/**************************************************************************
 *
 * Copyright (c) 2006-2007 Tungsten Graphics, Inc., Cedar Park, TX., USA
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/
/*
 * Authors: Thomas Hellström <thomas-at-tungstengraphics-dot-com>
 */

#include <linux/dma-buf-map.h>
#include <linux/export.h>
#include <linux/highmem.h>
#include <linux/mem_encrypt.h>
#include <xen/xen.h>

#include <drm/drm_cache.h>

/* A small bounce buffer that fits on the stack. */
#define MEMCPY_BOUNCE_SIZE 128

#if defined(CONFIG_X86)
#include <asm/smp.h>

/*
 * clflushopt is an unordered instruction which needs fencing with mfence or
 * sfence to avoid ordering issues.  For drm_clflush_page this fencing happens
 * in the caller.
 */
static void
drm_clflush_page(struct page *page)
{
        uint8_t *page_virtual;
        unsigned int i;
        const int size = boot_cpu_data.x86_clflush_size;

        if (unlikely(page == NULL))
                return;

        page_virtual = kmap_atomic(page);
        for (i = 0; i < PAGE_SIZE; i += size)
                clflushopt(page_virtual + i);
        kunmap_atomic(page_virtual);
}

static void drm_cache_flush_clflush(struct page *pages[],
                                    unsigned long num_pages)
{
        unsigned long i;

        mb(); /*Full memory barrier used before so that CLFLUSH is ordered*/
        for (i = 0; i < num_pages; i++)
                drm_clflush_page(*pages++);
        mb(); /*Also used after CLFLUSH so that all cache is flushed*/
}
#endif

/**
 * drm_clflush_pages - Flush dcache lines of a set of pages.
 * @pages: List of pages to be flushed.
 * @num_pages: Number of pages in the array.
 *
 * Flush every data cache line entry that points to an address belonging
 * to a page in the array.
 */
void
drm_clflush_pages(struct page *pages[], unsigned long num_pages)
{

#if defined(CONFIG_X86)
        if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
                drm_cache_flush_clflush(pages, num_pages);
                return;
        }

        if (wbinvd_on_all_cpus())
                pr_err("Timed out waiting for cache flush\n");

#elif defined(__powerpc__)
        unsigned long i;

        for (i = 0; i < num_pages; i++) {
                struct page *page = pages[i];
                void *page_virtual;

                if (unlikely(page == NULL))
                        continue;

                page_virtual = kmap_atomic(page);
                flush_dcache_range((unsigned long)page_virtual,
                                   (unsigned long)page_virtual + PAGE_SIZE);
                kunmap_atomic(page_virtual);
        }
#else
        pr_err("Architecture has no drm_cache.c support\n");
        WARN_ON_ONCE(1);
#endif
}
EXPORT_SYMBOL(drm_clflush_pages);

/**
 * drm_clflush_sg - Flush dcache lines pointing to a scather-gather.
 * @st: struct sg_table.
 *
 * Flush every data cache line entry that points to an address in the
 * sg.
 */
void
drm_clflush_sg(struct sg_table *st)
{
#if defined(CONFIG_X86)
        if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
                struct sg_page_iter sg_iter;

                mb(); /*CLFLUSH is ordered only by using memory barriers*/
                for_each_sgtable_page(st, &sg_iter, 0)
                        drm_clflush_page(sg_page_iter_page(&sg_iter));
                mb(); /*Make sure that all cache line entry is flushed*/

                return;
        }

        if (wbinvd_on_all_cpus())
                pr_err("Timed out waiting for cache flush\n");
#else
        pr_err("Architecture has no drm_cache.c support\n");
        WARN_ON_ONCE(1);
#endif
}
EXPORT_SYMBOL(drm_clflush_sg);

/**
 * drm_clflush_virt_range - Flush dcache lines of a region
 * @addr: Initial kernel memory address.
 * @length: Region size.
 *
 * Flush every data cache line entry that points to an address in the
 * region requested.
 */
void
drm_clflush_virt_range(void *addr, unsigned long length)
{
#if defined(CONFIG_X86)
        if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
                const int size = boot_cpu_data.x86_clflush_size;
                void *end = addr + length;

                addr = (void *)(((unsigned long)addr) & -size);
                mb(); /*CLFLUSH is only ordered with a full memory barrier*/
                for (; addr < end; addr += size)
                        clflushopt(addr);
                clflushopt(end - 1); /* force serialisation */
                mb(); /*Ensure that every data cache line entry is flushed*/
                return;
        }

        if (wbinvd_on_all_cpus())
                pr_err("Timed out waiting for cache flush\n");
#else
        pr_err("Architecture has no drm_cache.c support\n");
        WARN_ON_ONCE(1);
#endif
}
EXPORT_SYMBOL(drm_clflush_virt_range);

bool drm_need_swiotlb(int dma_bits)
{
        struct resource *tmp;
        resource_size_t max_iomem = 0;

        /*
         * Xen paravirtual hosts require swiotlb regardless of requested dma
         * transfer size.
         *
         * NOTE: Really, what it requires is use of the dma_alloc_coherent
         *       allocator used in ttm_dma_populate() instead of
         *       ttm_populate_and_map_pages(), which bounce buffers so much in
         *       Xen it leads to swiotlb buffer exhaustion.
         */
        if (xen_pv_domain())
                return true;

