OVMS3-idf/components/vfs/vfs_uart.c

974 lines
26 KiB
C

// Copyright 2015-2017 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 <stdbool.h>
#include <stdarg.h>
#include <sys/errno.h>
#include <sys/lock.h>
#include <sys/fcntl.h>
#include <sys/param.h>
#include "esp_vfs.h"
#include "esp_vfs_dev.h"
#include "esp_attr.h"
#include "driver/uart.h"
#include "sdkconfig.h"
#include "driver/uart_select.h"
#include "esp32/rom/uart.h"
// TODO: make the number of UARTs chip dependent
#define UART_NUM SOC_UART_NUM
// Token signifying that no character is available
#define NONE -1
#if CONFIG_NEWLIB_STDOUT_LINE_ENDING_CRLF
# define DEFAULT_TX_MODE ESP_LINE_ENDINGS_CRLF
#elif CONFIG_NEWLIB_STDOUT_LINE_ENDING_CR
# define DEFAULT_TX_MODE ESP_LINE_ENDINGS_CR
#else
# define DEFAULT_TX_MODE ESP_LINE_ENDINGS_LF
#endif
#if CONFIG_NEWLIB_STDIN_LINE_ENDING_CRLF
# define DEFAULT_RX_MODE ESP_LINE_ENDINGS_CRLF
#elif CONFIG_NEWLIB_STDIN_LINE_ENDING_CR
# define DEFAULT_RX_MODE ESP_LINE_ENDINGS_CR
#else
# define DEFAULT_RX_MODE ESP_LINE_ENDINGS_LF
#endif
// UART write bytes function type
typedef void (*tx_func_t)(int, int);
// UART read bytes function type
typedef int (*rx_func_t)(int);
// Basic functions for sending and receiving bytes over UART
static void uart_tx_char(int fd, int c);
static int uart_rx_char(int fd);
// Functions for sending and receiving bytes which use UART driver
static void uart_tx_char_via_driver(int fd, int c);
static int uart_rx_char_via_driver(int fd);
typedef struct {
// Pointers to UART peripherals
uart_dev_t* uart;
// One-character buffer used for newline conversion code, per UART
int peek_char;
// per-UART locks, lazily initialized
_lock_t read_lock;
_lock_t write_lock;
// Per-UART non-blocking flag. Note: default implementation does not honor this
// flag, all reads are non-blocking. This option becomes effective if UART
// driver is used.
bool non_blocking;
// Newline conversion mode when transmitting
esp_line_endings_t tx_mode;
// Newline conversion mode when receiving
esp_line_endings_t rx_mode;
// Functions used to write bytes to UART. Default to "basic" functions.
tx_func_t tx_func;
// Functions used to read bytes from UART. Default to "basic" functions.
rx_func_t rx_func;
} vfs_uart_context_t;
#define VFS_CTX_DEFAULT_VAL(uart_dev) (vfs_uart_context_t) {\
.uart = (uart_dev),\
.peek_char = NONE,\
.tx_mode = DEFAULT_TX_MODE,\
.rx_mode = DEFAULT_RX_MODE,\
.tx_func = uart_tx_char,\
.rx_func = uart_rx_char,\
}
//If the context should be dynamically initialized, remove this structure
//and point s_ctx to allocated data.
