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/*
* PiLC HAT firmware
* I2C debugging slave
*
* Copyright (c) 2016 Michael Buesch <m@bues.ch>
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "dbg_slave.h"
#include "i2c_slave.h"
#include "util.h"
#define DBGSLAVE_MAX_DELAY 42
static uint8_t dbgslave_data;
static uint8_t dbgslave_tx_delay;
static uint8_t dbgslave_rx_delay;
static void dbgslave_delay(uint8_t delay)
{
while (delay--)
__asm__ __volatile__ ("nop\n");
}
static uint8_t dbgslave_transmit(bool start)
{
dbgslave_delay(dbgslave_tx_delay);
if (++dbgslave_tx_delay >= DBGSLAVE_MAX_DELAY)
dbgslave_tx_delay = 0;
return (uint8_t)(dbgslave_data | (start ? 0x02 : 0x00));
}
static bool dbgslave_receive(bool start, uint8_t data)
{
dbgslave_delay(dbgslave_rx_delay);
if (++dbgslave_rx_delay >= DBGSLAVE_MAX_DELAY)
dbgslave_rx_delay = 0;
dbgslave_data = (uint8_t)((data & ~0x03) | (start ? 0x01 : 0x00));
return true;
}
static const struct i2c_slave_ops __flash dbgslave_i2c_slave_ops = {
.transmit = dbgslave_transmit,
.receive = dbgslave_receive,
};
void dbgslave_init(void)
{
i2cs_add_slave(DBGSLAVE_ADDR, &dbgslave_i2c_slave_ops);
}
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