arch/xtensa/mm/mmu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * xtensa mmu stuff
   4  *
   5  * Extracted from init.c
   6  */
   7 #include <linux/bootmem.h>
   8 #include <linux/percpu.h>
   9 #include <linux/init.h>
  10 #include <linux/string.h>
  11 #include <linux/slab.h>
  12 #include <linux/cache.h>
  13
  14 #include <asm/tlb.h>
  15 #include <asm/tlbflush.h>
  16 #include <asm/mmu_context.h>
  17 #include <asm/page.h>
  18 #include <asm/initialize_mmu.h>
  19 #include <asm/io.h>
  20
  21 #if defined(CONFIG_HIGHMEM)
  22 static void * __init init_pmd(unsigned long vaddr, unsigned long n_pages)
  23 {
  24         pgd_t *pgd = pgd_offset_k(vaddr);
  25         pmd_t *pmd = pmd_offset(pgd, vaddr);
  26         pte_t *pte;
  27         unsigned long i;
  28
  29         n_pages = ALIGN(n_pages, PTRS_PER_PTE);
  30
  31         pr_debug("%s: vaddr: 0x%08lx, n_pages: %ld\n",
  32                  __func__, vaddr, n_pages);
  33
  34         pte = alloc_bootmem_low_pages(n_pages * sizeof(pte_t));
  35
  36         for (i = 0; i < n_pages; ++i)
  37                 pte_clear(NULL, 0, pte + i);
  38
  39         for (i = 0; i < n_pages; i += PTRS_PER_PTE, ++pmd) {
  40                 pte_t *cur_pte = pte + i;
  41
  42                 BUG_ON(!pmd_none(*pmd));
  43                 set_pmd(pmd, __pmd(((unsigned long)cur_pte) & PAGE_MASK));
  44                 BUG_ON(cur_pte != pte_offset_kernel(pmd, 0));
  45                 pr_debug("%s: pmd: 0x%p, pte: 0x%p\n",
  46                          __func__, pmd, cur_pte);
  47         }
  48         return pte;
  49 }
  50
  51 static void __init fixedrange_init(void)
  52 {
  53         init_pmd(__fix_to_virt(0), __end_of_fixed_addresses);
  54 }
  55 #endif
  56
  57 void __init paging_init(void)
  58 {
  59         memset(swapper_pg_dir, 0, PAGE_SIZE);
  60 #ifdef CONFIG_HIGHMEM
  61         fixedrange_init();
  62         pkmap_page_table = init_pmd(PKMAP_BASE, LAST_PKMAP);
  63         kmap_init();
  64 #endif
  65 }
  66
  67 /*
  68  * Flush the mmu and reset associated register to default values.
  69  */
  70 void init_mmu(void)
  71 {
  72 #if !(XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY)
  73         /*
  74          * Writing zeros to the instruction and data TLBCFG special
  75          * registers ensure that valid values exist in the register.
  76          *
  77          * For existing PGSZID<w> fields, zero selects the first element
  78          * of the page-size array.  For nonexistent PGSZID<w> fields,
  79          * zero is the best value to write.  Also, when changing PGSZID<w>
  80          * fields, the corresponding TLB must be flushed.
  81          */
  82         set_itlbcfg_register(0);
  83         set_dtlbcfg_register(0);
  84 #endif
  85 #if XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY && defined(CONFIG_OF)
  86         /*
  87          * Update the IO area mapping in case xtensa_kio_paddr has changed
  88          */
  89         write_dtlb_entry(__pte(xtensa_kio_paddr + CA_WRITEBACK),
  90                         XCHAL_KIO_CACHED_VADDR + 6);
  91         write_itlb_entry(__pte(xtensa_kio_paddr + CA_WRITEBACK),
  92                         XCHAL_KIO_CACHED_VADDR + 6);
  93         write_dtlb_entry(__pte(xtensa_kio_paddr + CA_BYPASS),
  94                         XCHAL_KIO_BYPASS_VADDR + 6);
  95         write_itlb_entry(__pte(xtensa_kio_paddr + CA_BYPASS),
  96                         XCHAL_KIO_BYPASS_VADDR + 6);
  97 #endif
  98
  99         local_flush_tlb_all();
 100
 101         /* Set rasid register to a known value. */
 102
 103         set_rasid_register(ASID_INSERT(ASID_USER_FIRST));
 104
 105         /* Set PTEVADDR special register to the start of the page
 106          * table, which is in kernel mappable space (ie. not
 107          * statically mapped).  This register's value is undefined on
 108          * reset.
 109          */
 110         set_ptevaddr_register(PGTABLE_START);
 111 }