static vfs_uart_context_t s_context[UART_NUM] = {
VFS_CTX_DEFAULT_VAL(&UART0),
VFS_CTX_DEFAULT_VAL(&UART1),
#if UART_NUM > 2
VFS_CTX_DEFAULT_VAL(&UART2),
#endif
};
static vfs_uart_context_t* s_ctx[UART_NUM] = {
&s_context[0],
&s_context[1],
#if UART_NUM > 2
&s_context[2],
#endif
};
/* Lock ensuring that uart_select is used from only one task at the time */
static _lock_t s_one_select_lock;
static esp_vfs_select_sem_t _select_sem = {.sem = NULL};
static fd_set *_readfds = NULL;
static fd_set *_writefds = NULL;
static fd_set *_errorfds = NULL;
static fd_set *_readfds_orig = NULL;
static fd_set *_writefds_orig = NULL;
static fd_set *_errorfds_orig = NULL;
static void uart_end_select(void);
static int 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
int fd = -1;
if (strcmp(path, "/0") == 0) {
fd = 0;
} else if (strcmp(path, "/1") == 0) {
fd = 1;
} else if (strcmp(path, "/2") == 0) {
fd = 2;
} else {
errno = ENOENT;
return fd;
}
s_ctx[fd]->non_blocking = ((flags & O_NONBLOCK) == O_NONBLOCK);
return fd;
}
static void uart_tx_char(int fd, int c)
{
uart_dev_t* uart = s_ctx[fd]->uart;
while (uart->status.txfifo_cnt >= 127) {
;
}
uart->fifo.rw_byte = c;
}
static void uart_tx_char_via_driver(int fd, int c)
{
char ch = (char) c;
uart_write_bytes(fd, &ch, 1);
}
static int uart_rx_char(int fd)
{
uart_dev_t* uart = s_ctx[fd]->uart;
if (uart->status.rxfifo_cnt == 0) {
return NONE;
}
return uart->fifo.rw_byte;
}
static int uart_rx_char_via_driver(int fd)
{
uint8_t c;
int timeout = s_ctx[fd]->non_blocking ? 0 : portMAX_DELAY;
int n = uart_read_bytes(fd, &c, 1, timeout);
if (n <= 0) {
return NONE;
}
return c;
}
static ssize_t uart_write(int fd, const void * data, size_t size)
{
assert(fd >=0 && fd < 3);
const char *data_c = (const char *)data;
/* 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_ctx[fd]->write_lock);
for (size_t i = 0; i < size; i++) {
int c = data_c[i];
if (c == '\n' && s_ctx[fd]->tx_mode != ESP_LINE_ENDINGS_LF) {
s_ctx[fd]->tx_func(fd, '\r');
if (s_ctx[fd]->tx_mode == ESP_LINE_ENDINGS_CR) {
continue;
}
}
s_ctx[fd]->tx_func(fd, c);
}
_lock_release_recursive(&s_ctx[fd]->write_lock);
return size;
}
/* Helper function which returns a previous character or reads a new one from
* UART. Previous character can be returned ("pushed back") using
* uart_return_char function.
*/
static int uart_read_char(int fd)
{
/* return character from peek buffer, if it is there */
if (s_ctx[fd]->peek_char != NONE) {
int c = s_ctx[fd]->peek_char;
s_ctx[fd]->peek_char = NONE;
return c;
}
return s_ctx[fd]->rx_func(fd);
}
/* Push back a character; it will be returned by next call to uart_read_char */
static void uart_return_char(int fd, int c)
{
assert(s_ctx[fd]->peek_char == NONE);
s_ctx[fd]->peek_char = c;
}
static ssize_t uart_read(int fd, void* data, size_t size)
{
assert(fd >=0 && fd < 3);
char *data_c = (char *) data;
size_t received = 0;
_lock_acquire_recursive(&s_ctx[fd]->read_lock);
while (received < size) {
int c = uart_read_char(fd);
if (c == '\r') {
if (s_ctx[fd]->rx_mode == ESP_LINE_ENDINGS_CR) {
c = '\n';
} else if (s_ctx[fd]->rx_mode == ESP_LINE_ENDINGS_CRLF) {
/* look ahead */
int c2 = uart_read_char(fd);
if (c2 == NONE) {
/* could not look ahead, put the current character back */
uart_return_char(fd, c);
break;
}
if (c2 == '\n') {
/* this was \r\n sequence. discard \r, return \n */
c = '\n';
} else {
/* \r followed by something else. put the second char back,
* it will be processed on next iteration. return \r now.
