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uart: add a function to query current UART settings

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This patch adds a function to query UART settings in an unintrusive way.
It can be used using a uart index or a devpath and it strives to just
read out the settings without affecting the state of the UART.

Signed-off-by: Tapani Utriainen <tapani@technexion.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
This commit is contained in:
Tapani Utriainen
2017-05-19 21:28:30 +08:00
committed by Brendan Le Foll
parent d6edf76680
commit a6f2464bb1
2 changed files with 126 additions and 0 deletions
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91
src/uart/uart.c
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@@ -351,6 +351,97 @@ mraa_uart_stop(mraa_uart_context dev)
return MRAA_SUCCESS;
}
mraa_result_t
mraa_uart_settings(int index, const char **devpath, const char **name, int* baudrate, int* databits, int* stopbits, mraa_uart_parity_t* parity, unsigned int* ctsrts, unsigned int* xonxoff) {
struct termios term;
int fd;
if (plat == NULL) {
return MRAA_ERROR_PLATFORM_NOT_INITIALISED;
}
/* Access through UART index? */
if (index >= 0 && index < plat->uart_dev_count) {
if (devpath != NULL) {
*devpath = plat->uart_dev[index].device_path;
}
if (name != NULL) {
*name = plat->uart_dev[index].name;
}
}
/* is any information that requires opening the device requested? */
if (baudrate != NULL || stopbits != NULL || parity != NULL || databits != NULL || ctsrts != NULL || xonxoff != NULL) {
const char *dev;
/* Access UART by index or devpath? */
if (index >=0 && index < plat->uart_dev_count) {
dev = plat->uart_dev[index].device_path;
} else
if (devpath != NULL) {
dev = *devpath;
} else {
return MRAA_ERROR_INVALID_RESOURCE;
}
fd = open(dev, O_RDONLY | O_NOCTTY);
if (fd < 0) {
return MRAA_ERROR_INVALID_RESOURCE;
}
if (tcgetattr(fd, &term)) {
close(fd);
return MRAA_ERROR_INVALID_RESOURCE;
}
if (databits != NULL) {
switch (term.c_cflag & CSIZE) {
case CS8:
*databits = 8;
break;
case CS7:
*databits = 7;
break;
case CS6:
*databits = 6;
break;
case CS5:
*databits = 5;
default: /* Cannot happen? Linux kernel CSIZE mask is exactly two bits wide */
break;
}
}
if (stopbits != NULL) {
*stopbits = term.c_cflag & CSTOPB ? 2 : 1;
}
if (parity != NULL) {
if (term.c_cflag & PARODD) *parity = MRAA_UART_PARITY_ODD;
else
if (term.c_cflag & PARENB) *parity = MRAA_UART_PARITY_EVEN;
else
*parity = MRAA_UART_PARITY_NONE;
}
if (baudrate != NULL) {
*baudrate = speed_to_uint(cfgetospeed(&term));
}
if (ctsrts != NULL) {
*ctsrts = term.c_cflag & CRTSCTS;
}
if (xonxoff != NULL) {
*xonxoff = term.c_cflag & (IXON|IXOFF);
}
close(fd);
}
return MRAA_SUCCESS;
}
mraa_result_t
mraa_uart_flush(mraa_uart_context dev)
{