// SPDX-License-Identifier: GPL-2.0-or-later
/*
    User DMA

    Copyright (C) 2003-2004  Kevin Thayer <nufan_wfk at yahoo.com>
    Copyright (C) 2004  Chris Kennedy <c@groovy.org>
    Copyright (C) 2005-2007  Hans Verkuil <hverkuil@xs4all.nl>

 */

#include "ivtv-driver.h"
#include "ivtv-udma.h"

void ivtv_udma_get_page_info(struct ivtv_dma_page_info *dma_page, unsigned long first, unsigned long size)
{
        dma_page->uaddr = first & PAGE_MASK;
        dma_page->offset = first & ~PAGE_MASK;
        dma_page->tail = 1 + ((first+size-1) & ~PAGE_MASK);
        dma_page->first = (first & PAGE_MASK) >> PAGE_SHIFT;
        dma_page->last = ((first+size-1) & PAGE_MASK) >> PAGE_SHIFT;
        dma_page->page_count = dma_page->last - dma_page->first + 1;
        if (dma_page->page_count == 1) dma_page->tail -= dma_page->offset;
}

int ivtv_udma_fill_sg_list (struct ivtv_user_dma *dma, struct ivtv_dma_page_info *dma_page, int map_offset)
{
        int i, offset;
        unsigned long flags;

        if (map_offset < 0)
                return map_offset;

        offset = dma_page->offset;

        /* Fill SG Array with new values */
        for (i = 0; i < dma_page->page_count; i++) {
                unsigned int len = (i == dma_page->page_count - 1) ?
                        dma_page->tail : PAGE_SIZE - offset;

                if (PageHighMem(dma->map[map_offset])) {
                        void *src;

                        if (dma->bouncemap[map_offset] == NULL)
                                dma->bouncemap[map_offset] = alloc_page(GFP_KERNEL);
                        if (dma->bouncemap[map_offset] == NULL)
                                return -1;
                        local_irq_save(flags);
                        src = kmap_atomic(dma->map[map_offset]) + offset;
                        memcpy(page_address(dma->bouncemap[map_offset]) + offset, src, len);
                        kunmap_atomic(src);
                        local_irq_restore(flags);
                        sg_set_page(&dma->SGlist[map_offset], dma->bouncemap[map_offset], len, offset);
                }
                else {
                        sg_set_page(&dma->SGlist[map_offset], dma->map[map_offset], len, offset);
                }
                offset = 0;
                map_offset++;
        }
        return map_offset;
}

void ivtv_udma_fill_sg_array (struct ivtv_user_dma *dma, u32 buffer_offset, u32 buffer_offset_2, u32 split) {
        int i;
        struct scatterlist *sg;

        for_each_sg(dma->SGlist, sg, dma->SG_length, i) {
                dma->SGarray[i].size = cpu_to_le32(sg_dma_len(sg));
                dma->SGarray[i].src = cpu_to_le32(sg_dma_address(sg));
                dma->SGarray[i].dst = cpu_to_le32(buffer_offset);
                buffer_offset += sg_dma_len(sg);

                split -= sg_dma_len(sg);
                if (split == 0)
                        buffer_offset = buffer_offset_2;
        }
}

/* User DMA Buffers */
void ivtv_udma_alloc(struct ivtv *itv)
{
        if (itv->udma.SG_handle == 0) {
                /* Map DMA Page Array Buffer */
                itv->udma.SG_handle = pci_map_single(itv->pdev, itv->udma.SGarray,
                           sizeof(itv->udma.SGarray), PCI_DMA_TODEVICE);
                ivtv_udma_sync_for_cpu(itv);
        }
}

int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
                       void __user *userbuf, int size_in_bytes)
{
        struct ivtv_dma_page_info user_dma;
        struct ivtv_user_dma *dma = &itv->udma;
        int err;

        IVTV_DEBUG_DMA("ivtv_udma_setup, dst: 0x%08x\n", (unsigned int)ivtv_dest_addr);

