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dma: add abstraction layer for dma

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io-wait
Felix Kopp 3 years ago
parent f7cbcc924b
commit c4717d8fce
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GPG Key ID: C478BA0A85F75728
5 changed files with 146 additions and 22 deletions
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24
arch/at91sam3x8e/serial.c
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@ -2,6 +2,7 @@
/* See the end of this file for copyright, licensing, and warranty information. */
#include <ardix/atomic.h>
#include <ardix/dma.h>
#include <ardix/io.h>
#include <ardix/malloc.h>
#include <ardix/ringbuf.h>
@ -83,7 +84,7 @@ void arch_serial_exit(struct serial_device *dev)
ssize_t arch_serial_write(struct serial_device *dev, const void *buf, size_t len)
{
struct arch_serial_buffer *arch_buf = NULL;
struct dmabuf *dmabuf = NULL;
struct arch_serial_device *arch_dev = to_arch_serial_device(dev);
if (arch_dev->tx_next != NULL)
@ -92,23 +93,22 @@ ssize_t arch_serial_write(struct serial_device *dev, const void *buf, size_t len
if (len >= (1 << 16)) /* DMA uses 16-bit counters */
len = 0xffff;
arch_buf = malloc(sizeof(*arch_buf) + len);
if (arch_buf == NULL)
dmabuf = dmabuf_create(&dev->device, len);
if (dmabuf == NULL)
return -ENOMEM;
memcpy(&arch_buf->data[0], buf, len);
arch_buf->len = (uint16_t)len;
memcpy(&dmabuf->data[0], buf, len);
if (arch_dev->tx_current == NULL) {
arch_dev->tx_current = arch_buf;
REG_UART_PDC_TPR = (uint32_t)&arch_buf->data[0];
REG_UART_PDC_TCR = arch_buf->len;
arch_dev->tx_current = dmabuf;
REG_UART_PDC_TPR = (uint32_t)&dmabuf->data[0];
REG_UART_PDC_TCR = (uint16_t)dmabuf->len;
/* we weren't transmitting, so the interrupt was masked */
REG_UART_IER = REG_UART_IER_ENDTX_MASK;
} else {
arch_dev->tx_next = arch_buf;
REG_UART_PDC_TNPR = (uint32_t)&arch_buf->data[0];
REG_UART_PDC_TNCR = arch_buf->len;
arch_dev->tx_next = dmabuf;
REG_UART_PDC_TNPR = (uint32_t)&dmabuf->data[0];
REG_UART_PDC_TNCR = (uint16_t)dmabuf->len;
}
return (ssize_t)len;
@ -128,7 +128,7 @@ void irq_uart(void)
/* REG_UART_PDC_TCR has reached zero */
if (state & REG_UART_SR_ENDTX_MASK) {
/* this might be NULL but that's ok because free() tolerates that */
free(arch_serial_default_device.tx_current);
dmabuf_put(arch_serial_default_device.tx_current);
/* DMA automatically does this to the actual hardware registers */
arch_serial_default_device.tx_current = arch_serial_default_device.tx_next;

13
include/arch/at91sam3x8e/serial.h
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@ -3,27 +3,20 @@
#pragma once
#include <ardix/dma.h>
#include <ardix/serial.h>
#include <ardix/types.h>
#include <ardix/util.h>
#include <stdbool.h>
#ifndef CONFIG_ARCH_SERIAL_BUFSZ
#define CONFIG_ARCH_SERIAL_BUFSZ 32
#endif /* CONFIG_ARCH_SERIAL_BUFSZ */
struct arch_serial_buffer {
uint16_t len;
uint8_t data[];
};
/** Architecture-specific extension of `struct serial_device` */
struct arch_serial_device {
/** should always match REG_UART_PDC_TPR */
struct arch_serial_buffer *tx_current;
struct dmabuf *tx_current;
/** should always match REG_UART_PDC_TNPR */
struct arch_serial_buffer *tx_next;
struct dmabuf *tx_next;
struct serial_device device;
};

54
include/ardix/dma.h
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@ -0,0 +1,54 @@
/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
#pragma once
#include <ardix/device.h>
#include <ardix/kent.h>
#include <ardix/types.h>
struct dmabuf {
struct kent kent;
size_t len;
uint8_t data[0];
};
/**
* Create a new DMA buffer and its corresponding kent.
*
* @param dev: device to create the buffer for
* @param len: buffer length in bytes
* @returns a pointer to the buffer, or `NULL` on failure
*/
struct dmabuf *dmabuf_create(struct device *dev, size_t len);
/** Increment a DMA buffer's reference counter. */
void dmabuf_get(struct dmabuf *buf);
/** Decrement a DMA buffer's reference counter. */
void dmabuf_put(struct dmabuf *buf);
/*
* Copyright (c) 2021 Felix Kopp <sandtler@sandtler.club>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the copyright holder 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 HOLDER 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.
*/

1
kernel/Makefile
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@ -30,6 +30,7 @@ include $(ARDIX_KERNEL_PWD)/io/Makefile
ARDIX_SOURCES += \
$(ARDIX_KERNEL_PWD)/device.c \
$(ARDIX_KERNEL_PWD)/dma.c \
$(ARDIX_KERNEL_PWD)/kent.c \
$(ARDIX_KERNEL_PWD)/printk.c \
$(ARDIX_KERNEL_PWD)/ringbuf.c \

76
kernel/dma.c
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@ -0,0 +1,76 @@
/* SPDX-License-Identifier: BSD-3-Clause */
/* See the end of this file for copyright, licensing, and warranty information. */
#include <ardix/device.h>
#include <ardix/dma.h>
#include <ardix/kent.h>
#include <ardix/malloc.h>
#include <ardix/types.h>
#include <ardix/util.h>
#include <stddef.h>
static void dmabuf_destroy(struct kent *kent)
{
struct dmabuf *buf = container_of(kent, struct dmabuf, kent);
free(buf);
}
static struct kent_ops dma_kent_ops = {
.destroy = &dmabuf_destroy,
};
struct dmabuf *dmabuf_create(struct device *dev, size_t len)
{
int err = 0;
struct dmabuf *buf = malloc(sizeof(*buf) + len);
if (buf == NULL)
return NULL;
buf->kent.operations = &dma_kent_ops;
err = kent_init(&dev->kent, &buf->kent);
if (err != 0) {
free(buf);
return NULL;
}
buf->len = len;
return buf;
}
void dmabuf_get(struct dmabuf *buf)
{
kent_get(&buf->kent);
}
void dmabuf_put(struct dmabuf *buf)
{
kent_put(&buf->kent);
}
/*
* Copyright (c) 2021 Felix Kopp <sandtler@sandtler.club>
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the copyright holder 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 HOLDER 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.
*/
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