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applications: serial_lte_modem: Use downstream UART backend #23163

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Merged
merged 1 commit into from
Jul 11, 2025
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applications: serial_lte_modem: Use downstream UART backend #23163

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8 changes: 6 additions & 2 deletions applications/serial_lte_modem/overlay-cmux.conf
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Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,12 @@ CONFIG_SLM_SKIP_READY_MSG=y
# Zephyr modem subsystem
CONFIG_MODEM_MODULES=y
CONFIG_MODEM_CMUX=y
CONFIG_MODEM_BACKEND_UART=y
CONFIG_MODEM_BACKEND_UART_ASYNC_TRANSMIT_TIMEOUT_MS=1000

# Enable SLM UART backend
CONFIG_MODEM_BACKEND_UART=n
CONFIG_MODEM_BACKEND_UART_ASYNC=n
CONFIG_MODEM_BACKEND_UART_SLM=y
CONFIG_MODEM_BACKEND_UART_SLM_TRANSMIT_TIMEOUT_MS=1000

# debug options
#CONFIG_MODEM_CMUX_LOG_LEVEL_DBG=y
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16 changes: 10 additions & 6 deletions applications/serial_lte_modem/overlay-ppp-cmux-linux.conf
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Original file line number Diff line number Diff line change
Expand Up @@ -9,16 +9,21 @@ CONFIG_SLM_CMUX=y
CONFIG_SLM_PPP=y
CONFIG_SLM_CR_TERMINATION=y

# Assume at least baudrate 115200 for UART
# so CMUX frame can be received in 12 ms (134*10/115200)
CONFIG_MODEM_BACKEND_UART_ASYNC_RECEIVE_IDLE_TIMEOUT_MS=12
CONFIG_MODEM_CMUX_MTU=127
CONFIG_MODEM_CMUX_WORK_BUFFER_SIZE=536
CONFIG_SLM_CMUX_UART_BUFFER_SIZE=6000

# Enable SLM UART backend
CONFIG_MODEM_BACKEND_UART=n
CONFIG_MODEM_BACKEND_UART_ASYNC=n
CONFIG_MODEM_BACKEND_UART_SLM=y

# For sending full 6000 bytes at 115200 baudrate
# 6000 * 10 / 115200 = 521 ms
CONFIG_MODEM_BACKEND_UART_ASYNC_TRANSMIT_TIMEOUT_MS=521
CONFIG_MODEM_BACKEND_UART_ASYNC_HWFC=y
CONFIG_MODEM_BACKEND_UART_SLM_TRANSMIT_TIMEOUT_MS=521
# Assume at least baudrate 115200 for UART
# so CMUX frame can be received in 12 ms (134*10/115200)
CONFIG_MODEM_BACKEND_UART_SLM_RECEIVE_IDLE_TIMEOUT_MS=12

# These buffers are unused after AT#CMUX is enabled
# so use minimal buffer size
Expand All @@ -43,7 +48,6 @@ CONFIG_NET_L2_PPP=y
CONFIG_MODEM_MODULES=y
CONFIG_MODEM_CMUX=y
CONFIG_MODEM_PPP=y
CONFIG_MODEM_BACKEND_UART=y

# L2 protocol
CONFIG_NET_L2_PPP_MGMT=y
Expand Down
9 changes: 6 additions & 3 deletions applications/serial_lte_modem/overlay-ppp.conf
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Original file line number Diff line number Diff line change
Expand Up @@ -23,9 +23,12 @@ CONFIG_NET_NATIVE=y
CONFIG_NET_L2_PPP=y
CONFIG_MODEM_MODULES=y
CONFIG_MODEM_PPP=y
CONFIG_MODEM_BACKEND_UART=y
CONFIG_MODEM_BACKEND_UART_ASYNC_TRANSMIT_TIMEOUT_MS=1000
CONFIG_MODEM_BACKEND_UART_ASYNC_HWFC=y

# Enable SLM UART backend
CONFIG_MODEM_BACKEND_UART=n
CONFIG_MODEM_BACKEND_UART_ASYNC=n
CONFIG_MODEM_BACKEND_UART_SLM=y
CONFIG_MODEM_BACKEND_UART_SLM_TRANSMIT_TIMEOUT_MS=1000

