ioremap.c

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/*
 *  linux/arch/arm/mm/ioremap.c
 *
 * Re-map IO memory to kernel address space so that we can access it.
 *
 * (C) Copyright 1995 1996 Linus Torvalds
 *
 * Hacked for ARM by Phil Blundell <[email protected]>
 * Hacked to allow all architectures to build, and various cleanups
 * by Russell King
 *
 * This allows a driver to remap an arbitrary region of bus memory into
 * virtual space.  One should *only* use readl, writel, memcpy_toio and
 * so on with such remapped areas.
 *
 * Because the ARM only has a 32-bit address space we can't address the
 * whole of the (physical) PCI space at once.  PCI huge-mode addressing
 * allows us to circumvent this restriction by splitting PCI space into
 * two 2GB chunks and mapping only one at a time into processor memory.
 * We use MMU protection domains to trap any attempt to access the bank
 * that is not currently mapped.  (This isn't fully implemented yet.)
 */
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/io.h>
#include <linux/sizes.h>

#include <asm/cp15.h>
#include <asm/cputype.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/system_info.h>

#include <asm/mach/map.h>
#include <asm/mach/pci.h>
#include "mm.h"

int ioremap_page(unsigned long virt, unsigned long phys,
         const struct mem_type *mtype)
{
    return ioremap_page_range(virt, virt + PAGE_SIZE, phys,
                  __pgprot(mtype->prot_pte));
}
EXPORT_SYMBOL(ioremap_page);

void __check_kvm_seq(struct mm_struct *mm)
{
    unsigned int seq;

    do {
        seq = init_mm.context.kvm_seq;
        memcpy(pgd_offset(mm, VMALLOC_START),
               pgd_offset_k(VMALLOC_START),
               sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
                    pgd_index(VMALLOC_START)));
        mm->context.kvm_seq = seq;
    } while (seq != init_mm.context.kvm_seq);
}

#if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
/*
 * Section support is unsafe on SMP - If you iounmap and ioremap a region,
 * the other CPUs will not see this change until their next context switch.
 * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
 * which requires the new ioremap'd region to be referenced, the CPU will
 * reference the _old_ region.
 *
 * Note that get_vm_area_caller() allocates a guard 4K page, so we need to
 * mask the size back to 1MB aligned or we will overflow in the loop below.
 */
static void unmap_area_sections(unsigned long virt, unsigned long size)
{
    unsigned long addr = virt, end = virt + (size & ~(SZ_1M - 1));
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmdp;

    flush_cache_vunmap(addr, end);
    pgd = pgd_offset_k(addr);
    pud = pud_offset(pgd, addr);
    pmdp = pmd_offset(pud, addr);
    do {
        pmd_t pmd = *pmdp;

        if (!pmd_none(pmd)) {
            /*
             * Clear the PMD from the page table, and
             * increment the kvm sequence so others
             * notice this change.
             *
             * Note: this is still racy on SMP machines.
             */
            pmd_clear(pmdp);
            init_mm.context.kvm_seq++;

            /*
             * Free the page table, if there was one.
             */
            if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
                pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
        }

        addr += PMD_SIZE;
        pmdp += 2;
    } while (addr < end);

    /*
     * Ensure that the active_mm is up to date - we want to
     * catch any use-after-iounmap cases.
     */
    if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
        __check_kvm_seq(current->active_mm);

    flush_tlb_kernel_range(virt, end);
}

static int
remap_area_sections(unsigned long virt, unsigned long pfn,
            size_t size, const struct mem_type *type)
{
    unsigned long addr = virt, end = virt + size;
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;

