OVMS3-idf/components/vfs/vfs_uart.c

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// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <string.h>
#include "esp_vfs.h"
#include "esp_attr.h"
#include "sys/errno.h"
#include "sys/lock.h"
#include "soc/uart_struct.h"
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#include "sdkconfig.h"
static uart_dev_t* s_uarts[3] = {&UART0, &UART1, &UART2};
static _lock_t s_uart_locks[3]; // per-UART locks, lazily initialized
static int IRAM_ATTR uart_open(const char * path, int flags, int mode)
{
// this is fairly primitive, we should check if file is opened read only,
// and error out if write is requested
if (strcmp(path, "/0") == 0) {
return 0;
} else if (strcmp(path, "/1") == 0) {
return 1;
} else if (strcmp(path, "/2") == 0) {
return 2;
}
errno = ENOENT;
return -1;
}
static void IRAM_ATTR uart_tx_char(uart_dev_t* uart, int c)
{
while (uart->status.txfifo_cnt >= 127) {
;
}
uart->fifo.rw_byte = c;
}
static ssize_t IRAM_ATTR uart_write(int fd, const void * data, size_t size)
{
assert(fd >=0 && fd < 3);
const char *data_c = (const char *)data;
uart_dev_t* uart = s_uarts[fd];
/*
* Even though newlib does stream locking on each individual stream, we need
* a dedicated UART lock if two streams (stdout and stderr) point to the
* same UART.
*/
_lock_acquire_recursive(&s_uart_locks[fd]);
for (size_t i = 0; i < size; i++) {
#if CONFIG_NEWLIB_STDOUT_ADDCR
if (data_c[i]=='\n') {
uart_tx_char(uart, '\r');
}
#endif
uart_tx_char(uart, data_c[i]);
}
_lock_release_recursive(&s_uart_locks[fd]);
return size;
}
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static ssize_t IRAM_ATTR uart_read(int fd, void* data, size_t size)
{
assert(fd >=0 && fd < 3);
uint8_t *data_c = (uint8_t *) data;
uart_dev_t* uart = s_uarts[fd];
size_t received = 0;
_lock_acquire_recursive(&s_uart_locks[fd]);
while (uart->status.rxfifo_cnt > 0 && received < size) {
uint8_t c = uart->fifo.rw_byte;
#if CONFIG_NEWLIB_STDOUT_ADDCR
/* Convert \r\n sequences to \n.
* If \r is received, it is put into 'buffered_char' until the next
* character is received. Then depending on the character, we either
* drop \r (if the next one is \n) or output \r and then proceed to output
* the new character.
*/
const int NONE = -1;
static int buffered_char = NONE;
if (buffered_char != NONE) {
if (buffered_char == '\r' && c == '\n') {
buffered_char = NONE;
} else {
data_c[received] = buffered_char;
buffered_char = NONE;
++received;
if (received == size) {
/* We have placed the buffered character into the output buffer
* but there won't be enough space for the newly received one.
* Keep the new character in buffered_char until read is called
* again.
*/
buffered_char = c;
break;
}
}
}
if (c == '\r') {
buffered_char = c;
continue;
}
#endif //CONFIG_NEWLIB_STDOUT_ADDCR
data_c[received] = c;
++received;
}
_lock_release_recursive(&s_uart_locks[fd]);
if (received > 0) {
return received;
}
errno = EWOULDBLOCK;
return -1;
}
static int IRAM_ATTR uart_fstat(int fd, struct stat * st)
{
assert(fd >=0 && fd < 3);
st->st_mode = S_IFCHR;
return 0;
}
static int IRAM_ATTR uart_close(int fd)
{
assert(fd >=0 && fd < 3);
return 0;
}
void esp_vfs_dev_uart_register()
{
esp_vfs_t vfs = {
.fd_offset = 0,
.flags = ESP_VFS_FLAG_DEFAULT,
.write = &uart_write,
.open = &uart_open,
.fstat = &uart_fstat,
.close = &uart_close,
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.read = &uart_read,
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.lseek = NULL,
.stat = NULL,
.link = NULL,
.unlink = NULL,
.rename = NULL
};
ESP_ERROR_CHECK(esp_vfs_register("/dev/uart", &vfs, NULL));
}