ser_at91.c

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#include "hw/hw_ser.h"  /* Required for bus macros overrides */
#include <hw/hw_cpufreq.h>  /* CPU_FREQ */

#include "cfg/cfg_ser.h"
#include <cfg/debug.h>


#include <io/arm.h>

#include <cpu/attr.h>

#include <drv/ser.h>
#include <drv/ser_p.h>

#include <struct/fifobuf.h>


#define SERIRQ_PRIORITY 4 ///< default priority for serial irqs.

#ifndef SER_UART0_BUS_TXINIT

    #if !CPU_ARM_SAM7S_LARGE && !CPU_ARM_SAM7X
        #warning Check USART0 pins!
    #endif
    #define SER_UART0_BUS_TXINIT do { \
        PIOA_PDR = BV(RXD0) | BV(TXD0); \
    } while (0)

#endif

#ifndef SER_UART0_BUS_TXBEGIN

    #define SER_UART0_BUS_TXBEGIN
#endif

#ifndef SER_UART0_BUS_TXCHAR

    #define SER_UART0_BUS_TXCHAR(c) do { \
        US0_THR = (c); \
    } while (0)
#endif

#ifndef SER_UART0_BUS_TXEND

    #define SER_UART0_BUS_TXEND
#endif

/* End USART0 macros */

#ifndef SER_UART1_BUS_TXINIT

    #if !CPU_ARM_SAM7S_LARGE && !CPU_ARM_SAM7X
        #warning Check USART1 pins!
    #endif
    #define SER_UART1_BUS_TXINIT do { \
        PIOA_PDR = BV(RXD1) | BV(TXD1); \
    } while (0)

#endif

#ifndef SER_UART1_BUS_TXBEGIN

    #define SER_UART1_BUS_TXBEGIN
#endif

#ifndef SER_UART1_BUS_TXCHAR

    #define SER_UART1_BUS_TXCHAR(c) do { \
        US1_THR = (c); \
    } while (0)
#endif

#ifndef SER_UART1_BUS_TXEND

    #define SER_UART1_BUS_TXEND
#endif

#ifndef SER_SPI0_BUS_TXINIT

    #define SER_SPI0_BUS_TXINIT
#endif

#ifndef SER_SPI0_BUS_TXCLOSE

    #define SER_SPI0_BUS_TXCLOSE
#endif

#if CPU_ARM_SAM7X

    #ifndef SER_SPI1_BUS_TXINIT

        #define SER_SPI1_BUS_TXINIT
    #endif

    #ifndef SER_SPI1_BUS_TXCLOSE

        #define SER_SPI1_BUS_TXCLOSE
    #endif
#endif
/*\}*/




/* From the high-level serial driver */
extern struct Serial *ser_handles[SER_CNT];

/* TX and RX buffers */
static unsigned char uart0_txbuffer[CONFIG_UART0_TXBUFSIZE];
static unsigned char uart0_rxbuffer[CONFIG_UART0_RXBUFSIZE];

static unsigned char uart1_txbuffer[CONFIG_UART1_TXBUFSIZE];
static unsigned char uart1_rxbuffer[CONFIG_UART1_RXBUFSIZE];

static unsigned char spi0_txbuffer[CONFIG_SPI0_TXBUFSIZE];
static unsigned char spi0_rxbuffer[CONFIG_SPI0_RXBUFSIZE];
#if CPU_ARM_SAM7X
static unsigned char spi1_txbuffer[CONFIG_SPI1_TXBUFSIZE];
static unsigned char spi1_rxbuffer[CONFIG_SPI1_RXBUFSIZE];
#endif

struct ArmSerial
{
    struct SerialHardware hw;
    volatile bool sending;
};

static ISR_PROTO(uart0_irq_dispatcher);
static ISR_PROTO(uart1_irq_dispatcher);
static ISR_PROTO(spi0_irq_handler);
#if CPU_ARM_SAM7X
static ISR_PROTO(spi1_irq_handler);
#endif
/*
 * Callbacks for USART0
 */
static void uart0_init(
    UNUSED_ARG(struct SerialHardware *, _hw),
    UNUSED_ARG(struct Serial *, ser))
{
    US0_IDR = 0xFFFFFFFF;
    /* Set the vector. */
    AIC_SVR(US0_ID) = uart0_irq_dispatcher;
    /* Initialize to level sensitive with defined priority. */
    AIC_SMR(US0_ID) = AIC_SRCTYPE_INT_LEVEL_SENSITIVE | SERIRQ_PRIORITY;
    PMC_PCER = BV(US0_ID);