    /*
     * Remove and free any PTE-based mapping, and
     * sync the current kernel mapping.
     */
    unmap_area_sections(virt, size);

    pgd = pgd_offset_k(addr);
    pud = pud_offset(pgd, addr);
    pmd = pmd_offset(pud, addr);
    do {
        pmd[0] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
        pfn += SZ_1M >> PAGE_SHIFT;
        pmd[1] = __pmd(__pfn_to_phys(pfn) | type->prot_sect);
        pfn += SZ_1M >> PAGE_SHIFT;
        flush_pmd_entry(pmd);

        addr += PMD_SIZE;
        pmd += 2;
    } while (addr < end);

    return 0;
}

static int
remap_area_supersections(unsigned long virt, unsigned long pfn,
             size_t size, const struct mem_type *type)
{
    unsigned long addr = virt, end = virt + size;
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;

    /*
     * Remove and free any PTE-based mapping, and
     * sync the current kernel mapping.
     */
    unmap_area_sections(virt, size);

    pgd = pgd_offset_k(virt);
    pud = pud_offset(pgd, addr);
    pmd = pmd_offset(pud, addr);
    do {
        unsigned long super_pmd_val, i;

        super_pmd_val = __pfn_to_phys(pfn) | type->prot_sect |
                PMD_SECT_SUPER;
        super_pmd_val |= ((pfn >> (32 - PAGE_SHIFT)) & 0xf) << 20;

        for (i = 0; i < 8; i++) {
            pmd[0] = __pmd(super_pmd_val);
            pmd[1] = __pmd(super_pmd_val);
            flush_pmd_entry(pmd);

            addr += PMD_SIZE;
            pmd += 2;
        }

        pfn += SUPERSECTION_SIZE >> PAGE_SHIFT;
    } while (addr < end);

    return 0;
}
#endif

void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
    unsigned long offset, size_t size, unsigned int mtype, void *caller)
{
    const struct mem_type *type;
    int err;
    unsigned long addr;
    struct vm_struct * area;

#ifndef CONFIG_ARM_LPAE
    /*
     * High mappings must be supersection aligned
     */
    if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
        return NULL;
#endif

    type = get_mem_type(mtype);
    if (!type)
        return NULL;

    /*
     * Page align the mapping size, taking account of any offset.
     */
    size = PAGE_ALIGN(offset + size);

    /*
     * Try to reuse one of the static mapping whenever possible.
     */
    read_lock(&vmlist_lock);
    for (area = vmlist; area; area = area->next) {
        if (!size || (sizeof(phys_addr_t) == 4 && pfn >= 0x100000))
            break;
        if (!(area->flags & VM_ARM_STATIC_MAPPING))
            continue;
        if ((area->flags & VM_ARM_MTYPE_MASK) != VM_ARM_MTYPE(mtype))
            continue;
        if (__phys_to_pfn(area->phys_addr) > pfn ||
            __pfn_to_phys(pfn) + size-1 > area->phys_addr + area->size-1)
            continue;
        /* we can drop the lock here as we know *area is static */
        read_unlock(&vmlist_lock);
        addr = (unsigned long)area->addr;
        addr += __pfn_to_phys(pfn) - area->phys_addr;
        return (void __iomem *) (offset + addr);
    }
    read_unlock(&vmlist_lock);

    /*
     * Don't allow RAM to be mapped - this causes problems with ARMv6+
     */
    if (WARN_ON(pfn_valid(pfn)))
        return NULL;

    area = get_vm_area_caller(size, VM_IOREMAP, caller);
    if (!area)
        return NULL;
    addr = (unsigned long)area->addr;
    area->phys_addr = __pfn_to_phys(pfn);

#if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
    if (DOMAIN_IO == 0 &&
        (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) ||
           cpu_is_xsc3()) && pfn >= 0x100000 &&
           !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) {
        area->flags |= VM_ARM_SECTION_MAPPING;
        err = remap_area_supersections(addr, pfn, size, type);
    } else if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
        area->flags |= VM_ARM_SECTION_MAPPING;
        err = remap_area_sections(addr, pfn, size, type);
    } else
#endif
        err = ioremap_page_range(addr, addr + size, __pfn_to_phys(pfn),
                     __pgprot(type->prot_pte));

    if (err) {
        vunmap((void *)addr);
        return NULL;
    }

    flush_cache_vmap(addr, addr + size);
    return (void __iomem *) (offset + addr);
}

void __iomem *__arm_ioremap_caller(unsigned long phys_addr, size_t size,
    unsigned int mtype, void *caller)
{
    unsigned long last_addr;
    unsigned long offset = phys_addr & ~PAGE_MASK;
    unsigned long pfn = __phys_to_pfn(phys_addr);

