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/*

 * QEMU model of the Xilinx SPI Controller

 *

 * Copyright (C) 2010 Edgar E. Iglesias.

 * Copyright (C) 2012 Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>

 * Copyright (C) 2012 PetaLogix

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include "sysbus.h"

#include "sysemu/sysemu.h"

#include "qemu/log.h"

#include "fifo.h"

#include "ssi.h"

#ifdef XILINX_SPI_ERR_DEBUG

#define DB_PRINT(...) do { \

    fprintf(stderr,  ": %s: ", __func__); \

    fprintf(stderr, ## __VA_ARGS__); \

    } while (0);

#else

    #define DB_PRINT(...)

#endif

#define R_DGIER     (0x1c / 4)

#define R_DGIER_IE  (1 << 31)

#define R_IPISR     (0x20 / 4)

#define IRQ_DRR_NOT_EMPTY    (1 << (31 - 23))

#define IRQ_DRR_OVERRUN      (1 << (31 - 26))

#define IRQ_DRR_FULL         (1 << (31 - 27))

#define IRQ_TX_FF_HALF_EMPTY (1 << 6)

#define IRQ_DTR_UNDERRUN     (1 << 3)

#define IRQ_DTR_EMPTY        (1 << (31 - 29))

#define R_IPIER     (0x28 / 4)

#define R_SRR       (0x40 / 4)

#define R_SPICR     (0x60 / 4)

#define R_SPICR_TXFF_RST     (1 << 5)

#define R_SPICR_RXFF_RST     (1 << 6)

#define R_SPICR_MTI          (1 << 8)

#define R_SPISR     (0x64 / 4)

#define SR_TX_FULL    (1 << 3)

#define SR_TX_EMPTY   (1 << 2)

#define SR_RX_FULL    (1 << 1)

#define SR_RX_EMPTY   (1 << 0)

#define R_SPIDTR    (0x68 / 4)

#define R_SPIDRR    (0x6C / 4)

#define R_SPISSR    (0x70 / 4)

#define R_TX_FF_OCY (0x74 / 4)

#define R_RX_FF_OCY (0x78 / 4)

#define R_MAX       (0x7C / 4)

#define FIFO_CAPACITY 256

typedef struct XilinxSPI {

    SysBusDevice busdev;

    MemoryRegion mmio;

    qemu_irq irq;

    int irqline;

    uint8_t num_cs;

    qemu_irq *cs_lines;

    SSIBus *spi;

    Fifo8 rx_fifo;

    Fifo8 tx_fifo;

    uint32_t regs[R_MAX];

} XilinxSPI;

static void txfifo_reset(XilinxSPI *s)

{

    fifo8_reset(&s->tx_fifo);

    s->regs[R_SPISR] &= ~SR_TX_FULL;

    s->regs[R_SPISR] |= SR_TX_EMPTY;

}

static void rxfifo_reset(XilinxSPI *s)

{

    fifo8_reset(&s->rx_fifo);

    s->regs[R_SPISR] |= SR_RX_EMPTY;

    s->regs[R_SPISR] &= ~SR_RX_FULL;

}

static void xlx_spi_update_cs(XilinxSPI *s)

{

   int i;

    for (i = 0; i < s->num_cs; ++i) {

        qemu_set_irq(s->cs_lines[i], !(~s->regs[R_SPISSR] & 1 << i));

    }

}

static void xlx_spi_update_irq(XilinxSPI *s)

{

    uint32_t pending;

    s->regs[R_IPISR] |=

            (!fifo8_is_empty(&s->rx_fifo) ? IRQ_DRR_NOT_EMPTY : 0) |

            (fifo8_is_full(&s->rx_fifo) ? IRQ_DRR_FULL : 0);

    pending = s->regs[R_IPISR] & s->regs[R_IPIER];

    pending = pending && (s->regs[R_DGIER] & R_DGIER_IE);

    pending = !!pending;

