/*
 * Copyright (c) 2004, 2005, 2006 Voltaire, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * 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
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * 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.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/scatterlist.h>

#include "iscsi_iser.h"

#define ISER_KMALLOC_THRESHOLD 0x20000 /* 128K - kmalloc limit */

/**
 * Decrements the reference count for the
 * registered buffer & releases it
 *
 * returns 0 if released, 1 if deferred
 */
int iser_regd_buff_release(struct iser_regd_buf *regd_buf)
{
        struct ib_device *dev;

        if ((atomic_read(&regd_buf->ref_count) == 0) ||
            atomic_dec_and_test(&regd_buf->ref_count)) {
                /* if we used the dma mr, unreg is just NOP */
                if (regd_buf->reg.is_fmr)
                        iser_unreg_mem(&regd_buf->reg);

                if (regd_buf->dma_addr) {
                        dev = regd_buf->device->ib_device;
                        ib_dma_unmap_single(dev,
                                         regd_buf->dma_addr,
                                         regd_buf->data_size,
                                         regd_buf->direction);
                }
                /* else this regd buf is associated with task which we */
                /* dma_unmap_single/sg later */
                return 0;
        } else {
                iser_dbg("Release deferred, regd.buff: 0x%p\n", regd_buf);
                return 1;
        }
}

/**
 * iser_reg_single - fills registered buffer descriptor with
 *                   registration information
 */
void iser_reg_single(struct iser_device *device,
                     struct iser_regd_buf *regd_buf,
                     enum dma_data_direction direction)
{
        u64 dma_addr;

        dma_addr = ib_dma_map_single(device->ib_device,
                                     regd_buf->virt_addr,
                                     regd_buf->data_size, direction);
        BUG_ON(ib_dma_mapping_error(device->ib_device, dma_addr));

        regd_buf->reg.lkey = device->mr->lkey;
        regd_buf->reg.len  = regd_buf->data_size;
        regd_buf->reg.va   = dma_addr;
        regd_buf->reg.is_fmr = 0;

        regd_buf->dma_addr  = dma_addr;
        regd_buf->direction = direction;
}

/**
 * iser_start_rdma_unaligned_sg
 */
static int iser_start_rdma_unaligned_sg(struct iscsi_iser_task *iser_task,
                                        enum iser_data_dir cmd_dir)
{
        int dma_nents;
        struct ib_device *dev;
        char *mem = NULL;
        struct iser_data_buf *data = &iser_task->data[cmd_dir];
        unsigned long  cmd_data_len = data->data_len;

        if (cmd_data_len > ISER_KMALLOC_THRESHOLD)
                mem = (void *)__get_free_pages(GFP_NOIO,
                      ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
        else
                mem = kmalloc(cmd_data_len, GFP_NOIO);

        if (mem == NULL) {
                iser_err("Failed to allocate mem size %d %d for copying sglist\n",
                         data->size,(int)cmd_data_len);
                return -ENOMEM;
        }

        if (cmd_dir == ISER_DIR_OUT) {
                /* copy the unaligned sg the buffer which is used for RDMA */
                struct scatterlist *sgl = (struct scatterlist *)data->buf;
                struct scatterlist *sg;
                int i;
                char *p, *from;

                p = mem;
                for_each_sg(sgl, sg, data->size, i) {
                        from = kmap_atomic(sg_page(sg), KM_USER0);
                        memcpy(p,
                               from + sg->offset,
                               sg->length);
                        kunmap_atomic(from, KM_USER0);
                        p += sg->length;
                }
        }

        sg_init_one(&iser_task->data_copy[cmd_dir].sg_single, mem, cmd_data_len);
        iser_task->data_copy[cmd_dir].buf  =
                &iser_task->data_copy[cmd_dir].sg_single;
        iser_task->data_copy[cmd_dir].size = 1;

        iser_task->data_copy[cmd_dir].copy_buf  = mem;

        dev = iser_task->iser_conn->ib_conn->device->ib_device;
        dma_nents = ib_dma_map_sg(dev,
                                  &iser_task->data_copy[cmd_dir].sg_single,
                                  1,
                                  (cmd_dir == ISER_DIR_OUT) ?
                                  DMA_TO_DEVICE : DMA_FROM_DEVICE);
        BUG_ON(dma_nents == 0);

