1 /* Copyright 2018 SiFive, Inc */
2 /* SPDX-License-Identifier: Apache-2.0 */
9 /*! @brief The configuration for a SPI transfer */
10 struct metal_spi_config {
11 /*! @brief The protocol for the SPI transfer */
18 /*! @brief The polarity of the SPI transfer, equivalent to CPOL */
19 unsigned int polarity : 1;
20 /*! @brief The phase of the SPI transfer, equivalent to CPHA */
21 unsigned int phase : 1;
22 /*! @brief The endianness of the SPI transfer */
23 unsigned int little_endian : 1;
24 /*! @brief The active state of the chip select line */
25 unsigned int cs_active_high : 1;
26 /*! @brief The chip select ID to activate for the SPI transfer */
30 struct metal_spi_vtable {
31 void (*init)(struct metal_spi *spi, int baud_rate);
32 int (*transfer)(struct metal_spi *spi, struct metal_spi_config *config, size_t len, char *tx_buf, char *rx_buf);
33 int (*get_baud_rate)(struct metal_spi *spi);
34 int (*set_baud_rate)(struct metal_spi *spi, int baud_rate);
37 /*! @brief A handle for a SPI device */
39 const struct metal_spi_vtable *vtable;
42 /*! @brief Get a handle for a SPI device
43 * @param device_num The index of the desired SPI device
44 * @return A handle to the SPI device, or NULL if the device does not exist*/
45 struct metal_spi *metal_spi_get_device(int device_num);
47 /*! @brief Initialize a SPI device with a certain baud rate
48 * @param spi The handle for the SPI device to initialize
49 * @param baud_rate The baud rate to set the SPI device to
51 inline void metal_spi_init(struct metal_spi *spi, int baud_rate) { spi->vtable->init(spi, baud_rate); }
53 /*! @brief Perform a SPI transfer
54 * @param spi The handle for the SPI device to perform the transfer
55 * @param config The configuration for the SPI transfer.
56 * @param len The number of bytes to transfer
57 * @param tx_buf The buffer to send over the SPI bus. Must be len bytes long. If NULL, the SPI will transfer the value 0.
58 * @param rx_buf The buffer to receive data into. Must be len bytes long. If NULL, the SPI will ignore received bytes.
59 * @return 0 if the transfer succeeds
61 inline int metal_spi_transfer(struct metal_spi *spi, struct metal_spi_config *config, size_t len, char *tx_buf, char *rx_buf) {
62 return spi->vtable->transfer(spi, config, len, tx_buf, rx_buf);
65 /*! @brief Get the current baud rate of the SPI device
66 * @param spi The handle for the SPI device
67 * @return The baud rate in Hz
69 inline int metal_spi_get_baud_rate(struct metal_spi *spi) { return spi->vtable->get_baud_rate(spi); }
71 /*! @brief Set the current baud rate of the SPI device
72 * @param spi The handle for the SPI device
73 * @param baud_rate The desired baud rate of the SPI device
74 * @return 0 if the baud rate is successfully changed
76 inline int metal_spi_set_baud_rate(struct metal_spi *spi, int baud_rate) { return spi->vtable->set_baud_rate(spi, baud_rate); }