/*
 * 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.
 *
 * $Id: iser_memory.c 6964 2006-05-07 11:11:43Z ogerlitz $
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <asm/io.h>
#include <asm/scatterlist.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 device *dma_device;

	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.rkey != 0)
			iser_unreg_mem(&regd_buf->reg);

		if (regd_buf->dma_addr) {
			dma_device = regd_buf->device->ib_device->dma_device;
			dma_unmap_single(dma_device,
					 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)
{
	dma_addr_t dma_addr;

	dma_addr  = dma_map_single(device->ib_device->dma_device,
				   regd_buf->virt_addr,
				   regd_buf->data_size, direction);
	BUG_ON(dma_mapping_error(dma_addr));

	regd_buf->reg.lkey = device->mr->lkey;
	regd_buf->reg.rkey = 0; /* indicate there's no need to unreg */
	regd_buf->reg.len  = regd_buf->data_size;
	regd_buf->reg.va   = dma_addr;

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

/**
 * iser_start_rdma_unaligned_sg
 */
int iser_start_rdma_unaligned_sg(struct iscsi_iser_cmd_task  *iser_ctask,
				 enum iser_data_dir cmd_dir)
{
	int dma_nents;
	struct device *dma_device;
	char *mem = NULL;
	struct iser_data_buf *data = &iser_ctask->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,
		      long_log2(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 *sg = (struct scatterlist *)data->buf;
		int i;
		char *p, *from;

		for (p = mem, i = 0; i < data->size; i++) {
			from = kmap_atomic(sg[i].page, KM_USER0);
			memcpy(p,
			       from + sg[i].offset,
			       sg[i].length);
			kunmap_atomic(from, KM_USER0);
			p += sg[i].length;
		}
	}

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

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

	dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;

	if (cmd_dir == ISER_DIR_OUT)
		dma_nents = dma_map_sg(dma_device,
				       &iser_ctask->data_copy[cmd_dir].sg_single,
				       1, DMA_TO_DEVICE);
	else
		dma_nents = dma_map_sg(dma_device,
				       &iser_ctask->data_copy[cmd_dir].sg_single,
				       1, DMA_FROM_DEVICE);

	BUG_ON(dma_nents == 0);

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

/**
 * iser_finalize_rdma_unaligned_sg
 */
void iser_finalize_rdma_unaligned_sg(struct iscsi_iser_cmd_task *iser_ctask,
				     enum iser_data_dir         cmd_dir)
{
	struct device *dma_device;
	struct iser_data_buf *mem_copy;
	unsigned long  cmd_data_len;

	dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
	mem_copy   = &iser_ctask->data_copy[cmd_dir];

	if (cmd_dir == ISER_DIR_OUT)
		dma_unmap_sg(dma_device, &mem_copy->sg_single, 1,
			     DMA_TO_DEVICE);
	else
		dma_unmap_sg(dma_device, &mem_copy->sg_single, 1,
			     DMA_FROM_DEVICE);

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

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

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

		for (p = mem, i = 0; i < sg_size; i++){
			to = kmap_atomic(sg[i].page, KM_SOFTIRQ0);
			memcpy(to + sg[i].offset,
			       p,
			       sg[i].length);
			kunmap_atomic(to, KM_SOFTIRQ0);
			p += sg[i].length;
		}
	}

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

	if (cmd_data_len > ISER_KMALLOC_THRESHOLD)
		free_pages((unsigned long)mem_copy->copy_buf,
			   long_log2(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 scatterlist *sg = (struct scatterlist *)data->buf;
	dma_addr_t first_addr, last_addr, page;
	int start_aligned, end_aligned;
	unsigned int cur_page = 0;
	unsigned long total_sz = 0;
	int i;

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

	for (i = 0; i < data->dma_nents; i++) {
		total_sz += sg_dma_len(&sg[i]);

		first_addr = sg_dma_address(&sg[i]);
		last_addr  = first_addr + sg_dma_len(&sg[i]);

		start_aligned = !(first_addr & ~PAGE_MASK);
		end_aligned   = !(last_addr  & ~PAGE_MASK);

		/* continue to collect page fragments till aligned or SG ends */
		while (!end_aligned && (i + 1 < data->dma_nents)) {
			i++;
			total_sz += sg_dma_len(&sg[i]);
			last_addr = sg_dma_address(&sg[i]) + sg_dma_len(&sg[i]);
			end_aligned = !(last_addr  & ~PAGE_MASK);
		}

		first_addr = first_addr & PAGE_MASK;

		for (page = first_addr; page < last_addr; page += PAGE_SIZE)
			page_vec->pages[cur_page++] = 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 MASK_4K			((1UL << 12) - 1) /* 0xFFF */
#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 scatterlist *sg;
	dma_addr_t end_addr, next_addr;
	int i, cnt;
	unsigned int ret_len = 0;

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

	for (cnt = 0, i = 0; i < data->dma_nents; i++, cnt++) {
		/* iser_dbg("Checking sg iobuf [%d]: phys=0x%08lX "
		   "offset: %ld sz: %ld\n", i,
		   (unsigned long)page_to_phys(sg[i].page),
		   (unsigned long)sg[i].offset,
		   (unsigned long)sg[i].length); */
		end_addr = sg_dma_address(&sg[i]) +
			   sg_dma_len(&sg[i]);
		/* iser_dbg("Checking sg iobuf end address "
		       "0x%08lX\n", end_addr); */
		if (i + 1 < data->dma_nents) {
			next_addr = sg_dma_address(&sg[i+1]);
			/* are i, i+1 fragments of the same page? */
			if (end_addr == next_addr)
				continue;
			else if (!IS_4K_ALIGNED(end_addr)) {
				ret_len = cnt + 1;
				break;
			}
		}
	}
	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 scatterlist *sg = (struct scatterlist *)data->buf;
	int i;

	for (i = 0; i < data->size; i++)
		iser_err("sg[%d] dma_addr:0x%lX page:0x%p "
			 "off:%d sz:%d dma_len:%d\n",
			 i, (unsigned long)sg_dma_address(&sg[i]),
			 sg[i].page, sg[i].offset,
			 sg[i].length,sg_dma_len(&sg[i]));
}

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

/**
 * 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_cmd_task *iser_ctask,
		      enum   iser_data_dir        cmd_dir)
{
	struct iser_conn     *ib_conn = iser_ctask->iser_conn->ib_conn;
	struct iser_data_buf *mem = &iser_ctask->data[cmd_dir];
	struct iser_regd_buf *regd_buf;
	int aligned_len;
	int err;

	regd_buf = &iser_ctask->rdma_regd[cmd_dir];

	aligned_len = iser_data_buf_aligned_len(mem);
	if (aligned_len != mem->size) {
		iser_err("rdma alignment violation %d/%d aligned\n",
			 aligned_len, mem->size);
		iser_data_buf_dump(mem);
		/* allocate copy buf, if we are writing, copy the */
		/* unaligned scatterlist, dma map the copy        */
		if (iser_start_rdma_unaligned_sg(iser_ctask, cmd_dir) != 0)
				return -ENOMEM;
		mem = &iser_ctask->data_copy[cmd_dir];
	}

	iser_page_vec_build(mem, ib_conn->page_vec);
	err = iser_reg_page_vec(ib_conn, ib_conn->page_vec, &regd_buf->reg);
	if (err)
		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;
}