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// sam3x8e serial port
//
// Copyright (C) 2016 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include <string.h> // memmove
#include "autoconf.h" // CONFIG_SERIAL_BAUD
#include "board/gpio.h" // gpio_peripheral
#include "board/io.h" // readb
#include "board/irq.h" // irq_save
#include "board/misc.h" // console_get_input
#include "command.h" // DECL_CONSTANT
#include "sam3x8e.h" // UART
#include "sched.h" // DECL_INIT
#define SERIAL_BUFFER_SIZE 96
static char receive_buf[SERIAL_BUFFER_SIZE];
static uint32_t receive_pos;
static char transmit_buf[SERIAL_BUFFER_SIZE];
static uint32_t transmit_pos, transmit_max;
/****************************************************************
* Serial hardware
****************************************************************/
DECL_CONSTANT(SERIAL_BAUD, CONFIG_SERIAL_BAUD);
static void
serial_init(void)
{
gpio_peripheral('A', PIO_PA8A_URXD, 'A', 1);
gpio_peripheral('A', PIO_PA9A_UTXD, 'A', 0);
// Reset uart
PMC->PMC_PCER0 = 1 << ID_UART;
UART->UART_PTCR = UART_PTCR_RXTDIS | UART_PTCR_TXTDIS;
UART->UART_CR = UART_CR_RSTRX | UART_CR_RSTTX | UART_CR_RXDIS | UART_CR_TXDIS;
UART->UART_IDR = 0xFFFFFFFF;
// Enable uart
UART->UART_MR = (US_MR_CHRL_8_BIT | US_MR_NBSTOP_1_BIT | UART_MR_PAR_NO
| UART_MR_CHMODE_NORMAL);
UART->UART_BRGR = SystemCoreClock / (16 * CONFIG_SERIAL_BAUD);
UART->UART_IER = UART_IER_RXRDY;
NVIC_EnableIRQ(UART_IRQn);
NVIC_SetPriority(UART_IRQn, 0);
UART->UART_CR = UART_CR_RXEN | UART_CR_TXEN;
}
DECL_INIT(serial_init);
void __visible
UART_Handler(void)
{
uint32_t status = UART->UART_SR;
if (status & UART_SR_RXRDY) {
uint8_t data = UART->UART_RHR;
if (receive_pos >= sizeof(receive_buf))
// Serial overflow - ignore it as crc error will force retransmit
return;
receive_buf[receive_pos++] = data;
return;
}
if (status & UART_SR_TXRDY) {
if (transmit_pos >= transmit_max)
UART->UART_IDR = UART_IDR_TXRDY;
else
UART->UART_THR = transmit_buf[transmit_pos++];
}
}
// Enable tx interrupts
static void
enable_tx_irq(void)
{
UART->UART_IER = UART_IDR_TXRDY;
}
/****************************************************************
* Console access functions
****************************************************************/
// Return a buffer (and length) containing any incoming messages
char *
console_get_input(uint8_t *plen)
{
*plen = readb(&receive_pos);
return receive_buf;
}
// Remove from the receive buffer the given number of bytes
void
console_pop_input(uint8_t len)
{
uint32_t copied = 0;
for (;;) {
uint32_t rpos = readb(&receive_pos);
uint32_t needcopy = rpos - len;
if (needcopy) {
memmove(&receive_buf[copied], &receive_buf[copied + len]
, needcopy - copied);
copied = needcopy;
}
irqstatus_t flag = irq_save();
if (rpos != readb(&receive_pos)) {
// Raced with irq handler - retry
irq_restore(flag);
continue;
}
receive_pos = needcopy;
irq_restore(flag);
break;
}
}
// Return an output buffer that the caller may fill with transmit messages
char *
console_get_output(uint8_t len)
{
uint32_t tpos = readb(&transmit_pos), tmax = readb(&transmit_max);
if (tpos >= tmax) {
tpos = tmax = 0;
writeb(&transmit_max, 0);
writeb(&transmit_pos, 0);
}
if (tmax + len <= sizeof(transmit_buf))
return &transmit_buf[tmax];
if (tmax - tpos + len > sizeof(transmit_buf))
return NULL;
// Disable TX irq and move buffer
writeb(&transmit_max, 0);
tpos = readb(&transmit_pos);
tmax -= tpos;
memmove(&transmit_buf[0], &transmit_buf[tpos], tmax);
writeb(&transmit_pos, 0);
writeb(&transmit_max, tmax);
enable_tx_irq();
return &transmit_buf[tmax];
}
// Accept the given number of bytes added to the transmit buffer
void
console_push_output(uint8_t len)
{
writeb(&transmit_max, readb(&transmit_max) + len);
enable_tx_irq();
}
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