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/*
* Copyright 2007,2008 Free Software Foundation, Inc.
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "spi.h"
#include "memory_map.h"
#include "pic.h"
#include "nonstdio.h"
void (*volatile spi_callback)(void); //SPI callback when xfer complete.
static void spi_irq_handler(unsigned irq);
void
spi_init(void)
{
/*
* f_sclk = f_wb / ((div + 1) * 2)
*/
spi_regs->div = 1; // 0 = Div by 2 (25 MHz); 1 = Div-by-4 (12.5 MHz)
}
void
spi_wait(void)
{
while (spi_regs->ctrl & SPI_CTRL_GO_BSY)
;
}
uint32_t
spi_transact(bool readback, int slave, uint32_t data, int length, uint32_t flags)
{
flags &= (SPI_CTRL_TXNEG | SPI_CTRL_RXNEG);
int ctrl = SPI_CTRL_ASS | (SPI_CTRL_CHAR_LEN_MASK & length) | flags;
spi_wait();
// Tell it which SPI slave device to access
spi_regs->ss = slave & 0xffff;
// Data we will send
spi_regs->txrx0 = data;
// Run it -- write once and rewrite with GO set
spi_regs->ctrl = ctrl;
spi_regs->ctrl = ctrl | SPI_CTRL_GO_BSY;
if(readback) {
spi_wait();
return spi_regs->txrx0;
}
else
return 0;
}
void spi_register_callback(void (*volatile callback)(void)) {
spi_callback = callback;
}
static void spi_irq_handler(unsigned irq) {
// printf("SPI IRQ handler\n");
// uint32_t wat = spi_regs->ctrl; //read a register just to clear the interrupt
//spi_regs->ctrl &= ~SPI_CTRL_IE;
if(spi_callback) spi_callback(); //we could just use the PIC to register the user's callback, but this provides the ability to do other things later
}
uint32_t spi_get_data(void) {
return spi_regs->txrx0;
}
bool
spi_async_transact(int slave, uint32_t data, int length, uint32_t flags, void (*volatile callback)(void)) {
flags &= (SPI_CTRL_TXNEG | SPI_CTRL_RXNEG);
int ctrl = SPI_CTRL_ASS | SPI_CTRL_IE | (SPI_CTRL_CHAR_LEN_MASK & length) | flags;
if(spi_regs->ctrl & SPI_CTRL_GO_BSY) {
printf("Async SPI busy!\n");
return false; //we don't wait on busy, we just return failure. we count on the host to not set up another transaction before the last one finishes.
}
// Tell it which SPI slave device to access
spi_regs->ss = slave & 0xffff;
// Data we will send
spi_regs->txrx0 = data;
spi_register_callback(callback);
pic_register_handler(IRQ_SPI, spi_irq_handler);
// Run it -- write once and rewrite with GO set
spi_regs->ctrl = ctrl;
spi_regs->ctrl = ctrl | SPI_CTRL_GO_BSY;
return true;
}
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