portapack-mayhem/firmware/baseband/audio_dma.cpp

/*
 * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
 *
 * This file is part of PortaPack.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#include "audio_dma.hpp"

#include <cstdint>
#include <cstddef>
#include <array>

#include "hal.h"
#include "gpdma.hpp"

using namespace lpc43xx;

#include "portapack_dma.hpp"

namespace audio {
namespace dma {

constexpr uint32_t gpdma_ahb_master_peripheral = 1;
constexpr uint32_t gpdma_ahb_master_memory = 0;
constexpr uint32_t gpdma_ahb_master_lli_fetch = 0;

constexpr uint32_t gpdma_rx_peripheral = 0x9;		/* I2S0 DMA request 1 */
constexpr uint32_t gpdma_rx_src_peripheral = gpdma_rx_peripheral;
constexpr uint32_t gpdma_rx_dest_peripheral = gpdma_rx_peripheral;

constexpr uint32_t gpdma_tx_peripheral = 0xa;		/* I2S0 DMA request 2 */
constexpr uint32_t gpdma_tx_src_peripheral = gpdma_tx_peripheral;
constexpr uint32_t gpdma_tx_dest_peripheral = gpdma_tx_peripheral;

constexpr gpdma::channel::LLIPointer lli_pointer(const void* lli) {
	return {
		.lm = gpdma_ahb_master_lli_fetch,
		.r = 0,
		.lli = reinterpret_cast<uint32_t>(lli),
	};
}

constexpr gpdma::channel::Control control_tx(const size_t transfer_bytes) {
	return {
		.transfersize = gpdma::buffer_words(transfer_bytes, 4),
		.sbsize = 4,  /* Burst size: 32 */
		.dbsize = 4,  /* Burst size: 32 */
		.swidth = 2,  /* Source transfer width: word (32 bits) */
		.dwidth = 2,  /* Destination transfer width: word (32 bits) */
		.s = gpdma_ahb_master_memory,
		.d = gpdma_ahb_master_peripheral,
		.si = 1,
		.di = 0,
		.prot1 = 0,
		.prot2 = 0,
		.prot3 = 0,
		.i = 1,
	};
}

constexpr gpdma::channel::Config config_tx() {
	return {
		.e = 0,
		.srcperipheral = gpdma_tx_src_peripheral,
		.destperipheral = gpdma_tx_dest_peripheral,
		.flowcntrl = gpdma::FlowControl::MemoryToPeripheral_DMAControl,
		.ie = 1,
		.itc = 1,
		.l = 0,
		.a = 0,
		.h = 0,
	};
}

constexpr gpdma::channel::Control control_rx(const size_t transfer_bytes) {
	return {
		.transfersize = gpdma::buffer_words(transfer_bytes, 4),
		.sbsize = 4,  /* Burst size: 32 */
		.dbsize = 4,  /* Burst size: 32 */
		.swidth = 2,  /* Source transfer width: word (32 bits) */
		.dwidth = 2,  /* Destination transfer width: word (32 bits) */
		.s = gpdma_ahb_master_peripheral,
		.d = gpdma_ahb_master_memory,
		.si = 0,
		.di = 1,
		.prot1 = 0,
		.prot2 = 0,
		.prot3 = 0,
		.i = 1,
	};
}

constexpr gpdma::channel::Config config_rx() {
	return {
		.e = 0,
		.srcperipheral = gpdma_rx_src_peripheral,
		.destperipheral = gpdma_rx_dest_peripheral,
		.flowcntrl = gpdma::FlowControl::PeripheralToMemory_DMAControl,
		.ie = 1,
		.itc = 1,
		.l = 0,
		.a = 0,
		.h = 0,
	};
}

/* TODO: Clean up terminology around "buffer", "transfer", "samples" */

constexpr size_t buffer_samples_log2n = 7;
constexpr size_t buffer_samples = (1 << buffer_samples_log2n);
constexpr size_t transfers_per_buffer_log2n = 2;
constexpr size_t transfers_per_buffer = (1 << transfers_per_buffer_log2n);
constexpr size_t transfer_samples = buffer_samples / transfers_per_buffer;
constexpr size_t transfers_mask = transfers_per_buffer - 1;

constexpr size_t buffer_bytes = buffer_samples * sizeof(sample_t);
constexpr size_t transfer_bytes = transfer_samples * sizeof(sample_t);

