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/****************************************************************************
*
* Copyright (C) 2012,2013 PX4 Development Team. All rights reserved.
*
* 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 PX4 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.
*
****************************************************************************/
/**
* @file serial.c
*
* Serial communication for the PX4IO module.
*/
#include <stdint.h>
#include <unistd.h>
#include <termios.h>
#include <fcntl.h>
#include <string.h>
#include <nuttx/arch.h>
#include <arch/board/board.h>
/* XXX might be able to prune these */
#include <chip.h>
#include <up_internal.h>
#include <up_arch.h>
#include <stm32_internal.h>
#include <systemlib/hx_stream.h>
//#define DEBUG
#include "px4io.h"
static volatile bool sending = false;
static void dma_callback(DMA_HANDLE handle, uint8_t status, void *arg);
static DMA_HANDLE tx_dma;
static DMA_HANDLE rx_dma;
#define MAX_RW_REGS 32 // by agreement w/FMU
#pragma pack(push, 1)
struct IOPacket {
uint8_t count;
#define PKT_CTRL_WRITE (1<<7)
uint8_t spare;
uint8_t page;
uint8_t offset;
uint16_t regs[MAX_RW_REGS];
};
#pragma pack(pop)
static struct IOPacket dma_packet;
/* serial register accessors */
#define REG(_x) (*(volatile uint32_t *)(PX4FMU_SERIAL_BASE + _x))
#define rSR REG(STM32_USART_SR_OFFSET)
#define rDR REG(STM32_USART_DR_OFFSET)
#define rBRR REG(STM32_USART_BRR_OFFSET)
#define rCR1 REG(STM32_USART_CR1_OFFSET)
#define rCR2 REG(STM32_USART_CR2_OFFSET)
#define rCR3 REG(STM32_USART_CR3_OFFSET)
#define rGTPR REG(STM32_USART_GTPR_OFFSET)
void
interface_init(void)
{
/* allocate DMA */
tx_dma = stm32_dmachannel(PX4FMU_SERIAL_TX_DMA);
rx_dma = stm32_dmachannel(PX4FMU_SERIAL_RX_DMA);
/* configure pins for serial use */
stm32_configgpio(PX4FMU_SERIAL_TX_GPIO);
stm32_configgpio(PX4FMU_SERIAL_RX_GPIO);
/* reset and configure the UART */
rCR1 = 0;
rCR2 = 0;
rCR3 = 0;
/* configure line speed */
uint32_t usartdiv32 = PX4FMU_SERIAL_CLOCK / (PX4FMU_SERIAL_BITRATE / 2);
uint32_t mantissa = usartdiv32 >> 5;
uint32_t fraction = (usartdiv32 - (mantissa << 5) + 1) >> 1;
rBRR = (mantissa << USART_BRR_MANT_SHIFT) | (fraction << USART_BRR_FRAC_SHIFT);
/* enable UART and DMA */
rCR3 = USART_CR3_DMAR | USART_CR3_DMAT;
rCR1 = USART_CR1_RE | USART_CR1_TE | USART_CR1_UE;
/* configure DMA */
stm32_dmasetup(
tx_dma,
(uint32_t)&rDR,
(uint32_t)&dma_packet,
sizeof(dma_packet),
DMA_CCR_DIR |
DMA_CCR_MINC |
DMA_CCR_PSIZE_8BITS |
DMA_CCR_MSIZE_8BITS);
stm32_dmasetup(
rx_dma,
(uint32_t)&rDR,
(uint32_t)&dma_packet,
sizeof(dma_packet),
DMA_CCR_MINC |
DMA_CCR_PSIZE_8BITS |
DMA_CCR_MSIZE_8BITS);
/* start receive DMA ready for the first packet */
stm32_dmastart(rx_dma, dma_callback, NULL, false);
debug("serial init");
}
void
interface_tick()
{
/* XXX look for stuck/damaged DMA and reset? */
}
static void
dma_callback(DMA_HANDLE handle, uint8_t status, void *arg)
{
if (!(status & DMA_STATUS_TCIF)) {
/* XXX what do we do here? it's fatal! */
return;
}
/* if this is transmit-complete, make a note */
if (handle == tx_dma) {
sending = false;
return;
}
/* we just received a request; sort out what to do */
/* XXX implement check byte */
/* XXX if we care about overruns, check the UART received-data-ready bit */
bool send_reply = false;
if (dma_packet.count & PKT_CTRL_WRITE) {
/* it's a blind write - pass it on */
registers_set(dma_packet.page, dma_packet.offset, &dma_packet.regs[0], dma_packet.count);
} else {
/* it's a read - get register pointer for reply */
int result;
unsigned count;
uint16_t *registers;
result = registers_get(dma_packet.page, dma_packet.offset, ®isters, &count);
if (result < 0)
count = 0;
/* constrain reply to packet size */
if (count > MAX_RW_REGS)
count = MAX_RW_REGS;
/* copy reply registers into DMA buffer */
send_reply = true;
memcpy((void *)&dma_packet.regs[0], registers, count);
dma_packet.count = count;
}
/* re-set DMA for reception first, so we are ready to receive before we start sending */
stm32_dmastart(rx_dma, dma_callback, NULL, false);
/* if we have a reply to send, start that now */
if (send_reply)
stm32_dmastart(tx_dma, dma_callback, NULL, false);
}
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