status & AT91C_TWI_NACK) {
*AT91C_TWI_IDR = AT91C_TWI_TXCOMP | AT91C_TWI_RXRDY | AT91C_TWI_TXRDY | AT91C_TWI_NACK;
twi_state = TWI_ERROR;
// TODO: TWI_BLMC_UPDATE?
return;
}
/* tx register ready for new data */
if (status & AT91C_TWI_TXRDY) {
if (twi_count != twi_size) {
/* feed next byte */
*AT91C_TWI_THR = twi_data[twi_count++];
} else {
/* wait for TXCOMP */
*AT91C_TWI_IDR = AT91C_TWI_RXRDY | AT91C_TWI_TXRDY;
*AT91C_TWI_IER = AT91C_TWI_TXCOMP | AT91C_TWI_NACK;
}
}
/* rx register has data */
if (status & AT91C_TWI_RXRDY) {
/* get data */
twi_data[twi_count++] = *AT91C_TWI_RHR;
/* transfer complete? */
if (twi_count == twi_size) {
/* send STOP and wait for TXCOMP */
*AT91C_TWI_CR = AT91C_TWI_STOP;
*AT91C_TWI_IDR = AT91C_TWI_TXRDY;
*AT91C_TWI_IER = AT91C_TWI_TXCOMP | AT91C_TWI_NACK;
}
}
/* transfer really complete? */
if (status & AT91C_TWI_TXCOMP) {
/* are we doing a blmc update? */
if (twi_state == TWI_BLMC_UPDATE) {
uint32_t addr = (*AT91C_TWI_MMR >> 16) & 0x7F;
if (addr != TWI_ADDR_BL4) {
/* increase address */
*AT91C_TWI_MMR += (1<<16);
/* send next value to next blmc */
*AT91C_TWI_THR = *twi_data++;
} else {
// TODO:
}
} else {
*AT91C_TWI_IDR = AT91C_TWI_TXCOMP | AT91C_TWI_RXRDY | AT91C_TWI_TXRDY | AT91C_TWI_NACK;
twi_state = TWI_IDLE;
}
}
}
uint32_t twi_setpwm(uint8_t *values)
{
if (twi_state != TWI_IDLE)
return 1;
twi_state = TWI_BLMC_UPDATE;
twi_data = values; /* data is not copied! */
twi_size = 0;
twi_count = 0;
*AT91C_TWI_MMR = (TWI_ADDR_BL1 << 16) | AT91C_TWI_IADRSZ_1_BYTE;
*AT91C_TWI_IADR = CMD_SET_PWM;
*AT91C_TWI_THR = *twi_data++;
*AT91C_TWI_IER = AT91C_TWI_TXRDY | AT91C_TWI_NACK;
return 0;
}
uint32_t twi_cmd(uint8_t addr, struct blmc_cmd *cmd)
{
if (twi_state != TWI_IDLE)
return 1;
/* TODO: locking needed? */
twi_state = TWI_GENERIC_CMD;
/* read transfer, or write transfer with payload */
if (cmd->mode & BLMC_CMD_READ || cmd->size != 0) {
/* set address, direction, argument count and command bytes */
*AT91C_TWI_MMR = (addr << 16) | (cmd->mode & 0xFF) << 8;
*AT91C_TWI_IADR = cmd->cmd;
/* write transfer without payload */
} else {
/* use one cmd byte as payload (needed to start transfer) */
cmd->mode--;
*AT91C_TWI_MMR = (addr << 16) | (cmd->mode & 0xFF) << 8;
*AT91C_TWI_IADR = (cmd->cmd) >> 8;
}
/* isr needs data & size parameters */
twi_data = cmd->data;
twi_size = cmd->size;
twi_count = 0;
if (cmd->mode & BLMC_CMD_READ) {
*AT91C_TWI_CR = AT91C_TWI_START;
*AT91C_TWI_IER = AT91C_TWI_RXRDY | AT91C_TWI_NACK;
} else {
*AT91C_TWI_THR = (twi_size != 0) ? cmd->data[twi_count++] : (cmd->cmd & 0xFF);
*AT91C_TWI_IER = AT91C_TWI_TXRDY | AT91C_TWI_NACK;
}
/*
* wait for end
* TODO: locking needed?
* TODO: timeout?
*/
while (twi_state != TWI_IDLE && twi_state != TWI_ERROR);
if (twi_state != TWI_IDLE) {
twi_state = TWI_IDLE;
return 1;
}
return 0;
}
void at91_twi_test(void)
{
uint32_t i;
for (i = TWI_ADDR_BL1; i <= TWI_ADDR_BL4; i++) {
struct blmc_cmd cmd = {
.cmd = CMD_BOOT_LOADER,
.mode = BLMC_CMD_WRITE | BLMC_CMD_0_ARG,
};
uint32_t ret = twi_cmd(i, &cmd);
printf("twi[0x%02lx](%ld) ", i, ret);
volatile uint32_t x;
for (x = 0; x < 200000; x++);
uint8_t buf[16];
cmd.cmd = CMD_GET_INFO,
cmd.mode = BLMC_CMD_READ | BLMC_CMD_0_ARG,
cmd.size = sizeof(buf),
cmd.data = buf,
ret = twi_cmd(i, &cmd);
printf("boot(%ld):'%s' ", ret, buf);
cmd.cmd = CMD_GET_SIGNATURE;
cmd.size = 4;
ret = twi_cmd(i, &cmd);
printf("sig(%ld):0x%02x%02x%02x ", ret, buf[0], buf[1], buf[2]);
cmd.cmd = CMD_BOOT_APPLICATION;
cmd.mode = BLMC_CMD_WRITE | BLMC_CMD_0_ARG;
cmd.size = 0;
ret = twi_cmd(i, &cmd);
for (x = 0; x < 200000; x++);
cmd.cmd = CMD_GET_INFO,
cmd.mode = BLMC_CMD_READ | BLMC_CMD_0_ARG,
cmd.size = sizeof(buf),
cmd.data = buf,
ret = twi_cmd(i, &cmd);
printf("app(%ld):'%s'\n\r", ret, buf);
}
}
void at91_twi_init(void)
{
/* enable Clock */
*AT91C_PMC_PCER = (1 << AT91C_ID_TWI);
/* SDA & SCL from Peripheral A, Open Drain, no Pullup */
AT91S_PIO *pio = AT91C_BASE_PIOA;
pio->PIO_ASR = AT91C_PA3_TWD | AT91C_PA4_TWCK;
pio->PIO_PDR = AT91C_PA3_TWD | AT91C_PA4_TWCK;
pio->PIO_MDER = AT91C_PA3_TWD | AT91C_PA4_TWCK;
pio->PIO_PPUDR = AT91C_PA3_TWD | AT91C_PA4_TWCK;
/* set TWI Clock */
*AT91C_TWI_CWGR = TWI_CLK(200000) | (5<<16);
/* disable all (known) interrupts */
*AT91C_TWI_IDR = AT91C_TWI_TXCOMP | AT91C_TWI_RXRDY | AT91C_TWI_TXRDY | AT91C_TWI_NACK;
/* level triggered, own vector */
AT91S_AIC *aic = AT91C_BASE_AIC;
aic->AIC_SMR[AT91C_ID_TWI] = IRQPRIO_TWI | AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL;
aic->AIC_SVR[AT91C_ID_TWI] = (uint32_t)twi_isr;
aic->AIC_IECR = (1 << AT91C_ID_TWI);
/* enable teh monster */
*AT91C_TWI_CR = AT91C_TWI_MSEN;
}
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