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drivers: serial: uart_rtt: Virtual UARTs over RTT channels

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>
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pkral78 authored and carlescufi committed Jul 15, 2019
1 parent 61733a8 commit b7db90da43544ca0fbf4ad165bd4b66a9a255fe0
Showing with 230 additions and 0 deletions.
  1. +2 −0 CODEOWNERS
  2. +1 −0 drivers/serial/CMakeLists.txt
  3. +2 −0 drivers/serial/Kconfig
  4. +105 −0 drivers/serial/Kconfig.rtt
  5. +120 −0 drivers/serial/uart_rtt.c
@@ -151,6 +151,8 @@
/drivers/serial/*ns16550* @gnuless
/drivers/serial/Kconfig.litex @mateusz-holenko @kgugala @pgielda
/drivers/serial/uart_liteuart.c @mateusz-holenko @kgugala @pgielda
/drivers/serial/Kconfig.rtt @carlescufi @pkral78
/drivers/serial/uart_rtt.c @carlescufi @pkral78
/drivers/net/ @jukkar @tbursztyka
/drivers/ptp_clock/ @jukkar
/drivers/spi/ @tbursztyka
@@ -29,6 +29,7 @@ zephyr_library_sources_if_kconfig(uart_psoc6.c)
zephyr_library_sources_if_kconfig(uart_pl011.c)
zephyr_library_sources_if_kconfig(uart_rv32m1_lpuart.c)
zephyr_library_sources_if_kconfig(uart_liteuart.c)
zephyr_library_sources_ifdef(CONFIG_UART_RTT_DRIVER uart_rtt.c)

zephyr_library_sources_ifdef(CONFIG_USERSPACE uart_handlers.c)

@@ -125,4 +125,6 @@ source "drivers/serial/Kconfig.rv32m1_lpuart"

source "drivers/serial/Kconfig.litex"

source "drivers/serial/Kconfig.rtt"

endif # SERIAL
@@ -0,0 +1,105 @@
# Kconfig - Virtual UART RTT driver option
#
# Copyright (c) 2019 omSquare s.r.o.
#
# SPDX-License-Identifier: Apache-2.0

menuconfig UART_RTT
bool "Enable UART RTT driver"
depends on USE_SEGGER_RTT
help
This option enables access RTT channel as UART device.

if UART_RTT

config UART_RTT_0
bool "Enable UART on RTT channel 0"
depends on SEGGER_RTT_MAX_NUM_UP_BUFFERS >= 1 && SEGGER_RTT_MAX_NUM_DOWN_BUFFERS >= 1
depends on SEGGER_RTT_MODE_NO_BLOCK_SKIP
select SERIAL_HAS_DRIVER
select UART_RTT_DRIVER
help
Enable UART on (default) RTT channel 0. Default channel has to be configured in non-blocking skip mode.

config UART_RTT_1
bool "Enable UART on RTT channel 1"
depends on SEGGER_RTT_MAX_NUM_UP_BUFFERS >= 2 && SEGGER_RTT_MAX_NUM_DOWN_BUFFERS >= 2
select SERIAL_HAS_DRIVER
select UART_RTT_DRIVER
help
Enable UART on RTT channel 1

if UART_RTT_1

config UART_RTT_1_TX_BUFFER_SIZE
int "Size of RTT_1 TX buffer (up to host)"
range 1 65535
default 1024
help
Size of the RTT up buffer for UART 1 transmission.

config UART_RTT_1_RX_BUFFER_SIZE
int "Size of RTT_1 RX buffer (down from host)"
range 1 65535
default 16
help
Size of the RTT down buffer for UART 1 reception.

endif

config UART_RTT_2
bool "Enable UART on RTT channel 2"
depends on SEGGER_RTT_MAX_NUM_UP_BUFFERS >= 3 && SEGGER_RTT_MAX_NUM_DOWN_BUFFERS >= 3
select SERIAL_HAS_DRIVER
select UART_RTT_DRIVER
help
Enable UART on RTT channel 2

if UART_RTT_2

config UART_RTT_2_TX_BUFFER_SIZE
int "Size of RTT_2 TX buffer (up to host)"
range 1 65535
default 1024
help
Size of the RTT up buffer for UART 2 transmission.

config UART_RTT_2_RX_BUFFER_SIZE
int "Size of RTT_2 RX buffer (down from host)"
range 1 65535
default 16
help
Size of the RTT down buffer for UART 2 reception.

endif

config UART_RTT_3
bool "Enable UART on RTT channel 3"
depends on SEGGER_RTT_MAX_NUM_UP_BUFFERS >= 4 && SEGGER_RTT_MAX_NUM_DOWN_BUFFERS >= 4
select SERIAL_HAS_DRIVER
select UART_RTT_DRIVER
help
Enable UART on RTT channel 3

if UART_RTT_3

config UART_RTT_3_TX_BUFFER_SIZE
int "Size of RTT_3 TX buffer (up to host)"
range 1 65535
default 1024
help
Size of the RTT up buffer for UART 3 transmission.

config UART_RTT_3_RX_BUFFER_SIZE
int "Size of RTT_3 RX buffer (down from host)"
range 1 65535
default 16
help
Size of the RTT down buffer for UART 3 reception.

endif

config UART_RTT_DRIVER
bool

endif
@@ -0,0 +1,120 @@
/*
* 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

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