nes-proj/platform/stepper-robot/sam7s-spi.c

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#include <AT91SAM7S64.h>
#include <stdint.h>
#include <dev/spi.h>
#include <sam7s-spi.h>
/* Prevents interrupts using SPI at inappropriate times */
unsigned char spi_busy = 0;
#define SPI_SPEED 1000000 /* 1MHz clock*/
#define SPI_DLYBCT 1
#define SPI_DLYBS 20
#define SPI_TRANSFER (AT91C_PA12_MISO | AT91C_PA13_MOSI | AT91C_PA14_SPCK)
#define SPI_CS (AT91C_PA11_NPCS0 | AT91C_PA31_NPCS1)
void
spi_init()
{
static uint8_t initialised = 0;
if (!initialised) {
*AT91C_SPI_CR = AT91C_SPI_SPIDIS | AT91C_SPI_SWRST;
*AT91C_PMC_PCER = (1 << AT91C_ID_SPI);
*AT91C_PIOA_ASR = SPI_TRANSFER | SPI_CS;
*AT91C_PIOA_PDR = SPI_TRANSFER | SPI_CS;
*AT91C_PIOA_PPUER = AT91C_PA12_MISO | SPI_CS;
*AT91C_SPI_MR = (AT91C_SPI_MSTR | AT91C_SPI_PS_FIXED
| AT91C_SPI_MODFDIS | AT91C_SPI_PCS);
/* It seems necessary to set the clock speed for chip select 0
even if it's not used. */
AT91C_SPI_CSR[0] = (MCK/SPI_SPEED)<<8;
*AT91C_SPI_CR = AT91C_SPI_SPIEN;
initialised = 1;
}
}
void
spi_init_chip_select(unsigned int chip, unsigned int speed,
unsigned int dlybct,
unsigned int dlybs, unsigned int phase,
unsigned int polarity)
{
spi_init();
AT91C_SPI_CSR[chip] =
((dlybct<<24) | (dlybs<<16) | (((MCK+speed/2)/speed)<<8)
| (phase?AT91C_SPI_NCPHA:0) | (polarity?AT91C_SPI_CPOL:0)
| AT91C_SPI_BITS_8 | AT91C_SPI_CSAAT);
}
#if 0
#define DBG_SEND dbg_blocking_putchar('>');
#define DBG_RECV dbg_blocking_putchar('<');
#else
#define DBG_SEND
#define DBG_RECV
#endif
void
spi_transfer(unsigned int chip, const struct spi_block *block, unsigned int blocks)
{
spi_busy = 1;
while(!(*AT91C_SPI_SR & AT91C_SPI_TXEMPTY)); /* wait unti previous transfer is done */
/* Clear any data left in the receiver */
(void)*AT91C_SPI_RDR;
(void)*AT91C_SPI_RDR;
/* Select chip */
*AT91C_SPI_MR = ((*AT91C_SPI_MR & ~AT91C_SPI_PCS)
| ((~(1<<chip) & 0x0f) << 16));
while(blocks-- > 0) {
struct spi_block current = *block++;
if (current.send) {
if (current.receive) {
/* Send and receive */
while(current.len-- > 0) {
while(!(*AT91C_SPI_SR & AT91C_SPI_TDRE));
*AT91C_SPI_TDR = *current.send++;
DBG_SEND;
while(!(*AT91C_SPI_SR & AT91C_SPI_RDRF));
*current.receive++ = *AT91C_SPI_RDR;
DBG_RECV;
}
} else {
/* Send only */
while(current.len-- > 0) {
while(!(*AT91C_SPI_SR & AT91C_SPI_TDRE));
*AT91C_SPI_TDR = *current.send++;
DBG_SEND;
while(!(*AT91C_SPI_SR & AT91C_SPI_RDRF));
(void)*AT91C_SPI_RDR;
DBG_RECV;
}
}
} else {
if (current.receive) {
/* Receive only */
while(current.len-- > 0) {
while(!(*AT91C_SPI_SR & AT91C_SPI_TDRE));
*AT91C_SPI_TDR = 0;
DBG_SEND;
while(!(*AT91C_SPI_SR & AT91C_SPI_RDRF));
*current.receive++ = *AT91C_SPI_RDR;
DBG_RECV;
}
} else {
/* Clock only */
while(current.len-- > 0) {
while(!(*AT91C_SPI_SR & AT91C_SPI_TDRE));
*AT91C_SPI_TDR = 0;
DBG_SEND;
while(!(*AT91C_SPI_SR & AT91C_SPI_RDRF));
(void)*AT91C_SPI_RDR;
DBG_RECV;
}
}
}
}
*AT91C_SPI_CR = AT91C_SPI_LASTXFER;
spi_busy = 0;
}