*/
uart_return_char(fd, c2);
}
}
} else if (c == NONE) {
break;
}
data_c[received] = (char) c;
++received;
if (c == '\n') {
break;
}
}
_lock_release_recursive(&s_ctx[fd]->read_lock);
if (received > 0) {
return received;
}
errno = EWOULDBLOCK;
return -1;
}
static int uart_fstat(int fd, struct stat * st)
{
assert(fd >=0 && fd < 3);
st->st_mode = S_IFCHR;
return 0;
}
static int uart_close(int fd)
{
assert(fd >=0 && fd < 3);
return 0;
}
static int uart_fcntl(int fd, int cmd, int arg)
{
assert(fd >=0 && fd < 3);
int result = 0;
if (cmd == F_GETFL) {
if (s_ctx[fd]->non_blocking) {
result |= O_NONBLOCK;
}
} else if (cmd == F_SETFL) {
s_ctx[fd]->non_blocking = (arg & O_NONBLOCK) != 0;
} else {
// unsupported operation
result = -1;
errno = ENOSYS;
}
return result;
}
static int uart_access(const char *path, int amode)
{
int ret = -1;
if (strcmp(path, "/0") == 0 || strcmp(path, "/1") == 0 || strcmp(path, "/2") == 0) {
if (F_OK == amode) {
ret = 0; //path exists
} else {
if ((((amode & R_OK) == R_OK) || ((amode & W_OK) == W_OK)) && ((amode & X_OK) != X_OK)) {
ret = 0; //path is readable and/or writable but not executable
} else {
errno = EACCES;
}
}
} else {
errno = ENOENT;
}
return ret;
}
static int uart_fsync(int fd)
{
assert(fd >= 0 && fd < 3);
_lock_acquire_recursive(&s_ctx[fd]->write_lock);
uart_tx_wait_idle((uint8_t) fd);
_lock_release_recursive(&s_ctx[fd]->write_lock);
return 0;
}
static void select_notif_callback(uart_port_t uart_num, uart_select_notif_t uart_select_notif, BaseType_t *task_woken)
{
switch (uart_select_notif) {
case UART_SELECT_READ_NOTIF:
if (FD_ISSET(uart_num, _readfds_orig)) {
FD_SET(uart_num, _readfds);
esp_vfs_select_triggered_isr(_select_sem, task_woken);
}
break;
case UART_SELECT_WRITE_NOTIF:
if (FD_ISSET(uart_num, _writefds_orig)) {
FD_SET(uart_num, _writefds);
esp_vfs_select_triggered_isr(_select_sem, task_woken);
}
break;
case UART_SELECT_ERROR_NOTIF:
if (FD_ISSET(uart_num, _errorfds_orig)) {
FD_SET(uart_num, _errorfds);
esp_vfs_select_triggered_isr(_select_sem, task_woken);
}
break;
}
}
static esp_err_t uart_start_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, esp_vfs_select_sem_t select_sem)
{
if (_lock_try_acquire(&s_one_select_lock)) {
return ESP_ERR_INVALID_STATE;
}
const int max_fds = MIN(nfds, UART_NUM);
portENTER_CRITICAL(uart_get_selectlock());
if (_readfds || _writefds || _errorfds || _readfds_orig || _writefds_orig || _errorfds_orig || _select_sem.sem) {
portEXIT_CRITICAL(uart_get_selectlock());
uart_end_select();
return ESP_ERR_INVALID_STATE;
}
if ((_readfds_orig = malloc(sizeof(fd_set))) == NULL) {
portEXIT_CRITICAL(uart_get_selectlock());
uart_end_select();
return ESP_ERR_NO_MEM;
}
if ((_writefds_orig = malloc(sizeof(fd_set))) == NULL) {
portEXIT_CRITICAL(uart_get_selectlock());
uart_end_select();
return ESP_ERR_NO_MEM;
}
if ((_errorfds_orig = malloc(sizeof(fd_set))) == NULL) {
portEXIT_CRITICAL(uart_get_selectlock());