static std::array<sample_t, buffer_samples> buffer_tx;
static std::array<sample_t, buffer_samples> buffer_rx;

static std::array<gpdma::channel::LLI, transfers_per_buffer> lli_tx_loop;
static std::array<gpdma::channel::LLI, transfers_per_buffer> lli_rx_loop;

static constexpr auto& gpdma_channel_i2s0_tx = gpdma::channels[portapack::i2s0_tx_gpdma_channel_number];
static constexpr auto& gpdma_channel_i2s0_rx = gpdma::channels[portapack::i2s0_rx_gpdma_channel_number];

static volatile const gpdma::channel::LLI* tx_next_lli = nullptr;
static volatile const gpdma::channel::LLI* rx_next_lli = nullptr;

static void tx_transfer_complete() {
	tx_next_lli = gpdma_channel_i2s0_tx.next_lli();
}

static void tx_error() {
	disable();
}

static void rx_transfer_complete() {
	rx_next_lli = gpdma_channel_i2s0_rx.next_lli();
}

static void rx_error() {
	disable();
}

void init() {
	gpdma_channel_i2s0_tx.set_handlers(tx_transfer_complete, tx_error);
	gpdma_channel_i2s0_rx.set_handlers(rx_transfer_complete, rx_error);

	// LPC_GPDMA->SYNC |= (1 << gpdma_rx_peripheral);
	// LPC_GPDMA->SYNC |= (1 << gpdma_tx_peripheral);
}

static void configure_tx() {
	const auto peripheral = reinterpret_cast<uint32_t>(&LPC_I2S0->TXFIFO);
	const auto control_value = control_tx(transfer_bytes);
	for(size_t i=0; i<lli_tx_loop.size(); i++) {
		const auto memory = reinterpret_cast<uint32_t>(&buffer_tx[i * transfer_samples]);
		lli_tx_loop[i].srcaddr = memory;
		lli_tx_loop[i].destaddr = peripheral;
		lli_tx_loop[i].lli = lli_pointer(&lli_tx_loop[(i + 1) % lli_tx_loop.size()]);
		lli_tx_loop[i].control = control_value;
	}
}

static void configure_rx() {
	const auto peripheral = reinterpret_cast<uint32_t>(&LPC_I2S0->RXFIFO);
	const auto control_value = control_rx(transfer_bytes);
	for(size_t i=0; i<lli_rx_loop.size(); i++) {
		const auto memory = reinterpret_cast<uint32_t>(&buffer_rx[i * transfer_samples]);
		lli_rx_loop[i].srcaddr = peripheral;
		lli_rx_loop[i].destaddr = memory;
		lli_rx_loop[i].lli = lli_pointer(&lli_rx_loop[(i + 1) % lli_rx_loop.size()]);
		lli_rx_loop[i].control = control_value;
	}
}

void configure() {
	configure_tx();
	configure_rx();
}

void enable() {
	const auto gpdma_config_tx = config_tx();
	const auto gpdma_config_rx = config_rx();

	gpdma_channel_i2s0_tx.configure(lli_tx_loop[0], gpdma_config_tx);
	gpdma_channel_i2s0_rx.configure(lli_rx_loop[0], gpdma_config_rx);

	gpdma_channel_i2s0_tx.enable();
	gpdma_channel_i2s0_rx.enable();
}

void disable() {
	gpdma_channel_i2s0_tx.disable();
	gpdma_channel_i2s0_rx.disable();
}

buffer_t tx_empty_buffer() {
	const auto next_lli = tx_next_lli;
	if( next_lli ) {
		const size_t next_index = next_lli - &lli_tx_loop[0];
		const size_t free_index = (next_index + transfers_per_buffer - 2) & transfers_mask;
		return { reinterpret_cast<sample_t*>(lli_tx_loop[free_index].srcaddr), transfer_samples };
	} else {
		return { nullptr, 0 };
	}
}

buffer_t rx_empty_buffer() {
	const auto next_lli = rx_next_lli;
	if( next_lli ) {
		const size_t next_index = next_lli - &lli_rx_loop[0];
		const size_t free_index = (next_index + transfers_per_buffer - 2) & transfers_mask;
		return { reinterpret_cast<sample_t*>(lli_rx_loop[free_index].srcaddr), transfer_samples };
	} else {
		return { nullptr, 0 };
	}
}

} /* namespace dma */
} /* namespace audio */