soc: arm: atmel_sam0: improve radio off handling for samr3x

Improve the radio off code, mainly:

- Compile the file only if necessary, ie, LORA radio not in use
- Use pin information from DT, so that we do not need to hardcode pins
  and can switch to dt-spec APIs.
- Improve error handling, includes, etc.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

soc/arm/atmel_sam0/common/CMakeLists.txt

@@ -13,8 +13,9 @@ zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMD20 soc_samd2x.c)
 zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMD21 soc_samd2x.c)
 zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMR21 soc_samd2x.c)
 zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAML21 soc_saml2x.c)
-zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMR34 soc_saml2x.c soc_samr34.c)
+zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMR34 soc_saml2x.c)
-zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMR35 soc_saml2x.c soc_samr34.c)
+zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMR35 soc_saml2x.c)
+zephyr_sources_ifdef(CONFIG_SOC_ATMEL_SAMR3X_RADIO_OFF_SETUP soc_samr3x_radio_off.c)
 
 zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAMD51 soc_samd5x.c)
 zephyr_sources_ifdef(CONFIG_SOC_SERIES_SAME51 soc_samd5x.c)

soc/arm/atmel_sam0/common/Kconfig.saml2x

@@ -72,3 +72,15 @@ config SOC_ATMEL_SAML_OSC16M_AS_MAIN
 endchoice
 
 endif # SOC_SERIES_SAML21 || SOC_SERIES_SAMR34 || SOC_SERIES_SAMR35
+
+config SOC_ATMEL_SAMR3X_RADIO_OFF_SETUP
+	bool "Configure LoRa radio pins if not in use"
+	default y if !LORA
+	depends on SOC_SERIES_SAMR34 || SOC_SERIES_SAMR35
+	help
+	  As detailed in DS70005356C, LoRa radio SPI pins do not have pull-ups,
+	  so when the radio is not in use, it's important that CS is kept high,
+	  to avoid unexpected behavior and increased current consumption. To
+	  further reduce power consumption, radio can be kept in reset state by
+	  keeping nRST pin low. When enabling this option, both CS and nRST will
+	  be configured high and low, respectively.

soc/arm/atmel_sam0/common/soc_samr34.c

@@ -1,32 +0,0 @@
-/*
- * Copyright (c) 2021 Argentum Systems Ltd.
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
-#include <zephyr/init.h>
-#include <zephyr/drivers/gpio.h>
-#include <soc.h>
-
-#if !(ATMEL_SAM0_DT_SERCOM_CHECK(4, atmel_sam0_spi) && CONFIG_SPI_SAM0)
-/* When the radio is not in use, it's important that #CS is set high, to avoid
- * unexpected behavior and increased current consumption... see Chapter 10 of
- * DS70005356C. We also hold the radio in reset.
- */
-static int soc_pinconf_init(void)
-{
-	const struct device *const portb = DEVICE_DT_GET(DT_NODELABEL(portb));
-
-
-	if (!device_is_ready(portb)) {
-		return -ENODEV;
-	}
-
-	gpio_pin_configure(portb, 31, GPIO_OUTPUT_HIGH);
-	gpio_pin_configure(portb, 15, GPIO_OUTPUT_LOW);
-
-	return 0;
-}
-
-SYS_INIT(soc_pinconf_init, PRE_KERNEL_2, 0);
-#endif

soc/arm/atmel_sam0/common/soc_samr3x_radio_off.c

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2021 Argentum Systems Ltd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/devicetree.h>
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/init.h>
+
+static int radio_off_setup(void)
+{
+	int ret;
+	const struct gpio_dt_spec reset = GPIO_DT_SPEC_GET(DT_NODELABEL(lora), reset_gpios);
+	const struct gpio_dt_spec cs = GPIO_DT_SPEC_GET(DT_NODELABEL(sercom4), cs_gpios);
+
+	if (!gpio_is_ready_dt(&reset) || !gpio_is_ready_dt(&cs)) {
+		return -ENODEV;
+	}
+
+	ret = gpio_pin_configure_dt(&reset, GPIO_OUTPUT_ACTIVE);
+	if (ret < 0) {
+		return ret;
+	}
+
+	ret = gpio_pin_configure_dt(&cs, GPIO_OUTPUT_INACTIVE);
+	if (ret < 0) {
+		return ret;
+	}
+
+	return 0;
+}
+
+SYS_INIT(radio_off_setup, PRE_KERNEL_2, 0);