spicontrol.c File Reference

#include <xinu.h>

Include dependency graph for spicontrol.c:

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Functions
devcall	spicontrol (struct dentry *devptr, int32 func, int32 arg1, int32 arg2)

Function Documentation

spicontrol()

devcall spicontrol	(	struct dentry *	devptr,
		int32	func,
		int32	arg1,
		int32	arg2
	)

Definition at line 9 of file spicontrol.c.

References spi_csreg::ch, spi_csreg::chconf, spi_csreg::chrx, spi_csreg::chstat, spi_csreg::chtx, dentry::dvcsr, spi_transfer::length, OK, spi_transfer::rxbuf, SPI_CHCONF_FORCE, SPI_CHSTAT_RXS, SPI_CHSTAT_TXS, SPI_CTRL_TRANSFER, and spi_transfer::txbuf.

{
    struct  spi_csreg *csrptr;  /* SPI control and status regs  */
    struct  spi_transfer *msg;  /* Message pointer      */
    int i;          /* For loop index       */

    /* Get the pointer to the SPI CSRs */

    csrptr = (struct spi_csreg *)devptr->dvcsr;

    /* Get the pointer to the message */

    msg = (struct spi_transfer *)arg1;

    switch(func) {

     /* This is a SPI transfer */

     case SPI_CTRL_TRANSFER:

        for(i = 0; i < msg->length; i++) {

            /* Wait while the transmit register is not empty */

            while((csrptr->ch[0].chstat & SPI_CHSTAT_TXS) == 0);

            /* Send a byte */

            csrptr->ch[0].chtx = msg->txbuf[i];

            /* Wait until there is a byte in the receive register */

            while((csrptr->ch[0].chstat & SPI_CHSTAT_RXS) == 0);

            /* Read the byte from the receive register */

            msg->rxbuf[i] = csrptr->ch[0].chrx;
        }

        /* End the transfer by changing CS level */

        csrptr->ch[0].chconf &= ~SPI_CHCONF_FORCE;
        csrptr->ch[0].chconf |= SPI_CHCONF_FORCE;

        break;
    }

    return OK;
}