Root/arch/s390/kernel/mem_detect.c

1/*
2 * Copyright IBM Corp. 2008, 2009
3 *
4 * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
5 */
6
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <asm/ipl.h>
10#include <asm/sclp.h>
11#include <asm/setup.h>
12
13#define ADDR2G (1ULL << 31)
14
15static void find_memory_chunks(struct mem_chunk chunk[])
16{
17    unsigned long long memsize, rnmax, rzm;
18    unsigned long addr = 0, size;
19    int i = 0, type;
20
21    rzm = sclp_get_rzm();
22    rnmax = sclp_get_rnmax();
23    memsize = rzm * rnmax;
24    if (!rzm)
25        rzm = 1ULL << 17;
26    if (sizeof(long) == 4) {
27        rzm = min(ADDR2G, rzm);
28        memsize = memsize ? min(ADDR2G, memsize) : ADDR2G;
29    }
30    do {
31        size = 0;
32        type = tprot(addr);
33        do {
34            size += rzm;
35            if (memsize && addr + size >= memsize)
36                break;
37        } while (type == tprot(addr + size));
38        if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
39            chunk[i].addr = addr;
40            chunk[i].size = size;
41            chunk[i].type = type;
42            i++;
43        }
44        addr += size;
45    } while (addr < memsize && i < MEMORY_CHUNKS);
46}
47
48void detect_memory_layout(struct mem_chunk chunk[])
49{
50    unsigned long flags, cr0;
51
52    memset(chunk, 0, MEMORY_CHUNKS * sizeof(struct mem_chunk));
53    /* Disable IRQs, DAT and low address protection so tprot does the
54     * right thing and we don't get scheduled away with low address
55     * protection disabled.
56     */
57    flags = __arch_local_irq_stnsm(0xf8);
58    __ctl_store(cr0, 0, 0);
59    __ctl_clear_bit(0, 28);
60    find_memory_chunks(chunk);
61    __ctl_load(cr0, 0, 0);
62    arch_local_irq_restore(flags);
63}
64EXPORT_SYMBOL(detect_memory_layout);
65

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