sci.h

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/* KallistiOS ##version##
 
   dc/sci.h
   Copyright (C) 2025 Ruslan Rostovtsev
 
*/
 
/** \file    dc/sci.h
    \brief   Serial Communication Interface functionality.
    \ingroup system_sci
 
    This file provides access to the Dreamcast/Naomi SCI module, which can operate
    in both UART and SPI modes.
 
    \author Ruslan Rostovtsev
*/
 
#ifndef __DC_SCI_H
#define __DC_SCI_H
 
#include <sys/cdefs.h>
__BEGIN_DECLS
 
#include <arch/types.h>
#include <arch/dmac.h>
#include <stdint.h>
#include <stdbool.h>
 
/** \defgroup system_sci    SCI
    \brief                  Driver for the Serial Communication Interface
    \ingroup                system
 
    @{
*/
 
/*
 * Baudrate configuration for SH7750 SCI (PCLK = 50 MHz)
 *
 * The maximum achievable baudrate depends on internal divider settings.
 *
 * Asynchronous mode (UART):
 *   Formula: BRR = (PCLK / (64 × 2^(2n-1) × Baudrate)) - 1, where n = 0–3 (CKS bits)
 *   Maximum with internal clock (n=0, BRR=0): ~1,562,500 bps
 *
 * Synchronous mode (SPI):
 *   Formula: BRR = (PCLK / (8 × 2^(2n-1) × Baudrate)) - 1, where n = 0–3 (CKS bits)
 *   Maximum with internal clock (n=0, BRR=0): ~12.5 Mbps
 */
 
/** \brief Preset baudrates for UART mode of SCI (internal clock) */
#define SCI_UART_BAUD_4800     4800        /* Error < 0.2%, very reliable */
#define SCI_UART_BAUD_9600     9600        /* Error < 0.2%, very reliable */
#define SCI_UART_BAUD_19200    19200       /* Error < 0.5%, very reliable */
#define SCI_UART_BAUD_38400    38400       /* Error < 0.8%, very reliable */
#define SCI_UART_BAUD_57600    57600       /* Error < 0.5%, very reliable */
#define SCI_UART_BAUD_76800    76800       /* Error ~1.7%, reliable */
#define SCI_UART_BAUD_115200   115200      /* Error ~3.1%, acceptable */
#define SCI_UART_BAUD_230400   230400      /* Error ~3.1%, acceptable */
#define SCI_UART_BAUD_256000   256000      /* Error ~1.7%, reliable */
#define SCI_UART_BAUD_312500   312500      /* Perfect match, error 0% */
#define SCI_UART_BAUD_390625   390625      /* Perfect match, error 0% */
#define SCI_UART_BAUD_460800   460800      /* Error ~13.0%, not recommended */
#define SCI_UART_BAUD_576000   576000      /* Error < 0.5%, very reliable */
#define SCI_UART_BAUD_781250   781250      /* Perfect match, error 0% */
#define SCI_UART_BAUD_921600   921600      /* Error ~15.2%, not recommended */
#define SCI_UART_BAUD_1562500  1562500     /* Theoretical max, n=0, BRR=0, error 0% */
 
/** \brief Preset baudrates for SPI mode of SCI (internal clock) */
#define SCI_SPI_BAUD_250K      250000      /* Perfect match, error 0% */
#define SCI_SPI_BAUD_312K      312500      /* Perfect match, error 0% */
#define SCI_SPI_BAUD_500K      500000      /* Perfect match, error 0% */
#define SCI_SPI_BAUD_625K      625000      /* Perfect match, error 0% */
#define SCI_SPI_BAUD_781K      781250      /* Perfect match, error 0% */
#define SCI_SPI_BAUD_1M562K    1562500     /* Perfect match, error 0% */
#define SCI_SPI_BAUD_3M125K    3125000     /* Perfect match, error 0% */
#define SCI_SPI_BAUD_6M250K    6250000     /* Perfect match, error 0% */
#define SCI_SPI_BAUD_12M500K   12500000    /* Theoretical max, n=0, BRR=0, error 0% */
 
