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/*
* Copyright (c) 2017-2018 Richard Braun.
* Copyright (c) 2017 Jerko Lenstra.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#include <errno.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <lib/cbuf.h>
#include <lib/macros.h>
#include "cpu.h"
#include "uart.h"
#include "thread.h"
#define UART_USART1_ADDR 0x40011000
#define UART_USART1_IRQ 37
#define UART_SR_RXNE 0x00000020
#define UART_SR_TXE 0x00000080
#define UART_CR1_RE 0x00000004
#define UART_CR1_TE 0x00000008
#define UART_CR1_RXNEIE 0x00000020
#define UART_CR1_UE 0x00002000
#define UART_BUFFER_SIZE 16
#if !ISP2(UART_BUFFER_SIZE)
#error "invalid buffer size"
#endif
struct uart_regs {
uint32_t sr;
uint32_t dr;
uint32_t brr;
uint32_t cr1;
uint32_t cr2;
uint32_t cr3;
uint32_t gtpr;
};
static volatile struct uart_regs *uart_usart1_regs;
/*
* Data shared between threads and the interrupt handler.
*
* Interrupts and preemption must be disabled when accessing these data.
*/
static uint8_t uart_buffer[UART_BUFFER_SIZE];
static struct cbuf uart_cbuf;
static struct thread *uart_waiter;
static void
uart_irq_handler(void *arg)
{
uint32_t reg;
bool spurious;
int error;
(void)arg;
spurious = true;
for (;;) {
reg = uart_usart1_regs->sr;
if (!(reg & UART_SR_RXNE)) {
break;
}
spurious = false;
reg = uart_usart1_regs->dr;
error = cbuf_pushb(&uart_cbuf, (uint8_t)reg, false);
if (error) {
printf("uart: error: buffer full\n");
break;
}
}
if (!spurious) {
thread_wakeup(uart_waiter);
}
}
void
uart_setup(void)
{
cbuf_init(&uart_cbuf, uart_buffer, sizeof(uart_buffer));
uart_usart1_regs = (void *)UART_USART1_ADDR;
uart_usart1_regs->cr1 |= UART_CR1_UE
| UART_CR1_RXNEIE
| UART_CR1_TE
| UART_CR1_RE;
cpu_irq_register(UART_USART1_IRQ, uart_irq_handler, NULL);
}
static void
uart_tx_wait(void)
{
/*
* XXX The QEMU stm32f2xx_usart driver doesn't seem to correctly emulate
* the UART_SR_TXE bit.
*/
#if 0
uint32_t sr;
for (;;) {
sr = uart_usart1_regs->sr;
if (sr & UART_SR_TXE) {
break;
}
}
#endif
}
static void
uart_write_byte(uint8_t byte)
{
uart_tx_wait();
uart_usart1_regs->dr = byte;
}
void
uart_write(uint8_t byte)
{
if (byte == '\n') {
uart_write_byte('\r');
}
uart_write_byte(byte);
}
int
uart_read(uint8_t *byte)
{
uint32_t primask;
int error;
primask = thread_preempt_disable_intr_save();
if (uart_waiter) {
error = EBUSY;
goto out;
}
for (;;) {
error = cbuf_popb(&uart_cbuf, byte);
if (!error) {
break;
}
uart_waiter = thread_self();
thread_sleep();
uart_waiter = NULL;
}
error = 0;
out:
thread_preempt_enable_intr_restore(primask);
return error;
}
|
