/*
 *  linux/arch/arm/mm/nommu.c
 *
 * ARM uCLinux supporting functions.
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/kernel.h>

#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/sections.h>
#include <asm/page.h>
#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/mach/arch.h>
#include <asm/cputype.h>
#include <asm/mpu.h>
#include <asm/procinfo.h>

#include "mm.h"

unsigned long vectors_base;

#ifdef CONFIG_ARM_MPU
struct mpu_rgn_info mpu_rgn_info;

/* Region number */
static void rgnr_write(u32 v)
{
        asm("mcr        p15, 0, %0, c6, c2, 0" : : "r" (v));
}

/* Data-side / unified region attributes */

/* Region access control register */
static void dracr_write(u32 v)
{
        asm("mcr        p15, 0, %0, c6, c1, 4" : : "r" (v));
}

/* Region size register */
static void drsr_write(u32 v)
{
        asm("mcr        p15, 0, %0, c6, c1, 2" : : "r" (v));
}

/* Region base address register */
static void drbar_write(u32 v)
{
        asm("mcr        p15, 0, %0, c6, c1, 0" : : "r" (v));
}

static u32 drbar_read(void)
{
        u32 v;
        asm("mrc        p15, 0, %0, c6, c1, 0" : "=r" (v));
        return v;
}
/* Optional instruction-side region attributes */

/* I-side Region access control register */
static void iracr_write(u32 v)
{
        asm("mcr        p15, 0, %0, c6, c1, 5" : : "r" (v));
}

/* I-side Region size register */
static void irsr_write(u32 v)
{
        asm("mcr        p15, 0, %0, c6, c1, 3" : : "r" (v));
}

/* I-side Region base address register */
static void irbar_write(u32 v)
{
        asm("mcr        p15, 0, %0, c6, c1, 1" : : "r" (v));
}

static unsigned long irbar_read(void)
{
        unsigned long v;
        asm("mrc        p15, 0, %0, c6, c1, 1" : "=r" (v));
        return v;
}

/* MPU initialisation functions */
void __init adjust_lowmem_bounds_mpu(void)
{
        phys_addr_t phys_offset = PHYS_OFFSET;
        phys_addr_t aligned_region_size, specified_mem_size, rounded_mem_size;
        struct memblock_region *reg;
        bool first = true;
        phys_addr_t mem_start;
        phys_addr_t mem_end;

        for_each_memblock(memory, reg) {
                if (first) {
                        /*
                         * Initially only use memory continuous from
                         * PHYS_OFFSET */
                        if (reg->base != phys_offset)
                                panic("First memory bank must be contiguous from PHYS_OFFSET");

                        mem_start = reg->base;
                        mem_end = reg->base + reg->size;
                        specified_mem_size = reg->size;
                        first = false;
                } else {
                        /*
                         * memblock auto merges contiguous blocks, remove
                         * all blocks afterwards in one go (we can't remove
                         * blocks separately while iterating)
                         */
                        pr_notice("Ignoring RAM after %pa, memory at %pa ignored\n",
                                  &mem_end, &reg->base);
                        memblock_remove(reg->base, 0 - reg->base);
                        break;
                }
        }

        /*
         * MPU has curious alignment requirements: Size must be power of 2, and
         * region start must be aligned to the region size
         */
        if (phys_offset != 0)
                pr_info("PHYS_OFFSET != 0 => MPU Region size constrained by alignment requirements\n");

        /*
         * Maximum aligned region might overflow phys_addr_t if phys_offset is
         * 0. Hence we keep everything below 4G until we take the smaller of
         * the aligned_region_size and rounded_mem_size, one of which is
         * guaranteed to be smaller than the maximum physical address.
         */
        aligned_region_size = (phys_offset - 1) ^ (phys_offset);
        /* Find the max power-of-two sized region that fits inside our bank */
        rounded_mem_size = (1 <<  __fls(specified_mem_size)) - 1;

        /* The actual region size is the smaller of the two */
        aligned_region_size = aligned_region_size < rounded_mem_size
                                ? aligned_region_size + 1
                                : rounded_mem_size + 1;

        if (aligned_region_size != specified_mem_size) {
                pr_warn("Truncating memory from %pa to %pa (MPU region constraints)",
                                &specified_mem_size, &aligned_region_size);
                memblock_remove(mem_start + aligned_region_size,
                                specified_mem_size - aligned_region_size);

                mem_end = mem_start + aligned_region_size;
        }

        pr_debug("MPU Region from %pa size %pa (end %pa))\n",
                &phys_offset, &aligned_region_size, &mem_end);

