drivers/staging/media/tegra-vde/dmabuf-cache.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * NVIDIA Tegra Video decoder driver
 *
 * Copyright (C) 2016-2019 GRATE-DRIVER project
 */

#include <linux/dma-buf.h>
#include <linux/iova.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/module.h>

#include "vde.h"

MODULE_IMPORT_NS(DMA_BUF);

struct tegra_vde_cache_entry {
	enum dma_data_direction dma_dir;
	struct dma_buf_attachment *a;
	struct delayed_work dwork;
	struct tegra_vde *vde;
	struct list_head list;
	struct sg_table *sgt;
	struct iova *iova;
	unsigned int refcnt;
};

static void tegra_vde_release_entry(struct tegra_vde_cache_entry *entry)
{
	struct dma_buf *dmabuf = entry->a->dmabuf;

	WARN_ON_ONCE(entry->refcnt);

	if (entry->vde->domain)
		tegra_vde_iommu_unmap(entry->vde, entry->iova);

	dma_buf_unmap_attachment(entry->a, entry->sgt, entry->dma_dir);
	dma_buf_detach(dmabuf, entry->a);
	dma_buf_put(dmabuf);

	list_del(&entry->list);
	kfree(entry);
}

static void tegra_vde_delayed_unmap(struct work_struct *work)
{
	struct tegra_vde_cache_entry *entry;
	struct tegra_vde *vde;

	entry = container_of(work, struct tegra_vde_cache_entry,
			     dwork.work);
	vde = entry->vde;

	mutex_lock(&vde->map_lock);
	tegra_vde_release_entry(entry);
	mutex_unlock(&vde->map_lock);
}

int tegra_vde_dmabuf_cache_map(struct tegra_vde *vde,
			       struct dma_buf *dmabuf,
			       enum dma_data_direction dma_dir,
			       struct dma_buf_attachment **ap,
			       dma_addr_t *addrp)
{
	struct device *dev = vde->miscdev.parent;
	struct dma_buf_attachment *attachment;
	struct tegra_vde_cache_entry *entry;
	struct sg_table *sgt;
	struct iova *iova;
	int err;

	mutex_lock(&vde->map_lock);

	list_for_each_entry(entry, &vde->map_list, list) {
		if (entry->a->dmabuf != dmabuf)
			continue;

		if (!cancel_delayed_work(&entry->dwork))
			continue;

		if (entry->dma_dir != dma_dir)
			entry->dma_dir = DMA_BIDIRECTIONAL;

		dma_buf_put(dmabuf);

		if (vde->domain)
			*addrp = iova_dma_addr(&vde->iova, entry->iova);
		else
			*addrp = sg_dma_address(entry->sgt->sgl);

		goto ref;
	}

	attachment = dma_buf_attach(dmabuf, dev);
	if (IS_ERR(attachment)) {
		dev_err(dev, "Failed to attach dmabuf\n");
		err = PTR_ERR(attachment);
		goto err_unlock;
	}

	sgt = dma_buf_map_attachment(attachment, dma_dir);
	if (IS_ERR(sgt)) {
		dev_err(dev, "Failed to get dmabufs sg_table\n");
		err = PTR_ERR(sgt);
		goto err_detach;
	}

	if (!vde->domain && sgt->nents > 1) {
		dev_err(dev, "Sparse DMA region is unsupported, please enable IOMMU\n");
		err = -EINVAL;
		goto err_unmap;
	}

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry) {
		err = -ENOMEM;
		goto err_unmap;
	}

	if (vde->domain) {
		err = tegra_vde_iommu_map(vde, sgt, &iova, dmabuf->size);
		if (err)
			goto err_free;

		*addrp = iova_dma_addr(&vde->iova, iova);
	} else {
		*addrp = sg_dma_address(sgt->sgl);
		iova = NULL;
	}

	INIT_DELAYED_WORK(&entry->dwork, tegra_vde_delayed_unmap);
	list_add(&entry->list, &vde->map_list);

	entry->dma_dir = dma_dir;
	entry->iova = iova;
	entry->vde = vde;
	entry->sgt = sgt;
	entry->a = attachment;
ref:
	entry->refcnt++;

	*ap = entry->a;

	mutex_unlock(&vde->map_lock);

	return 0;

err_free:
	kfree(entry);
err_unmap:
	dma_buf_unmap_attachment(attachment, sgt, dma_dir);
err_detach:
	dma_buf_detach(dmabuf, attachment);
err_unlock:
	mutex_unlock(&vde->map_lock);

	return err;
}

void tegra_vde_dmabuf_cache_unmap(struct tegra_vde *vde,
				  struct dma_buf_attachment *a,
				  bool release)
{
	struct tegra_vde_cache_entry *entry;

	mutex_lock(&vde->map_lock);

	list_for_each_entry(entry, &vde->map_list, list) {
		if (entry->a != a)
			continue;

		WARN_ON_ONCE(!entry->refcnt);

		if (--entry->refcnt == 0) {
			if (release)
				tegra_vde_release_entry(entry);
			else
				schedule_delayed_work(&entry->dwork, 5 * HZ);
		}
		break;
	}

	mutex_unlock(&vde->map_lock);
}

void tegra_vde_dmabuf_cache_unmap_sync(struct tegra_vde *vde)
{
	struct tegra_vde_cache_entry *entry, *tmp;

	mutex_lock(&vde->map_lock);

	list_for_each_entry_safe(entry, tmp, &vde->map_list, list) {
		if (entry->refcnt)
			continue;

		if (!cancel_delayed_work(&entry->dwork))
			continue;

		tegra_vde_release_entry(entry);
	}

	mutex_unlock(&vde->map_lock);
}

void tegra_vde_dmabuf_cache_unmap_all(struct tegra_vde *vde)
{
	struct tegra_vde_cache_entry *entry, *tmp;

	mutex_lock(&vde->map_lock);

	while (!list_empty(&vde->map_list)) {
		list_for_each_entry_safe(entry, tmp, &vde->map_list, list) {
			if (!cancel_delayed_work(&entry->dwork))
				continue;

			tegra_vde_release_entry(entry);
		}

		mutex_unlock(&vde->map_lock);
		schedule();
		mutex_lock(&vde->map_lock);
	}

	mutex_unlock(&vde->map_lock);
}