boards: shields: introduce SparkFun u-blox SARA-R4 shield

SparkFun offers an Arduino-R3 compatible shield using the SARA-R410M-02B
LTE Cat M1/NB-IoT modem.

Now, that the basic SARA-R4 modem driver is implemented, let's enable
the shield for several MCUs supporting Arduino-R3 compatible headers.

Product Link:
https://www.sparkfun.com/products/14997

Signed-off-by: Michael Scott <[email protected]>

Author: mike-scott

boards/shields/sparkfun_sara_r4/boards/disco_l475_iot1.conf

@@ -0,0 +1 @@
+CONFIG_UART_4=y

boards/shields/sparkfun_sara_r4/boards/frdm_k64f.conf

@@ -0,0 +1 @@
+CONFIG_UART_MCUX_3=y

boards/shields/sparkfun_sara_r4/boards/nrf52840_pca10056.conf

@@ -0,0 +1,2 @@
+CONFIG_GPIO_NRF_P1=y
+CONFIG_UART_1_NRF_UARTE=y

boards/shields/sparkfun_sara_r4/boards/nrf52840_pca10056.overlay

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2019 Foundries.io
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&arduino_serial {
+	tx-pin = <34>;
+	rx-pin = <33>;
+};

boards/shields/sparkfun_sara_r4/sparkfun_sara_r4.conf

@@ -0,0 +1,12 @@
+# Enable u-blox SARA-R4 modem
+CONFIG_MODEM=y
+CONFIG_MODEM_SHELL=y
+CONFIG_MODEM_UBLOX_SARA_R4=y
+CONFIG_UART_INTERRUPT_DRIVEN=y
+
+# extend retry timing to 20 seconds for LTE/LTE-M
+CONFIG_COAP_INIT_ACK_TIMEOUT_MS=20000
+
+# Hack: disable IPv6 for now
+# CONFIG_NET_IPV6 is not set
+# CONFIG_NET_CONFIG_NEED_IPV6 is not set

boards/shields/sparkfun_sara_r4/sparkfun_sara_r4.overlay

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2019 Foundries.io
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&arduino_serial {
+	current-speed = <115200>;
+	status = "ok";
+
+	sara_r4 {
+		compatible = "ublox,sara-r4";
+		label = "ublox-sara-r4";
+		mdm-power-gpios = <&arduino_header 11 0>; /* D5 */
+		mdm-reset-gpios = <&arduino_header 12 0>; /* D6 */
+		status = "ok";
+	};
+};