}

static int mpu_present(void)
{
        return ((read_cpuid_ext(CPUID_EXT_MMFR0) & MMFR0_PMSA) == MMFR0_PMSAv7);
}

static int mpu_max_regions(void)
{
        /*
         * We don't support a different number of I/D side regions so if we
         * have separate instruction and data memory maps then return
         * whichever side has a smaller number of supported regions.
         */
        u32 dregions, iregions, mpuir;
        mpuir = read_cpuid(CPUID_MPUIR);

        dregions = iregions = (mpuir & MPUIR_DREGION_SZMASK) >> MPUIR_DREGION;

        /* Check for separate d-side and i-side memory maps */
        if (mpuir & MPUIR_nU)
                iregions = (mpuir & MPUIR_IREGION_SZMASK) >> MPUIR_IREGION;

        /* Use the smallest of the two maxima */
        return min(dregions, iregions);
}

static int mpu_iside_independent(void)
{
        /* MPUIR.nU specifies whether there is *not* a unified memory map */
        return read_cpuid(CPUID_MPUIR) & MPUIR_nU;
}

static int mpu_min_region_order(void)
{
        u32 drbar_result, irbar_result;
        /* We've kept a region free for this probing */
        rgnr_write(MPU_PROBE_REGION);
        isb();
        /*
         * As per ARM ARM, write 0xFFFFFFFC to DRBAR to find the minimum
         * region order
        */
        drbar_write(0xFFFFFFFC);
        drbar_result = irbar_result = drbar_read();
        drbar_write(0x0);
        /* If the MPU is non-unified, we use the larger of the two minima*/
        if (mpu_iside_independent()) {
                irbar_write(0xFFFFFFFC);
                irbar_result = irbar_read();
                irbar_write(0x0);
        }
        isb(); /* Ensure that MPU region operations have completed */
        /* Return whichever result is larger */
        return __ffs(max(drbar_result, irbar_result));
}

static int mpu_setup_region(unsigned int number, phys_addr_t start,
                        unsigned int size_order, unsigned int properties)
{
        u32 size_data;

        /* We kept a region free for probing resolution of MPU regions*/
        if (number > mpu_max_regions() || number == MPU_PROBE_REGION)
                return -ENOENT;

        if (size_order > 32)
                return -ENOMEM;

        if (size_order < mpu_min_region_order())
                return -ENOMEM;

        /* Writing N to bits 5:1 (RSR_SZ)  specifies region size 2^N+1 */
        size_data = ((size_order - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN;

        dsb(); /* Ensure all previous data accesses occur with old mappings */
        rgnr_write(number);
        isb();
        drbar_write(start);
        dracr_write(properties);
        isb(); /* Propagate properties before enabling region */
        drsr_write(size_data);

        /* Check for independent I-side registers */
        if (mpu_iside_independent()) {
                irbar_write(start);
                iracr_write(properties);
                isb();
                irsr_write(size_data);
        }
        isb();

        /* Store region info (we treat i/d side the same, so only store d) */
        mpu_rgn_info.rgns[number].dracr = properties;
        mpu_rgn_info.rgns[number].drbar = start;
        mpu_rgn_info.rgns[number].drsr = size_data;
        return 0;
}

/*
* Set up default MPU regions, doing nothing if there is no MPU
*/
void __init mpu_setup(void)
{
        int region_err;
        if (!mpu_present())
                return;

        region_err = mpu_setup_region(MPU_RAM_REGION, PHYS_OFFSET,
                                        ilog2(memblock.memory.regions[0].size),
                                        MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL);
        if (region_err) {
                panic("MPU region initialization failure! %d", region_err);
        } else {
                pr_info("Using ARMv7 PMSA Compliant MPU. "
                         "Region independence: %s, Max regions: %d\n",
                        mpu_iside_independent() ? "Yes" : "No",
                        mpu_max_regions());
        }
}
#else
static void adjust_lowmem_bounds_mpu(void) {}
static void __init mpu_setup(void) {}
#endif /* CONFIG_ARM_MPU */

#ifdef CONFIG_CPU_CP15
#ifdef CONFIG_CPU_HIGH_VECTOR
static unsigned long __init setup_vectors_base(void)
{
        unsigned long reg = get_cr();

        set_cr(reg | CR_V);
        return 0xffff0000;
}
#else /* CONFIG_CPU_HIGH_VECTOR */
/* Write exception base address to VBAR */
static inline void set_vbar(unsigned long val)
{
        asm("mcr p15, 0, %0, c12, c0, 0" : : "r" (val) : "cc");
}