uart_end_select();
return ESP_ERR_NO_MEM;
}
//uart_set_select_notif_callback set the callbacks in UART ISR
for (int i = 0; i < max_fds; ++i) {
if (FD_ISSET(i, readfds) || FD_ISSET(i, writefds) || FD_ISSET(i, exceptfds)) {
uart_set_select_notif_callback(i, select_notif_callback);
}
}
_select_sem = select_sem;
_readfds = readfds;
_writefds = writefds;
_errorfds = exceptfds;
*_readfds_orig = *readfds;
*_writefds_orig = *writefds;
*_errorfds_orig = *exceptfds;
FD_ZERO(readfds);
FD_ZERO(writefds);
FD_ZERO(exceptfds);
for (int i = 0; i < max_fds; ++i) {
if (FD_ISSET(i, _readfds_orig)) {
size_t buffered_size;
if (uart_get_buffered_data_len(i, &buffered_size) == ESP_OK && buffered_size > 0) {
// signalize immediately when data is buffered
FD_SET(i, _readfds);
esp_vfs_select_triggered(_select_sem);
}
}
}
portEXIT_CRITICAL(uart_get_selectlock());
// s_one_select_lock is not released on successfull exit - will be
// released in uart_end_select()
return ESP_OK;
}
static void uart_end_select(void)
{
portENTER_CRITICAL(uart_get_selectlock());
for (int i = 0; i < UART_NUM; ++i) {
uart_set_select_notif_callback(i, NULL);
}
_select_sem.sem = NULL;
_readfds = NULL;
_writefds = NULL;
_errorfds = NULL;
if (_readfds_orig) {
free(_readfds_orig);
_readfds_orig = NULL;
}
if (_writefds_orig) {
free(_writefds_orig);
_writefds_orig = NULL;
}
if (_errorfds_orig) {
free(_errorfds_orig);
_errorfds_orig = NULL;
}
portEXIT_CRITICAL(uart_get_selectlock());
_lock_release(&s_one_select_lock);
}
#ifdef CONFIG_VFS_SUPPORT_TERMIOS
static int uart_tcsetattr(int fd, int optional_actions, const struct termios *p)
{
if (fd < 0 || fd >= UART_NUM) {
errno = EBADF;
return -1;
}
if (p == NULL) {
errno = EINVAL;
return -1;
}
switch (optional_actions) {
case TCSANOW:
// nothing to do
break;
case TCSADRAIN:
if (uart_wait_tx_done(fd, portMAX_DELAY) != ESP_OK) {
errno = EINVAL;
return -1;
}
/* FALLTHRU */
case TCSAFLUSH:
if (uart_flush_input(fd) != ESP_OK) {
errno = EINVAL;
return -1;
}
break;
default:
errno = EINVAL;
return -1;
}
if (p->c_iflag & IGNCR) {
s_ctx[fd]->rx_mode = ESP_LINE_ENDINGS_CRLF;
} else if (p->c_iflag & ICRNL) {
s_ctx[fd]->rx_mode = ESP_LINE_ENDINGS_CR;
} else {
s_ctx[fd]->rx_mode = ESP_LINE_ENDINGS_LF;
}
// output line endings are not supported because there is no alternative in termios for converting LF to CR
{
uart_word_length_t data_bits;
const tcflag_t csize_bits = p->c_cflag & CSIZE;
switch (csize_bits) {
case CS5:
data_bits = UART_DATA_5_BITS;
break;
case CS6:
data_bits = UART_DATA_6_BITS;
break;
case CS7:
data_bits = UART_DATA_7_BITS;
break;
case CS8:
data_bits = UART_DATA_8_BITS;
break;
default:
errno = EINVAL;
return -1;
}
if (uart_set_word_length(fd, data_bits) != ESP_OK) {
errno = EINVAL;
return -1;
}
}
if (uart_set_stop_bits(fd, (p->c_cflag & CSTOPB) ? UART_STOP_BITS_2 : UART_STOP_BITS_1) != ESP_OK) {
errno = EINVAL;
return -1;
}
if (uart_set_parity(fd, (p->c_cflag & PARENB) ?