        /* Still in USE */
        if (dma->SG_length || dma->page_count) {
                IVTV_DEBUG_WARN("ivtv_udma_setup: SG_length %d page_count %d still full?\n",
                           dma->SG_length, dma->page_count);
                return -EBUSY;
        }

        ivtv_udma_get_page_info(&user_dma, (unsigned long)userbuf, size_in_bytes);

        if (user_dma.page_count <= 0) {
                IVTV_DEBUG_WARN("ivtv_udma_setup: Error %d page_count from %d bytes %d offset\n",
                           user_dma.page_count, size_in_bytes, user_dma.offset);
                return -EINVAL;
        }

        /* Pin user pages for DMA Xfer */
        err = pin_user_pages_unlocked(user_dma.uaddr, user_dma.page_count,
                        dma->map, FOLL_FORCE);

        if (user_dma.page_count != err) {
                IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",
                           err, user_dma.page_count);
                if (err >= 0) {
                        unpin_user_pages(dma->map, err);
                        return -EINVAL;
                }
                return err;
        }

        dma->page_count = user_dma.page_count;

        /* Fill SG List with new values */
        if (ivtv_udma_fill_sg_list(dma, &user_dma, 0) < 0) {
                unpin_user_pages(dma->map, dma->page_count);
                dma->page_count = 0;
                return -ENOMEM;
        }

        /* Map SG List */
        dma->SG_length = pci_map_sg(itv->pdev, dma->SGlist, dma->page_count, PCI_DMA_TODEVICE);

        /* Fill SG Array with new values */
        ivtv_udma_fill_sg_array (dma, ivtv_dest_addr, 0, -1);

        /* Tag SG Array with Interrupt Bit */
        dma->SGarray[dma->SG_length - 1].size |= cpu_to_le32(0x80000000);

        ivtv_udma_sync_for_device(itv);
        return dma->page_count;
}

void ivtv_udma_unmap(struct ivtv *itv)
{
        struct ivtv_user_dma *dma = &itv->udma;

        IVTV_DEBUG_INFO("ivtv_unmap_user_dma\n");

        /* Nothing to free */
        if (dma->page_count == 0)
                return;

        /* Unmap Scatterlist */
        if (dma->SG_length) {
                pci_unmap_sg(itv->pdev, dma->SGlist, dma->page_count, PCI_DMA_TODEVICE);
                dma->SG_length = 0;
        }
        /* sync DMA */
        ivtv_udma_sync_for_cpu(itv);

        unpin_user_pages(dma->map, dma->page_count);
        dma->page_count = 0;
}

void ivtv_udma_free(struct ivtv *itv)
{
        int i;

        /* Unmap SG Array */
        if (itv->udma.SG_handle) {
                pci_unmap_single(itv->pdev, itv->udma.SG_handle,
                         sizeof(itv->udma.SGarray), PCI_DMA_TODEVICE);
        }

        /* Unmap Scatterlist */
        if (itv->udma.SG_length) {
                pci_unmap_sg(itv->pdev, itv->udma.SGlist, itv->udma.page_count, PCI_DMA_TODEVICE);
        }

        for (i = 0; i < IVTV_DMA_SG_OSD_ENT; i++) {
                if (itv->udma.bouncemap[i])
                        __free_page(itv->udma.bouncemap[i]);
        }
}

void ivtv_udma_start(struct ivtv *itv)
{
        IVTV_DEBUG_DMA("start UDMA\n");
        write_reg(itv->udma.SG_handle, IVTV_REG_DECDMAADDR);
        write_reg_sync(read_reg(IVTV_REG_DMAXFER) | 0x01, IVTV_REG_DMAXFER);
        set_bit(IVTV_F_I_DMA, &itv->i_flags);
        set_bit(IVTV_F_I_UDMA, &itv->i_flags);
        clear_bit(IVTV_F_I_UDMA_PENDING, &itv->i_flags);
}

void ivtv_udma_prepare(struct ivtv *itv)
{
        unsigned long flags;

        spin_lock_irqsave(&itv->dma_reg_lock, flags);
        if (!test_bit(IVTV_F_I_DMA, &itv->i_flags))
                ivtv_udma_start(itv);
        else
                set_bit(IVTV_F_I_UDMA_PENDING, &itv->i_flags);
        spin_unlock_irqrestore(&itv->dma_reg_lock, flags);
}