        /*
         * Enforce dma_alloc_coherent when memory encryption is active as well
         * for the same reasons as for Xen paravirtual hosts.
         */
        if (mem_encrypt_active())
                return true;

        for (tmp = iomem_resource.child; tmp; tmp = tmp->sibling)
                max_iomem = max(max_iomem,  tmp->end);

        return max_iomem > ((u64)1 << dma_bits);
}
EXPORT_SYMBOL(drm_need_swiotlb);

static void memcpy_fallback(struct dma_buf_map *dst,
                            const struct dma_buf_map *src,
                            unsigned long len)
{
        if (!dst->is_iomem && !src->is_iomem) {
                memcpy(dst->vaddr, src->vaddr, len);
        } else if (!src->is_iomem) {
                dma_buf_map_memcpy_to(dst, src->vaddr, len);
        } else if (!dst->is_iomem) {
                memcpy_fromio(dst->vaddr, src->vaddr_iomem, len);
        } else {
                /*
                 * Bounce size is not performance tuned, but using a
                 * bounce buffer like this is significantly faster than
                 * resorting to ioreadxx() + iowritexx().
                 */
                char bounce[MEMCPY_BOUNCE_SIZE];
                void __iomem *_src = src->vaddr_iomem;
                void __iomem *_dst = dst->vaddr_iomem;

                while (len >= MEMCPY_BOUNCE_SIZE) {
                        memcpy_fromio(bounce, _src, MEMCPY_BOUNCE_SIZE);
                        memcpy_toio(_dst, bounce, MEMCPY_BOUNCE_SIZE);
                        _src += MEMCPY_BOUNCE_SIZE;
                        _dst += MEMCPY_BOUNCE_SIZE;
                        len -= MEMCPY_BOUNCE_SIZE;
                }
                if (len) {
                        memcpy_fromio(bounce, _src, MEMCPY_BOUNCE_SIZE);
                        memcpy_toio(_dst, bounce, MEMCPY_BOUNCE_SIZE);
                }
        }
}

#ifdef CONFIG_X86

static DEFINE_STATIC_KEY_FALSE(has_movntdqa);

static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
{
        kernel_fpu_begin();

        while (len >= 4) {
                asm("movntdqa   (%0), %%xmm0\n"
                    "movntdqa 16(%0), %%xmm1\n"
                    "movntdqa 32(%0), %%xmm2\n"
                    "movntdqa 48(%0), %%xmm3\n"
                    "movaps %%xmm0,   (%1)\n"
                    "movaps %%xmm1, 16(%1)\n"
                    "movaps %%xmm2, 32(%1)\n"
                    "movaps %%xmm3, 48(%1)\n"
                    :: "r" (src), "r" (dst) : "memory");
                src += 64;
                dst += 64;
                len -= 4;
        }
        while (len--) {
                asm("movntdqa (%0), %%xmm0\n"
                    "movaps %%xmm0, (%1)\n"
                    :: "r" (src), "r" (dst) : "memory");
                src += 16;
                dst += 16;
        }

        kernel_fpu_end();
}

/*
 * __drm_memcpy_from_wc copies @len bytes from @src to @dst using
 * non-temporal instructions where available. Note that all arguments
 * (@src, @dst) must be aligned to 16 bytes and @len must be a multiple
 * of 16.
 */
static void __drm_memcpy_from_wc(void *dst, const void *src, unsigned long len)
{
        if (unlikely(((unsigned long)dst | (unsigned long)src | len) & 15))
                memcpy(dst, src, len);
        else if (likely(len))
                __memcpy_ntdqa(dst, src, len >> 4);
}

/**
 * drm_memcpy_from_wc - Perform the fastest available memcpy from a source
 * that may be WC.
 * @dst: The destination pointer
 * @src: The source pointer
 * @len: The size of the area o transfer in bytes
 *
 * Tries an arch optimized memcpy for prefetching reading out of a WC region,
 * and if no such beast is available, falls back to a normal memcpy.
 */
void drm_memcpy_from_wc(struct dma_buf_map *dst,
                        const struct dma_buf_map *src,
                        unsigned long len)
{
        if (WARN_ON(in_interrupt())) {
                memcpy_fallback(dst, src, len);
                return;
        }

        if (static_branch_likely(&has_movntdqa)) {
                __drm_memcpy_from_wc(dst->is_iomem ?
                                     (void __force *)dst->vaddr_iomem :
                                     dst->vaddr,
                                     src->is_iomem ?
                                     (void const __force *)src->vaddr_iomem :
                                     src->vaddr,
                                     len);
                return;
        }

        memcpy_fallback(dst, src, len);
}
EXPORT_SYMBOL(drm_memcpy_from_wc);

/*
 * drm_memcpy_init_early - One time initialization of the WC memcpy code
 */
void drm_memcpy_init_early(void)
{
        /*
         * Some hypervisors (e.g. KVM) don't support VEX-prefix instructions
         * emulation. So don't enable movntdqa in hypervisor guest.
         */
        if (static_cpu_has(X86_FEATURE_XMM4_1) &&
            !boot_cpu_has(X86_FEATURE_HYPERVISOR))
                static_branch_enable(&has_movntdqa);
}
#else
void drm_memcpy_from_wc(struct dma_buf_map *dst,
                        const struct dma_buf_map *src,
                        unsigned long len)
{
        WARN_ON(in_interrupt());

        memcpy_fallback(dst, src, len);
}
EXPORT_SYMBOL(drm_memcpy_from_wc);

void drm_memcpy_init_early(void)
{
}
#endif /* CONFIG_X86 */