((p->c_cflag & PARODD) ? UART_PARITY_ODD : UART_PARITY_EVEN)
:
UART_PARITY_DISABLE) != ESP_OK) {
errno = EINVAL;
return -1;
}
if (p->c_cflag & (CBAUD | CBAUDEX)) {
if (p->c_ispeed != p->c_ospeed) {
errno = EINVAL;
return -1;
} else {
uint32_t b;
if (p->c_cflag & BOTHER) {
b = p->c_ispeed;
} else {
switch (p->c_ispeed) {
case B0:
b = 0;
break;
case B50:
b = 50;
break;
case B75:
b = 75;
break;
case B110:
b = 110;
break;
case B134:
b = 134;
break;
case B150:
b = 150;
break;
case B200:
b = 200;
break;
case B300:
b = 300;
break;
case B600:
b = 600;
break;
case B1200:
b = 1200;
break;
case B1800:
b = 1800;
break;
case B2400:
b = 2400;
break;
case B4800:
b = 4800;
break;
case B9600:
b = 9600;
break;
case B19200:
b = 19200;
break;
case B38400:
b = 38400;
break;
case B57600:
b = 57600;
break;
case B115200:
b = 115200;
break;
case B230400:
b = 230400;
break;
case B460800:
b = 460800;
break;
case B500000:
b = 500000;
break;
case B576000:
b = 576000;
break;
case B921600:
b = 921600;
break;
case B1000000:
b = 1000000;
break;
case B1152000:
b = 1152000;
break;
case B1500000:
b = 1500000;
break;
case B2000000:
b = 2000000;
break;
case B2500000:
b = 2500000;
break;
case B3000000:
b = 3000000;
break;
case B3500000:
b = 3500000;
break;
case B4000000:
b = 4000000;
break;
default:
errno = EINVAL;
return -1;
}
}
if (uart_set_baudrate(fd, b) != ESP_OK) {
errno = EINVAL;
return -1;
}
}
}
return 0;
}
static int uart_tcgetattr(int fd, struct termios *p)
{
if (fd < 0 || fd >= UART_NUM) {
errno = EBADF;
return -1;
}
if (p == NULL) {
errno = EINVAL;
return -1;
}
memset(p, 0, sizeof(struct termios));
if (s_ctx[fd]->rx_mode == ESP_LINE_ENDINGS_CRLF) {
p->c_iflag |= IGNCR;
} else if (s_ctx[fd]->rx_mode == ESP_LINE_ENDINGS_CR) {
p->c_iflag |= ICRNL;
}
{
uart_word_length_t data_bits;
if (uart_get_word_length(fd, &data_bits) != ESP_OK) {
errno = EINVAL;
return -1;
}
p->c_cflag &= (~CSIZE);
switch (data_bits) {
case UART_DATA_5_BITS:
p->c_cflag |= CS5;
break;
case UART_DATA_6_BITS:
p->c_cflag |= CS6;
break;
case UART_DATA_7_BITS:
p->c_cflag |= CS7;
break;
case UART_DATA_8_BITS:
p->c_cflag |= CS8;
break;
default:
errno = ENOSYS;
return -1;
}
}
{
uart_stop_bits_t stop_bits;
if (uart_get_stop_bits(fd, &stop_bits) != ESP_OK) {
errno = EINVAL;
return -1;
}
switch (stop_bits) {
case UART_STOP_BITS_1:
// nothing to do
break;
case UART_STOP_BITS_2:
p->c_cflag |= CSTOPB;
break;
default:
// UART_STOP_BITS_1_5 is unsupported by termios
errno = ENOSYS;
return -1;
}
}
{
uart_parity_t parity_mode;
if (uart_get_parity(fd, &parity_mode) != ESP_OK) {
errno = EINVAL;
return -1;
}
switch (parity_mode) {
case UART_PARITY_EVEN:
p->c_cflag |= PARENB;
break;
case UART_PARITY_ODD:
p->c_cflag |= (PARENB | PARODD);
break;
case UART_PARITY_DISABLE:
// nothing to do
break;
default:
errno = ENOSYS;
return -1;
}
}
{
uint32_t baudrate;
if (uart_get_baudrate(fd, &baudrate) != ESP_OK) {
errno = EINVAL;
return -1;
}
p->c_cflag |= (CBAUD | CBAUDEX);
speed_t sp;
switch (baudrate) {
case 0:
sp = B0;
break;
case 50:
sp = B50;
break;
case 75:
sp = B75;
break;
case 110:
sp = B110;
break;