        iser_task->data_copy[cmd_dir].dma_nents = dma_nents;
        return 0;
}

/**
 * iser_finalize_rdma_unaligned_sg
 */
void iser_finalize_rdma_unaligned_sg(struct iscsi_iser_task *iser_task,
                                     enum iser_data_dir         cmd_dir)
{
        struct ib_device *dev;
        struct iser_data_buf *mem_copy;
        unsigned long  cmd_data_len;

        dev = iser_task->iser_conn->ib_conn->device->ib_device;
        mem_copy = &iser_task->data_copy[cmd_dir];

        ib_dma_unmap_sg(dev, &mem_copy->sg_single, 1,
                        (cmd_dir == ISER_DIR_OUT) ?
                        DMA_TO_DEVICE : DMA_FROM_DEVICE);

        if (cmd_dir == ISER_DIR_IN) {
                char *mem;
                struct scatterlist *sgl, *sg;
                unsigned char *p, *to;
                unsigned int sg_size;
                int i;

                /* copy back read RDMA to unaligned sg */
                mem     = mem_copy->copy_buf;

                sgl     = (struct scatterlist *)iser_task->data[ISER_DIR_IN].buf;
                sg_size = iser_task->data[ISER_DIR_IN].size;

                p = mem;
                for_each_sg(sgl, sg, sg_size, i) {
                        to = kmap_atomic(sg_page(sg), KM_SOFTIRQ0);
                        memcpy(to + sg->offset,
                               p,
                               sg->length);
                        kunmap_atomic(to, KM_SOFTIRQ0);
                        p += sg->length;
                }
        }

        cmd_data_len = iser_task->data[cmd_dir].data_len;

        if (cmd_data_len > ISER_KMALLOC_THRESHOLD)
                free_pages((unsigned long)mem_copy->copy_buf,
                           ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
        else
                kfree(mem_copy->copy_buf);

        mem_copy->copy_buf = NULL;
}

/**
 * iser_sg_to_page_vec - Translates scatterlist entries to physical addresses
 * and returns the length of resulting physical address array (may be less than
 * the original due to possible compaction).
 *
 * we build a "page vec" under the assumption that the SG meets the RDMA
 * alignment requirements. Other then the first and last SG elements, all
 * the "internal" elements can be compacted into a list whose elements are
 * dma addresses of physical pages. The code supports also the weird case
 * where --few fragments of the same page-- are present in the SG as
 * consecutive elements. Also, it handles one entry SG.
 */
static int iser_sg_to_page_vec(struct iser_data_buf *data,
                               struct iser_page_vec *page_vec,
                               struct ib_device *ibdev)
{
        struct scatterlist *sgl = (struct scatterlist *)data->buf;
        struct scatterlist *sg;
        u64 first_addr, last_addr, page;
        int end_aligned;
        unsigned int cur_page = 0;
        unsigned long total_sz = 0;
        int i;

        /* compute the offset of first element */
        page_vec->offset = (u64) sgl[0].offset & ~MASK_4K;

        for_each_sg(sgl, sg, data->dma_nents, i) {
                unsigned int dma_len = ib_sg_dma_len(ibdev, sg);

                total_sz += dma_len;

                first_addr = ib_sg_dma_address(ibdev, sg);
                last_addr  = first_addr + dma_len;

                end_aligned   = !(last_addr  & ~MASK_4K);

                /* continue to collect page fragments till aligned or SG ends */
                while (!end_aligned && (i + 1 < data->dma_nents)) {
                        sg = sg_next(sg);
                        i++;
                        dma_len = ib_sg_dma_len(ibdev, sg);
                        total_sz += dma_len;
                        last_addr = ib_sg_dma_address(ibdev, sg) + dma_len;
                        end_aligned = !(last_addr  & ~MASK_4K);
                }

                /* handle the 1st page in the 1st DMA element */
                if (cur_page == 0) {
                        page = first_addr & MASK_4K;
                        page_vec->pages[cur_page] = page;
                        cur_page++;
                        page += SIZE_4K;
                } else
                        page = first_addr;

                for (; page < last_addr; page += SIZE_4K) {
                        page_vec->pages[cur_page] = page;
                        cur_page++;
                }

        }
        page_vec->data_size = total_sz;
        iser_dbg("page_vec->data_size:%d cur_page %d\n", page_vec->data_size,cur_page);
        return cur_page;
}

#define IS_4K_ALIGNED(addr)     ((((unsigned long)addr) & ~MASK_4K) == 0)

