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66 lines
1.6 KiB
C++
66 lines
1.6 KiB
C++
/*
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* \brief Advanced DMA 2
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* \author Martin Stein
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* \date 2015-02-05
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*/
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/*
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* Copyright (C) 2015-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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/* Genode includes */
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#include <dataspace/client.h>
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/* local includes */
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#include <adma2.h>
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using namespace Adma2;
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Table::Table(Ram_allocator &ram, Region_map &rm)
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:
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_ds(ram, rm, _ds_size, UNCACHED),
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_base_virt(_ds.local_addr<Desc::access_t>()),
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_base_phys(Dataspace_client(_ds.cap()).phys_addr())
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{ }
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int Table::setup_request(size_t const size, addr_t const buffer_phys)
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{
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/* sanity check */
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static size_t constexpr max_size = _max_desc * Desc::Length::max;
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if (size > max_size) {
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Genode::error("block request too large");
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return -1;
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}
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/* install new descriptors till they cover all requested bytes */
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addr_t consumed = 0;
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for (int index = 0; consumed < size; index++) {
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/* clamp current request to maximum request size */
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size_t const remaining = size - consumed;
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size_t const curr = min(Desc::Length::max, remaining);
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/* assemble new descriptor */
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Desc::access_t desc = 0;
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Desc::Address::set(desc, buffer_phys + consumed);
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Desc::Length::set(desc, curr);
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Desc::Act1::set(desc, 0);
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Desc::Act2::set(desc, 1);
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Desc::Valid::set(desc, 1);
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/* let last descriptor generate transfer-complete signal */
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if (consumed + curr == size) { Desc::End::set(desc, 1); }
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/* install and account descriptor */
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_base_virt[index] = desc;
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consumed += curr;
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}
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/* ensure that all descriptor writes were actually executed */
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asm volatile ("dsb #15" ::: "memory");
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return 0;
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}
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