// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021 Intel Corporation
 * Author: Johannes Berg <johannes@sipsolutions.net>
 */
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/logic_iomem.h>
#include <asm/io.h>

struct logic_iomem_region {
        const struct resource *res;
        const struct logic_iomem_region_ops *ops;
        struct list_head list;
};

struct logic_iomem_area {
        const struct logic_iomem_ops *ops;
        void *priv;
};

#define AREA_SHIFT      24
#define MAX_AREA_SIZE   (1 << AREA_SHIFT)
#define MAX_AREAS       ((1U << 31) / MAX_AREA_SIZE)
#define AREA_BITS       ((MAX_AREAS - 1) << AREA_SHIFT)
#define AREA_MASK       (MAX_AREA_SIZE - 1)
#ifdef CONFIG_64BIT
#define IOREMAP_BIAS    0xDEAD000000000000UL
#define IOREMAP_MASK    0xFFFFFFFF00000000UL
#else
#define IOREMAP_BIAS    0x80000000UL
#define IOREMAP_MASK    0x80000000UL
#endif

static DEFINE_MUTEX(regions_mtx);
static LIST_HEAD(regions_list);
static struct logic_iomem_area mapped_areas[MAX_AREAS];

int logic_iomem_add_region(struct resource *resource,
                           const struct logic_iomem_region_ops *ops)
{
        struct logic_iomem_region *rreg;
        int err;

        if (WARN_ON(!resource || !ops))
                return -EINVAL;

        if (WARN_ON((resource->flags & IORESOURCE_TYPE_BITS) != IORESOURCE_MEM))
                return -EINVAL;

        rreg = kzalloc_obj(*rreg);
        if (!rreg)
                return -ENOMEM;

        err = request_resource(&iomem_resource, resource);
        if (err) {
                kfree(rreg);
                return -ENOMEM;
        }

        mutex_lock(&regions_mtx);
        rreg->res = resource;
        rreg->ops = ops;
        list_add_tail(&rreg->list, &regions_list);
        mutex_unlock(&regions_mtx);

        return 0;
}
EXPORT_SYMBOL(logic_iomem_add_region);

#ifndef CONFIG_INDIRECT_IOMEM_FALLBACK
static void __iomem *real_ioremap(phys_addr_t offset, size_t size)
{
        WARN(1, "invalid ioremap(0x%llx, 0x%zx)\n",
             (unsigned long long)offset, size);
        return NULL;
}

static void real_iounmap(volatile void __iomem *addr)
{
        WARN(1, "invalid iounmap for addr 0x%llx\n",
             (unsigned long long)(uintptr_t __force)addr);
}
#endif /* CONFIG_INDIRECT_IOMEM_FALLBACK */

void __iomem *ioremap(phys_addr_t offset, size_t size)
{
        void __iomem *ret = NULL;
        struct logic_iomem_region *rreg, *found = NULL;
        int i;

        mutex_lock(&regions_mtx);
        list_for_each_entry(rreg, &regions_list, list) {
                if (rreg->res->start > offset)
                        continue;
                if (rreg->res->end < offset + size - 1)
                        continue;
                found = rreg;
                break;
        }

        if (!found)
                goto out;

        for (i = 0; i < MAX_AREAS; i++) {
                long offs;

                if (mapped_areas[i].ops)
                        continue;

                offs = rreg->ops->map(offset - found->res->start,
                                      size, &mapped_areas[i].ops,
                                      &mapped_areas[i].priv);
                if (offs < 0) {
                        mapped_areas[i].ops = NULL;
                        break;
                }

                if (WARN_ON(!mapped_areas[i].ops)) {
                        mapped_areas[i].ops = NULL;
                        break;
                }

                ret = (void __iomem *)(IOREMAP_BIAS + (i << AREA_SHIFT) + offs);
                break;
        }
out:
        mutex_unlock(&regions_mtx);
        if (ret)
                return ret;
        return real_ioremap(offset, size);
}
EXPORT_SYMBOL(ioremap);

static inline struct logic_iomem_area *
get_area(const volatile void __iomem *addr)
{
        unsigned long a = (unsigned long)addr;
        unsigned int idx;

        if (WARN_ON((a & IOREMAP_MASK) != IOREMAP_BIAS))
                return NULL;

        idx = (a & AREA_BITS) >> AREA_SHIFT;

        if (mapped_areas[idx].ops)
                return &mapped_areas[idx];

        return NULL;
}

void iounmap(volatile void __iomem *addr)
{
        struct logic_iomem_area *area = get_area(addr);

        if (!area) {
                real_iounmap(addr);
                return;
        }

        if (area->ops->unmap)
                area->ops->unmap(area->priv);

        mutex_lock(&regions_mtx);
        area->ops = NULL;
        area->priv = NULL;
        mutex_unlock(&regions_mtx);
}
EXPORT_SYMBOL(iounmap);

