rmm.c

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/*
 * rmm.c
 *
 * DSP-BIOS Bridge driver support functions for TI OMAP processors.
 *
 * Copyright (C) 2005-2006 Texas Instruments, Inc.
 *
 * This package is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 *  This memory manager provides general heap management and arbitrary
 *  alignment for any number of memory segments.
 *
 *  Notes:
 *
 *  Memory blocks are allocated from the end of the first free memory
 *  block large enough to satisfy the request.  Alignment requirements
 *  are satisfied by "sliding" the block forward until its base satisfies
 *  the alignment specification; if this is not possible then the next
 *  free block large enough to hold the request is tried.
 *
 *  Since alignment can cause the creation of a new free block - the
 *  unused memory formed between the start of the original free block
 *  and the start of the allocated block - the memory manager must free
 *  this memory to prevent a memory leak.
 *
 *  Overlay memory is managed by reserving through rmm_alloc, and freeing
 *  it through rmm_free. The memory manager prevents DSP code/data that is
 *  overlayed from being overwritten as long as the memory it runs at has
 *  been allocated, and not yet freed.
 */

#include <linux/types.h>
#include <linux/list.h>

/*  ----------------------------------- Host OS */
#include <dspbridge/host_os.h>

/*  ----------------------------------- DSP/BIOS Bridge */
#include <dspbridge/dbdefs.h>

/*  ----------------------------------- This */
#include <dspbridge/rmm.h>

/*
 *  ======== rmm_header ========
 *  This header is used to maintain a list of free memory blocks.
 */
struct rmm_header {
    struct rmm_header *next;    /* form a free memory link list */
    u32 size;       /* size of the free memory */
    u32 addr;       /* DSP address of memory block */
};

/*
 *  ======== rmm_ovly_sect ========
 *  Keeps track of memory occupied by overlay section.
 */
struct rmm_ovly_sect {
    struct list_head list_elem;
    u32 addr;       /* Start of memory section */
    u32 size;       /* Length (target MAUs) of section */
    s32 page;       /* Memory page */
};

/*
 *  ======== rmm_target_obj ========
 */
struct rmm_target_obj {
    struct rmm_segment *seg_tab;
    struct rmm_header **free_list;
    u32 num_segs;
    struct list_head ovly_list; /* List of overlay memory in use */
};

static bool alloc_block(struct rmm_target_obj *target, u32 segid, u32 size,
            u32 align, u32 *dsp_address);
static bool free_block(struct rmm_target_obj *target, u32 segid, u32 addr,
               u32 size);

/*
 *  ======== rmm_alloc ========
 */
int rmm_alloc(struct rmm_target_obj *target, u32 segid, u32 size,
             u32 align, u32 *dsp_address, bool reserve)
{
    struct rmm_ovly_sect *sect, *prev_sect = NULL;
    struct rmm_ovly_sect *new_sect;
    u32 addr;
    int status = 0;

    if (!reserve) {
        if (!alloc_block(target, segid, size, align, dsp_address)) {
            status = -ENOMEM;
        } else {
            /* Increment the number of allocated blocks in this
             * segment */
            target->seg_tab[segid].number++;
        }
        goto func_end;
    }
    /* An overlay section - See if block is already in use. If not,
     * insert into the list in ascending address size. */
    addr = *dsp_address;
    /*  Find place to insert new list element. List is sorted from
     *  smallest to largest address. */
    list_for_each_entry(sect, &target->ovly_list, list_elem) {
        if (addr <= sect->addr) {
            /* Check for overlap with sect */
            if ((addr + size > sect->addr) || (prev_sect &&
                               (prev_sect->addr +
                                prev_sect->size >
                                addr))) {
                status = -ENXIO;
            }
            break;
        }
        prev_sect = sect;
    }
    if (!status) {
        /* No overlap - allocate list element for new section. */
        new_sect = kzalloc(sizeof(struct rmm_ovly_sect), GFP_KERNEL);
        if (new_sect == NULL) {
            status = -ENOMEM;
        } else {
            new_sect->addr = addr;
            new_sect->size = size;
            new_sect->page = segid;
            if (list_is_last(&sect->list_elem, &target->ovly_list))
                /* Put new section at the end of the list */
                list_add_tail(&new_sect->list_elem,
                        &target->ovly_list);
            else
                /* Put new section just before sect */
                list_add_tail(&new_sect->list_elem,
                        &sect->list_elem);
        }
    }
func_end:
    return status;
}