/*
 * Security extensions, bits[7:4], permitted values,
 * 0b0000 - not implemented, 0b0001/0b0010 - implemented
 */
static inline bool security_extensions_enabled(void)
{
        /* Check CPUID Identification Scheme before ID_PFR1 read */
        if ((read_cpuid_id() & 0x000f0000) == 0x000f0000)
                return !!cpuid_feature_extract(CPUID_EXT_PFR1, 4);
        return 0;
}

static unsigned long __init setup_vectors_base(void)
{
        unsigned long base = 0, reg = get_cr();

        set_cr(reg & ~CR_V);
        if (security_extensions_enabled()) {
                if (IS_ENABLED(CONFIG_REMAP_VECTORS_TO_RAM))
                        base = CONFIG_DRAM_BASE;
                set_vbar(base);
        } else if (IS_ENABLED(CONFIG_REMAP_VECTORS_TO_RAM)) {
                if (CONFIG_DRAM_BASE != 0)
                        pr_err("Security extensions not enabled, vectors cannot be remapped to RAM, vectors base will be 0x00000000\n");
        }

        return base;
}
#endif /* CONFIG_CPU_HIGH_VECTOR */
#endif /* CONFIG_CPU_CP15 */

void __init arm_mm_memblock_reserve(void)
{
#ifndef CONFIG_CPU_V7M
        vectors_base = IS_ENABLED(CONFIG_CPU_CP15) ? setup_vectors_base() : 0;
        /*
         * Register the exception vector page.
         * some architectures which the DRAM is the exception vector to trap,
         * alloc_page breaks with error, although it is not NULL, but "0."
         */
        memblock_reserve(vectors_base, 2 * PAGE_SIZE);
#else /* ifndef CONFIG_CPU_V7M */
        /*
         * There is no dedicated vector page on V7-M. So nothing needs to be
         * reserved here.
         */
#endif
}

void __init adjust_lowmem_bounds(void)
{
        phys_addr_t end;
        adjust_lowmem_bounds_mpu();
        end = memblock_end_of_DRAM();
        high_memory = __va(end - 1) + 1;
        memblock_set_current_limit(end);
}

/*
 * paging_init() sets up the page tables, initialises the zone memory
 * maps, and sets up the zero page, bad page and bad page tables.
 */
void __init paging_init(const struct machine_desc *mdesc)
{
        early_trap_init((void *)vectors_base);
        mpu_setup();
        bootmem_init();
}

/*
 * We don't need to do anything here for nommu machines.
 */
void setup_mm_for_reboot(void)
{
}

void flush_dcache_page(struct page *page)
{
        __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
}
EXPORT_SYMBOL(flush_dcache_page);

void flush_kernel_dcache_page(struct page *page)
{
        __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
}
EXPORT_SYMBOL(flush_kernel_dcache_page);

void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
                       unsigned long uaddr, void *dst, const void *src,
                       unsigned long len)
{
        memcpy(dst, src, len);
        if (vma->vm_flags & VM_EXEC)
                __cpuc_coherent_user_range(uaddr, uaddr + len);
}

void __iomem *__arm_ioremap_pfn(unsigned long pfn, unsigned long offset,
                                size_t size, unsigned int mtype)
{
        if (pfn >= (0x100000000ULL >> PAGE_SHIFT))
                return NULL;
        return (void __iomem *) (offset + (pfn << PAGE_SHIFT));
}
EXPORT_SYMBOL(__arm_ioremap_pfn);

void __iomem *__arm_ioremap_caller(phys_addr_t phys_addr, size_t size,
                                   unsigned int mtype, void *caller)
{
        return (void __iomem *)phys_addr;
}

void __iomem * (*arch_ioremap_caller)(phys_addr_t, size_t, unsigned int, void *);

void __iomem *ioremap(resource_size_t res_cookie, size_t size)
{
        return __arm_ioremap_caller(res_cookie, size, MT_DEVICE,
                                    __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap);

void __iomem *ioremap_cache(resource_size_t res_cookie, size_t size)
        __alias(ioremap_cached);

void __iomem *ioremap_cached(resource_size_t res_cookie, size_t size)
{
        return __arm_ioremap_caller(res_cookie, size, MT_DEVICE_CACHED,
                                    __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_cache);
EXPORT_SYMBOL(ioremap_cached);

void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size)
{
        return __arm_ioremap_caller(res_cookie, size, MT_DEVICE_WC,
                                    __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_wc);

void *arch_memremap_wb(phys_addr_t phys_addr, size_t size)
{
        return (void *)phys_addr;
}

void __iounmap(volatile void __iomem *addr)
{
}
EXPORT_SYMBOL(__iounmap);

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

void iounmap(volatile void __iomem *addr)
{
}
EXPORT_SYMBOL(iounmap);