    /*
     * - Reset USART0
     * - Set serial param: mode Normal, 8bit data, 1bit stop, parity none
     * - Enable both the receiver and the transmitter
     * - Enable only the RX complete interrupt
     */
    US0_CR = BV(US_RSTRX) | BV(US_RSTTX);
    US0_MR = US_CHMODE_NORMAL | US_CHRL_8 | US_NBSTOP_1 | US_PAR_NO;
    US0_CR = BV(US_RXEN) | BV(US_TXEN);
    US0_IER = BV(US_RXRDY);

    SER_UART0_BUS_TXINIT;

    /* Enable the USART IRQ */
    AIC_IECR = BV(US0_ID);

    SER_STROBE_INIT;
}

static void uart0_cleanup(UNUSED_ARG(struct SerialHardware *, _hw))
{
    US0_CR = BV(US_RSTRX) | BV(US_RSTTX) | BV(US_RXDIS) | BV(US_TXDIS) | BV(US_RSTSTA);
}

static void uart0_enabletxirq(struct SerialHardware *_hw)
{
    struct ArmSerial *hw = (struct ArmSerial *)_hw;

    /*
     * WARNING: racy code here!  The tx interrupt sets hw->sending to false
     * when it runs with an empty fifo.  The order of statements in the
     * if-block matters.
     */
    if (!hw->sending)
    {
        hw->sending = true;
        /*
         * - Enable the transmitter
         * - Enable TX empty interrupt
         */
        SER_UART0_BUS_TXBEGIN;
        US0_IER = BV(US_TXEMPTY);
    }
}

static void uart0_setbaudrate(UNUSED_ARG(struct SerialHardware *, _hw), unsigned long rate)
{
    /* Compute baud-rate period */
    US0_BRGR = CPU_FREQ / (16 * rate);
    //DB(kprintf("uart0_setbaudrate(rate=%lu): period=%d\n", rate, period);)
}

static void uart0_setparity(UNUSED_ARG(struct SerialHardware *, _hw), int parity)
{
    US0_MR &= ~US_PAR_MASK;
    /* Set UART parity */
    switch(parity)
    {
        case SER_PARITY_NONE:
        {
            /* Parity none. */
            US0_MR |= US_PAR_NO;
            break;
        }
        case SER_PARITY_EVEN:
        {
            /* Even parity. */
            US0_MR |= US_PAR_EVEN;
            break;
        }
        case SER_PARITY_ODD:
        {
            /* Odd parity. */
            US0_MR |= US_PAR_ODD;
            break;
        }
        default:
            ASSERT(0);
    }

}
/*
 * Callbacks for USART1
 */
static void uart1_init(
    UNUSED_ARG(struct SerialHardware *, _hw),
    UNUSED_ARG(struct Serial *, ser))
{
    US1_IDR = 0xFFFFFFFF;
    /* Set the vector. */
    AIC_SVR(US1_ID) = uart1_irq_dispatcher;
    /* Initialize to level sensitive with defined priority. */
    AIC_SMR(US1_ID) = AIC_SRCTYPE_INT_LEVEL_SENSITIVE | SERIRQ_PRIORITY;
    PMC_PCER = BV(US1_ID);

    /*
     * - Reset USART1
     * - Set serial param: mode Normal, 8bit data, 1bit stop, parity none
     * - Enable both the receiver and the transmitter
     * - Enable only the RX complete interrupt
     */
    US1_CR = BV(US_RSTRX) | BV(US_RSTTX);
    US1_MR = US_CHMODE_NORMAL | US_CHRL_8 | US_NBSTOP_1 | US_PAR_NO;
    US1_CR = BV(US_RXEN) | BV(US_TXEN);
    US1_IER = BV(US_RXRDY);

    SER_UART1_BUS_TXINIT;

    /* Enable the USART IRQ */
    AIC_IECR = BV(US1_ID);

    SER_STROBE_INIT;
}

static void uart1_cleanup(UNUSED_ARG(struct SerialHardware *, _hw))
{
    US1_CR = BV(US_RSTRX) | BV(US_RSTTX) | BV(US_RXDIS) | BV(US_TXDIS) | BV(US_RSTSTA);
}

static void uart1_enabletxirq(struct SerialHardware *_hw)
{
    struct ArmSerial *hw = (struct ArmSerial *)_hw;