/**
 * iser_data_buf_aligned_len - Tries to determine the maximal correctly aligned
 * for RDMA sub-list of a scatter-gather list of memory buffers, and  returns
 * the number of entries which are aligned correctly. Supports the case where
 * consecutive SG elements are actually fragments of the same physcial page.
 */
static unsigned int iser_data_buf_aligned_len(struct iser_data_buf *data,
                                              struct ib_device *ibdev)
{
        struct scatterlist *sgl, *sg;
        u64 end_addr, next_addr;
        int i, cnt;
        unsigned int ret_len = 0;

        sgl = (struct scatterlist *)data->buf;

        cnt = 0;
        for_each_sg(sgl, sg, data->dma_nents, i) {
                /* iser_dbg("Checking sg iobuf [%d]: phys=0x%08lX "
                   "offset: %ld sz: %ld\n", i,
                   (unsigned long)sg_phys(sg),
                   (unsigned long)sg->offset,
                   (unsigned long)sg->length); */
                end_addr = ib_sg_dma_address(ibdev, sg) +
                           ib_sg_dma_len(ibdev, sg);
                /* iser_dbg("Checking sg iobuf end address "
                       "0x%08lX\n", end_addr); */
                if (i + 1 < data->dma_nents) {
                        next_addr = ib_sg_dma_address(ibdev, sg_next(sg));
                        /* are i, i+1 fragments of the same page? */
                        if (end_addr == next_addr) {
                                cnt++;
                                continue;
                        } else if (!IS_4K_ALIGNED(end_addr)) {
                                ret_len = cnt + 1;
                                break;
                        }
                }
                cnt++;
        }
        if (i == data->dma_nents)
                ret_len = cnt;  /* loop ended */
        iser_dbg("Found %d aligned entries out of %d in sg:0x%p\n",
                 ret_len, data->dma_nents, data);
        return ret_len;
}

static void iser_data_buf_dump(struct iser_data_buf *data,
                               struct ib_device *ibdev)
{
        struct scatterlist *sgl = (struct scatterlist *)data->buf;
        struct scatterlist *sg;
        int i;

        if (iser_debug_level == 0)
                return;

        for_each_sg(sgl, sg, data->dma_nents, i)
                iser_warn("sg[%d] dma_addr:0x%lX page:0x%p "
                         "off:0x%x sz:0x%x dma_len:0x%x\n",
                         i, (unsigned long)ib_sg_dma_address(ibdev, sg),
                         sg_page(sg), sg->offset,
                         sg->length, ib_sg_dma_len(ibdev, sg));
}

static void iser_dump_page_vec(struct iser_page_vec *page_vec)
{
        int i;

        iser_err("page vec length %d data size %d\n",
                 page_vec->length, page_vec->data_size);
        for (i = 0; i < page_vec->length; i++)
                iser_err("%d %lx\n",i,(unsigned long)page_vec->pages[i]);
}

static void iser_page_vec_build(struct iser_data_buf *data,
                                struct iser_page_vec *page_vec,
                                struct ib_device *ibdev)
{
        int page_vec_len = 0;

        page_vec->length = 0;
        page_vec->offset = 0;

        iser_dbg("Translating sg sz: %d\n", data->dma_nents);
        page_vec_len = iser_sg_to_page_vec(data, page_vec, ibdev);
        iser_dbg("sg len %d page_vec_len %d\n", data->dma_nents,page_vec_len);

        page_vec->length = page_vec_len;

        if (page_vec_len * SIZE_4K < page_vec->data_size) {
                iser_err("page_vec too short to hold this SG\n");
                iser_data_buf_dump(data, ibdev);
                iser_dump_page_vec(page_vec);
                BUG();
        }
}

int iser_dma_map_task_data(struct iscsi_iser_task *iser_task,
                            struct iser_data_buf *data,
                            enum iser_data_dir iser_dir,
                            enum dma_data_direction dma_dir)
{
        struct ib_device *dev;

        iser_task->dir[iser_dir] = 1;
        dev = iser_task->iser_conn->ib_conn->device->ib_device;

        data->dma_nents = ib_dma_map_sg(dev, data->buf, data->size, dma_dir);
        if (data->dma_nents == 0) {
                iser_err("dma_map_sg failed!!!\n");
                return -EINVAL;
        }
        return 0;
}

