system/dev/block/mtk-sdmmc/dma_descriptors.h

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#pragma once

#include "mtk-sdmmc.h"

namespace {

static constexpr size_t kDescriptorChecksumSize = 16;
static constexpr uint64_t kAddressMask = 0xffffffff;

uint32_t CalculateChecksum(const void* buf) {
    const uint8_t* buf_u8 = reinterpret_cast<const uint8_t*>(buf);
    uint32_t sum = 0;
    for (size_t i = 0; i < kDescriptorChecksumSize; i++) {
        sum += buf_u8[i];
    }

    return (0xff - (sum & 0xff)) & 0xff;
}

}  // namespace

namespace sdmmc {

struct GpDmaDescriptor {
    void SetNext(uint64_t addr) {
        info = GpDmaDescriptorInfo().set_reg_value(info).set_next_addr(addr).reg_value();
        next = addr & kAddressMask;
    }

    void SetBDmaDesc(uint64_t addr) {
        info = GpDmaDescriptorInfo().set_reg_value(info).set_bdma_desc_addr(addr).reg_value();
        bdma_desc = addr & kAddressMask;
    }

    void SetChecksum() {
        auto info_reg = GpDmaDescriptorInfo().set_reg_value(info).set_checksum(0);
        info = info_reg.reg_value();
        info = info_reg.set_checksum(CalculateChecksum(this)).reg_value();
    }

    uint32_t info      = 0;  // See GpDmaDescriptorInfo in mtk-sdmmc-reg.h.
    uint32_t next      = 0;  // Physical address of the next GpDmaDesecriptor.
    uint32_t bdma_desc = 0;  // Physical address of the BDmaDescriptor.
    uint32_t size      = 0;  // Values here and below are ignored when using one GPDMA descriptor at
    uint32_t arg       = 0;  // a time.
    uint32_t blknum    = 0;
    uint32_t cmd       = 0;
};

struct BDmaDescriptor {
    static constexpr size_t kMaxBufferSize = 0xffff & ~kPageMask;
    static_assert(kMaxBufferSize > 0);
    static_assert(kMaxBufferSize % PAGE_SIZE == 0);

    void SetNext(uint64_t addr) {
        info = BDmaDescriptorInfo().set_reg_value(info).set_next_addr(addr).reg_value();
        next = addr & kAddressMask;
    }

    void SetBuffer(uint64_t addr) {
        info = BDmaDescriptorInfo().set_reg_value(info).set_buffer_addr(addr).reg_value();
        buffer = addr & kAddressMask;
    }

    void SetChecksum() {
        auto info_reg = BDmaDescriptorInfo().set_reg_value(info).set_checksum(0);
        info = info_reg.reg_value();
        info = info_reg.set_checksum(CalculateChecksum(this)).reg_value();
    }

    uint32_t info   = 0;  // See BDmaDescriptorInfo in mtk-sdmmc-reg.h.
    uint32_t next   = 0;  // Physical address of the next BDmaDescriptor.
    uint32_t buffer = 0;  // Physical address of the data buffer.
    uint32_t size   = 0;  // Size of the data buffer.
};

}  // namespace sdmmc