    /*
     * WARNING: racy code here!  The tx interrupt sets hw->sending to false
     * when it runs with an empty fifo.  The order of statements in the
     * if-block matters.
     */
    if (!hw->sending)
    {
        hw->sending = true;
        /*
         * - Enable the transmitter
         * - Enable TX empty interrupt
         */
        SER_UART1_BUS_TXBEGIN;
        US1_IER = BV(US_TXEMPTY);
    }
}

static void uart1_setbaudrate(UNUSED_ARG(struct SerialHardware *, _hw), unsigned long rate)
{
    /* Compute baud-rate period */
    US1_BRGR = CPU_FREQ / (16 * rate);
    //DB(kprintf("uart0_setbaudrate(rate=%lu): period=%d\n", rate, period);)
}

static void uart1_setparity(UNUSED_ARG(struct SerialHardware *, _hw), int parity)
{
    US1_MR &= ~US_PAR_MASK;
    /* Set UART parity */
    switch(parity)
    {
        case SER_PARITY_NONE:
        {
            /* Parity none. */
            US1_MR |= US_PAR_NO;
            break;
        }
        case SER_PARITY_EVEN:
        {
            /* Even parity. */
            US1_MR |= US_PAR_EVEN;
            break;
        }
        case SER_PARITY_ODD:
        {
            /* Odd parity. */
            US1_MR |= US_PAR_ODD;
            break;
        }
        default:
            ASSERT(0);
    }

}

/* SPI driver */
static void spi0_init(UNUSED_ARG(struct SerialHardware *, _hw), UNUSED_ARG(struct Serial *, ser))
{
    /* Disable PIO on SPI pins */
    PIOA_PDR = BV(SPI0_SPCK) | BV(SPI0_MOSI) | BV(SPI0_MISO);

    /* Reset device */
    SPI0_CR = BV(SPI_SWRST);

    /*
     * Set SPI to master mode, fixed peripheral select, chip select directly connected to a peripheral device,
     * SPI clock set to MCK, mode fault detection disabled, loopback disable, NPCS0 active, Delay between CS = 0
     */
    SPI0_MR = BV(SPI_MSTR) | BV(SPI_MODFDIS);

    /*
     * Set SPI mode.
     * At reset clock division factor is set to 0, that is
     * *forbidden*. Set SPI clock to minimum to keep it valid.
     */
    SPI0_CSR0 = BV(SPI_NCPHA) | (255 << SPI_SCBR_SHIFT);

    /* Disable all irqs */
    SPI0_IDR = 0xFFFFFFFF;
    /* Set the vector. */
    AIC_SVR(SPI0_ID) = spi0_irq_handler;
    /* Initialize to edge triggered with defined priority. */
    AIC_SMR(SPI0_ID) = AIC_SRCTYPE_INT_EDGE_TRIGGERED | SERIRQ_PRIORITY;
    /* Enable the USART IRQ */
    AIC_IECR = BV(SPI0_ID);
    PMC_PCER = BV(SPI0_ID);

    /* Enable interrupt on tx buffer empty */
    SPI0_IER = BV(SPI_TXEMPTY);

    /* Enable SPI */
    SPI0_CR = BV(SPI_SPIEN);


    SER_SPI0_BUS_TXINIT;

    SER_STROBE_INIT;
}

static void spi0_cleanup(UNUSED_ARG(struct SerialHardware *, _hw))
{
    /* Disable SPI */
    SPI0_CR = BV(SPI_SPIDIS);

    /* Disable all irqs */
    SPI0_IDR = 0xFFFFFFFF;

    SER_SPI0_BUS_TXCLOSE;

    /* Enable PIO on SPI pins */
    PIOA_PER = BV(SPI0_SPCK) | BV(SPI0_MOSI) | BV(SPI0_MISO);
}

static void spi0_starttx(struct SerialHardware *_hw)
{
    struct ArmSerial *hw = (struct ArmSerial *)_hw;

    cpu_flags_t flags;
    IRQ_SAVE_DISABLE(flags);

    /* Send data only if the SPI is not already transmitting */
    if (!hw->sending && !fifo_isempty(&ser_handles[SER_SPI0]->txfifo))
    {
        hw->sending = true;
        SPI0_TDR = fifo_pop(&ser_handles[SER_SPI0]->txfifo);
    }

