/*
 * Based on linux/arch/arm/mm/nommu.c
 *
 * ARM PMSAv7 supporting functions.
 */

#include <linux/bitops.h>
#include <linux/memblock.h>
#include <linux/string.h>

#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/cputype.h>
#include <asm/mpu.h>
#include <asm/sections.h>

#include "mm.h"

struct region {
        phys_addr_t base;
        phys_addr_t size;
        unsigned long subreg;
};

static struct region __initdata mem[MPU_MAX_REGIONS];
#ifdef CONFIG_XIP_KERNEL
static struct region __initdata xip[MPU_MAX_REGIONS];
#endif

static unsigned int __initdata mpu_min_region_order;
static unsigned int __initdata mpu_max_regions;

static int __init __mpu_min_region_order(void);
static int __init __mpu_max_regions(void);

#ifndef CONFIG_CPU_V7M

#define DRBAR   __ACCESS_CP15(c6, 0, c1, 0)
#define IRBAR   __ACCESS_CP15(c6, 0, c1, 1)
#define DRSR    __ACCESS_CP15(c6, 0, c1, 2)
#define IRSR    __ACCESS_CP15(c6, 0, c1, 3)
#define DRACR   __ACCESS_CP15(c6, 0, c1, 4)
#define IRACR   __ACCESS_CP15(c6, 0, c1, 5)
#define RNGNR   __ACCESS_CP15(c6, 0, c2, 0)

/* Region number */
static inline void rgnr_write(u32 v)
{
        write_sysreg(v, RNGNR);
}

/* Data-side / unified region attributes */

/* Region access control register */
static inline void dracr_write(u32 v)
{
        write_sysreg(v, DRACR);
}

/* Region size register */
static inline void drsr_write(u32 v)
{
        write_sysreg(v, DRSR);
}

/* Region base address register */
static inline void drbar_write(u32 v)
{
        write_sysreg(v, DRBAR);
}

static inline u32 drbar_read(void)
{
        return read_sysreg(DRBAR);
}
/* Optional instruction-side region attributes */

/* I-side Region access control register */
static inline void iracr_write(u32 v)
{
        write_sysreg(v, IRACR);
}

/* I-side Region size register */
static inline void irsr_write(u32 v)
{
        write_sysreg(v, IRSR);
}

/* I-side Region base address register */
static inline void irbar_write(u32 v)
{
        write_sysreg(v, IRBAR);
}

static inline u32 irbar_read(void)
{
        return read_sysreg(IRBAR);
}

#else

static inline void rgnr_write(u32 v)
{
        writel_relaxed(v, BASEADDR_V7M_SCB + MPU_RNR);
}

/* Data-side / unified region attributes */

/* Region access control register */
static inline void dracr_write(u32 v)
{
        u32 rsr = readl_relaxed(BASEADDR_V7M_SCB + MPU_RASR) & GENMASK(15, 0);

        writel_relaxed((v << 16) | rsr, BASEADDR_V7M_SCB + MPU_RASR);
}

/* Region size register */
static inline void drsr_write(u32 v)
{
        u32 racr = readl_relaxed(BASEADDR_V7M_SCB + MPU_RASR) & GENMASK(31, 16);

        writel_relaxed(v | racr, BASEADDR_V7M_SCB + MPU_RASR);
}

/* Region base address register */
static inline void drbar_write(u32 v)
{
        writel_relaxed(v, BASEADDR_V7M_SCB + MPU_RBAR);
}

static inline u32 drbar_read(void)
{
        return readl_relaxed(BASEADDR_V7M_SCB + MPU_RBAR);
}

/* ARMv7-M only supports a unified MPU, so I-side operations are nop */

static inline void iracr_write(u32 v) {}
static inline void irsr_write(u32 v) {}
static inline void irbar_write(u32 v) {}
static inline unsigned long irbar_read(void) {return 0;}

#endif

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

static bool __init try_split_region(phys_addr_t base, phys_addr_t size, struct region *region)
{
        unsigned long  subreg, bslots, sslots;
        phys_addr_t abase = base & ~(size - 1);
        phys_addr_t asize = base + size - abase;
        phys_addr_t p2size = 1 << __fls(asize);
        phys_addr_t bdiff, sdiff;

        if (p2size != asize)
                p2size *= 2;

        bdiff = base - abase;
        sdiff = p2size - asize;
        subreg = p2size / MPU_NR_SUBREGS;

        if ((bdiff % subreg) || (sdiff % subreg))
                return false;

        bslots = bdiff / subreg;
        sslots = sdiff / subreg;

        if (bslots || sslots) {
                int i;

                if (subreg < MPU_MIN_SUBREG_SIZE)
                        return false;

                if (bslots + sslots > MPU_NR_SUBREGS)
                        return false;

                for (i = 0; i < bslots; i++)
                        _set_bit(i, &region->subreg);

                for (i = 1; i <= sslots; i++)
                        _set_bit(MPU_NR_SUBREGS - i, &region->subreg);
        }

        region->base = abase;
        region->size = p2size;

        return true;
}

static int __init allocate_region(phys_addr_t base, phys_addr_t size,
                                  unsigned int limit, struct region *regions)
{
        int count = 0;
        phys_addr_t diff = size;
        int attempts = MPU_MAX_REGIONS;

        while (diff) {
                /* Try cover region as is (maybe with help of subregions) */
                if (try_split_region(base, size, &regions[count])) {
                        count++;
                        base += size;
                        diff -= size;
                        size = diff;
                } else {
                        /*
                         * Maximum aligned region might overflow phys_addr_t
                         * if "base" is 0. Hence we keep everything below 4G
                         * until we take the smaller of the aligned region
                         * size ("asize") and rounded region size ("p2size"),
                         * one of which is guaranteed to be smaller than the
                         * maximum physical address.
                         */
                        phys_addr_t asize = (base - 1) ^ base;
                        phys_addr_t p2size = (1 <<  __fls(diff)) - 1;

