uart.h

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#ifndef _IPXE_UART_H
#define _IPXE_UART_H

/** @file
 *
 * Generic UART
 *
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdint.h>
#include <ipxe/refcnt.h>
#include <ipxe/list.h>

/** A generic UART */
struct uart {
        /** Reference count */
        struct refcnt refcnt;
        /** Name */
        const char *name;
        /** List of registered UARTs */
        struct list_head list;

        /** Baud rate (if specified) */
        unsigned int baud;

        /** UART operations */
        struct uart_operations *op;
        /** Driver-private data */
        void *priv;
};

/** UART operations */
struct uart_operations {
        /**
         * Transmit byte
         *
         * @v uart              UART
         * @v byte              Byte to transmit
         * @ret rc              Return status code
         */
        void ( * transmit ) ( struct uart *uart, uint8_t byte );
        /**
         * Check if data is ready
         *
         * @v uart              UART
         * @ret ready           Data is ready
         */
        int ( * data_ready ) ( struct uart *uart );
        /**
         * Receive byte
         *
         * @v uart              UART
         * @ret byte            Received byte
         */
        uint8_t ( * receive ) ( struct uart *uart );
        /**
         * Initialise UART
         *
         * @v uart              UART
         * @ret rc              Return status code
         */
        int ( * init ) ( struct uart *uart );
        /**
         * Flush transmitted data
         *
         * @v uart              UART
         */
        void ( * flush ) ( struct uart *uart );
};

/**
 * Transmit byte
 *
 * @v uart              UART
 * @v byte              Byte to transmit
 * @ret rc              Return status code
 */
static inline __attribute__ (( always_inline )) void
uart_transmit ( struct uart *uart, uint8_t byte ) {

        uart->op->transmit ( uart, byte );
}

/**
 * Check if data is ready
 *
 * @v uart              UART
 * @ret ready           Data is ready
 */
static inline __attribute__ (( always_inline )) int
uart_data_ready ( struct uart *uart ) {

        return uart->op->data_ready ( uart );
}

/**
 * Receive byte
 *
 * @v uart              UART
 * @ret byte            Received byte
 */
static inline __attribute__ (( always_inline )) uint8_t
uart_receive ( struct uart *uart ) {

        return uart->op->receive ( uart );
}

/**
 * Initialise UART
 *
 * @v uart              UART
 * @ret rc              Return status code
 */
static inline __attribute__ (( always_inline )) int
uart_init ( struct uart *uart ) {

        return uart->op->init ( uart );
}

/**
 * Flush transmitted data
 *
 * @v uart              UART
 */
static inline __attribute__ (( always_inline )) void
uart_flush ( struct uart *uart ) {

        uart->op->flush ( uart );
}

extern struct list_head uarts;
extern struct uart_operations null_uart_operations;

/**
 * Get reference to UART
 *
 * @v uart              UART
 * @ret uart            UART
 */
static inline __attribute__ (( always_inline )) struct uart *
uart_get ( struct uart *uart ) {

        ref_get ( &uart->refcnt );
        return uart;
}

/**
 * Drop reference to UART
 *
 * @v uart              UART
 */
static inline __attribute__ (( always_inline )) void
uart_put ( struct uart *uart ) {

        ref_put ( &uart->refcnt );
}

/**
 * Nullify UART
 *
 * @v uart              UART
 */
static inline __attribute__ (( always_inline )) void
uart_nullify ( struct uart *uart ) {

        uart->op = &null_uart_operations;
}

extern struct uart * alloc_uart ( size_t priv_len );
extern int uart_register ( struct uart *uart );
extern int uart_register_fixed ( void );
extern void uart_unregister ( struct uart *uart );
extern struct uart * uart_find ( const char *name );

#endif /* _IPXE_UART_H */