zephyr/include/spi.h

/* spi.h - public SPI driver API */

/*
 * Copyright (c) 2015 Intel Corporation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef __SPI_H__
#define __SPI_H__

/**
 * @brief SPI Interface
 * @defgroup spi_interface SPI Interface
 * @ingroup io_interfaces
 * @{
 */

#include <stdint.h>
#include <stddef.h>
#include <device.h>

#ifdef __cplusplus
extern "C" {
#endif

/* SPI Polarity & Phase Modes */
#define SPI_MODE_CPOL		0x1
#define SPI_MODE_CPHA		0x2
#define SPI_MODE_LOOP		0x4

#define SPI_MODE_MASK		(0x7)
#define SPI_MODE(_in_)		((_in_) & SPI_MODE_MASK)

/* SPI Transfer modes (host controller dependent) */
#define SPI_TRANSFER_MSB	(0 << 3)
#define SPI_TRANSFER_LSB	(1 << 3)

#define SPI_TRANSFER_MASK	(0x8)

#define SPI_WORD_SIZE_MASK	(0xFF << 4)
#define SPI_WORD_SIZE_GET(_in_) (((_in_) & SPI_WORD_SIZE_MASK) >> 4)
#define SPI_WORD(_in_) ((_in_) << 4)

/*
 * config is a bit field with the following parts:
 * mode			[ 0 : 1 ]   - Polarity and phase mode
 * transfer_mode	[ 2 ]       - LSB or MSB first transfer mode
 * loop_mode		[ 3 ]       - Enable or disable loopback mode
 * word_size		[ 4 : 11 ]  - Size of a data train in bits
 * RESERVED		[ 12 : 31 ] - undefined usage
 *
 * max_sys_freq is the maximum frequency supported by the slave it
 * will deal with. This value depends on the host controller (the driver
 * may present a specific format for setting it).
 */
struct spi_config {
	uint32_t	config;
	uint32_t	max_sys_freq;
};

typedef int (*spi_api_configure)(struct device *dev,
				 struct spi_config *config);
typedef int (*spi_api_slave_select)(struct device *dev, uint32_t slave);
typedef int (*spi_api_io)(struct device *dev,
			  uint8_t *tx_buf, uint32_t tx_buf_len,
			  uint8_t *rx_buf, uint32_t rx_buf_len);
typedef int (*spi_api_control)(struct device *dev);

struct spi_driver_api {
	spi_api_configure configure;
	spi_api_slave_select slave_select;
	spi_api_io transceive;
	spi_api_control suspend;
	spi_api_control resume;
};

/**
 * @brief Configure a host controller for operating against slaves
 * @param dev Pointer to the device structure for the driver instance
 * @param config Pointer to the application provided configuration
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int spi_configure(struct device *dev,
				struct spi_config *config)
{
	struct spi_driver_api *api = (struct spi_driver_api *)dev->driver_api;

	return api->configure(dev, config);
}

/**
 * @brief Select a slave to deal with.
 *
 * Note: This is meaningful only if the controller supports per-slave
 * addressing (One SS line per-slave). If not, this will not have any effect
 * and you will have to consider daisy-chaining to deal with multiple slave
 * on the same line.
 *
 * @param dev Pointer to the device structure for the driver instance
 * @param slave An integer identifying the slave
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int spi_slave_select(struct device *dev, uint32_t slave)
{
	struct spi_driver_api *api = (struct spi_driver_api *)dev->driver_api;

	if (!api->slave_select) {
		return DEV_OK;
	}

	return api->slave_select(dev, slave);
}

/**
 * @brief Read a defined amount of data from an SPI driver
 * @param dev Pointer to the device structure for the driver instance
 * @param buf Memory buffer that data should be transferred to
 * @param len Size of the memory buffer available for writing to
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int spi_read(struct device *dev, uint8_t *buf, uint32_t len)
{
	struct spi_driver_api *api = (struct spi_driver_api *)dev->driver_api;

	return api->transceive(dev, NULL, 0, buf, len);
}

/**
 * @brief Write a defined amount of data through an SPI driver
 * @param dev Pointer to the device structure for the driver instance
 * @param buf Memory buffer that data should be transferred from
 * @param len Size of the memory buffer available for reading from
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int spi_write(struct device *dev, uint8_t *buf, uint32_t len)
{
	struct spi_driver_api *api = (struct spi_driver_api *)dev->driver_api;

	return api->transceive(dev, buf, len, NULL, 0);
}

/**
 * @brief Read and write defined amount of data through an SPI driver
 *
 * Note: This is meant for full-duplex transmission.
 *
 * @param dev Pointer to the device structure for the driver instance
 * @param tx_buf Memory buffer that data should be transferred from
 * @param tx_buf_len Size of the memory buffer available for reading from
 * @param rx_buf Memory buffer that data should be transferred to
 * @param rx_buf_len Size of the memory buffer available for writing to
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int spi_transceive(struct device *dev,
			  uint8_t *tx_buf, uint32_t tx_buf_len,
			  uint8_t *rx_buf, uint32_t rx_buf_len)
{
	struct spi_driver_api *api = (struct spi_driver_api *)dev->driver_api;

	return api->transceive(dev, tx_buf, tx_buf_len, rx_buf, rx_buf_len);
}

/**
 * @brief Suspend the SPI host controller operations
 * @param dev Pointer to the device structure for the driver instance
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int spi_suspend(struct device *dev)
{
	struct spi_driver_api *api = (struct spi_driver_api *)dev->driver_api;

	return api->suspend(dev);
}

/**
 * @brief Resume the SPI host controller operations
 * @param dev Pointer to the device structure for the driver instance
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int spi_resume(struct device *dev)
{
	struct spi_driver_api *api = (struct spi_driver_api *)dev->driver_api;

	return api->resume(dev);
}

#ifdef __cplusplus
}
#endif

/**
 * @}
 */

#endif /* __SPI_H__ */