Many modems implement socket-based APIs to manage data connections.
This layer provides much of the groundwork for keeping track of
these "sockets" throughout their lifecycle (from the initial offload
API calls through the command handler call back layers):
- structure for holding socket data like IP protocol, destination,
source and incoming packet sizes
- configuration to note modem starting socket id and number of
sockets
- methods to get/put socket structs from/to the pool
- function to update the # and size of packets in the modem receive
queue
- prebuilt modem_socket_poll() method for socket offload poll() API
Example modem driver setup code looks like this:
/* socket data */
static struct modem_socket_config socket_config;
static struct modem_socket sockets[MDM_MAX_SOCKETS];
static int modem_init(struct device *dev)
{
...
/* setup socket config */
socket_config.sockets = &sockets[0];
socket_config.sockets_len = ARRAY_SIZE(sockets);
socket_config.base_socket_num = 0;
ret = modem_socket_init(&socket_config);
...
}
Signed-off-by: Michael Scott <mike@foundries.io>
This is a generic command handler implementation which uses the
supplied modem interface to process incoming data and hand it
back to the modem driver via callbacks defined for:
- modem responses
- unsolicited messages
- specified handlers for current operation
The individual modem drivers define functions as command handlers
via the MODEM_CMD_DEFINE() macro.
To use these handlers, a modem operation defines a series of
modem_cmd structures and passes them to the modem_cmd_send()
function. The modem_cmd includes data for:
- a matching string for when to execute the handler
- # of parameters to parse after the matching string
- delimeters for the parameters
Example modem driver setup code looks like this:
/* create modem context object */
static struct modem_context mctx;
/* net_buf receive pool */
NET_BUF_POOL_DEFINE(mdm_recv_pool, MDM_RECV_MAX_BUF,
MDM_RECV_BUF_SIZE, 0, NULL);
/* modem cmds */
static struct modem_cmd_handler_data cmd_handler_data;
static u8_t cmd_read_buf[MDM_RECV_BUF_SIZE];
static u8_t cmd_match_buf[MDM_RECV_BUF_SIZE];
/* modem response handlers */
static struct modem_cmd response_cmds[] = {
MODEM_CMD("OK", on_cmd_ok, 0U, ""),
MODEM_CMD("ERROR", on_cmd_error, 0U, ""),
MODEM_CMD("+CME ERROR: ", on_cmd_exterror, 1U, ""),
};
/* unsolicited handlers */
static struct modem_cmd unsol_cmds[] = {
MODEM_CMD("+UUSOCL: ", on_cmd_socknotifyclose, 1U, ""),
MODEM_CMD("+UUSORD: ", on_cmd_socknotifydata, 2U, ","),
MODEM_CMD("+UUSORF: ", on_cmd_socknotifydata, 2U, ","),
MODEM_CMD("+CREG: ", on_cmd_socknotifycreg, 1U, ""),
};
/* setup cmd handler data */
cmd_handler_data.cmds[CMD_RESP] = response_cmds;
cmd_handler_data.cmds_len[CMD_RESP] = ARRAY_SIZE(response_cmds);
cmd_handler_data.cmds[CMD_UNSOL] = unsol_cmds;
cmd_handler_data.cmds_len[CMD_UNSOL] = ARRAY_SIZE(unsol_cmds);
cmd_handler_data.read_buf = &cmd_read_buf[0];
cmd_handler_data.read_buf_len = sizeof(cmd_read_buf);
cmd_handler_data.match_buf = &cmd_match_buf[0];
cmd_handler_data.match_buf_len = sizeof(cmd_match_buf);
cmd_handler_data.buf_pool = &mdm_recv_pool;
cmd_handler_data.alloc_timeout = BUF_ALLOC_TIMEOUT;
ret = modem_cmd_handler_init(&mctx.cmd_handler, &cmd_handler_data);
Signed-off-by: Michael Scott <mike@foundries.io>
Initial support for modems in Zephyr use the following driver model:
- Main portions of code live in the modem specific driver.
This includes internal socket management, command parsing, etc.
- They leverage a UART-based modem receiver helper to gather data.
- Interface with Zephyr networking via net_context offload APIs.
This implementation was good enough to kick start interest in
supporting modem usage in Zephyr, but lacks future scalability:
- The net_context offload APIs don't allow for operations such
as offloaded DNS, SSL/TLS and other HW specific features.