#ifndef CONFIG_INDIRECT_IOMEM_FALLBACK
#define MAKE_FALLBACK(op, sz)                                           \
static u##sz real_raw_read ## op(const volatile void __iomem *addr)     \
{                                                                       \
        WARN(1, "Invalid read" #op " at address %llx\n",                \
             (unsigned long long)(uintptr_t __force)addr);              \
        return (u ## sz)~0ULL;                                          \
}                                                                       \
                                                                        \
static void real_raw_write ## op(u ## sz val,                           \
                                 volatile void __iomem *addr)           \
{                                                                       \
        WARN(1, "Invalid writeq" #op " of 0x%llx at address %llx\n",    \
             (unsigned long long)val,                                   \
             (unsigned long long)(uintptr_t __force)addr);\
}                                                                       \

MAKE_FALLBACK(b, 8);
MAKE_FALLBACK(w, 16);
MAKE_FALLBACK(l, 32);
#ifdef CONFIG_64BIT
MAKE_FALLBACK(q, 64);
#endif

static void real_memset_io(volatile void __iomem *addr, int value, size_t size)
{
        WARN(1, "Invalid memset_io at address 0x%llx\n",
             (unsigned long long)(uintptr_t __force)addr);
}

static void real_memcpy_fromio(void *buffer, const volatile void __iomem *addr,
                               size_t size)
{
        WARN(1, "Invalid memcpy_fromio at address 0x%llx\n",
             (unsigned long long)(uintptr_t __force)addr);

        memset(buffer, 0xff, size);
}

static void real_memcpy_toio(volatile void __iomem *addr, const void *buffer,
                             size_t size)
{
        WARN(1, "Invalid memcpy_toio at address 0x%llx\n",
             (unsigned long long)(uintptr_t __force)addr);
}
#endif /* CONFIG_INDIRECT_IOMEM_FALLBACK */

#define MAKE_OP(op, sz)                                                 \
u##sz __raw_read ## op(const volatile void __iomem *addr)               \
{                                                                       \
        struct logic_iomem_area *area = get_area(addr);                 \
                                                                        \
        if (!area)                                                      \
                return real_raw_read ## op(addr);                       \
                                                                        \
        return (u ## sz) area->ops->read(area->priv,                    \
                                         (unsigned long)addr & AREA_MASK,\
                                         sz / 8);                       \
}                                                                       \
EXPORT_SYMBOL(__raw_read ## op);                                        \
                                                                        \
void __raw_write ## op(u ## sz val, volatile void __iomem *addr)        \
{                                                                       \
        struct logic_iomem_area *area = get_area(addr);                 \
                                                                        \
        if (!area) {                                                    \
                real_raw_write ## op(val, addr);                        \
                return;                                                 \
        }                                                               \
                                                                        \
        area->ops->write(area->priv,                                    \
                         (unsigned long)addr & AREA_MASK,               \
                         sz / 8, val);                                  \
}                                                                       \
EXPORT_SYMBOL(__raw_write ## op)

MAKE_OP(b, 8);
MAKE_OP(w, 16);
MAKE_OP(l, 32);
#ifdef CONFIG_64BIT
MAKE_OP(q, 64);
#endif

void memset_io(volatile void __iomem *addr, int value, size_t size)
{
        struct logic_iomem_area *area = get_area(addr);
        unsigned long offs, start;

        if (!area) {
                real_memset_io(addr, value, size);
                return;
        }

        start = (unsigned long)addr & AREA_MASK;

        if (area->ops->set) {
                area->ops->set(area->priv, start, value, size);
                return;
        }

        for (offs = 0; offs < size; offs++)
                area->ops->write(area->priv, start + offs, 1, value);
}
EXPORT_SYMBOL(memset_io);

void memcpy_fromio(void *buffer, const volatile void __iomem *addr,
                   size_t size)
{
        struct logic_iomem_area *area = get_area(addr);
        u8 *buf = buffer;
        unsigned long offs, start;

        if (!area) {
                real_memcpy_fromio(buffer, addr, size);
                return;
        }

        start = (unsigned long)addr & AREA_MASK;

        if (area->ops->copy_from) {
                area->ops->copy_from(area->priv, buffer, start, size);
                return;
        }

        for (offs = 0; offs < size; offs++)
                buf[offs] = area->ops->read(area->priv, start + offs, 1);
}
EXPORT_SYMBOL(memcpy_fromio);

void memcpy_toio(volatile void __iomem *addr, const void *buffer, size_t size)
{
        struct logic_iomem_area *area = get_area(addr);
        const u8 *buf = buffer;
        unsigned long offs, start;

        if (!area) {
                real_memcpy_toio(addr, buffer, size);
                return;
        }

        start = (unsigned long)addr & AREA_MASK;

        if (area->ops->copy_to) {
                area->ops->copy_to(area->priv, start, buffer, size);
                return;
        }

        for (offs = 0; offs < size; offs++)
                area->ops->write(area->priv, start + offs, 1, buf[offs]);
}
EXPORT_SYMBOL(memcpy_toio);