hw/char/bcm2835_aux.c - qemu - Git at Google

 /*
  * BCM2835 (Raspberry Pi / Pi 2) Aux block (mini UART and SPI).
  * Copyright (c) 2015, Microsoft
  * Written by Andrew Baumann
  * Based on pl011.c, copyright terms below:
  *
  * Arm PrimeCell PL011 UART
  *
  * Copyright (c) 2006 CodeSourcery.
  * Written by Paul Brook
  *
  * This code is licensed under the GPL.
  *
  * At present only the core UART functions (data path for tx/rx) are
  * implemented. The following features/registers are unimplemented:
  *  - Line/modem control
  *  - Scratch register
  *  - Extra control
  *  - Baudrate
  *  - SPI interfaces
  */

 #include "qemu/osdep.h"
 #include "hw/char/bcm2835_aux.h"
 #include "qemu/log.h"

 #define AUX_IRQ         0x0
 #define AUX_ENABLES     0x4
 #define AUX_MU_IO_REG   0x40
 #define AUX_MU_IER_REG  0x44
 #define AUX_MU_IIR_REG  0x48
 #define AUX_MU_LCR_REG  0x4c
 #define AUX_MU_MCR_REG  0x50
 #define AUX_MU_LSR_REG  0x54
 #define AUX_MU_MSR_REG  0x58
 #define AUX_MU_SCRATCH  0x5c
 #define AUX_MU_CNTL_REG 0x60
 #define AUX_MU_STAT_REG 0x64
 #define AUX_MU_BAUD_REG 0x68

 /* bits in IER/IIR registers */
 #define TX_INT  0x1
 #define RX_INT  0x2

 static void bcm2835_aux_update(BCM2835AuxState *s)
 {
     /* signal an interrupt if either:
      * 1. rx interrupt is enabled and we have a non-empty rx fifo, or
      * 2. the tx interrupt is enabled (since we instantly drain the tx fifo)
      */
     s->iir = 0;
     if ((s->ier & RX_INT) && s->read_count != 0) {
         s->iir |= RX_INT;
     }
     if (s->ier & TX_INT) {
         s->iir |= TX_INT;
     }
     qemu_set_irq(s->irq, s->iir != 0);
 }

 static uint64_t bcm2835_aux_read(void *opaque, hwaddr offset, unsigned size)
 {
     BCM2835AuxState *s = opaque;
     uint32_t c, res;

     switch (offset) {
     case AUX_IRQ:
         return s->iir != 0;

     case AUX_ENABLES:
         return 1; /* mini UART permanently enabled */

     case AUX_MU_IO_REG:
         /* "DLAB bit set means access baudrate register" is NYI */
         c = s->read_fifo[s->read_pos];
         if (s->read_count > 0) {
             s->read_count--;
             if (++s->read_pos == BCM2835_AUX_RX_FIFO_LEN) {
                 s->read_pos = 0;
             }
         }
         qemu_chr_fe_accept_input(&s->chr);
         bcm2835_aux_update(s);
         return c;

     case AUX_MU_IER_REG:
         /* "DLAB bit set means access baudrate register" is NYI */
         return 0xc0 | s->ier; /* FIFO enables always read 1 */

     case AUX_MU_IIR_REG:
         res = 0xc0; /* FIFO enables */
         /* The spec is unclear on what happens when both tx and rx
          * interrupts are active, besides that this cannot occur. At
          * present, we choose to prioritise the rx interrupt, since
          * the tx fifo is always empty. */
         if (s->read_count != 0) {
             res |= 0x4;
         } else {
             res |= 0x2;
         }
         if (s->iir == 0) {
             res |= 0x1;
         }
         return res;

     case AUX_MU_LCR_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
         return 0;

     case AUX_MU_MCR_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
         return 0;

     case AUX_MU_LSR_REG:
         res = 0x60; /* tx idle, empty */
         if (s->read_count != 0) {
             res |= 0x1;
         }
         return res;

     case AUX_MU_MSR_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MSR_REG unsupported\n", __func__);
         return 0;

     case AUX_MU_SCRATCH:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
         return 0;

     case AUX_MU_CNTL_REG:
         return 0x3; /* tx, rx enabled */

     case AUX_MU_STAT_REG:
         res = 0x30e; /* space in the output buffer, empty tx fifo, idle tx/rx */
         if (s->read_count > 0) {
             res |= 0x1; /* data in input buffer */
             assert(s->read_count < BCM2835_AUX_RX_FIFO_LEN);
             res |= ((uint32_t)s->read_count) << 16; /* rx fifo fill level */
         }
         return res;