/*
 *  ======== rmm_create ========
 */
int rmm_create(struct rmm_target_obj **target_obj,
              struct rmm_segment seg_tab[], u32 num_segs)
{
    struct rmm_header *hptr;
    struct rmm_segment *sptr, *tmp;
    struct rmm_target_obj *target;
    s32 i;
    int status = 0;

    /* Allocate DBL target object */
    target = kzalloc(sizeof(struct rmm_target_obj), GFP_KERNEL);

    if (target == NULL)
        status = -ENOMEM;

    if (status)
        goto func_cont;

    target->num_segs = num_segs;
    if (!(num_segs > 0))
        goto func_cont;

    /* Allocate the memory for freelist from host's memory */
    target->free_list = kzalloc(num_segs * sizeof(struct rmm_header *),
                            GFP_KERNEL);
    if (target->free_list == NULL) {
        status = -ENOMEM;
    } else {
        /* Allocate headers for each element on the free list */
        for (i = 0; i < (s32) num_segs; i++) {
            target->free_list[i] =
                kzalloc(sizeof(struct rmm_header), GFP_KERNEL);
            if (target->free_list[i] == NULL) {
                status = -ENOMEM;
                break;
            }
        }
        /* Allocate memory for initial segment table */
        target->seg_tab = kzalloc(num_segs * sizeof(struct rmm_segment),
                                GFP_KERNEL);
        if (target->seg_tab == NULL) {
            status = -ENOMEM;
        } else {
            /* Initialize segment table and free list */
            sptr = target->seg_tab;
            for (i = 0, tmp = seg_tab; num_segs > 0;
                 num_segs--, i++) {
                *sptr = *tmp;
                hptr = target->free_list[i];
                hptr->addr = tmp->base;
                hptr->size = tmp->length;
                hptr->next = NULL;
                tmp++;
                sptr++;
            }
        }
    }
func_cont:
    /* Initialize overlay memory list */
    if (!status)
        INIT_LIST_HEAD(&target->ovly_list);

    if (!status) {
        *target_obj = target;
    } else {
        *target_obj = NULL;
        if (target)
            rmm_delete(target);

    }

    return status;
}

/*
 *  ======== rmm_delete ========
 */
void rmm_delete(struct rmm_target_obj *target)
{
    struct rmm_ovly_sect *sect, *tmp;
    struct rmm_header *hptr;
    struct rmm_header *next;
    u32 i;

    kfree(target->seg_tab);

    list_for_each_entry_safe(sect, tmp, &target->ovly_list, list_elem) {
        list_del(&sect->list_elem);
        kfree(sect);
    }

    if (target->free_list != NULL) {
        /* Free elements on freelist */
        for (i = 0; i < target->num_segs; i++) {
            hptr = next = target->free_list[i];
            while (next) {
                hptr = next;
                next = hptr->next;
                kfree(hptr);
            }
        }
        kfree(target->free_list);
    }

    kfree(target);
}

/*
 *  ======== rmm_free ========
 */
bool rmm_free(struct rmm_target_obj *target, u32 segid, u32 dsp_addr, u32 size,
          bool reserved)
{
    struct rmm_ovly_sect *sect, *tmp;
    bool ret = false;

    /*
     *  Free or unreserve memory.
     */
    if (!reserved) {
        ret = free_block(target, segid, dsp_addr, size);
        if (ret)
            target->seg_tab[segid].number--;

    } else {
        /* Unreserve memory */
        list_for_each_entry_safe(sect, tmp, &target->ovly_list,
                list_elem) {
            if (dsp_addr == sect->addr) {
                /* Remove from list */
                list_del(&sect->list_elem);
                kfree(sect);
                return true;
            }
        }
    }
    return ret;
}

