Standard interface for SPI peripherals

openrtx/include/peripherals/spi.h

@@ -0,0 +1,155 @@
+/***************************************************************************
+ *   Copyright (C) 2024 by Federico Amedeo Izzo IU2NUO,                    *
+ *                         Niccolò Izzo IU2KIN                             *
+ *                         Frederik Saraci IU2NRO                          *
+ *                         Silvano Seva IU2KWO                             *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 3 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
+ ***************************************************************************/
+
+#ifndef SPI_H
+#define SPI_H
+
+#include <stdint.h>
+#include <pthread.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Enumeration type for SPI configuration flags
+ */
+enum SPIFlags
+{
+    SPI_FLAG_CPOL   = 1,  ///< Clock line is high when idle.
+    SPI_FLAG_CPHA   = 2,  ///< Data lines are sampled on clock falling edge.
+    SPI_LSB_FIRST   = 4,  ///< Transfer data LSB first.
+    SPI_HALF_DUPLEX = 8   ///< Half-duplex data transfer mode, on a single data line
+};
+
+struct spiDevice;
+
+/**
+ * Transfer data on the SPI bus.
+ *
+ * @param dev: SPI device handle.
+ * @param txBuf: pointer to TX buffer, can be NULL.
+ * @param txSize: number of bytes to send.
+ * @param rxBuf: pointer to RX buffer, can be NULL.
+ * @param rxSize: number of bytes to receive.
+ * @return zero on success, a negative error code otherwise.
+ */
+typedef int (*spi_transfer_impl)(const struct spiDevice *dev, const void *txBuf,
+                                 const size_t txSize, void *rxBuf, const size_t rxSize);
+
+/**
+ * SPI peripheral descriptor.
+ */
+struct spiDevice
+{
+    const spi_transfer_impl transfer; ///< Device-specific implementation of the SPI transfer function
+    const void              *priv;    ///< Pointer to device driver private data
+    const pthread_mutex_t   *mutex;   ///< Pointer to mutex for exclusive access
+};
+
+
+/**
+ * Acquire exclusive ownership on an SPI peripheral.
+ *
+ * @param dev: pointer to peripheral descriptor.
+ * @return zero on success, a negative error code on failure.
+ */
+static inline int spi_acquire(const struct spiDevice *dev)
+{
+    if(dev->mutex == NULL)
+        return 0;
+
+    return pthread_mutex_lock((pthread_mutex_t *) dev->mutex);
+}
+
+/**
+ * Attempt to acquire exclusive ownership on an SPI peripheral.
+ *
+ * @param dev: pointer to peripheral descriptor.
+ * @return zero on success, a negative error code on failure.
+ */
+static inline int spi_tryAcquire(const struct spiDevice *dev)
+{
+    if(dev->mutex == NULL)
+        return 0;
+
+    return pthread_mutex_trylock((pthread_mutex_t *) dev->mutex);
+}
+
+/**
+ * Release exclusive ownership on an SPI peripheral.
+ *
+ * @param dev: pointer to peripheral descriptor.
+ * @return zero on success, a negative error code on failure.
+ */
+static inline int spi_release(const struct spiDevice *dev)
+{
+    if(dev->mutex == NULL)
+        return 0;
+
+    return pthread_mutex_unlock((pthread_mutex_t *) dev->mutex);
+}
+
+/**
+ * Transfer data on the SPI bus.
+ *
+ * @param txBuf: pointer to TX buffer, can be NULL.
+ * @param txSize: number of bytes to send.
+ * @param rxBuf: pointer to RX buffer, can be NULL.
+ * @param rxSize: number of bytes to receive.
+ * @return zero on success, a negative error code otherwise.
+ */
+static inline int spi_transfer(const struct spiDevice *dev, const void *txBuf,
+                               const size_t txSize, void *rxBuf, const size_t rxSize)
+{
+    return dev->transfer(dev, txBuf, txSize, rxBuf, rxSize);
+}
+
+/**
+ * Send data on the SPI bus.
+ *
+ * @param txBuf: pointer to TX buffer.
+ * @param txSize: number of bytes to send.
+ * @return zero on success, a negative error code otherwise.
+ */
+static inline int spi_send(const struct spiDevice *dev, const void *txBuf,
+                           const size_t txSize)
+{
+    return dev->transfer(dev, txBuf, txSize, NULL, 0);
+}
+
+/**
+ * Receive data from the SPI bus.
+ *
+ * @param rxBuf: pointer to RX buffer.
+ * @param rxSize: number of bytes to receive.
+ * @return zero on success, a negative error code otherwise.
+ */
+static inline int spi_receive(const struct spiDevice *dev, void *rxBuf,
+                              const size_t rxSize)
+{
+    return dev->transfer(dev, NULL, 0, rxBuf, rxSize);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SPI */