gpioread.c

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/* gpioread.c - gpioread */

#include <xinu.h>

/*------------------------------------------------------------------------
 *  gpioread  -  Read aspecified set of GPIO pins
 *------------------------------------------------------------------------
 */
devcall gpioread(
      struct dentry *devptr,    /* Entry in device switch table */
      char *value,          /* Pointer to a 32bit buffer    */
      int32 pinmask         /* Pins from which to read  */
    )
{
    struct gpio_csreg *csrptr;  /* Pointer to GPIO CSRs     */

    /* Obtain the address of the CSR from the device switch table   */

    csrptr = (struct gpio_csreg *)(devptr->dvcsr);
    
    /* Access the GPIO pins, use the mask to select a subset, and   */
    /*  store the result in the specified buffer        */

    *((uint32 *)value) = csrptr->datain & pinmask;

    return OK;
}