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/*

**  linux/amiga/chipram.c

**

**      Modified 03-May-94 by Geert Uytterhoeven

**                           (Geert.Uytterhoeven@cs.kuleuven.ac.be)

**          - 64-bit aligned allocations for full AGA compatibility

*/

#include <linux/types.h>

#include <linux/kernel.h>

#include <asm/bootinfo.h>

#include <asm/amigahw.h>

struct chip_desc {

        unsigned first   :  1;

        unsigned last    :  1;

        unsigned alloced :  1;

        unsigned length  : 24;

        long pad;                                       /* We suppose this makes this struct 64 bits long!! */

};

#define DP(ptr) ((struct chip_desc *)(ptr))

static unsigned long chipsize;

void amiga_chip_init (void)

{

  struct chip_desc *dp;

  if (!AMIGAHW_PRESENT(CHIP_RAM))

    return;

  chipsize = boot_info.bi_amiga.chip_size;

  /* initialize start boundary */

  dp = DP(chipaddr);

  dp->first = 1;

  dp->alloced = 0;

  dp->length = chipsize - 2*sizeof(*dp);

  /* initialize end boundary */

  dp = DP(chipaddr + chipsize) - 1;

  dp->last = 1;

  dp->alloced = 0;

  dp->length = chipsize - 2*sizeof(*dp);

#ifdef DEBUG

  printk ("chipram end boundary is %p, length is %d\n", dp,

          dp->length);

#endif

}

void *amiga_chip_alloc (long size)

{

        /* last chunk */

        struct chip_desc *dp;

        void *ptr;

        /* round off */

        size = (size + 7) & ~7;

#ifdef DEBUG

        printk ("chip_alloc: allocate %ld bytes\n", size);

#endif

        /*

         * get pointer to descriptor for last chunk by

         * going backwards from end chunk

         */

        dp = DP(chipaddr + chipsize) - 1;

        dp = DP((unsigned long)dp - dp->length) - 1;

        while ((dp->alloced || dp->length < size)

               && !dp->first)

                dp = DP ((unsigned long)dp - dp[-1].length) - 2;

        if (dp->alloced || dp->length < size) {

                printk ("no chipmem available for %ld allocation\n", size);

                return NULL;

        }

        if (dp->length < (size + 2*sizeof(*dp))) {

                /* length too small to split; allocate the whole thing */

                dp->alloced = 1;

                ptr = (void *)(dp+1);

                dp = DP((unsigned long)ptr + dp->length);

                dp->alloced = 1;

#ifdef DEBUG

                printk ("chip_alloc: no split\n");

#endif

        } else {

                /* split the extent; use the end part */

                long newsize = dp->length - (2*sizeof(*dp) + size);

#ifdef DEBUG

                printk ("chip_alloc: splitting %d to %ld\n", dp->length,

                        newsize);

#endif

                dp->length = newsize;

                dp = DP((unsigned long)(dp+1) + newsize);

                dp->first = dp->last = 0;

                dp->alloced = 0;

                dp->length = newsize;

                dp++;

                dp->first = dp->last = 0;

                dp->alloced = 1;

                dp->length = size;

                ptr = (void *)(dp+1);

                dp = DP((unsigned long)ptr + size);

                dp->alloced = 1;

                dp->length = size;

        }

#ifdef DEBUG

        printk ("chip_alloc: returning %p\n", ptr);

#endif

        if ((unsigned long)ptr & 7)

                panic("chip_alloc: alignment violation\n");

        return ptr;

}

void amiga_chip_free (void *ptr)

{

        struct chip_desc *sdp = DP(ptr) - 1, *dp2;

        struct chip_desc *edp = DP((unsigned long)ptr + sdp->length);

        /* deallocate the chunk */

        sdp->alloced = edp->alloced = 0;

        /* check if we should merge with the previous chunk */

        if (!sdp->first && !sdp[-1].alloced) {

                dp2 = DP((unsigned long)sdp - sdp[-1].length) - 2;

                dp2->length += sdp->length + 2*sizeof(*sdp);

                edp->length = dp2->length;

                sdp = dp2;

        }

        /* check if we should merge with the following chunk */

        if (!edp->last && !edp[1].alloced) {

                dp2 = DP((unsigned long)edp + edp[1].length) + 2;

                dp2->length += edp->length + 2*sizeof(*sdp);

                sdp->length = dp2->length;

                edp = dp2;

        }

}