mem_detect.c

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/*
 * Copyright IBM Corp. 2008, 2009
 *
 * Author(s): Heiko Carstens <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/ipl.h>
#include <asm/sclp.h>
#include <asm/setup.h>

#define ADDR2G (1ULL << 31)

static void find_memory_chunks(struct mem_chunk chunk[])
{
    unsigned long long memsize, rnmax, rzm;
    unsigned long addr = 0, size;
    int i = 0, type;

    rzm = sclp_get_rzm();
    rnmax = sclp_get_rnmax();
    memsize = rzm * rnmax;
    if (!rzm)
        rzm = 1ULL << 17;
    if (sizeof(long) == 4) {
        rzm = min(ADDR2G, rzm);
        memsize = memsize ? min(ADDR2G, memsize) : ADDR2G;
    }
    do {
        size = 0;
        type = tprot(addr);
        do {
            size += rzm;
            if (memsize && addr + size >= memsize)
                break;
        } while (type == tprot(addr + size));
        if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
            chunk[i].addr = addr;
            chunk[i].size = size;
            chunk[i].type = type;
            i++;
        }
        addr += size;
    } while (addr < memsize && i < MEMORY_CHUNKS);
}

void detect_memory_layout(struct mem_chunk chunk[])
{
    unsigned long flags, cr0;

    memset(chunk, 0, MEMORY_CHUNKS * sizeof(struct mem_chunk));
    /* Disable IRQs, DAT and low address protection so tprot does the
     * right thing and we don't get scheduled away with low address
     * protection disabled.
     */
    flags = __arch_local_irq_stnsm(0xf8);
    __ctl_store(cr0, 0, 0);
    __ctl_clear_bit(0, 28);
    find_memory_chunks(chunk);
    __ctl_load(cr0, 0, 0);
    arch_local_irq_restore(flags);
}
EXPORT_SYMBOL(detect_memory_layout);

/*
 * Move memory chunks array from index "from" to index "to"
 */
static void mem_chunk_move(struct mem_chunk chunk[], int to, int from)
{
    int cnt = MEMORY_CHUNKS - to;

    memmove(&chunk[to], &chunk[from], cnt * sizeof(struct mem_chunk));
}

/*
 * Initialize memory chunk
 */
static void mem_chunk_init(struct mem_chunk *chunk, unsigned long addr,
               unsigned long size, int type)
{
    chunk->type = type;
    chunk->addr = addr;
    chunk->size = size;
}

/*
 * Create memory hole with given address, size, and type
 */
void create_mem_hole(struct mem_chunk chunk[], unsigned long addr,
             unsigned long size, int type)
{
    unsigned long lh_start, lh_end, lh_size, ch_start, ch_end, ch_size;
    int i, ch_type;

    for (i = 0; i < MEMORY_CHUNKS; i++) {
        if (chunk[i].size == 0)
            continue;

        /* Define chunk properties */
        ch_start = chunk[i].addr;
        ch_size = chunk[i].size;
        ch_end = ch_start + ch_size - 1;
        ch_type = chunk[i].type;

        /* Is memory chunk hit by memory hole? */
        if (addr + size <= ch_start)
            continue; /* No: memory hole in front of chunk */
        if (addr > ch_end)
            continue; /* No: memory hole after chunk */

        /* Yes: Define local hole properties */
        lh_start = max(addr, chunk[i].addr);
        lh_end = min(addr + size - 1, ch_end);
        lh_size = lh_end - lh_start + 1;

        if (lh_start == ch_start && lh_end == ch_end) {
            /* Hole covers complete memory chunk */
            mem_chunk_init(&chunk[i], lh_start, lh_size, type);
        } else if (lh_end == ch_end) {
            /* Hole starts in memory chunk and convers chunk end */
            mem_chunk_move(chunk, i + 1, i);
            mem_chunk_init(&chunk[i], ch_start, ch_size - lh_size,
                       ch_type);
            mem_chunk_init(&chunk[i + 1], lh_start, lh_size, type);
            i += 1;
        } else if (lh_start == ch_start) {
            /* Hole ends in memory chunk */
            mem_chunk_move(chunk, i + 1, i);
            mem_chunk_init(&chunk[i], lh_start, lh_size, type);
            mem_chunk_init(&chunk[i + 1], lh_end + 1,
                       ch_size - lh_size, ch_type);
            break;
        } else {
            /* Hole splits memory chunk */
            mem_chunk_move(chunk, i + 2, i);
            mem_chunk_init(&chunk[i], ch_start,
                       lh_start - ch_start, ch_type);
            mem_chunk_init(&chunk[i + 1], lh_start, lh_size, type);
            mem_chunk_init(&chunk[i + 2], lh_end + 1,
                       ch_end - lh_end, ch_type);
            break;
        }
    }
}