    IRQ_RESTORE(flags);
}

static void spi0_setbaudrate(UNUSED_ARG(struct SerialHardware *, _hw), unsigned long rate)
{
    SPI0_CSR0 &= ~SPI_SCBR;

    ASSERT((uint8_t)DIV_ROUND(CPU_FREQ, rate));
    SPI0_CSR0 |= DIV_ROUND(CPU_FREQ, rate) << SPI_SCBR_SHIFT;
}

#if CPU_ARM_SAM7X
/* SPI driver */
static void spi1_init(UNUSED_ARG(struct SerialHardware *, _hw), UNUSED_ARG(struct Serial *, ser))
{
    /* Disable PIO on SPI pins */
    PIOA_PDR = BV(SPI1_SPCK) | BV(SPI1_MOSI) | BV(SPI1_MISO);

    /* SPI1 pins are on B peripheral function! */
    PIOA_BSR = BV(SPI1_SPCK) | BV(SPI1_MOSI) | BV(SPI1_MISO);

    /* Reset device */
    SPI1_CR = BV(SPI_SWRST);

    /*
     * Set SPI to master mode, fixed peripheral select, chip select directly connected to a peripheral device,
     * SPI clock set to MCK, mode fault detection disabled, loopback disable, NPCS0 active, Delay between CS = 0
     */
    SPI1_MR = BV(SPI_MSTR) | BV(SPI_MODFDIS);

    /*
     * Set SPI mode.
     * At reset clock division factor is set to 0, that is
     * *forbidden*. Set SPI clock to minimum to keep it valid.
     */
    SPI1_CSR0 = BV(SPI_NCPHA) | (255 << SPI_SCBR_SHIFT);

    /* Disable all irqs */
    SPI1_IDR = 0xFFFFFFFF;
    /* Set the vector. */
    AIC_SVR(SPI1_ID) = spi1_irq_handler;
    /* Initialize to edge triggered with defined priority. */
    AIC_SMR(SPI1_ID) = AIC_SRCTYPE_INT_EDGE_TRIGGERED | SERIRQ_PRIORITY;
    /* Enable the USART IRQ */
    AIC_IECR = BV(SPI1_ID);
    PMC_PCER = BV(SPI1_ID);

    /* Enable interrupt on tx buffer empty */
    SPI1_IER = BV(SPI_TXEMPTY);

    /* Enable SPI */
    SPI1_CR = BV(SPI_SPIEN);


    SER_SPI1_BUS_TXINIT;

    SER_STROBE_INIT;
}

static void spi1_cleanup(UNUSED_ARG(struct SerialHardware *, _hw))
{
    /* Disable SPI */
    SPI1_CR = BV(SPI_SPIDIS);

    /* Disable all irqs */
    SPI1_IDR = 0xFFFFFFFF;

    SER_SPI1_BUS_TXCLOSE;

    /* Enable PIO on SPI pins */
    PIOA_PER = BV(SPI1_SPCK) | BV(SPI1_MOSI) | BV(SPI1_MISO);
}

static void spi1_starttx(struct SerialHardware *_hw)
{
    struct ArmSerial *hw = (struct ArmSerial *)_hw;

    cpu_flags_t flags;
    IRQ_SAVE_DISABLE(flags);

    /* Send data only if the SPI is not already transmitting */
    if (!hw->sending && !fifo_isempty(&ser_handles[SER_SPI1]->txfifo))
    {
        hw->sending = true;
        SPI1_TDR = fifo_pop(&ser_handles[SER_SPI1]->txfifo);
    }

    IRQ_RESTORE(flags);
}

static void spi1_setbaudrate(UNUSED_ARG(struct SerialHardware *, _hw), unsigned long rate)
{
    SPI1_CSR0 &= ~SPI_SCBR;

    ASSERT((uint8_t)DIV_ROUND(CPU_FREQ, rate));
    SPI1_CSR0 |= DIV_ROUND(CPU_FREQ, rate) << SPI_SCBR_SHIFT;
}
#endif

static void spi_setparity(UNUSED_ARG(struct SerialHardware *, _hw), UNUSED_ARG(int, parity))
{
    // nop
}


static bool tx_sending(struct SerialHardware* _hw)
{
    struct ArmSerial *hw = (struct ArmSerial *)_hw;
    return hw->sending;
}

