source: rtems/c/src/lib/libbsp/m68k/gen68360/startup/alloc360.c @ 5f0fdeb

/*
 * MC68360 buffer descriptor allocation routines
 *
 * W. Eric Norum
 * Saskatchewan Accelerator Laboratory
 * University of Saskatchewan
 * Saskatoon, Saskatchewan, CANADA
 * eric@skatter.usask.ca
 *
 *  $Id$
 */

#include <rtems.h>
#include <bsp.h>
#include <rtems/m68k/m68360.h>
#include <rtems/error.h>

/*
 * Allocation order:
 *      - Dual-Port RAM section 1
 *      - Dual-Port RAM section 3
 *      - Dual-Port RAM section 0
 *      - Dual-Port RAM section 2
 */
static struct {
        char            *base;
        unsigned int    size;
        unsigned int    used;
} bdregions[] = {
        { (char *)&m360.dpram1[0],      sizeof m360.dpram1,     0 },
        { (char *)&m360.dpram3[0],      sizeof m360.dpram3,     0 },
        { (char *)&m360.dpram0[0],      sizeof m360.dpram0,     0 },
        { (char *)&m360.dpram2[0],      sizeof m360.dpram2,     0 },
};

/*
 * Send a command to the CPM RISC processer
 */
void *
M360AllocateBufferDescriptors (int count)
{
        unsigned int i;
        ISR_Level level;
        void *bdp = NULL;
        unsigned int want = count * sizeof(m360BufferDescriptor_t);

        /*
         * Running with interrupts disabled is usually considered bad
         * form, but this routine is probably being run as part of an
         * initialization sequence so the effect shouldn't be too severe.
         */
        _ISR_Disable (level);
        for (i = 0 ; i < sizeof(bdregions) / sizeof(bdregions[0]) ; i++) {
                /*
                 * Verify that the region exists.
                 * This test is necessary since some chips have
                 * less dual-port RAM.
                 */
                if (bdregions[i].used == 0) {
                        volatile unsigned char *cp = bdregions[i].base;
                        *cp = 0xAA;
                        if (*cp != 0xAA) {
                                bdregions[i].used = bdregions[i].size;
                                continue;
                        }
                        *cp = 0x55;
                        if (*cp != 0x55) {
                                bdregions[i].used = bdregions[i].size;
                                continue;
                        }
                        *cp = 0x0;
                }
                if (bdregions[i].size - bdregions[i].used >= want) {
                        bdp = bdregions[i].base + bdregions[i].used;
                        bdregions[i].used += want;
                        break;
                }
        }
        _ISR_Enable (level);
        if (bdp == NULL)
                rtems_panic ("Can't allocate %d buffer descriptor(s).\n", count);
        return bdp;
}

void *
M360AllocateRiscTimers (int count)
{
        /*
         * Convert the count to the number of buffer descriptors
         * of equal or larger size.  This ensures that all buffer
         * descriptors are allocated with appropriate alignment.
         */
        return M360AllocateBufferDescriptors (((count * 4) +
                                        sizeof(m360BufferDescriptor_t) - 1) /
                                        sizeof(m360BufferDescriptor_t));
}