include: Add initial LoRa API

Add initial LoRa API for P2P mode.

Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>

include/drivers/lora.h

@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2019 Manivannan Sadhasivam
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_DRIVERS_LORA_H_
+#define ZEPHYR_INCLUDE_DRIVERS_LORA_H_
+
+/**
+ * @file
+ * @brief Public LoRa APIs
+ */
+
+#include <zephyr/types.h>
+#include <device.h>
+
+enum lora_signal_bandwidth {
+	BW_125_KHZ = 0,
+	BW_250_KHZ,
+	BW_500_KHZ,
+};
+
+enum lora_datarate {
+	SF_6 = 6,
+	SF_7,
+	SF_8,
+	SF_9,
+	SF_10,
+	SF_11,
+	SF_12,
+};
+
+enum lora_coding_rate {
+	CR_4_5 = 1,
+	CR_4_6 = 2,
+	CR_4_7 = 3,
+	CR_4_8 = 4,
+};
+
+struct lora_modem_config {
+	u32_t frequency;
+	enum lora_signal_bandwidth bandwidth;
+	enum lora_datarate datarate;
+	enum lora_coding_rate coding_rate;
+	u16_t preamble_len;
+	s8_t tx_power;
+	bool tx;
+};
+
+/**
+ * @typedef lora_api_config()
+ * @brief Callback API for configuring the LoRa module
+ *
+ * @see lora_config() for argument descriptions.
+ */
+typedef int (*lora_api_config)(struct device *dev,
+			       struct lora_modem_config *config);
+
+/**
+ * @typedef lora_api_send()
+ * @brief Callback API for sending data over LoRa
+ *
+ * @see lora_send() for argument descriptions.
+ */
+typedef int (*lora_api_send)(struct device *dev,
+			     u8_t *data, u32_t data_len);
+
+/**
+ * @typedef lora_api_recv()
+ * @brief Callback API for receiving data over LoRa
+ *
+ * @see lora_recv() for argument descriptions.
+ */
+typedef int (*lora_api_recv)(struct device *dev, u8_t *data, u8_t size,
+			     s32_t timeout);
+
+struct lora_driver_api {
+	lora_api_config config;
+	lora_api_send	send;
+	lora_api_recv	recv;
+};
+
+/**
+ * @brief Configure the LoRa modem
+ *
+ * @param dev     LoRa device
+ * @param config  Data structure containing the intended configuration for the
+		  modem
+ * @return 0 on success, negative on error
+ */
+static inline int lora_config(struct device *dev,
+			      struct lora_modem_config *config)
+{
+	const struct lora_driver_api *api = dev->driver_api;
+
+	return api->config(dev, config);
+}
+
+/**
+ * @brief Send data over LoRa
+ *
+ * @note This is a non-blocking call.
+ *
+ * @param dev       LoRa device
+ * @param data      Data to be sent
+ * @param data_len  Length of the data to be sent
+ * @return 0 on success, negative on error
+ */
+static inline int lora_send(struct device *dev,
+			    u8_t *data, u32_t data_len)
+{
+	const struct lora_driver_api *api = dev->driver_api;
+
+	return api->send(dev, data, data_len);
+}
+
+/**
+ * @brief Receive data over LoRa
+ *
+ * @note This is a blocking call.
+ *
+ * @param dev       LoRa device
+ * @param data      Buffer to hold received data
+ * @param size      Size of the buffer to hold the received data. Max size
+		    allowed is 255.
+ * @param timeout   Timeout value in milliseconds. API also accepts, K_NO_WAIT
+		    for no wait time and K_FOREVER for blocking until
+		    data arrives.
+ * @return Length of the data received on success, negative on error
+ */
+static inline int lora_recv(struct device *dev, u8_t *data, u8_t size,
+			    s32_t timeout)
+{
+	const struct lora_driver_api *api = dev->driver_api;
+
+	return api->recv(dev, data, size, timeout);
+}
+
+#endif	/* ZEPHYR_INCLUDE_DRIVERS_LORA_H_ */