// SPDX-License-Identifier: GPL-2.0-or-later
/*******************************************************************************
 * SCSI RDMA Protocol lib functions
 *
 * Copyright (C) 2006 FUJITA Tomonori <tomof@acm.org>
 * Copyright (C) 2016 Bryant G. Ly <bryantly@linux.vnet.ibm.com> IBM Corp.
 *
 ***********************************************************************/

#define pr_fmt(fmt)     "libsrp: " fmt

#include <linux/printk.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/kfifo.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/module.h>
#include <scsi/srp.h>
#include <target/target_core_base.h>
#include "libsrp.h"
#include "ibmvscsi_tgt.h"

static int srp_iu_pool_alloc(struct srp_queue *q, size_t max,
                             struct srp_buf **ring)
{
        struct iu_entry *iue;
        int i;

        q->pool = kzalloc_objs(struct iu_entry *, max);
        if (!q->pool)
                return -ENOMEM;
        q->items = kzalloc_objs(struct iu_entry, max);
        if (!q->items)
                goto free_pool;

        spin_lock_init(&q->lock);
        kfifo_init(&q->queue, (void *)q->pool, max * sizeof(void *));

        for (i = 0, iue = q->items; i < max; i++) {
                kfifo_in(&q->queue, (void *)&iue, sizeof(void *));
                iue->sbuf = ring[i];
                iue++;
        }
        return 0;

free_pool:
        kfree(q->pool);
        return -ENOMEM;
}

static void srp_iu_pool_free(struct srp_queue *q)
{
        kfree(q->items);
        kfree(q->pool);
}

static struct srp_buf **srp_ring_alloc(struct device *dev,
                                       size_t max, size_t size)
{
        struct srp_buf **ring;
        int i;

        ring = kzalloc_objs(struct srp_buf *, max);
        if (!ring)
                return NULL;

        for (i = 0; i < max; i++) {
                ring[i] = kzalloc_obj(*ring[i]);
                if (!ring[i])
                        goto out;
                ring[i]->buf = dma_alloc_coherent(dev, size, &ring[i]->dma,
                                                  GFP_KERNEL);
                if (!ring[i]->buf)
                        goto out;
        }
        return ring;

out:
        for (i = 0; i < max && ring[i]; i++) {
                if (ring[i]->buf) {
                        dma_free_coherent(dev, size, ring[i]->buf,
                                          ring[i]->dma);
                }
                kfree(ring[i]);
        }
        kfree(ring);

        return NULL;
}

static void srp_ring_free(struct device *dev, struct srp_buf **ring,
                          size_t max, size_t size)
{
        int i;

        for (i = 0; i < max; i++) {
                dma_free_coherent(dev, size, ring[i]->buf, ring[i]->dma);
                kfree(ring[i]);
        }
        kfree(ring);
}

int srp_target_alloc(struct srp_target *target, struct device *dev,
                     size_t nr, size_t iu_size)
{
        int err;

        spin_lock_init(&target->lock);

        target->dev = dev;

        target->srp_iu_size = iu_size;
        target->rx_ring_size = nr;
        target->rx_ring = srp_ring_alloc(target->dev, nr, iu_size);
        if (!target->rx_ring)
                return -ENOMEM;
        err = srp_iu_pool_alloc(&target->iu_queue, nr, target->rx_ring);
        if (err)
                goto free_ring;

        dev_set_drvdata(target->dev, target);
        return 0;

free_ring:
        srp_ring_free(target->dev, target->rx_ring, nr, iu_size);
        return -ENOMEM;
}

void srp_target_free(struct srp_target *target)
{
        dev_set_drvdata(target->dev, NULL);
        srp_ring_free(target->dev, target->rx_ring, target->rx_ring_size,
                      target->srp_iu_size);
        srp_iu_pool_free(&target->iu_queue);
}

struct iu_entry *srp_iu_get(struct srp_target *target)
{
        struct iu_entry *iue = NULL;

        if (kfifo_out_locked(&target->iu_queue.queue, (void *)&iue,
                             sizeof(void *),
                             &target->iu_queue.lock) != sizeof(void *)) {
                WARN_ONCE(1, "unexpected fifo state");
                return NULL;
        }
        if (!iue)
                return iue;
        iue->target = target;
        iue->flags = 0;
        return iue;
}

void srp_iu_put(struct iu_entry *iue)
{
        kfifo_in_locked(&iue->target->iu_queue.queue, (void *)&iue,
                        sizeof(void *), &iue->target->iu_queue.lock);
}