                        size = asize < p2size ? asize + 1 : p2size + 1;
                }

                if (count > limit)
                        break;

                if (!attempts)
                        break;

                attempts--;
        }

        return count;
}

/* MPU initialisation functions */
void __init adjust_lowmem_bounds_mpu(void)
{
        phys_addr_t  specified_mem_size = 0, total_mem_size = 0;
        struct memblock_region *reg;
        bool first = true;
        phys_addr_t mem_start;
        phys_addr_t mem_end;
        unsigned int mem_max_regions;
        int num, i;

        if (!mpu_present())
                return;

        /* Free-up MPU_PROBE_REGION */
        mpu_min_region_order = __mpu_min_region_order();

        /* How many regions are supported */
        mpu_max_regions = __mpu_max_regions();

        mem_max_regions = min((unsigned int)MPU_MAX_REGIONS, mpu_max_regions);

        /* We need to keep one slot for background region */
        mem_max_regions--;

#ifndef CONFIG_CPU_V7M
        /* ... and one for vectors */
        mem_max_regions--;
#endif

#ifdef CONFIG_XIP_KERNEL
        /* plus some regions to cover XIP ROM */
        num = allocate_region(CONFIG_XIP_PHYS_ADDR, __pa(_exiprom) - CONFIG_XIP_PHYS_ADDR,
                              mem_max_regions, xip);

        mem_max_regions -= num;
#endif

        for_each_memblock(memory, reg) {
                if (first) {
                        phys_addr_t phys_offset = PHYS_OFFSET;

                        /*
                         * 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;
                }
        }

        memset(mem, 0, sizeof(mem));
        num = allocate_region(mem_start, specified_mem_size, mem_max_regions, mem);

        for (i = 0; i < num; i++) {
                unsigned long  subreg = mem[i].size / MPU_NR_SUBREGS;

                total_mem_size += mem[i].size - subreg * hweight_long(mem[i].subreg);

                pr_debug("MPU: base %pa size %pa disable subregions: %*pbl\n",
                         &mem[i].base, &mem[i].size, MPU_NR_SUBREGS, &mem[i].subreg);
        }

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

static int __init __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_mputype();

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

static int __init __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 __init mpu_setup_region(unsigned int number, phys_addr_t start,
                                   unsigned int size_order, unsigned int properties,
                                   unsigned int subregions, bool need_flush)
{
        u32 size_data;

        /* We kept a region free for probing resolution of MPU regions*/
        if (number > mpu_max_regions
            || number >= MPU_MAX_REGIONS)
                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;
        size_data |= subregions << MPU_RSR_SD;

        if (need_flush)
                flush_cache_all();

        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;

        mpu_rgn_info.used++;

        return 0;
}

/*
* Set up default MPU regions, doing nothing if there is no MPU
*/
void __init mpu_setup(void)
{
        int i, region = 0, err = 0;

        if (!mpu_present())
                return;

        /* Setup MPU (order is important) */

        /* Background */
        err |= mpu_setup_region(region++, 0, 32,
                                MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0RW,
                                0, false);

#ifdef CONFIG_XIP_KERNEL
        /* ROM */
        for (i = 0; i < ARRAY_SIZE(xip); i++) {
                /*
                 * In case we overwrite RAM region we set earlier in
                 * head-nommu.S (which is cachable) all subsequent
                 * data access till we setup RAM bellow would be done
                 * with BG region (which is uncachable), thus we need
                 * to clean and invalidate cache.
                 */
                bool need_flush = region == MPU_RAM_REGION;

                if (!xip[i].size)
                        continue;

                err |= mpu_setup_region(region++, xip[i].base, ilog2(xip[i].size),
                                        MPU_AP_PL1RO_PL0NA | MPU_RGN_NORMAL,
                                        xip[i].subreg, need_flush);
        }
#endif

        /* RAM */
        for (i = 0; i < ARRAY_SIZE(mem); i++) {
                if (!mem[i].size)
                        continue;

                err |= mpu_setup_region(region++, mem[i].base, ilog2(mem[i].size),
                                        MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL,
                                        mem[i].subreg, false);
        }

        /* Vectors */
#ifndef CONFIG_CPU_V7M
        err |= mpu_setup_region(region++, vectors_base, ilog2(2 * PAGE_SIZE),
                                MPU_AP_PL1RW_PL0NA | MPU_RGN_NORMAL,
                                0, false);
#endif
        if (err) {
                panic("MPU region initialization failure! %d", err);
        } else {
                pr_info("Using ARMv7 PMSA Compliant MPU. "
                         "Region independence: %s, Used %d of %d regions\n",
                        mpu_iside_independent() ? "Yes" : "No",
                        mpu_rgn_info.used, mpu_max_regions);
        }
}