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modem: cellular: baudrate update from devicetree #97702

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4dd6c4e
modem: chat: dynamic selection of request
JordanYates Oct 16, 2025
9df0cf4
tests: modem: chat: test command from function
JordanYates Oct 16, 2025
2e3c4e0
modem: cellular: baudrate update from devicetree
JordanYates Oct 16, 2025
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6 changes: 6 additions & 0 deletions doc/releases/migration-guide-4.3.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,12 @@ MISC
the ``NRF_ETR`` symbols. Also the driver needs to be explicitly enabled via
:kconfig:option:`DEBUG_DRIVER` as it is no longer built by default.

Modem
=====

* ``CONFIG_MODEM_CELLULAR_NEW_BAUDRATE`` has been removed. Updated baudrates
are now specified in devicetree as the ``target-speed`` property.

PWM
===

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6 changes: 0 additions & 6 deletions drivers/modem/Kconfig.cellular
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Expand Up @@ -63,12 +63,6 @@ config MODEM_CELLULAR_USER_PIPE_BUFFER_SIZES
int "The size of the buffers used for each user pipe in bytes."
default 128

config MODEM_CELLULAR_NEW_BAUDRATE
int "New baudrate to configure modem to, if supported"
range 9600 4000000
default 3000000 if DT_HAS_U_BLOX_LARA_R6_ENABLED
default 115200

config MODEM_CELLULAR_NEW_BAUDRATE_DELAY
int "Time modem takes to change baudrate, in milliseconds"
range 0 1000
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17 changes: 14 additions & 3 deletions drivers/modem/modem_cellular.c
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Expand Up @@ -108,6 +108,8 @@ struct modem_cellular_data {
struct modem_backend_uart uart_backend;
uint8_t uart_backend_receive_buf[CONFIG_MODEM_CELLULAR_UART_BUFFER_SIZES];
uint8_t uart_backend_transmit_buf[CONFIG_MODEM_CELLULAR_UART_BUFFER_SIZES];
const char *target_baudrate_req;
uint32_t target_baudrate;
uint32_t original_baudrate;

/* CMUX */
Expand Down Expand Up @@ -1062,7 +1064,7 @@ static void modem_cellular_set_baudrate_event_handler(struct modem_cellular_data

/* Update UART port baudrate and preserve the original value */
data->original_baudrate = modem_cellular_baudrate_update(
data, CONFIG_MODEM_CELLULAR_NEW_BAUDRATE);
data, data->target_baudrate);
break;

case MODEM_CELLULAR_EVENT_BUS_CLOSED:
Expand Down Expand Up @@ -2181,6 +2183,14 @@ static void modem_cellular_init_apn(struct modem_cellular_data *data)
modem_cellular_chat_callback_handler);
}

__maybe_unused static uint16_t modem_baudrate_cmd(const uint8_t **request, void *user_data)
{
struct modem_cellular_data *data = (struct modem_cellular_data *)user_data;

*request = data->target_baudrate_req;
return strlen(*request);
}

static int modem_cellular_init(const struct device *dev)
{
struct modem_cellular_data *data = (struct modem_cellular_data *)dev->data;
Expand Down Expand Up @@ -2656,8 +2666,7 @@ MODEM_CHAT_SCRIPT_DEFINE(u_blox_sara_r5_periodic_chat_script,
#if DT_HAS_COMPAT_STATUS_OKAY(u_blox_lara_r6)
MODEM_CHAT_SCRIPT_CMDS_DEFINE(u_blox_lara_r6_set_baudrate_chat_script_cmds,
MODEM_CHAT_SCRIPT_CMD_RESP("ATE0", ok_match),
MODEM_CHAT_SCRIPT_CMD_RESP("AT+IPR="
STRINGIFY(CONFIG_MODEM_CELLULAR_NEW_BAUDRATE), ok_match));
MODEM_CHAT_SCRIPT_CMD_RESP_FN(modem_baudrate_cmd, ok_match));