// FIXME: move into compiler.h?  Ditch?
#if COMPILER_C99
    #define C99INIT(name,val) .name = val
#elif defined(__GNUC__)
    #define C99INIT(name,val) name: val
#else
    #warning No designated initializers, double check your code
    #define C99INIT(name,val) (val)
#endif

/*
 * High-level interface data structures
 */
static const struct SerialHardwareVT UART0_VT =
{
    C99INIT(init, uart0_init),
    C99INIT(cleanup, uart0_cleanup),
    C99INIT(setBaudrate, uart0_setbaudrate),
    C99INIT(setParity, uart0_setparity),
    C99INIT(txStart, uart0_enabletxirq),
    C99INIT(txSending, tx_sending),
};

static const struct SerialHardwareVT UART1_VT =
{
    C99INIT(init, uart1_init),
    C99INIT(cleanup, uart1_cleanup),
    C99INIT(setBaudrate, uart1_setbaudrate),
    C99INIT(setParity, uart1_setparity),
    C99INIT(txStart, uart1_enabletxirq),
    C99INIT(txSending, tx_sending),
};

static const struct SerialHardwareVT SPI0_VT =
{
    C99INIT(init, spi0_init),
    C99INIT(cleanup, spi0_cleanup),
    C99INIT(setBaudrate, spi0_setbaudrate),
    C99INIT(setParity, spi_setparity),
    C99INIT(txStart, spi0_starttx),
    C99INIT(txSending, tx_sending),
};
#if CPU_ARM_SAM7X
static const struct SerialHardwareVT SPI1_VT =
{
    C99INIT(init, spi1_init),
    C99INIT(cleanup, spi1_cleanup),
    C99INIT(setBaudrate, spi1_setbaudrate),
    C99INIT(setParity, spi_setparity),
    C99INIT(txStart, spi1_starttx),
    C99INIT(txSending, tx_sending),
};
#endif

static struct ArmSerial UARTDescs[SER_CNT] =
{
    {
        C99INIT(hw, ) {
            C99INIT(table, &UART0_VT),
            C99INIT(txbuffer, uart0_txbuffer),
            C99INIT(rxbuffer, uart0_rxbuffer),
            C99INIT(txbuffer_size, sizeof(uart0_txbuffer)),
            C99INIT(rxbuffer_size, sizeof(uart0_rxbuffer)),
        },
        C99INIT(sending, false),
    },
    {
        C99INIT(hw, ) {
            C99INIT(table, &UART1_VT),
            C99INIT(txbuffer, uart1_txbuffer),
            C99INIT(rxbuffer, uart1_rxbuffer),
            C99INIT(txbuffer_size, sizeof(uart1_txbuffer)),
            C99INIT(rxbuffer_size, sizeof(uart1_rxbuffer)),
        },
        C99INIT(sending, false),
    },

    {
        C99INIT(hw, ) {
            C99INIT(table, &SPI0_VT),
            C99INIT(txbuffer, spi0_txbuffer),
            C99INIT(rxbuffer, spi0_rxbuffer),
            C99INIT(txbuffer_size, sizeof(spi0_txbuffer)),
            C99INIT(rxbuffer_size, sizeof(spi0_rxbuffer)),
        },
        C99INIT(sending, false),
    },
    #if CPU_ARM_SAM7X
    {
        C99INIT(hw, ) {
            C99INIT(table, &SPI1_VT),
            C99INIT(txbuffer, spi1_txbuffer),
            C99INIT(rxbuffer, spi1_rxbuffer),
            C99INIT(txbuffer_size, sizeof(spi1_txbuffer)),
            C99INIT(rxbuffer_size, sizeof(spi1_rxbuffer)),
        },
        C99INIT(sending, false),
    }

    #endif
};

struct SerialHardware *ser_hw_getdesc(int unit)
{
    ASSERT(unit < SER_CNT);
    return &UARTDescs[unit].hw;
}

INLINE void uart0_irq_tx(void)
{
    SER_STROBE_ON;

    struct FIFOBuffer * const txfifo = &ser_handles[SER_UART0]->txfifo;

    if (fifo_isempty(txfifo))
    {
        /*
         * - Disable the TX empty interrupts
         */
        US0_IDR = BV(US_TXEMPTY);
        SER_UART0_BUS_TXEND;
        UARTDescs[SER_UART0].sending = false;
    }
    else
    {
        char c = fifo_pop(txfifo);
        SER_UART0_BUS_TXCHAR(c);
    }