void iser_dma_unmap_task_data(struct iscsi_iser_task *iser_task)
{
        struct ib_device *dev;
        struct iser_data_buf *data;

        dev = iser_task->iser_conn->ib_conn->device->ib_device;

        if (iser_task->dir[ISER_DIR_IN]) {
                data = &iser_task->data[ISER_DIR_IN];
                ib_dma_unmap_sg(dev, data->buf, data->size, DMA_FROM_DEVICE);
        }

        if (iser_task->dir[ISER_DIR_OUT]) {
                data = &iser_task->data[ISER_DIR_OUT];
                ib_dma_unmap_sg(dev, data->buf, data->size, DMA_TO_DEVICE);
        }
}

/**
 * iser_reg_rdma_mem - Registers memory intended for RDMA,
 * obtaining rkey and va
 *
 * returns 0 on success, errno code on failure
 */
int iser_reg_rdma_mem(struct iscsi_iser_task *iser_task,
                      enum   iser_data_dir        cmd_dir)
{
        struct iscsi_conn    *iscsi_conn = iser_task->iser_conn->iscsi_conn;
        struct iser_conn     *ib_conn = iser_task->iser_conn->ib_conn;
        struct iser_device   *device = ib_conn->device;
        struct ib_device     *ibdev = device->ib_device;
        struct iser_data_buf *mem = &iser_task->data[cmd_dir];
        struct iser_regd_buf *regd_buf;
        int aligned_len;
        int err;
        int i;
        struct scatterlist *sg;

        regd_buf = &iser_task->rdma_regd[cmd_dir];

        aligned_len = iser_data_buf_aligned_len(mem, ibdev);
        if (aligned_len != mem->dma_nents) {
                iscsi_conn->fmr_unalign_cnt++;
                iser_warn("rdma alignment violation %d/%d aligned\n",
                         aligned_len, mem->size);
                iser_data_buf_dump(mem, ibdev);

                /* unmap the command data before accessing it */
                iser_dma_unmap_task_data(iser_task);

                /* allocate copy buf, if we are writing, copy the */
                /* unaligned scatterlist, dma map the copy        */
                if (iser_start_rdma_unaligned_sg(iser_task, cmd_dir) != 0)
                                return -ENOMEM;
                mem = &iser_task->data_copy[cmd_dir];
        }

        /* if there a single dma entry, FMR is not needed */
        if (mem->dma_nents == 1) {
                sg = (struct scatterlist *)mem->buf;

                regd_buf->reg.lkey = device->mr->lkey;
                regd_buf->reg.rkey = device->mr->rkey;
                regd_buf->reg.len  = ib_sg_dma_len(ibdev, &sg[0]);
                regd_buf->reg.va   = ib_sg_dma_address(ibdev, &sg[0]);
                regd_buf->reg.is_fmr = 0;

                iser_dbg("PHYSICAL Mem.register: lkey: 0x%08X rkey: 0x%08X  "
                         "va: 0x%08lX sz: %ld]\n",
                         (unsigned int)regd_buf->reg.lkey,
                         (unsigned int)regd_buf->reg.rkey,
                         (unsigned long)regd_buf->reg.va,
                         (unsigned long)regd_buf->reg.len);
        } else { /* use FMR for multiple dma entries */
                iser_page_vec_build(mem, ib_conn->page_vec, ibdev);
                err = iser_reg_page_vec(ib_conn, ib_conn->page_vec, &regd_buf->reg);
                if (err) {
                        iser_data_buf_dump(mem, ibdev);
                        iser_err("mem->dma_nents = %d (dlength = 0x%x)\n",
                                 mem->dma_nents,
                                 ntoh24(iser_task->desc.iscsi_header.dlength));
                        iser_err("page_vec: data_size = 0x%x, length = %d, offset = 0x%x\n",
                                 ib_conn->page_vec->data_size, ib_conn->page_vec->length,
                                 ib_conn->page_vec->offset);
                        for (i=0 ; i<ib_conn->page_vec->length ; i++)
                                iser_err("page_vec[%d] = 0x%llx\n", i,
                                         (unsigned long long) ib_conn->page_vec->pages[i]);
                        return err;
                }
        }

        /* take a reference on this regd buf such that it will not be released *
         * (eg in send dto completion) before we get the scsi response         */
        atomic_inc(&regd_buf->ref_count);
        return 0;
}