spi.c

来自「开发三星s3c44b0引导程序」· C语言 代码 · 共 70 行

#include <config.h>
#include <hardware.h>

#ifdef CFG_DRIVER_SPI

#define SPI_CLK 5000000
#define SPI_ID	13

void spi_init( void) {
   static pio_t *pioa = PIOA_BASE;
   static pio_t *piob = PIOB_BASE;
   static spi_t *spi = SPI_BASE;
   static apmc_t *apmc;

   apmc = (apmc_t *)APMC_BASE;
   
  /* pio ... */
  pioa->pdr = 0x0001ff80;
  piob->pdr = 0x020ff000;
  piob->bsr = 0x020ff000;

  /* open SPI clock */
  apmc->pcer = (1 << SPI_ID);


   spi->cr = SWRST;
   spi->cr = SPIEN;
   spi->mr = PS | MSTR;
   spi->csr3 = (((ARM_CLK/SPI_CLK/2)<<8)&SCBR) | NCPHA;

   /* Setup the DataFlash card mode */
   piob->codr = PIO(7);
   piob->oer  = PIO(7);
   piob->per  = PIO(7);

   /* Setup the SPI pins for the DataFlash card */
   pioa->sodr = PIO(6);
   pioa->oer  = PIO(6);
   pioa->per  = PIO(6);
   pioa->pdr  = PIO(3) | PIO(2) | PIO(1) | PIO(0);
}

void write_spi( char * spi_msg, int size) {
   static spi_t * spi = SPI_BASE;

   while (size--) {
      while (!(spi->sr & TDRE)); /* wait for previous transmission */
/*      printf("Writing 0x%x in spi->tdr.\n", (char)*spi_msg);  
*/
      spi->tdr = 0x00070000 | (0x000000ff & *spi_msg++);
   }
   while (!(spi->sr & TDRE)); /* wait for last transmission to finish */
}

void read_spi( char * spi_msg, int size) {
   static spi_t * spi = SPI_BASE;
   volatile unsigned long dummy;

   dummy = spi->rdr; /* clear the RDRF just in case */
   while (size--) {
      write_spi(spi_msg, 1);
      while (!(spi->sr & RDRF)); /* wait for shift in done */
/*      printf("Reading 0x%x from spi->rdr.\n", (char)spi->rdr);
*/
      *spi_msg++ = spi->rdr;
   }
}

#endif