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
  15 static 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
  48 void 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 }
  64 EXPORT_SYMBOL(detect_memory_layout);