    /* This call lies right in the data paths so don't call the

       irq chain unless things really changed.  */

    if (pending != s->irqline) {

        s->irqline = pending;

        DB_PRINT("irq_change of state %d ISR:%x IER:%X\n",

                    pending, s->regs[R_IPISR], s->regs[R_IPIER]);

        qemu_set_irq(s->irq, pending);

    }

}

static void xlx_spi_do_reset(XilinxSPI *s)

{

    memset(s->regs, 0, sizeof s->regs);

    rxfifo_reset(s);

    txfifo_reset(s);

    s->regs[R_SPISSR] = ~0;

    xlx_spi_update_irq(s);

    xlx_spi_update_cs(s);

}

static void xlx_spi_reset(DeviceState *d)

{

    xlx_spi_do_reset(DO_UPCAST(XilinxSPI, busdev.qdev, d));

}

static inline int spi_master_enabled(XilinxSPI *s)

{

    return !(s->regs[R_SPICR] & R_SPICR_MTI);

}

static void spi_flush_txfifo(XilinxSPI *s)

{

    uint32_t tx;

    uint32_t rx;

    while (!fifo8_is_empty(&s->tx_fifo)) {

        tx = (uint32_t)fifo8_pop(&s->tx_fifo);

        DB_PRINT("data tx:%x\n", tx);

        rx = ssi_transfer(s->spi, tx);

        DB_PRINT("data rx:%x\n", rx);

        if (fifo8_is_full(&s->rx_fifo)) {

            s->regs[R_IPISR] |= IRQ_DRR_OVERRUN;

        } else {

            fifo8_push(&s->rx_fifo, (uint8_t)rx);

            if (fifo8_is_full(&s->rx_fifo)) {

                s->regs[R_SPISR] |= SR_RX_FULL;

                s->regs[R_IPISR] |= IRQ_DRR_FULL;

            }

        }

        s->regs[R_SPISR] &= ~SR_RX_EMPTY;

        s->regs[R_SPISR] &= ~SR_TX_FULL;

        s->regs[R_SPISR] |= SR_TX_EMPTY;

        s->regs[R_IPISR] |= IRQ_DTR_EMPTY;

        s->regs[R_IPISR] |= IRQ_DRR_NOT_EMPTY;

    }

}

static uint64_t

spi_read(void *opaque, hwaddr addr, unsigned int size)

{

    XilinxSPI *s = opaque;

    uint32_t r = 0;

    addr >>= 2;

    switch (addr) {

    case R_SPIDRR:

        if (fifo8_is_empty(&s->rx_fifo)) {

            DB_PRINT("Read from empty FIFO!\n");

            return 0xdeadbeef;

        }

        s->regs[R_SPISR] &= ~SR_RX_FULL;

        r = fifo8_pop(&s->rx_fifo);

        if (fifo8_is_empty(&s->rx_fifo)) {

            s->regs[R_SPISR] |= SR_RX_EMPTY;

        }

        break;

    case R_SPISR:

        r = s->regs[addr];

        break;

    default:

        if (addr < ARRAY_SIZE(s->regs)) {

            r = s->regs[addr];

        }

        break;

    }

    DB_PRINT("addr=" TARGET_FMT_plx " = %x\n", addr * 4, r);

    xlx_spi_update_irq(s);

    return r;

}

static void

spi_write(void *opaque, hwaddr addr,

            uint64_t val64, unsigned int size)

{

    XilinxSPI *s = opaque;

    uint32_t value = val64;

    DB_PRINT("addr=" TARGET_FMT_plx " = %x\n", addr, value);

    addr >>= 2;

    switch (addr) {

    case R_SRR:

        if (value != 0xa) {

            DB_PRINT("Invalid write to SRR %x\n", value);

        } else {

            xlx_spi_do_reset(s);

        }

        break;

    case R_SPIDTR:

        s->regs[R_SPISR] &= ~SR_TX_EMPTY;

        fifo8_push(&s->tx_fifo, (uint8_t)value);

        if (fifo8_is_full(&s->tx_fifo)) {

            s->regs[R_SPISR] |= SR_TX_FULL;