    /*
     * Don't allow wraparound or zero size
     */
    last_addr = phys_addr + size - 1;
    if (!size || last_addr < phys_addr)
        return NULL;

    return __arm_ioremap_pfn_caller(pfn, offset, size, mtype,
            caller);
}

/*
 * Remap an arbitrary physical address space into the kernel virtual
 * address space. Needed when the kernel wants to access high addresses
 * directly.
 *
 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 * have to convert them into an offset in a page-aligned mapping, but the
 * caller shouldn't need to know that small detail.
 */
void __iomem *
__arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
          unsigned int mtype)
{
    return __arm_ioremap_pfn_caller(pfn, offset, size, mtype,
            __builtin_return_address(0));
}
EXPORT_SYMBOL(__arm_ioremap_pfn);

void __iomem * (*arch_ioremap_caller)(unsigned long, size_t,
                      unsigned int, void *) =
    __arm_ioremap_caller;

void __iomem *
__arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
{
    return arch_ioremap_caller(phys_addr, size, mtype,
        __builtin_return_address(0));
}
EXPORT_SYMBOL(__arm_ioremap);

/*
 * Remap an arbitrary physical address space into the kernel virtual
 * address space as memory. Needed when the kernel wants to execute
 * code in external memory. This is needed for reprogramming source
 * clocks that would affect normal memory for example. Please see
 * CONFIG_GENERIC_ALLOCATOR for allocating external memory.
 */
void __iomem *
__arm_ioremap_exec(unsigned long phys_addr, size_t size, bool cached)
{
    unsigned int mtype;

    if (cached)
        mtype = MT_MEMORY;
    else
        mtype = MT_MEMORY_NONCACHED;

    return __arm_ioremap_caller(phys_addr, size, mtype,
            __builtin_return_address(0));
}

void __iounmap(volatile void __iomem *io_addr)
{
    void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
    struct vm_struct *vm;

    read_lock(&vmlist_lock);
    for (vm = vmlist; vm; vm = vm->next) {
        if (vm->addr > addr)
            break;
        if (!(vm->flags & VM_IOREMAP))
            continue;
        /* If this is a static mapping we must leave it alone */
        if ((vm->flags & VM_ARM_STATIC_MAPPING) &&
            (vm->addr <= addr) && (vm->addr + vm->size > addr)) {
            read_unlock(&vmlist_lock);
            return;
        }
#if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
        /*
         * If this is a section based mapping we need to handle it
         * specially as the VM subsystem does not know how to handle
         * such a beast.
         */
        if ((vm->addr == addr) &&
            (vm->flags & VM_ARM_SECTION_MAPPING)) {
            unmap_area_sections((unsigned long)vm->addr, vm->size);
            break;
        }
#endif
    }
    read_unlock(&vmlist_lock);

    vunmap(addr);
}

void (*arch_iounmap)(volatile void __iomem *) = __iounmap;

void __arm_iounmap(volatile void __iomem *io_addr)
{
    arch_iounmap(io_addr);
}
EXPORT_SYMBOL(__arm_iounmap);

#ifdef CONFIG_PCI
int pci_ioremap_io(unsigned int offset, phys_addr_t phys_addr)
{
    BUG_ON(offset + SZ_64K > IO_SPACE_LIMIT);

    return ioremap_page_range(PCI_IO_VIRT_BASE + offset,
                  PCI_IO_VIRT_BASE + offset + SZ_64K,
                  phys_addr,
                  __pgprot(get_mem_type(MT_DEVICE)->prot_pte));
}
EXPORT_SYMBOL_GPL(pci_ioremap_io);
#endif