static int srp_direct_data(struct ibmvscsis_cmd *cmd, struct srp_direct_buf *md,
                           enum dma_data_direction dir, srp_rdma_t rdma_io,
                           int dma_map, int ext_desc)
{
        struct iu_entry *iue = NULL;
        struct scatterlist *sg = NULL;
        int err, nsg = 0, len;

        if (dma_map) {
                iue = cmd->iue;
                sg = cmd->se_cmd.t_data_sg;
                nsg = dma_map_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
                                 DMA_BIDIRECTIONAL);
                if (!nsg) {
                        pr_err("fail to map %p %d\n", iue,
                               cmd->se_cmd.t_data_nents);
                        return 0;
                }
                len = min(cmd->se_cmd.data_length, be32_to_cpu(md->len));
        } else {
                len = be32_to_cpu(md->len);
        }

        err = rdma_io(cmd, sg, nsg, md, 1, dir, len);

        if (dma_map)
                dma_unmap_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
                             DMA_BIDIRECTIONAL);

        return err;
}

static int srp_indirect_data(struct ibmvscsis_cmd *cmd, struct srp_cmd *srp_cmd,
                             struct srp_indirect_buf *id,
                             enum dma_data_direction dir, srp_rdma_t rdma_io,
                             int dma_map, int ext_desc)
{
        struct iu_entry *iue = NULL;
        struct srp_direct_buf *md = NULL;
        struct scatterlist dummy, *sg = NULL;
        dma_addr_t token = 0;
        int err = 0;
        int nmd, nsg = 0, len;

        if (dma_map || ext_desc) {
                iue = cmd->iue;
                sg = cmd->se_cmd.t_data_sg;
        }

        nmd = be32_to_cpu(id->table_desc.len) / sizeof(struct srp_direct_buf);

        if ((dir == DMA_FROM_DEVICE && nmd == srp_cmd->data_in_desc_cnt) ||
            (dir == DMA_TO_DEVICE && nmd == srp_cmd->data_out_desc_cnt)) {
                md = &id->desc_list[0];
                goto rdma;
        }

        if (ext_desc && dma_map) {
                md = dma_alloc_coherent(iue->target->dev,
                                        be32_to_cpu(id->table_desc.len),
                                        &token, GFP_KERNEL);
                if (!md) {
                        pr_err("Can't get dma memory %u\n",
                               be32_to_cpu(id->table_desc.len));
                        return -ENOMEM;
                }

                sg_init_one(&dummy, md, be32_to_cpu(id->table_desc.len));
                sg_dma_address(&dummy) = token;
                sg_dma_len(&dummy) = be32_to_cpu(id->table_desc.len);
                err = rdma_io(cmd, &dummy, 1, &id->table_desc, 1, DMA_TO_DEVICE,
                              be32_to_cpu(id->table_desc.len));
                if (err) {
                        pr_err("Error copying indirect table %d\n", err);
                        goto free_mem;
                }
        } else {
                pr_err("This command uses external indirect buffer\n");
                return -EINVAL;
        }

rdma:
        if (dma_map) {
                nsg = dma_map_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
                                 DMA_BIDIRECTIONAL);
                if (!nsg) {
                        pr_err("fail to map %p %d\n", iue,
                               cmd->se_cmd.t_data_nents);
                        err = -EIO;
                        goto free_mem;
                }
                len = min(cmd->se_cmd.data_length, be32_to_cpu(id->len));
        } else {
                len = be32_to_cpu(id->len);
        }

        err = rdma_io(cmd, sg, nsg, md, nmd, dir, len);

        if (dma_map)
                dma_unmap_sg(iue->target->dev, sg, cmd->se_cmd.t_data_nents,
                             DMA_BIDIRECTIONAL);

free_mem:
        if (token && dma_map) {
                dma_free_coherent(iue->target->dev,
                                  be32_to_cpu(id->table_desc.len), md, token);
        }
        return err;
}

static int data_out_desc_size(struct srp_cmd *cmd)
{
        int size = 0;
        u8 fmt = cmd->buf_fmt >> 4;

        switch (fmt) {
        case SRP_NO_DATA_DESC:
                break;
        case SRP_DATA_DESC_DIRECT:
                size = sizeof(struct srp_direct_buf);
                break;
        case SRP_DATA_DESC_INDIRECT:
                size = sizeof(struct srp_indirect_buf) +
                        sizeof(struct srp_direct_buf) * cmd->data_out_desc_cnt;
                break;
        default:
                pr_err("client error. Invalid data_out_format %x\n", fmt);
                break;
        }
        return size;
}

