cregit-Linux how code gets into the kernel

Release 4.7 drivers/infiniband/sw/rdmavt/dma.c

/*
 * Copyright(c) 2016 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * 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.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <linux/types.h>
#include <linux/scatterlist.h>
#include <rdma/ib_verbs.h>

#include "dma.h"


#define BAD_DMA_ADDRESS ((u64)0)

/*
 * The following functions implement driver specific replacements
 * for the ib_dma_*() functions.
 *
 * These functions return kernel virtual addresses instead of
 * device bus addresses since the driver uses the CPU to copy
 * data instead of using hardware DMA.
 */


static int rvt_mapping_error(struct ib_device *dev, u64 dma_addr) { return dma_addr == BAD_DMA_ADDRESS; }

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static u64 rvt_dma_map_single(struct ib_device *dev, void *cpu_addr, size_t size, enum dma_data_direction direction) { if (WARN_ON(!valid_dma_direction(direction))) return BAD_DMA_ADDRESS; return (u64)cpu_addr; }

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static void rvt_dma_unmap_single(struct ib_device *dev, u64 addr, size_t size, enum dma_data_direction direction) { /* This is a stub, nothing to be done here */ }

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static u64 rvt_dma_map_page(struct ib_device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction direction) { u64 addr; if (WARN_ON(!valid_dma_direction(direction))) return BAD_DMA_ADDRESS; if (offset + size > PAGE_SIZE) return BAD_DMA_ADDRESS; addr = (u64)page_address(page); if (addr) addr += offset; return addr; }

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static void rvt_dma_unmap_page(struct ib_device *dev, u64 addr, size_t size, enum dma_data_direction direction) { /* This is a stub, nothing to be done here */ }

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static int rvt_map_sg(struct ib_device *dev, struct scatterlist *sgl, int nents, enum dma_data_direction direction) { struct scatterlist *sg; u64 addr; int i; int ret = nents; if (WARN_ON(!valid_dma_direction(direction))) return 0; for_each_sg(sgl, sg, nents, i) { addr = (u64)page_address(sg_page(sg)); if (!addr) { ret = 0; break; } sg->dma_address = addr + sg->offset; #ifdef CONFIG_NEED_SG_DMA_LENGTH sg->dma_length = sg->length; #endif } return ret; }

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static void rvt_unmap_sg(struct ib_device *dev, struct scatterlist *sg, int nents, enum dma_data_direction direction) { /* This is a stub, nothing to be done here */ }

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static void rvt_sync_single_for_cpu(struct ib_device *dev, u64 addr, size_t size, enum dma_data_direction dir) { }

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static void rvt_sync_single_for_device(struct ib_device *dev, u64 addr, size_t size, enum dma_data_direction dir) { }

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static void *rvt_dma_alloc_coherent(struct ib_device *dev, size_t size, u64 *dma_handle, gfp_t flag) { struct page *p; void *addr = NULL; p = alloc_pages(flag, get_order(size)); if (p) addr = page_address(p); if (dma_handle) *dma_handle = (u64)addr; return addr; }

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static void rvt_dma_free_coherent(struct ib_device *dev, size_t size, void *cpu_addr, u64 dma_handle) { free_pages((unsigned long)cpu_addr, get_order(size)); }

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struct ib_dma_mapping_ops rvt_default_dma_mapping_ops = { .mapping_error = rvt_mapping_error, .map_single = rvt_dma_map_single, .unmap_single = rvt_dma_unmap_single, .map_page = rvt_dma_map_page, .unmap_page = rvt_dma_unmap_page, .map_sg = rvt_map_sg, .unmap_sg = rvt_unmap_sg, .sync_single_for_cpu = rvt_sync_single_for_cpu, .sync_single_for_device = rvt_sync_single_for_device, .alloc_coherent = rvt_dma_alloc_coherent, .free_coherent = rvt_dma_free_coherent };

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