MODEM_CHAT_SCRIPT_DEFINE(u_blox_lara_r6_set_baudrate_chat_script,
u_blox_lara_r6_set_baudrate_chat_script_cmds,
Expand Down Expand Up @@ -3141,6 +3150,8 @@ MODEM_CHAT_SCRIPT_DEFINE(sqn_gm02s_periodic_chat_script,
.chat_delimiter = "\r", \
.chat_filter = "\n", \
.ppp = &MODEM_CELLULAR_INST_NAME(ppp, inst), \
.target_baudrate_req = "AT+IPR=" STRINGIFY(DT_INST_PROP(inst, target_speed)), \
.target_baudrate = DT_INST_PROP(inst, target_speed), \
}; \
\
MODEM_CELLULAR_DEFINE_AND_INIT_USER_PIPES(inst, \
Expand Down
7 changes: 7 additions & 0 deletions dts/bindings/modem/u-blox,lara-r6.yaml
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Expand Up @@ -11,3 +11,10 @@ properties:
mdm-power-gpios:
type: phandle-array
required: true

target-speed:
type: int
default: 3000000
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Isn't baud rate dependent on host capabilities? Might a more conservative default of 1000000 be better?

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Absolutely, and this was the primary motivation for the change. The value of 3000000 was chosen to match the deprecated kconfig option, but I can drop it back to 921600 or something if that is preferable.

description:
UART baudrate which will be requested using AT commands and to which
UART interface will be reconfigured during initialization phase.
53 changes: 51 additions & 2 deletions include/zephyr/modem/chat.h
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Expand Up @@ -104,12 +104,34 @@ extern const struct modem_chat_match modem_chat_any_match;
/* Helper struct to match nothing. */
extern const struct modem_chat_match modem_chat_empty_matches[0];

/* Special value that signifies union member is `request_fn`, not `request` */
#define MODEM_CHAT_REQUEST_FN_LEN UINT16_MAX

/**
* @brief Function that retrieves the request to send
*
* @note The lifetime of the output request pointer must match or exceed the
* lifetime of script_chat.
*
* @note This function can be called multiple times per request that is sent.
*
* @param request pointer to store the request in
* @param user_data modem chat user data
*
* @retval Length of @a request
*/
typedef uint16_t (*modem_chat_script_request_fn)(const uint8_t **request, void *user_data);

/**
* @brief Modem chat script chat
*/
struct modem_chat_script_chat {
/** Request to send to modem */
const uint8_t *request;
union {
/** Request to send to modem */
const uint8_t *request;
/** Function that returns request to send to modem */
modem_chat_script_request_fn request_fn;
};
/** Size of request */
uint16_t request_size;
/** Expected responses to request */
Expand Down Expand Up @@ -147,6 +169,33 @@ struct modem_chat_script_chat {
.timeout = _timeout_ms, \
}

#define MODEM_CHAT_SCRIPT_CMD_RESP_FN(_request_fn, _response_match) \
{ \
.request_fn = _request_fn, \
.request_size = MODEM_CHAT_REQUEST_FN_LEN, \
.response_matches = &_response_match, \
.response_matches_size = 1, \
.timeout = 0, \
}

#define MODEM_CHAT_SCRIPT_CMD_RESP_MULT_FN(_request_fn, _response_matches) \
{ \
.request_fn = _request_fn, \
.request_size = MODEM_CHAT_REQUEST_FN_LEN, \
.response_matches = _response_matches, \
.response_matches_size = ARRAY_SIZE(_response_matches), \
.timeout = 0, \
}

#define MODEM_CHAT_SCRIPT_CMD_RESP_NONE_FN(_request_fn, _timeout_ms) \
{ \
.request_fn = _request_fn, \
.request_size = MODEM_CHAT_REQUEST_FN_LEN, \
.response_matches = NULL, \
.response_matches_size = 0, \
.timeout = _timeout_ms, \
}

#define MODEM_CHAT_SCRIPT_CMDS_DEFINE(_sym, ...) \
const static struct modem_chat_script_chat _sym[] = {__VA_ARGS__}