# L2 protocol
CONFIG_NET_L2_PPP_MGMT=y
Expand Down
9 changes: 5 additions & 4 deletions applications/serial_lte_modem/src/slm_cmux.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@
#endif
#include "slm_util.h"
#include <zephyr/logging/log.h>
#include <zephyr/modem/backend/uart.h>
#include <zephyr/modem/backend/uart_slm.h>
#include <zephyr/modem/cmux.h>
#include <zephyr/modem/pipe.h>
#include <assert.h>
Expand All @@ -35,7 +35,7 @@ static struct {
/* UART backend */
struct modem_pipe *uart_pipe;
bool uart_pipe_open;
struct modem_backend_uart uart_backend;
struct modem_backend_uart_slm uart_backend;
uint8_t uart_backend_receive_buf[CONFIG_SLM_CMUX_UART_BUFFER_SIZE]
__aligned(sizeof(void *));
uint8_t uart_backend_transmit_buf[CONFIG_SLM_CMUX_UART_BUFFER_SIZE];
Expand Down Expand Up @@ -348,15 +348,16 @@ static int cmux_start(void)
}

{
const struct modem_backend_uart_config uart_backend_config = {
const struct modem_backend_uart_slm_config uart_backend_config = {
.uart = DEVICE_DT_GET(DT_CHOSEN(ncs_slm_uart)),
.receive_buf = cmux.uart_backend_receive_buf,
.receive_buf_size = sizeof(cmux.uart_backend_receive_buf),
.transmit_buf = cmux.uart_backend_transmit_buf,
.transmit_buf_size = sizeof(cmux.uart_backend_transmit_buf),
};

cmux.uart_pipe = modem_backend_uart_init(&cmux.uart_backend, &uart_backend_config);
cmux.uart_pipe =
modem_backend_uart_slm_init(&cmux.uart_backend, &uart_backend_config);
if (!cmux.uart_pipe) {
return -ENODEV;
}
Expand Down
8 changes: 4 additions & 4 deletions applications/serial_lte_modem/src/slm_ppp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@
#include <modem/lte_lc.h>
#include <modem/pdn.h>
#include <zephyr/modem/ppp.h>
#include <zephyr/modem/backend/uart.h>
#include <zephyr/modem/backend/uart_slm.h>
#include <zephyr/net/ethernet.h>
#include <zephyr/net/net_if.h>
#include <zephyr/net/ppp.h>
Expand Down Expand Up @@ -594,20 +594,20 @@ int slm_ppp_init(void)
}

{
static struct modem_backend_uart ppp_uart_backend;
static struct modem_backend_uart_slm ppp_uart_backend;
static uint8_t ppp_uart_backend_receive_buf[sizeof(ppp_data_buf)]
__aligned(sizeof(void *));
static uint8_t ppp_uart_backend_transmit_buf[sizeof(ppp_data_buf)];

const struct modem_backend_uart_config uart_backend_config = {
const struct modem_backend_uart_slm_config uart_backend_config = {
.uart = ppp_uart_dev,
.receive_buf = ppp_uart_backend_receive_buf,
.receive_buf_size = sizeof(ppp_uart_backend_receive_buf),
.transmit_buf = ppp_uart_backend_transmit_buf,
.transmit_buf_size = sizeof(ppp_uart_backend_transmit_buf),
};

ppp_pipe = modem_backend_uart_init(&ppp_uart_backend, &uart_backend_config);
ppp_pipe = modem_backend_uart_slm_init(&ppp_uart_backend, &uart_backend_config);
if (!ppp_pipe) {
return -ENOSYS;
}
Expand Down
2 changes: 1 addition & 1 deletion west.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ manifest:
# https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/modules.html
- name: zephyr
repo-path: sdk-zephyr
revision: 926fafbe9f0745eb3c3f0b37e8bfa9c0afc1db13
revision: 964736df4b123d94117477fd05337f999b025026
import:
# In addition to the zephyr repository itself, NCS also
# imports the contents of zephyr/west.yml at the above
Expand Down
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