    SER_STROBE_OFF;
}

INLINE void uart0_irq_rx(void)
{
    SER_STROBE_ON;

    /* Should be read before US_CRS */
    ser_handles[SER_UART0]->status |= US0_CSR & (SERRF_RXSROVERRUN | SERRF_FRAMEERROR);
    US0_CR = BV(US_RSTSTA);

    char c = US0_RHR;
    struct FIFOBuffer * const rxfifo = &ser_handles[SER_UART0]->rxfifo;

    if (fifo_isfull(rxfifo))
        ser_handles[SER_UART0]->status |= SERRF_RXFIFOOVERRUN;
    else
        fifo_push(rxfifo, c);

    SER_STROBE_OFF;
}

static DECLARE_ISR(uart0_irq_dispatcher)
{
    if (US0_CSR & BV(US_RXRDY))
        uart0_irq_rx();

    if (US0_CSR & BV(US_TXEMPTY))
        uart0_irq_tx();

    /* Inform hw that we have served the IRQ */
    AIC_EOICR = 0;
}

INLINE void uart1_irq_tx(void)
{
    SER_STROBE_ON;

    struct FIFOBuffer * const txfifo = &ser_handles[SER_UART1]->txfifo;

    if (fifo_isempty(txfifo))
    {
        /*
         * - Disable the TX empty interrupts
         */
        US1_IDR = BV(US_TXEMPTY);
        SER_UART1_BUS_TXEND;
        UARTDescs[SER_UART1].sending = false;
    }
    else
    {
        char c = fifo_pop(txfifo);
        SER_UART1_BUS_TXCHAR(c);
    }

    SER_STROBE_OFF;
}

INLINE void uart1_irq_rx(void)
{
    SER_STROBE_ON;

    /* Should be read before US_CRS */
    ser_handles[SER_UART1]->status |= US1_CSR & (SERRF_RXSROVERRUN | SERRF_FRAMEERROR);
    US1_CR = BV(US_RSTSTA);

    char c = US1_RHR;
    struct FIFOBuffer * const rxfifo = &ser_handles[SER_UART1]->rxfifo;

    if (fifo_isfull(rxfifo))
        ser_handles[SER_UART1]->status |= SERRF_RXFIFOOVERRUN;
    else
        fifo_push(rxfifo, c);

    SER_STROBE_OFF;
}

static DECLARE_ISR(uart1_irq_dispatcher)
{
    if (US1_CSR & BV(US_RXRDY))
        uart1_irq_rx();

    if (US1_CSR & BV(US_TXEMPTY))
        uart1_irq_tx();

    /* Inform hw that we have served the IRQ */
    AIC_EOICR = 0;
}

static DECLARE_ISR(spi0_irq_handler)
{
    SER_STROBE_ON;

    char c = SPI0_RDR;
    /* Read incoming byte. */
    if (!fifo_isfull(&ser_handles[SER_SPI0]->rxfifo))
        fifo_push(&ser_handles[SER_SPI0]->rxfifo, c);
    /*
     * FIXME
    else
        ser_handles[SER_SPI0]->status |= SERRF_RXFIFOOVERRUN;
    */

    /* Send */
    if (!fifo_isempty(&ser_handles[SER_SPI0]->txfifo))
        SPI0_TDR = fifo_pop(&ser_handles[SER_SPI0]->txfifo);
    else
        UARTDescs[SER_SPI0].sending = false;

    /* Inform hw that we have served the IRQ */
    AIC_EOICR = 0;
    SER_STROBE_OFF;
}


#if CPU_ARM_SAM7X

static DECLARE_ISR(spi1_irq_handler)
{
    SER_STROBE_ON;

    char c = SPI1_RDR;
    /* Read incoming byte. */
    if (!fifo_isfull(&ser_handles[SER_SPI1]->rxfifo))
        fifo_push(&ser_handles[SER_SPI1]->rxfifo, c);
    /*
     * FIXME
    else
        ser_handles[SER_SPI1]->status |= SERRF_RXFIFOOVERRUN;
    */

    /* Send */
    if (!fifo_isempty(&ser_handles[SER_SPI1]->txfifo))
        SPI1_TDR = fifo_pop(&ser_handles[SER_SPI1]->txfifo);
    else
        UARTDescs[SER_SPI1].sending = false;

    /* Inform hw that we have served the IRQ */
    AIC_EOICR = 0;
    SER_STROBE_OFF;
}
#endif