Expand Down
17 changes: 11 additions & 6 deletions subsys/modem/modem_chat.c
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Expand Up @@ -275,19 +275,24 @@ static bool modem_chat_send_script_request_part(struct modem_chat *chat)
const struct modem_chat_script_chat *script_chat =
&chat->script->script_chats[chat->script_chat_it];

uint8_t *request_part;
const uint8_t *request_part;
uint16_t request_size;
uint16_t request_part_size;
int ret;

switch (chat->script_send_state) {
case MODEM_CHAT_SCRIPT_SEND_STATE_REQUEST:
request_part = (uint8_t *)(&script_chat->request[chat->script_send_pos]);
request_size = script_chat->request_size;
if (script_chat->request_size == MODEM_CHAT_REQUEST_FN_LEN) {
request_size = script_chat->request_fn(&request_part, chat->user_data);
request_part += chat->script_send_pos;
} else {
request_part = (uint8_t *)(&script_chat->request[chat->script_send_pos]);
request_size = script_chat->request_size;
}
break;

case MODEM_CHAT_SCRIPT_SEND_STATE_DELIMITER:
request_part = (uint8_t *)(&chat->delimiter[chat->script_send_pos]);
request_part = &chat->delimiter[chat->script_send_pos];
request_size = chat->delimiter_size;
break;

Expand Down Expand Up @@ -1007,9 +1012,9 @@ int modem_chat_script_chat_set_request(struct modem_chat_script_chat *script_cha
{
size_t size;

size = strnlen(request, UINT16_MAX + 1);
size = strnlen(request, UINT16_MAX);

if (size == (UINT16_MAX + 1)) {
if (size == (UINT16_MAX)) {
return -ENOMEM;
}

Expand Down
26 changes: 26 additions & 0 deletions tests/subsys/modem/modem_chat/src/main.c
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Expand Up @@ -148,6 +148,18 @@ static void on_script_result(struct modem_chat *cmd, enum modem_chat_script_resu
script_result_user_data = user_data;
}

/*************************************************************************************************/
/* Dynamic Command */
/*************************************************************************************************/

static uint16_t modem_baudrate_cmd(const uint8_t **request, void *user_data)
{
static const char cmd[] = "AT+IPR=921600";

*request = cmd;
return sizeof(cmd) - 1;
}

/*************************************************************************************************/
/* Script */
/*************************************************************************************************/
Expand All @@ -165,6 +177,7 @@ MODEM_CHAT_MATCHES_DEFINE(unsol_matches, MODEM_CHAT_MATCH("RDY", "", on_rdy),
MODEM_CHAT_SCRIPT_CMDS_DEFINE(
script_cmds, MODEM_CHAT_SCRIPT_CMD_RESP("AT", ok_match),
MODEM_CHAT_SCRIPT_CMD_RESP("ATE0", ok_match),
MODEM_CHAT_SCRIPT_CMD_RESP_FN(modem_baudrate_cmd, ok_match),
MODEM_CHAT_SCRIPT_CMD_RESP("IMEI?", imei_match), MODEM_CHAT_SCRIPT_CMD_RESP("", ok_match),
MODEM_CHAT_SCRIPT_CMD_RESP("AT+CREG?;+CGREG?", creg_match),
MODEM_CHAT_SCRIPT_CMD_RESP("", cgreg_match), MODEM_CHAT_SCRIPT_CMD_RESP("", ok_match),
Expand Down Expand Up @@ -345,6 +358,19 @@ ZTEST(modem_chat, test_script_no_error)

k_msleep(100);

/*
* Script sends "AT+IPR=921600\r\n"
* Modem responds "OK\r\n"
*/

modem_backend_mock_get(&mock, buffer, ARRAY_SIZE(buffer));
zassert_true(memcmp(buffer, "AT+IPR=921600\r\n", sizeof("AT+IPR=921600\r\n") - 1) == 0,
"Request not sent as expected");

modem_backend_mock_put(&mock, ok_response, sizeof(ok_response) - 1);

k_msleep(100);

/*
* Script sends "IMEI?\r\n"
* Modem responds "23412354123123\r\n"
Expand Down