do_sdevio.c

Minix3.11的源码。[MINIX 3是一个为高可靠性应用而设计的自由且简洁的类UNIX系统。]

/* The kernel call implemented in this file:
 *   m_type:	SYS_SDEVIO
 *
 * The parameters for this kernel call are:
 *    m2_i3:	DIO_REQUEST	(request input or output)	
 *    m2_i1:	DIO_TYPE	(flag indicating byte, word, or long)
 *    m2_l1:	DIO_PORT	(port to read/ write)	
 *    m2_p1:	DIO_VEC_ADDR	(virtual address of buffer)	
 *    m2_l2:	DIO_VEC_SIZE	(number of elements)	
 *    m2_i2:	DIO_VEC_PROC	(process where buffer is)	
 */

#include "../system.h"
#include <minix/devio.h>

#if USE_SDEVIO

/*===========================================================================*
 *			        do_sdevio                                    *
 *===========================================================================*/
PUBLIC int do_sdevio(m_ptr)
register message *m_ptr;	/* pointer to request message */
{
  int proc_nr = m_ptr->DIO_VEC_PROC;
  int count = m_ptr->DIO_VEC_SIZE;
  long port = m_ptr->DIO_PORT;
  phys_bytes phys_buf;

  /* Check if process number is OK. A process number is allowed here, because
   * driver may directly provide a pointer to a buffer at the user-process
   * that initiated the device I/O. Kernel processes, of course, are denied.
   */
  if (proc_nr == SELF) proc_nr = m_ptr->m_source;
  if (! isokprocn(proc_nr)) return(EINVAL);
  if (iskerneln(proc_nr)) return(EPERM);

  /* Get and check physical address. */
  if ((phys_buf = numap_local(proc_nr, (vir_bytes) m_ptr->DIO_VEC_ADDR, count)) == 0)
      return(EFAULT);

  /* Perform device I/O for bytes and words. Longs are not supported. */
  if (m_ptr->DIO_REQUEST == DIO_INPUT) { 
      switch (m_ptr->DIO_TYPE) {
      case DIO_BYTE: phys_insb(port, phys_buf, count); break; 
      case DIO_WORD: phys_insw(port, phys_buf, count); break; 
      default: return(EINVAL);
      } 
  } else if (m_ptr->DIO_REQUEST == DIO_OUTPUT) { 
      switch (m_ptr->DIO_TYPE) {
      case DIO_BYTE: phys_outsb(port, phys_buf, count); break; 
      case DIO_WORD: phys_outsw(port, phys_buf, count); break; 
      default: return(EINVAL);
      } 
  }
  else {
      return(EINVAL);
  }
  return(OK);
}

#endif /* USE_SDEVIO */