boards: arm: particle_boron: enable SARA-R4 modem

The Particle.io Boron is an nRF52840-based board with a connected
u-blox SARA-R4 modem.  The main board was previously upstreamed
without modem support.

Now that we have a driver to support the SARA-R4 modem, let's enable
it for the Boron board.

Signed-off-by: Michael Scott <mike@foundries.io>

boards/arm/particle_boron/CMakeLists.txt

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources(board.c)

boards/arm/particle_boron/Kconfig.defconfig

@@ -50,4 +50,20 @@ endif # IEEE802154
 config BT_CTLR
 	default BT
 
+if MODEM
+
+config UART_1_NRF_UARTE
+	default y
+
+config UART_1_NRF_FLOW_CONTROL
+	default y
+
+config MODEM_UBLOX_SARA_R4
+	default y
+
+config UART_INTERRUPT_DRIVEN
+	default y
+
+endif # MODEM
+
 endif # BOARD_PARTICLE_BORON

boards/arm/particle_boron/board.c

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2019 Foundries.io
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <init.h>
+#include "board.h"
+#include <gpio.h>
+
+static int particle_boron_init(struct device *dev)
+{
+
+	ARG_UNUSED(dev);
+
+#if defined(CONFIG_MODEM_UBLOX_SARA_R4)
+	struct device *gpio_dev;
+
+	/* Enable the serial buffer for SARA-R4 modem */
+	gpio_dev = device_get_binding(SERIAL_BUFFER_ENABLE_GPIO_NAME);
+	if (!gpio_dev) {
+		return -ENODEV;
+	}
+
+	gpio_pin_configure(gpio_dev, V_INT_DETECT_GPIO_PIN, GPIO_DIR_IN);
+
+	gpio_pin_configure(gpio_dev, SERIAL_BUFFER_ENABLE_GPIO_PIN,
+			   GPIO_DIR_OUT);
+#endif
+
+	return 0;
+}
+
+/* needs to be done after GPIO driver init */
+SYS_INIT(particle_boron_init, POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);

boards/arm/particle_boron/board.h

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2019 Foundries.io
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef __INC_BOARD_H
+#define __INC_BOARD_H
+
+/* pin used to enable the buffer power */
+#define SERIAL_BUFFER_ENABLE_GPIO_NAME  DT_NORDIC_NRF_GPIO_0_LABEL
+#define SERIAL_BUFFER_ENABLE_GPIO_PIN   25
+
+/* pin used to detect V_INT (buffer power) */
+#define V_INT_DETECT_GPIO_PIN		2
+
+#endif /* __INC_BOARD_H */

boards/arm/particle_boron/particle_boron.dts

@@ -6,6 +6,7 @@
 
 /dts-v1/;
 #include <nordic/nrf52840_qiaa.dtsi>
+#include <dt-bindings/gpio/gpio.h>
 #include "mesh_feather.dtsi"
 
 / {
@@ -23,10 +24,20 @@
 
 &uart1 { /* u-blox SARA-U2 or SARA-R4 */
 	compatible = "nordic,nrf-uarte";
-	current-speed = <921600>;
+	current-speed = <115200>;
 	status = "ok";
+
 	tx-pin = <37>;
 	rx-pin = <36>;
 	rts-pin = <39>;
 	cts-pin = <38>;
+
+	sara_r4 {
+		compatible = "ublox,sara-r4";
+		label = "ublox-sara-r4";
+		status = "ok";
+
+		mdm-power-gpios-gpio = <&gpio0 16 0>;
+		mdm-reset-gpios-gpio = <&gpio0 12 0>;
+	};
 };

boards/arm/particle_boron/particle_boron_defconfig

@@ -18,7 +18,6 @@ CONFIG_GPIO=y
 # enable uart driver
 CONFIG_SERIAL=y
 CONFIG_UART_0_NRF_UARTE=y
-CONFIG_UART_1_NRF_UARTE=y
 
 # enable power I2C interface
 CONFIG_I2C=y