/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright © 2008 Keith Packard <keithp@keithp.com>
 */

#ifndef _LINUX_IO_MAPPING_H
#define _LINUX_IO_MAPPING_H

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bug.h>
#include <linux/io.h>
#include <linux/pgtable.h>
#include <asm/page.h>

/*
 * The io_mapping mechanism provides an abstraction for mapping
 * individual pages from an io device to the CPU in an efficient fashion.
 *
 * See Documentation/driver-api/io-mapping.rst
 */

struct io_mapping {
        resource_size_t base;
        unsigned long size;
        pgprot_t prot;
        void __iomem *iomem;
};

#ifdef CONFIG_HAVE_ATOMIC_IOMAP

#include <linux/pfn.h>
#include <asm/iomap.h>
/*
 * For small address space machines, mapping large objects
 * into the kernel virtual space isn't practical. Where
 * available, use fixmap support to dynamically map pages
 * of the object at run time.
 */

static inline struct io_mapping *
io_mapping_init_wc(struct io_mapping *iomap,
                   resource_size_t base,
                   unsigned long size)
{
        pgprot_t prot;

        if (iomap_create_wc(base, size, &prot))
                return NULL;

        iomap->base = base;
        iomap->size = size;
        iomap->prot = prot;
        return iomap;
}

static inline void
io_mapping_fini(struct io_mapping *mapping)
{
        iomap_free(mapping->base, mapping->size);
}

/* Atomic map/unmap */
static inline void __iomem *
io_mapping_map_atomic_wc(struct io_mapping *mapping,
                         unsigned long offset)
{
        resource_size_t phys_addr;

        BUG_ON(offset >= mapping->size);
        phys_addr = mapping->base + offset;
        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                preempt_disable();
        else
                migrate_disable();
        pagefault_disable();
        return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
}

static inline void
io_mapping_unmap_atomic(void __iomem *vaddr)
{
        kunmap_local_indexed((void __force *)vaddr);
        pagefault_enable();
        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                preempt_enable();
        else
                migrate_enable();
}

static inline void __iomem *
io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
{
        resource_size_t phys_addr;

        BUG_ON(offset >= mapping->size);
        phys_addr = mapping->base + offset;
        return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
}

static inline void io_mapping_unmap_local(void __iomem *vaddr)
{
        kunmap_local_indexed((void __force *)vaddr);
}

static inline void __iomem *
io_mapping_map_wc(struct io_mapping *mapping,
                  unsigned long offset,
                  unsigned long size)
{
        resource_size_t phys_addr;

        BUG_ON(offset >= mapping->size);
        phys_addr = mapping->base + offset;

        return ioremap_wc(phys_addr, size);
}

static inline void
io_mapping_unmap(void __iomem *vaddr)
{
        iounmap(vaddr);
}

#else  /* HAVE_ATOMIC_IOMAP */

#include <linux/uaccess.h>

/* Create the io_mapping object*/
static inline struct io_mapping *
io_mapping_init_wc(struct io_mapping *iomap,
                   resource_size_t base,
                   unsigned long size)
{
        iomap->iomem = ioremap_wc(base, size);
        if (!iomap->iomem)
                return NULL;

        iomap->base = base;
        iomap->size = size;
        iomap->prot = pgprot_writecombine(PAGE_KERNEL);

        return iomap;
}

static inline void
io_mapping_fini(struct io_mapping *mapping)
{
        iounmap(mapping->iomem);
}

/* Non-atomic map/unmap */
static inline void __iomem *
io_mapping_map_wc(struct io_mapping *mapping,
                  unsigned long offset,
                  unsigned long size)
{
        return mapping->iomem + offset;
}

static inline void
io_mapping_unmap(void __iomem *vaddr)
{
}

/* Atomic map/unmap */
static inline void __iomem *
io_mapping_map_atomic_wc(struct io_mapping *mapping,
                         unsigned long offset)
{
        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                preempt_disable();
        else
                migrate_disable();
        pagefault_disable();
        return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
}

static inline void
io_mapping_unmap_atomic(void __iomem *vaddr)
{
        io_mapping_unmap(vaddr);
        pagefault_enable();
        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                preempt_enable();
        else
                migrate_enable();
}

static inline void __iomem *
io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
{
        return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
}

static inline void io_mapping_unmap_local(void __iomem *vaddr)
{
        io_mapping_unmap(vaddr);
}

#endif /* !HAVE_ATOMIC_IOMAP */

static inline struct io_mapping *
io_mapping_create_wc(resource_size_t base,
                     unsigned long size)
{
        struct io_mapping *iomap;

        iomap = kmalloc_obj(*iomap);
        if (!iomap)
                return NULL;

        if (!io_mapping_init_wc(iomap, base, size)) {
                kfree(iomap);
                return NULL;
        }

        return iomap;
}

static inline void
io_mapping_free(struct io_mapping *iomap)
{
        io_mapping_fini(iomap);
        kfree(iomap);
}

#endif /* _LINUX_IO_MAPPING_H */