/*
 *  ======== rmm_stat ========
 */
bool rmm_stat(struct rmm_target_obj *target, enum dsp_memtype segid,
          struct dsp_memstat *mem_stat_buf)
{
    struct rmm_header *head;
    bool ret = false;
    u32 max_free_size = 0;
    u32 total_free_size = 0;
    u32 free_blocks = 0;

    if ((u32) segid < target->num_segs) {
        head = target->free_list[segid];

        /* Collect data from free_list */
        while (head != NULL) {
            max_free_size = max(max_free_size, head->size);
            total_free_size += head->size;
            free_blocks++;
            head = head->next;
        }

        /* ul_size */
        mem_stat_buf->size = target->seg_tab[segid].length;

        /* num_free_blocks */
        mem_stat_buf->num_free_blocks = free_blocks;

        /* total_free_size */
        mem_stat_buf->total_free_size = total_free_size;

        /* len_max_free_block */
        mem_stat_buf->len_max_free_block = max_free_size;

        /* num_alloc_blocks */
        mem_stat_buf->num_alloc_blocks =
            target->seg_tab[segid].number;

        ret = true;
    }

    return ret;
}

/*
 *  ======== balloc ========
 *  This allocation function allocates memory from the lowest addresses
 *  first.
 */
static bool alloc_block(struct rmm_target_obj *target, u32 segid, u32 size,
            u32 align, u32 *dsp_address)
{
    struct rmm_header *head;
    struct rmm_header *prevhead = NULL;
    struct rmm_header *next;
    u32 tmpalign;
    u32 alignbytes;
    u32 hsize;
    u32 allocsize;
    u32 addr;

    alignbytes = (align == 0) ? 1 : align;
    prevhead = NULL;
    head = target->free_list[segid];

    do {
        hsize = head->size;
        next = head->next;

        addr = head->addr;  /* alloc from the bottom */

        /* align allocation */
        (tmpalign = (u32) addr % alignbytes);
        if (tmpalign != 0)
            tmpalign = alignbytes - tmpalign;

        allocsize = size + tmpalign;

        if (hsize >= allocsize) {   /* big enough */
            if (hsize == allocsize && prevhead != NULL) {
                prevhead->next = next;
                kfree(head);
            } else {
                head->size = hsize - allocsize;
                head->addr += allocsize;
            }

            /* free up any hole created by alignment */
            if (tmpalign)
                free_block(target, segid, addr, tmpalign);

            *dsp_address = addr + tmpalign;
            return true;
        }

        prevhead = head;
        head = next;

    } while (head != NULL);

    return false;
}

/*
 *  ======== free_block ========
 *  TO DO: free_block() allocates memory, which could result in failure.
 *  Could allocate an rmm_header in rmm_alloc(), to be kept in a pool.
 *  free_block() could use an rmm_header from the pool, freeing as blocks
 *  are coalesced.
 */
static bool free_block(struct rmm_target_obj *target, u32 segid, u32 addr,
               u32 size)
{
    struct rmm_header *head;
    struct rmm_header *thead;
    struct rmm_header *rhead;
    bool ret = true;

    /* Create a memory header to hold the newly free'd block. */
    rhead = kzalloc(sizeof(struct rmm_header), GFP_KERNEL);
    if (rhead == NULL) {
        ret = false;
    } else {
        /* search down the free list to find the right place for addr */
        head = target->free_list[segid];

        if (addr >= head->addr) {
            while (head->next != NULL && addr > head->next->addr)
                head = head->next;

            thead = head->next;

            head->next = rhead;
            rhead->next = thead;
            rhead->addr = addr;
            rhead->size = size;
        } else {
            *rhead = *head;
            head->next = rhead;
            head->addr = addr;
            head->size = size;
            thead = rhead->next;
        }

        /* join with upper block, if possible */
        if (thead != NULL && (rhead->addr + rhead->size) ==
            thead->addr) {
            head->next = rhead->next;
            thead->size = size + thead->size;
            thead->addr = addr;
            kfree(rhead);
            rhead = thead;
        }

        /* join with the lower block, if possible */
        if ((head->addr + head->size) == rhead->addr) {
            head->next = rhead->next;
            head->size = head->size + rhead->size;
            kfree(rhead);
        }
    }

    return ret;
}