        }

        if (!spi_master_enabled(s)) {

            goto done;

        } else {

            DB_PRINT("DTR and master enabled\n");

        }

        spi_flush_txfifo(s);

        break;

    case R_SPISR:

        DB_PRINT("Invalid write to SPISR %x\n", value);

        break;

    case R_IPISR:

        /* Toggle the bits.  */

        s->regs[addr] ^= value;

        break;

    /* Slave Select Register.  */

    case R_SPISSR:

        s->regs[addr] = value;

        xlx_spi_update_cs(s);

        break;

    case R_SPICR:

        /* FIXME: reset irq and sr state to empty queues.  */

        if (value & R_SPICR_RXFF_RST) {

            rxfifo_reset(s);

        }

        if (value & R_SPICR_TXFF_RST) {

            txfifo_reset(s);

        }

        value &= ~(R_SPICR_RXFF_RST | R_SPICR_TXFF_RST);

        s->regs[addr] = value;

        if (!(value & R_SPICR_MTI)) {

            spi_flush_txfifo(s);

        }

        break;

    default:

        if (addr < ARRAY_SIZE(s->regs)) {

            s->regs[addr] = value;

        }

        break;

    }

done:

    xlx_spi_update_irq(s);

}

static const MemoryRegionOps spi_ops = {

    .read = spi_read,

    .write = spi_write,

    .endianness = DEVICE_NATIVE_ENDIAN,

    .valid = {

        .min_access_size = 4,

        .max_access_size = 4

    }

};

static int xilinx_spi_init(SysBusDevice *dev)

{

    int i;

    XilinxSPI *s = FROM_SYSBUS(typeof(*s), dev);

    DB_PRINT("\n");

    s->spi = ssi_create_bus(&dev->qdev, "spi");

    sysbus_init_irq(dev, &s->irq);

    s->cs_lines = g_new(qemu_irq, s->num_cs);

    ssi_auto_connect_slaves(DEVICE(s), s->cs_lines, s->spi);

    for (i = 0; i < s->num_cs; ++i) {

        sysbus_init_irq(dev, &s->cs_lines[i]);

    }

    memory_region_init_io(&s->mmio, &spi_ops, s, "xilinx-spi", R_MAX * 4);

    sysbus_init_mmio(dev, &s->mmio);

    s->irqline = -1;

    fifo8_create(&s->tx_fifo, FIFO_CAPACITY);

    fifo8_create(&s->rx_fifo, FIFO_CAPACITY);

    return 0;

}

static const VMStateDescription vmstate_xilinx_spi = {

    .name = "xilinx_spi",

    .version_id = 1,

    .minimum_version_id = 1,

    .minimum_version_id_old = 1,

    .fields = (VMStateField[]) {

        VMSTATE_FIFO8(tx_fifo, XilinxSPI),

        VMSTATE_FIFO8(rx_fifo, XilinxSPI),

        VMSTATE_UINT32_ARRAY(regs, XilinxSPI, R_MAX),

        VMSTATE_END_OF_LIST()

    }

};

static Property xilinx_spi_properties[] = {

    DEFINE_PROP_UINT8("num-ss-bits", XilinxSPI, num_cs, 1),

    DEFINE_PROP_END_OF_LIST(),

};

static void xilinx_spi_class_init(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);

    k->init = xilinx_spi_init;

    dc->reset = xlx_spi_reset;

    dc->props = xilinx_spi_properties;

    dc->vmsd = &vmstate_xilinx_spi;

}

static TypeInfo xilinx_spi_info = {

    .name           = "xlnx.xps-spi",

    .parent         = TYPE_SYS_BUS_DEVICE,

    .instance_size  = sizeof(XilinxSPI),

    .class_init     = xilinx_spi_class_init,

};

static void xilinx_spi_register_types(void)

{

    type_register_static(&xilinx_spi_info);

}

type_init(xilinx_spi_register_types)