OpenModem/bertos/drv/spi_bitbang.c
2014-04-03 22:21:37 +02:00

121 lines
2.9 KiB
C

/**
* \file
* <!--
* This file is part of BeRTOS.
*
* Bertos 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 St, Fifth Floor, Boston, MA 02110-1301 USA
*
* As a special exception, you may use this file as part of a free software
* library without restriction. Specifically, if other files instantiate
* templates or use macros or inline functions from this file, or you compile
* this file and link it with other files to produce an executable, this
* file does not by itself cause the resulting executable to be covered by
* the GNU General Public License. This exception does not however
* invalidate any other reasons why the executable file might be covered by
* the GNU General Public License.
*
* Copyright 2003, 2004, 2006 Develer S.r.l. (http://www.develer.com/)
* Copyright 2000 Bernie Innocenti <bernie@codewiz.org>
*
* -->
*
* \brief Emulated SPI Master for DSP firmware download (impl.)
*
*
* \author Francesco Sacchi <batt@develer.com>
* \author Daniele Basile <asterix@develer.com>
*/
#include "spi_bitbang.h"
#include "hw/hw_spi.h"
#include "cfg/cfg_spi_bitbang.h"
#include <cfg/module.h>
#include <cpu/irq.h>
void spi_assertSS(void)
{
ATOMIC(SS_ACTIVE());
}
void spi_deassertSS(void)
{
ATOMIC(SS_INACTIVE());
}
/**
* Send byte \c c over MOSI line, CONFIG_SPI_DATAORDER first.
* SS pin state is left unchanged.
*/
uint8_t spi_sendRecv(uint8_t c)
{
uint8_t data = 0;
uint8_t shift = SPI_DATAORDER_START;
ATOMIC(
for (int i = 0; i < 8; i++)
{
/* Shift the i-th bit to MOSI */
if (c & shift)
MOSI_HIGH();
else
MOSI_LOW();
/* Assert clock */
SCK_ACTIVE();
data |= IS_MISO_HIGH() ? shift : 0;
/* De-assert clock */
SCK_INACTIVE();
SPI_DATAORDER_SHIFT(shift);
}
);
return data;
}
MOD_DEFINE(spi);
void spi_init(void)
{
ATOMIC(SPI_HW_INIT());
MOD_INIT(spi);
}
/**
* Read \param len from spi, and put it in \param _buff .
*/
void spi_read(void *_buff, size_t len)
{
uint8_t *buff = (uint8_t *)_buff;
while (len--)
/* Read byte from spi and put it in buffer. */
*buff++ = spi_sendRecv(0);
}
/**
* Write \param len to spi, and take it from \param _buff .
*/
void spi_write(const void *_buff, size_t len)
{
const uint8_t *buff = (const uint8_t *)_buff;
while (len--)
/* Write byte pointed at by *buff to spi */
spi_sendRecv(*buff++);
}