/** \brief Default baudrate for SPI mode */
#define SCI_SPI_BAUD_INIT   SCI_SPI_BAUD_312K     /* Initialization baudrate for SPI */
#define SCI_SPI_BAUD_MAX    SCI_SPI_BAUD_12M500K  /* Maximum baudrate for SPI */
 
/** \brief SCI operating mode definitions */
typedef enum {
    SCI_MODE_NONE = -1,  /**< No mode selected */
    SCI_MODE_UART = 0,   /**< UART (asynchronous) mode */
    SCI_MODE_SPI = 1     /**< SPI (synchronous) mode */
} sci_mode_t;
 
/** \brief Clock source options */
typedef enum {
    SCI_CLK_INT = 0,     /**< Use internal clock (default) */
    SCI_CLK_EXT = 1      /**< Use external clock (SCK pin) */
} sci_clock_t;
 
/** \brief UART configuration options */
typedef enum {
    SCI_UART_8N1 = 0x00,  /**< 8 data bits, no parity, 1 stop bit */
    SCI_UART_8N2 = 0x08,  /**< 8 data bits, no parity, 2 stop bits */
    SCI_UART_8E1 = 0x10,  /**< 8 data bits, even parity, 1 stop bit */
    SCI_UART_8O1 = 0x30,  /**< 8 data bits, odd parity, 1 stop bit */
    SCI_UART_7N1 = 0x40,  /**< 7 data bits, no parity, 1 stop bit */
    SCI_UART_7N2 = 0x48,  /**< 7 data bits, no parity, 2 stop bits */
    SCI_UART_7E1 = 0x50,  /**< 7 data bits, even parity, 1 stop bit */
    SCI_UART_7O1 = 0x70   /**< 7 data bits, odd parity, 1 stop bit */
} sci_uart_config_t;
 
/** \brief SPI CS pin options */
typedef enum {
    SCI_SPI_CS_NONE = -1, /**< No CS mode selected */
    SCI_SPI_CS_GPIO = 0,  /**< Use GPIO for SPI CS */
    SCI_SPI_CS_RTS = 1    /**< Use RTS from SCIF for SPI CS */
} sci_spi_cs_mode_t;
 
/** \brief Error codes for SCI operations */
typedef enum {
    SCI_OK = 0,                     /**< No error */
    SCI_ERR_NOT_INITIALIZED = -1,   /**< Not initialized or incorrect mode */
    SCI_ERR_PARAM = -2,             /**< Invalid parameter */
    SCI_ERR_TIMEOUT = -3,           /**< Operation timeout */
    SCI_ERR_OVERRUN = -4,           /**< Overrun error */
    SCI_ERR_FRAMING = -5,           /**< Framing error */
    SCI_ERR_PARITY = -6,            /**< Parity error */
    SCI_ERR_DMA = -7                /**< DMA error */
} sci_result_t;
 
/** \brief  Initialize the SCI port with specified parameters.
    \param  baud_rate       The baudrate to set.
    \param  mode            SCI_MODE_UART for UART mode, SCI_MODE_SPI for SPI mode.
    \param  clock_src       Clock source (internal or external).
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_init(uint32_t baud_rate, sci_mode_t mode, sci_clock_t clock_src);
 
/** \brief  Configure UART parameters.
    \param  config          UART configuration (data bits, parity, stop bits).
    \param  scsmr1          Pointer to store configuration value if needed.
*/
void sci_configure_uart(sci_uart_config_t config, uint8_t *scsmr1);
 
/** \brief  Configure SPI parameters.
    \param  cs              Chip select mode for SPI.
    \param  buffer_size     Size of DMA buffer to allocate,
                            0 for no DMA support, default is 512 bytes.
*/
void sci_configure_spi(sci_spi_cs_mode_t cs, size_t buffer_size);
 
/** \brief  Shutdown the SCI port.
*/
void sci_shutdown();
 
/** \brief  Read a single byte from the UART.
    \param  data            Pointer to store the read byte.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_read_byte(uint8_t *data);
 
/** \brief  Write a single byte to the UART.
    \param  data            The byte to write.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_write_byte(uint8_t data);
 
/** \brief  Write multiple bytes to the UART.
    \param  data            Buffer containing data to write.
    \param  len             Number of bytes to write.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_write_data(uint8_t *data, size_t len);
 
/** \brief  Read multiple bytes from the UART.
    \param  data            Buffer to store read data.
    \param  len             Number of bytes to read.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_read_data(uint8_t *data, size_t len);
 
/** \brief  Transfer data using DMA from the UART.
    \param  data            Buffer containing data to write.
    \param  len             Number of bytes to write.
    \param  callback        Optional callback function for completion notification.
    \param  cb_data         Data to pass to callback function.
    \return                 SCI_OK on success, error code otherwise.
 
