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drivers: serial: uart_rtt converted to devicetree
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Instantiate RTT UART instances from devicetree nodes instead of from
Kconfig symbols. While RTT is implemented using software, not hardware,
it is emulating a hardware device, and thus should be configured through
devicetree. This allows the simulated UART device to be selected via
devicetree aliases and chosen nodes.

The following devicetree snippet will instantiate RTT channels 0 and 2
as UART devices.
```
/ {
	rtt0: rtt_terminal {
		compatible = "segger,rtt-uart";
		label = "rtt_terminal";
		status = "okay";
	};

	rtt2: rtt_secondary {
		compatible = "segger,rtt-uart";
		label = "rtt_app_specific";
		status = "okay";
	};
};
```

Fixes the RTT portion of #10621.

Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>
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@carlescufi
Jordan Yates authored and carlescufi committed Sep 3, 2020
1 parent 742256f commit 3e33d73
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Showing 3 changed files with 68 additions and 90 deletions.
65 changes: 7 additions & 58 deletions drivers/serial/Kconfig.rtt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,11 @@ menuconfig UART_RTT

if UART_RTT

# Workaround for not being able to have commas in macro arguments
DT_COMPAT_SEGGER_RTT_UART := segger,rtt-uart

config UART_RTT_0
bool "Enable UART on RTT channel 0"
def_bool $(dt_nodelabel_has_compat,rtt0,$(DT_COMPAT_SEGGER_RTT_UART))
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
Expand All @@ -21,83 +24,29 @@ config UART_RTT_0
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"
def_bool $(dt_nodelabel_has_compat,rtt1,$(DT_COMPAT_SEGGER_RTT_UART))
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"
def_bool $(dt_nodelabel_has_compat,rtt2,$(DT_COMPAT_SEGGER_RTT_UART))
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"
def_bool $(dt_nodelabel_has_compat,rtt3,$(DT_COMPAT_SEGGER_RTT_UART))
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

Expand Down
66 changes: 34 additions & 32 deletions drivers/serial/uart_rtt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@
#include <drivers/uart.h>
#include <SEGGER_RTT.h>

#define DT_DRV_COMPAT segger_rtt_uart

struct uart_rtt_config {
void *up_buffer;
size_t up_size;
Expand Down Expand Up @@ -77,44 +79,44 @@ static const struct uart_driver_api uart_rtt_driver_api = {
.poll_out = uart_rtt_poll_out,
};

#if CONFIG_UART_RTT_0
#define UART_RTT(idx) DT_NODELABEL(rtt##idx)
#define UART_RTT_PROP(idx, prop) DT_PROP(UART_RTT(idx), prop)
#define UART_RTT_CONFIG_NAME(idx) uart_rtt##idx##_config

#define UART_RTT_CONFIG(idx) \
static \
uint8_t uart_rtt##idx##_tx_buf[UART_RTT_PROP(idx, tx_buffer_size)]; \
static \
uint8_t uart_rtt##idx##_rx_buf[UART_RTT_PROP(idx, rx_buffer_size)]; \
\
static const struct uart_rtt_config UART_RTT_CONFIG_NAME(idx) = { \
.up_buffer = uart_rtt##idx##_tx_buf, \
.up_size = sizeof(uart_rtt##idx##_tx_buf), \
.down_buffer = uart_rtt##idx##_rx_buf, \
.down_size = sizeof(uart_rtt##idx##_rx_buf), \
}

DEVICE_AND_API_INIT(uart_rtt0, "RTT_0", uart_rtt_init, NULL, NULL,
/* Initialize UART device after RTT init. */
PRE_KERNEL_2, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
&uart_rtt_driver_api);
#define UART_RTT_INIT(idx, config) \
DEVICE_AND_API_INIT(uart_rtt##idx, DT_LABEL(UART_RTT(idx)), \
uart_rtt_init, NULL, config, \
PRE_KERNEL_2, CONFIG_KERNEL_INIT_PRIORITY_DEVICE, \
&uart_rtt_driver_api)

#ifdef CONFIG_UART_RTT_0
UART_RTT_INIT(0, NULL);
#endif

#define UART_RTT_CHANNEL(n) \
static uint8_t \
uart_rtt##n##_tx_buffer[CONFIG_UART_RTT_##n##_TX_BUFFER_SIZE]; \
static uint8_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_AND_API_INIT(uart_rtt##n, uart_rtt##n##_name, uart_rtt_init, \
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);
#ifdef CONFIG_UART_RTT_1
UART_RTT_CONFIG(1);
UART_RTT_INIT(1, &UART_RTT_CONFIG_NAME(1));
#endif

#if CONFIG_UART_RTT_2
UART_RTT_CHANNEL(2);
#ifdef CONFIG_UART_RTT_2
UART_RTT_CONFIG(2);
UART_RTT_INIT(2, &UART_RTT_CONFIG_NAME(2));
#endif

#if CONFIG_UART_RTT_3
UART_RTT_CHANNEL(3);
#ifdef CONFIG_UART_RTT_3
UART_RTT_CONFIG(3);
UART_RTT_INIT(3, &UART_RTT_CONFIG_NAME(3));
#endif
27 changes: 27 additions & 0 deletions dts/bindings/serial/segger,rtt-uart.yaml
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
# Copyright (c) 2020, CSIRO.
# SPDX-License-Identifier: Apache-2.0

description: Segger RTT UART

compatible: "segger,rtt-uart"

include: uart-controller.yaml

properties:
tx-buffer-size:
type: int
default: 1024
description: |
Size of the RTT up buffer for transmission
Not used for RTT channel 0 as channel 0 is initialized at compile time,
see SEGGER_RTT_BUFFER_SIZE_UP.
required: false

rx-buffer-size:
type: int
default: 16
description: |
Size of the RTT down buffer for reception
Not used for RTT channel 0 as channel 0 is initialized at compile time,
see SEGGER_RTT_BUFFER_SIZE_DOWN.
required: false

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