case 134:
sp = B134;
break;
case 150:
sp = B150;
break;
case 200:
sp = B200;
break;
case 300:
sp = B300;
break;
case 600:
sp = B600;
break;
case 1200:
sp = B1200;
break;
case 1800:
sp = B1800;
break;
case 2400:
sp = B2400;
break;
case 4800:
sp = B4800;
break;
case 9600:
sp = B9600;
break;
case 19200:
sp = B19200;
break;
case 38400:
sp = B38400;
break;
case 57600:
sp = B57600;
break;
case 115200:
sp = B115200;
break;
case 230400:
sp = B230400;
break;
case 460800:
sp = B460800;
break;
case 500000:
sp = B500000;
break;
case 576000:
sp = B576000;
break;
case 921600:
sp = B921600;
break;
case 1000000:
sp = B1000000;
break;
case 1152000:
sp = B1152000;
break;
case 1500000:
sp = B1500000;
break;
case 2000000:
sp = B2000000;
break;
case 2500000:
sp = B2500000;
break;
case 3000000:
sp = B3000000;
break;
case 3500000:
sp = B3500000;
break;
case 4000000:
sp = B4000000;
break;
default:
p->c_cflag |= BOTHER;
sp = baudrate;
break;
}
p->c_ispeed = p->c_ospeed = sp;
}
return 0;
}
static int uart_tcdrain(int fd)
{
if (fd < 0 || fd >= UART_NUM) {
errno = EBADF;
return -1;
}
if (uart_wait_tx_done(fd, portMAX_DELAY) != ESP_OK) {
errno = EINVAL;
return -1;
}
return 0;
}
static int uart_tcflush(int fd, int select)
{
if (fd < 0 || fd >= UART_NUM) {
errno = EBADF;
return -1;
}
if (select == TCIFLUSH) {
if (uart_flush_input(fd) != ESP_OK) {
errno = EINVAL;
return -1;
}
} else {
// output flushing is not supported
errno = EINVAL;
return -1;
}
return 0;
}
#endif // CONFIG_VFS_SUPPORT_TERMIOS
void esp_vfs_dev_uart_register(void)
{
esp_vfs_t vfs = {
.flags = ESP_VFS_FLAG_DEFAULT,
.write = &uart_write,
.open = &uart_open,
.fstat = &uart_fstat,
.close = &uart_close,
.read = &uart_read,
.fcntl = &uart_fcntl,
.fsync = &uart_fsync,
.access = &uart_access,
.start_select = &uart_start_select,
.end_select = &uart_end_select,
#ifdef CONFIG_VFS_SUPPORT_TERMIOS
.tcsetattr = &uart_tcsetattr,
.tcgetattr = &uart_tcgetattr,
.tcdrain = &uart_tcdrain,
.tcflush = &uart_tcflush,
#endif // CONFIG_VFS_SUPPORT_TERMIOS
};
ESP_ERROR_CHECK(esp_vfs_register("/dev/uart", &vfs, NULL));
}
void esp_vfs_dev_uart_set_rx_line_endings(esp_line_endings_t mode)
{
for (int i = 0; i < UART_NUM; ++i) {
s_ctx[i]->rx_mode = mode;
}
}
void esp_vfs_dev_uart_set_tx_line_endings(esp_line_endings_t mode)
{
for (int i = 0; i < UART_NUM; ++i) {
s_ctx[i]->tx_mode = mode;
}
}
void esp_vfs_dev_uart_use_nonblocking(int uart_num)
{
_lock_acquire_recursive(&s_ctx[uart_num]->read_lock);
_lock_acquire_recursive(&s_ctx[uart_num]->write_lock);
s_ctx[uart_num]->tx_func = uart_tx_char;
s_ctx[uart_num]->rx_func = uart_rx_char;
_lock_release_recursive(&s_ctx[uart_num]->write_lock);
_lock_release_recursive(&s_ctx[uart_num]->read_lock);
}
void esp_vfs_dev_uart_use_driver(int uart_num)
{
_lock_acquire_recursive(&s_ctx[uart_num]->read_lock);
_lock_acquire_recursive(&s_ctx[uart_num]->write_lock);
s_ctx[uart_num]->tx_func = uart_tx_char_via_driver;
s_ctx[uart_num]->rx_func = uart_rx_char_via_driver;
_lock_release_recursive(&s_ctx[uart_num]->write_lock);
_lock_release_recursive(&s_ctx[uart_num]->read_lock);
}