    \note If callback is NULL, the function will wait for the DMA transfer to complete.
*/
sci_result_t sci_dma_write_data(const uint8_t *data, size_t len, dma_callback_t callback, void *cb_data);
 
/** \brief  Receive data using DMA from the UART.
    \param  data            Buffer to store received data.
    \param  len             Number of bytes to read.
    \param  callback        Optional callback function for completion notification.
    \param  cb_data         Data to pass to callback function.
    \return                 SCI_OK on success, error code otherwise.
 
    \note If callback is NULL, the function will wait for the DMA transfer to complete.
*/
sci_result_t sci_dma_read_data(uint8_t *data, size_t len, dma_callback_t callback, void *cb_data);
 
/** \brief  Wait for DMA transfer to complete in both UART and SPI modes.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_dma_wait_complete(void);
 
/** \brief  Set or clear the SPI chip select line.
    \param  enabled         true to assert CS (active low), false to deassert.
*/
void sci_spi_set_cs(bool enabled);
 
/** \brief  Read and write one byte to the SPI device simultaneously.
    \param  tx_byte         The byte to write out to the device.
    \param  rx_byte         Pointer to store the received byte.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_spi_rw_byte(uint8_t tx_byte, uint8_t *rx_byte);
 
/** \brief  Read and write multiple bytes to/from the SPI device.
    \param  tx_data         Buffer containing data to write.
    \param  rx_data         Buffer to store received data.
    \param  len             Number of bytes to transfer.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_spi_rw_data(const uint8_t *tx_data, uint8_t *rx_data, size_t len);
 
/** \brief  Write one byte to the SPI device.
    \param  tx_byte         The byte to write out to the device.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_spi_write_byte(uint8_t tx_byte);
 
/** \brief  Read one byte from the SPI device.
    \param  rx_byte         Pointer to store the received byte.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_spi_read_byte(uint8_t *rx_byte);
 
/** \brief  Write multiple bytes to the SPI device.
    \param  tx_data         Buffer containing data to write.
    \param  len             Number of bytes to transfer.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_spi_write_data(const uint8_t *tx_data, size_t len);
 
/** \brief  Read multiple bytes from the SPI device.
    \param  rx_data         Buffer to store received data.
    \param  len             Number of bytes to transfer.
    \return                 SCI_OK on success, error code otherwise.
*/
sci_result_t sci_spi_read_data(uint8_t *rx_data, size_t len);
 
/** \brief  Write multiple bytes to the SPI device using DMA.
    \param  tx_data         Buffer containing data to write.
    \param  len             Number of bytes to transfer.
    \param  callback        Optional callback function for completion notification.
    \param  cb_data         Data to pass to callback function.
    \return                 SCI_OK on success, error code otherwise.
 
    \note If callback is NULL, the function will wait for the DMA transfer to complete.
*/
sci_result_t sci_spi_dma_write_data(const uint8_t *tx_data, size_t len, dma_callback_t callback, void *cb_data);
 
/** \brief  Read multiple bytes from the SPI device using DMA.
    \param  rx_data         Buffer to store received data.
    \param  len             Number of bytes to transfer.
    \param  callback        Optional callback function for completion notification.
    \param  cb_data         Data to pass to callback function.
    \return                 SCI_OK on success, error code otherwise.
 
    \note If callback is NULL, the function will wait for the DMA transfer to complete.
*/
sci_result_t sci_spi_dma_read_data(uint8_t *rx_data, size_t len, dma_callback_t callback, void *cb_data);
 
/** @} */
 
__END_DECLS
 
#endif  /* __DC_SCI_H */