/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Device memory TCP support
 *
 * Authors:     Mina Almasry <almasrymina@google.com>
 *              Willem de Bruijn <willemb@google.com>
 *              Kaiyuan Zhang <kaiyuanz@google.com>
 *
 */
#ifndef _NET_DEVMEM_H
#define _NET_DEVMEM_H

#include <net/netmem.h>
#include <net/netdev_netlink.h>

struct netlink_ext_ack;

struct net_devmem_dmabuf_binding {
        struct dma_buf *dmabuf;
        struct dma_buf_attachment *attachment;
        struct sg_table *sgt;
        /* Physical NIC that does the actual DMA for this binding. */
        struct net_device *dev;
        /* Opaque cookie identifying the virtual device (e.g. netkit) the user
         * called bind-tx on. Used only for pointer comparison. Never
         * dereferenced.
         */
        void *vdev;
        struct gen_pool *chunk_pool;
        /* Protect dev */
        struct mutex lock;

        /* The user holds a ref (via the netlink API) for as long as they want
         * the binding to remain alive. Each page pool using this binding holds
         * a ref to keep the binding alive. The page_pool does not release the
         * ref until all the net_iovs allocated from this binding are released
         * back to the page_pool.
         *
         * The binding undos itself and unmaps the underlying dmabuf once all
         * those refs are dropped and the binding is no longer desired or in
         * use.
         *
         * net_devmem_get_net_iov() on dmabuf net_iovs will increment this
         * reference, making sure that the binding remains alive until all the
         * net_iovs are no longer used. net_iovs allocated from this binding
         * that are stuck in the TX path for any reason (such as awaiting
         * retransmits) hold a reference to the binding until the skb holding
         * them is freed.
         */
        struct percpu_ref ref;

        /* The list of bindings currently active. Used for netlink to notify us
         * of the user dropping the bind.
         */
        struct list_head list;

        /* rxq's this binding is active on. */
        struct xarray bound_rxqs;

        /* ID of this binding. Globally unique to all bindings currently
         * active.
         */
        u32 id;

        /* DMA direction, FROM_DEVICE for Rx binding, TO_DEVICE for Tx. */
        enum dma_data_direction direction;

        /* Array of net_iov pointers for this binding, sorted by virtual
         * address. This array is convenient to map the virtual addresses to
         * net_iovs in the TX path.
         */
        struct net_iov **tx_vec;

        struct work_struct unbind_w;
};

#if defined(CONFIG_NET_DEVMEM)
/* Owner of the dma-buf chunks inserted into the gen pool. Each scatterlist
 * entry from the dmabuf is inserted into the genpool as a chunk, and needs
 * this owner struct to keep track of some metadata necessary to create
 * allocations from this chunk.
 */
struct dmabuf_genpool_chunk_owner {
        struct net_iov_area area;
        struct net_devmem_dmabuf_binding *binding;

        /* dma_addr of the start of the chunk.  */
        dma_addr_t base_dma_addr;
};

void __net_devmem_dmabuf_binding_free(struct work_struct *wq);
struct net_devmem_dmabuf_binding *
net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
                       struct device *dma_dev,
                       enum dma_data_direction direction,
                       unsigned int dmabuf_fd, struct netdev_nl_sock *priv,
                       struct netlink_ext_ack *extack);
struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id);
void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
                                    struct net_devmem_dmabuf_binding *binding,
                                    struct netlink_ext_ack *extack);

static inline struct dmabuf_genpool_chunk_owner *
net_devmem_iov_to_chunk_owner(const struct net_iov *niov)
{
        struct net_iov_area *owner = net_iov_owner(niov);

        return container_of(owner, struct dmabuf_genpool_chunk_owner, area);
}

static inline struct net_devmem_dmabuf_binding *
net_devmem_iov_binding(const struct net_iov *niov)
{
        return net_devmem_iov_to_chunk_owner(niov)->binding;
}

static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
{
        return net_devmem_iov_binding(niov)->id;
}

static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
{
        struct net_iov_area *owner = net_iov_owner(niov);

        return owner->base_virtual +
               ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
}

static inline bool
net_devmem_dmabuf_binding_get(struct net_devmem_dmabuf_binding *binding)
{
        return percpu_ref_tryget(&binding->ref);
}

static inline void
net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
{
        percpu_ref_put(&binding->ref);
}

void net_devmem_get_net_iov(struct net_iov *niov);
void net_devmem_put_net_iov(struct net_iov *niov);

struct net_iov *
net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
void net_devmem_free_dmabuf(struct net_iov *ppiov);


struct net_devmem_dmabuf_binding *
net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id);
struct net_iov *
net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
                       size_t *off, size_t *size);

#else
struct net_devmem_dmabuf_binding;

static inline void
net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
{
}

static inline void net_devmem_get_net_iov(struct net_iov *niov)
{
}

static inline void net_devmem_put_net_iov(struct net_iov *niov)
{
}

static inline struct net_devmem_dmabuf_binding *
net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
                       struct device *dma_dev,
                       enum dma_data_direction direction,
                       unsigned int dmabuf_fd,
                       struct netdev_nl_sock *priv,
                       struct netlink_ext_ack *extack)
{
        return ERR_PTR(-EOPNOTSUPP);
}

static inline struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id)
{
        return NULL;
}

static inline void
net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
{
}

static inline int
net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
                                struct net_devmem_dmabuf_binding *binding,
                                struct netlink_ext_ack *extack)

{
        return -EOPNOTSUPP;
}

static inline struct net_iov *
net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
{
        return NULL;
}

static inline void net_devmem_free_dmabuf(struct net_iov *ppiov)
{
}

static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
{
        return 0;
}

static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
{
        return 0;
}

static inline struct net_devmem_dmabuf_binding *
net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id)
{
        return ERR_PTR(-EOPNOTSUPP);
}

static inline struct net_iov *
net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
                       size_t *off, size_t *size)
{
        return NULL;
}

static inline struct net_devmem_dmabuf_binding *
net_devmem_iov_binding(const struct net_iov *niov)
{
        return NULL;
}
#endif

#endif /* _NET_DEVMEM_H */