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drivers: serial: uart_rtt: Virtual UARTs over RTT channels

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Add support for virtual UART device that uses Segger RTT channels
for data transfers. Due to the RTT principle, this driver supports
only polling API.

Signed-off-by: Pavel Kral <pavel.kral@omsquare.com>
This commit is contained in:
Pavel Kral 2019-07-15 18:47:43 +02:00 • committed by Carles Cufí
commit b7db90da43
5 changed files with 230 additions and 0 deletions
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drivers/serial/uart_rtt.c Normal file
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/*
* Copyright (c) 2019 omSquare s.r.o.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <drivers/uart.h>
#include <SEGGER_RTT.h>
struct uart_rtt_config {
void *up_buffer;
size_t up_size;
void *down_buffer;
size_t down_size;
u8_t channel;
};
static inline const struct uart_rtt_config *get_dev_config(struct device *dev)
{
return dev->config->config_info;
}
static int uart_rtt_init(struct device *dev)
{
/*
* Channel 0 is initialized at compile-time, Kconfig ensures that
* it is configured in correct, non-blocking mode. Other channels
* need to be configured at run-time.
*/
if (get_dev_config(dev)) {
const struct uart_rtt_config *cfg = get_dev_config(dev);
SEGGER_RTT_ConfigUpBuffer(cfg->channel, dev->config->name,
cfg->up_buffer, cfg->up_size,
SEGGER_RTT_MODE_NO_BLOCK_SKIP);
SEGGER_RTT_ConfigDownBuffer(cfg->channel, dev->config->name,
cfg->down_buffer, cfg->down_size,
SEGGER_RTT_MODE_NO_BLOCK_SKIP);
}
return 0;
}
/**
* @brief Poll the device for input.
*
* @param dev UART device struct
* @param c Pointer to character
*
* @return 0 if a character arrived, -1 if the input buffer if empty.
*/
static int uart_rtt_poll_in(struct device *dev, unsigned char *c)
{
unsigned int ch =
get_dev_config(dev) ? get_dev_config(dev)->channel : 0;
unsigned int ret = SEGGER_RTT_Read(ch, c, 1);
return ret ? 0 : -1;
}
/**
* @brief Output a character in polled mode.
*
* @param dev UART device struct
* @param c Character to send
*/
static void uart_rtt_poll_out(struct device *dev, unsigned char c)
{
unsigned int ch =
get_dev_config(dev) ? get_dev_config(dev)->channel : 0;
SEGGER_RTT_Write(ch, &c, 1);
}
static const struct uart_driver_api uart_rtt_driver_api = {
.poll_in = uart_rtt_poll_in,
.poll_out = uart_rtt_poll_out,
};
#if CONFIG_UART_RTT_0
DEVICE_DEFINE(uart_rtt0, "RTT_0", uart_rtt_init, NULL, NULL, NULL,
/* Initialize UART device after RTT init. */
PRE_KERNEL_2, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
&uart_rtt_driver_api);
#endif
#define UART_RTT_CHANNEL(n) \
static u8_t \
uart_rtt##n##_tx_buffer[CONFIG_UART_RTT_##n##_TX_BUFFER_SIZE]; \
static u8_t \
uart_rtt##n##_rx_buffer[CONFIG_UART_RTT_##n##_RX_BUFFER_SIZE]; \
\
static const char uart_rtt##n##_name[] = "RTT_" #n "\0"; \
\
static const struct uart_rtt_config uart_rtt##n##_config = { \
.channel = n, \
.up_buffer = uart_rtt##n##_tx_buffer, \
.up_size = sizeof(uart_rtt##n##_tx_buffer), \
.down_buffer = uart_rtt##n##_rx_buffer, \
.down_size = sizeof(uart_rtt##n##_rx_buffer), \
}; \
\
DEVICE_DEFINE(uart_rtt##n, uart_rtt##n##_name, uart_rtt_init, NULL, \
NULL, &uart_rtt##n##_config, PRE_KERNEL_2, \
CONFIG_KERNEL_INIT_PRIORITY_DEVICE, \
&uart_rtt_driver_api)
#if CONFIG_UART_RTT_1
UART_RTT_CHANNEL(1);
#endif
#if CONFIG_UART_RTT_2
UART_RTT_CHANNEL(2);
#endif
#if CONFIG_UART_RTT_3
UART_RTT_CHANNEL(3);
#endif