/*
 * TODO: this can be called multiple times for a single command if it
 * has very long data.
 */
int srp_transfer_data(struct ibmvscsis_cmd *cmd, struct srp_cmd *srp_cmd,
                      srp_rdma_t rdma_io, int dma_map, int ext_desc)
{
        struct srp_direct_buf *md;
        struct srp_indirect_buf *id;
        enum dma_data_direction dir;
        int offset, err = 0;
        u8 format;

        if (!cmd->se_cmd.t_data_nents)
                return 0;

        offset = srp_cmd->add_cdb_len & ~3;

        dir = srp_cmd_direction(srp_cmd);
        if (dir == DMA_FROM_DEVICE)
                offset += data_out_desc_size(srp_cmd);

        if (dir == DMA_TO_DEVICE)
                format = srp_cmd->buf_fmt >> 4;
        else
                format = srp_cmd->buf_fmt & ((1U << 4) - 1);

        switch (format) {
        case SRP_NO_DATA_DESC:
                break;
        case SRP_DATA_DESC_DIRECT:
                md = (struct srp_direct_buf *)(srp_cmd->add_data + offset);
                err = srp_direct_data(cmd, md, dir, rdma_io, dma_map, ext_desc);
                break;
        case SRP_DATA_DESC_INDIRECT:
                id = (struct srp_indirect_buf *)(srp_cmd->add_data + offset);
                err = srp_indirect_data(cmd, srp_cmd, id, dir, rdma_io, dma_map,
                                        ext_desc);
                break;
        default:
                pr_err("Unknown format %d %x\n", dir, format);
                err = -EINVAL;
        }

        return err;
}

u64 srp_data_length(struct srp_cmd *cmd, enum dma_data_direction dir)
{
        struct srp_direct_buf *md;
        struct srp_indirect_buf *id;
        u64 len = 0;
        uint offset = cmd->add_cdb_len & ~3;
        u8 fmt;

        if (dir == DMA_TO_DEVICE) {
                fmt = cmd->buf_fmt >> 4;
        } else {
                fmt = cmd->buf_fmt & ((1U << 4) - 1);
                offset += data_out_desc_size(cmd);
        }

        switch (fmt) {
        case SRP_NO_DATA_DESC:
                break;
        case SRP_DATA_DESC_DIRECT:
                md = (struct srp_direct_buf *)(cmd->add_data + offset);
                len = be32_to_cpu(md->len);
                break;
        case SRP_DATA_DESC_INDIRECT:
                id = (struct srp_indirect_buf *)(cmd->add_data + offset);
                len = be32_to_cpu(id->len);
                break;
        default:
                pr_err("invalid data format %x\n", fmt);
                break;
        }
        return len;
}

int srp_get_desc_table(struct srp_cmd *srp_cmd, enum dma_data_direction *dir,
                       u64 *data_len)
{
        struct srp_indirect_buf *idb;
        struct srp_direct_buf *db;
        uint add_cdb_offset;
        int rc;

        /*
         * The pointer computations below will only be compiled correctly
         * if srp_cmd::add_data is declared as s8*, u8*, s8[] or u8[], so check
         * whether srp_cmd::add_data has been declared as a byte pointer.
         */
        BUILD_BUG_ON(!__same_type(srp_cmd->add_data[0], (s8)0)
                     && !__same_type(srp_cmd->add_data[0], (u8)0));

        BUG_ON(!dir);
        BUG_ON(!data_len);

        rc = 0;
        *data_len = 0;

        *dir = DMA_NONE;

        if (srp_cmd->buf_fmt & 0xf)
                *dir = DMA_FROM_DEVICE;
        else if (srp_cmd->buf_fmt >> 4)
                *dir = DMA_TO_DEVICE;

        add_cdb_offset = srp_cmd->add_cdb_len & ~3;
        if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_DIRECT) ||
            ((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_DIRECT)) {
                db = (struct srp_direct_buf *)(srp_cmd->add_data
                                               + add_cdb_offset);
                *data_len = be32_to_cpu(db->len);
        } else if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_INDIRECT) ||
                   ((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_INDIRECT)) {
                idb = (struct srp_indirect_buf *)(srp_cmd->add_data
                                                  + add_cdb_offset);

                *data_len = be32_to_cpu(idb->len);
        }
        return rc;
}

MODULE_DESCRIPTION("SCSI RDMA Protocol lib functions");
MODULE_AUTHOR("FUJITA Tomonori");
MODULE_LICENSE("GPL");