drivers: modem: introduce u-blox SARA-R4 modem driver

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 <[email protected]>

Author: mike-scott

drivers/modem/CMakeLists.txt

@@ -3,6 +3,11 @@
 zephyr_sources_ifdef(CONFIG_MODEM_RECEIVER modem_receiver.c)
 zephyr_sources_ifdef(CONFIG_MODEM_SHELL modem_shell.c)
 
+if(CONFIG_MODEM_UBLOX_SARA_R4)
+	zephyr_library_include_directories(${ZEPHYR_BASE}/subsys/net/ip)
+	zephyr_library_sources(ublox-sara-r4.c)
+endif()
+
 if(CONFIG_MODEM_WNCM14A2A)
 	zephyr_library_include_directories(${ZEPHYR_BASE}/subsys/net/ip)
 	zephyr_library_sources(wncm14a2a.c)

drivers/modem/Kconfig

@@ -46,6 +46,7 @@ config MODEM_SHELL
 	  Activate shell module that provides modem utilities like
 	  sending a command to the modem UART.
 
+source "drivers/modem/Kconfig.ublox-sara-r4"
 source "drivers/modem/Kconfig.wncm14a2a"
 
 endif # MODEM

drivers/modem/Kconfig.ublox-sara-r4

@@ -0,0 +1,59 @@
+# Kconfig - u-blox SARA R4 driver options
+
+#
+# Copyright (c) 2019 Foundries.io
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+config MODEM_UBLOX_SARA_R4
+	bool "Enable u-blox SARA-R4 LTE-CatM1/NB-IoT modem driver"
+	select MODEM_RECEIVER
+	select NET_OFFLOAD
+	imply GPIO
+	help
+	  Choose this setting to enable u-blox SARA-R4 LTE-CatM1/NB-IoT modem
+	  driver.
+
+if MODEM_UBLOX_SARA_R4
+
+config MODEM_UBLOX_SARA_R4_RX_STACK_SIZE
+	int "Stack size for the u-blox SARA-R4 modem driver RX thread"
+	default 1028
+	help
+	  This stack is used by the u-blox SARA-R4 RX thread.
+
+config MODEM_UBLOX_SARA_R4_RX_WORKQ_STACK_SIZE
+	int "Stack size for the u-blox SARA-R4 modem driver work queue"
+	default 2048
+	help
+	  This stack is used by the work queue to pass off net_pkt data
+	  to the rest of the network stack, letting the rx thread continue
+	  processing data.
+
+config MODEM_UBLOX_SARA_R4_APN
+	string "APN for establishing network connection"
+	default "hologram"
+	help
+	  This setting is used in the AT+CGDCONT command to set the APN name
+	  for the network connection context.  This value is specific to
+	  the network provider and may need to be changed.
+
+config MODEM_UBLOX_SARA_R4_MANUAL_MCCMNO
+	string "MCC/MNOfor establishing network connection"
+	help
+	  This setting is used in the AT+COPS command to set the MCC/MNO
+	  for the network connection context.  This value is specific to
+	  the network provider and may need to be changed if auto is not
+	  selected.
+
+config MODEM_UBLOX_SARA_R4_INIT_PRIORITY
+	int "u-blox SARA-R4 driver init priority"
+	default 80
+	help
+	  u-blox SARA-R4 device driver initialization priority.
+	  Do not mess with it unless you know what you are doing.
+	  Note that the priority needs to be lower than the net stack
+	  so that it can start before the networking sub-system.
+
+endif # MODEM_UBLOX_SARA_R4