- Since most of the code lives within the modem drivers, it's
very hard for the Zephyr community to improve the driver layer
over time. Bugs found in 1 driver probably affect others due
to copy/paste method of development.
- Lack of abstraction for different modem interfaces and command
handlers makes it impossible to write a "dummy" layer which
could be used for testing.
- Lack of centralized processing makes implementing low power modes
and other advanced topics more difficult.
Introducing the modem context helper driver and sub-layers:
- modem context helper acts as an umbrella for several configurable
layers and exposes this data to externals such as the modem shell.
Included in the helper is GPIO pin config functions which are
currently duplicated in most drivers.
- modem interface layer: this layer sits on the HW APIs for the
peripheral which communicates with the modem. Users of the modem
interface can handle data via read/write functions. Individual
modem drivers can select from (potentially) several modem
interfaces.
- modem command parser layer: this layer communicates with the
modem interface and processes the data for use by modem drivers.
Fixes: https://github.com/zephyrproject-rtos/zephyr/issues/17922
Signed-off-by: Michael Scott <mike@foundries.io>
The u-blox SARA-R4 modem modules are Ultra-compact LTE Cat
M1 / NB1 ready:
- Configurable with a single hardware version
- Flexible mode selection as LTE Cat M1, LTE Cat NB1, EGPRS -
only/preferred
- Low power consumption and longer battery life
- Extended range in buildings, basements, and with NB1,
underground
This driver introduces support for basic AT commands to
query modem information as well as socket connection
for TCP/UDP communication.
Signed-off-by: Michael Scott <mike@foundries.io>
In commit c1f24abb13 ("drivers: modem: wistron kconfig separation"),
A single line of the WNC-M14A2A congigs was left in the main modem
Kconfig.
Let's clean up the Kconfig file by removing the left over.
Signed-off-by: Michael Scott <mike@foundries.io>
Moved UART interrupt dependencies from concrete driver to
the modem receiver as it uses UART interrupt functions within.
This allows developing other UART interrupt based modems without
the need to depend on the aforementioned features explicitly.
Signed-off-by: Georgij Cernysiov <g.cernysiov@elco-automation.de>
Modem driver for WNCM14A2A was erroneously leaving the
selection of UART_INTERRUPT_DRIVEN up to CONSOLE_HANDLER.
Now, with the move to the new SHELL backend, this is no
longer happening.
Let's select it from the modem driver, instead of depending
on it.
Let's also add a dependency on SERIAL_SUPPORT_INTERRUPT
which the serial drivers enable to let us know
UART_INTERRUPT_DRIVEN is available.
Signed-off-by: Michael Scott <mike@foundries.io>
These settings enable use of the WNC-M14A2A LTE-M modem as the default
network interface for the nRF52840-DK board (nrf52840_pca10056).
They include the following settings when MODEM_WNCM14A2A is selected:
- UARTE1 pin setup
- DTS / DTS fixup additions for WNC-M14A2A
- Kconfig settings for modem driver
Signed-off-by: Michael Scott <mike@foundries.io>
These settings enable use of the WNC-M14A2A LTE-M modem as the default
network interface instead of ethernet.
They include the following settings when MODEM_WNCM14A2A is selected:
- UART 2 setup
- Avoid ETH_0 setup due to pin conflicts
- DTS addition for WNC-M14A2A
- Kconfig settings for modem driver
Signed-off-by: Michael Scott <mike@foundries.io>
Add a set of modem shell commands to support modem development.
Start with:
modem list: Lists all registered modems and related information
modem send <modem receiver index> <command>: Send command to modem
Signed-off-by: Michael Scott <mike@foundries.io>
The WNC-M14A2A (LTE / LTE-M) modem is presented as an Arduino-
compatible shield via AT&T's IoT Starter Kit v1.0. It was
originally intended to work with the FRDM-K64F board, but
in theory as long as the right pins are configured it can
work with any board that supports Arduino-compatible headers.
The driver utilizes the CONFIG_NET_OFFLOAD setting to avoid the
normal handling of IP packets, and instead uses a socket-like
UART interface to handle incoming and outgoing data.
Signed-off-by: Michael Scott <mike@foundries.io>
Modem drivers need a fast buffer-based receiver for passing data
back and forth from the UART to the driver. This provides an
efficient configuarable driver which merely sends and receives
but doesn't process the data, that's left up to the modem driver.
Signed-off-by: Michael Scott <mike@foundries.io>
Michael Scott