diff options
Diffstat (limited to 'arch/arm64/mm/mmu.c')
| -rw-r--r-- | arch/arm64/mm/mmu.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index a6885d896ab..f4dd585898c 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -25,6 +25,7 @@ #include <linux/nodemask.h> #include <linux/memblock.h> #include <linux/fs.h> +#include <linux/io.h> #include <asm/cputype.h> #include <asm/sections.h> @@ -251,6 +252,47 @@ static void __init create_mapping(phys_addr_t phys, unsigned long virt, } while (pgd++, addr = next, addr != end); } +#ifdef CONFIG_EARLY_PRINTK +/* + * Create an early I/O mapping using the pgd/pmd entries already populated + * in head.S as this function is called too early to allocated any memory. The + * mapping size is 2MB with 4KB pages or 64KB or 64KB pages. + */ +void __iomem * __init early_io_map(phys_addr_t phys, unsigned long virt) +{ + unsigned long size, mask; + bool page64k = IS_ENABLED(ARM64_64K_PAGES); + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + /* + * No early pte entries with !ARM64_64K_PAGES configuration, so using + * sections (pmd). + */ + size = page64k ? PAGE_SIZE : SECTION_SIZE; + mask = ~(size - 1); + + pgd = pgd_offset_k(virt); + pud = pud_offset(pgd, virt); + if (pud_none(*pud)) + return NULL; + pmd = pmd_offset(pud, virt); + + if (page64k) { + if (pmd_none(*pmd)) + return NULL; + pte = pte_offset_kernel(pmd, virt); + set_pte(pte, __pte((phys & mask) | PROT_DEVICE_nGnRE)); + } else { + set_pmd(pmd, __pmd((phys & mask) | PROT_SECT_DEVICE_nGnRE)); + } + + return (void __iomem *)((virt & mask) + (phys & ~mask)); +} +#endif + static void __init map_mem(void) { struct memblock_region *reg; |