     case AUX_MU_BAUD_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
         return 0;

     default:
         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
                       __func__, offset);
         return 0;
     }
 }

 static void bcm2835_aux_write(void *opaque, hwaddr offset, uint64_t value,
                               unsigned size)
 {
     BCM2835AuxState *s = opaque;
     unsigned char ch;

     switch (offset) {
     case AUX_ENABLES:
         if (value != 1) {
             qemu_log_mask(LOG_UNIMP, "%s: unsupported attempt to enable SPI "
                           "or disable UART\n", __func__);
         }
         break;

     case AUX_MU_IO_REG:
         /* "DLAB bit set means access baudrate register" is NYI */
         ch = value;
         /* XXX this blocks entire thread. Rewrite to use
          * qemu_chr_fe_write and background I/O callbacks */
         qemu_chr_fe_write_all(&s->chr, &ch, 1);
         break;

     case AUX_MU_IER_REG:
         /* "DLAB bit set means access baudrate register" is NYI */
         s->ier = value & (TX_INT | RX_INT);
         bcm2835_aux_update(s);
         break;

     case AUX_MU_IIR_REG:
         if (value & 0x2) {
             s->read_count = 0;
         }
         break;

     case AUX_MU_LCR_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
         break;

     case AUX_MU_MCR_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
         break;

     case AUX_MU_SCRATCH:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
         break;

     case AUX_MU_CNTL_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_CNTL_REG unsupported\n", __func__);
         break;

     case AUX_MU_BAUD_REG:
         qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
         break;

     default:
         qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
                       __func__, offset);
     }

     bcm2835_aux_update(s);
 }

 static int bcm2835_aux_can_receive(void *opaque)
 {
     BCM2835AuxState *s = opaque;

     return s->read_count < BCM2835_AUX_RX_FIFO_LEN;
 }

 static void bcm2835_aux_put_fifo(void *opaque, uint8_t value)
 {
     BCM2835AuxState *s = opaque;
     int slot;

     slot = s->read_pos + s->read_count;
     if (slot >= BCM2835_AUX_RX_FIFO_LEN) {
         slot -= BCM2835_AUX_RX_FIFO_LEN;
     }
     s->read_fifo[slot] = value;
     s->read_count++;
     if (s->read_count == BCM2835_AUX_RX_FIFO_LEN) {
         /* buffer full */
     }
     bcm2835_aux_update(s);
 }

 static void bcm2835_aux_receive(void *opaque, const uint8_t *buf, int size)
 {
     bcm2835_aux_put_fifo(opaque, *buf);
 }

 static const MemoryRegionOps bcm2835_aux_ops = {
     .read = bcm2835_aux_read,
     .write = bcm2835_aux_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
     .valid.min_access_size = 4,
     .valid.max_access_size = 4,
 };

 static const VMStateDescription vmstate_bcm2835_aux = {
     .name = TYPE_BCM2835_AUX,
     .version_id = 1,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_UINT8_ARRAY(read_fifo, BCM2835AuxState,
                             BCM2835_AUX_RX_FIFO_LEN),
         VMSTATE_UINT8(read_pos, BCM2835AuxState),
         VMSTATE_UINT8(read_count, BCM2835AuxState),
         VMSTATE_UINT8(ier, BCM2835AuxState),
         VMSTATE_UINT8(iir, BCM2835AuxState),
         VMSTATE_END_OF_LIST()
     }
 };

 static void bcm2835_aux_init(Object *obj)
 {
     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
     BCM2835AuxState *s = BCM2835_AUX(obj);

     memory_region_init_io(&s->iomem, OBJECT(s), &bcm2835_aux_ops, s,
                           TYPE_BCM2835_AUX, 0x100);
     sysbus_init_mmio(sbd, &s->iomem);
     sysbus_init_irq(sbd, &s->irq);
 }

 static void bcm2835_aux_realize(DeviceState *dev, Error **errp)
 {
     BCM2835AuxState *s = BCM2835_AUX(dev);

     qemu_chr_fe_set_handlers(&s->chr, bcm2835_aux_can_receive,
                              bcm2835_aux_receive, NULL, NULL, s, NULL, true);
 }

 static Property bcm2835_aux_props[] = {
     DEFINE_PROP_CHR("chardev", BCM2835AuxState, chr),
     DEFINE_PROP_END_OF_LIST(),
 };

 static void bcm2835_aux_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);

     dc->realize = bcm2835_aux_realize;
     dc->vmsd = &vmstate_bcm2835_aux;
     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
     dc->props = bcm2835_aux_props;
 }

 static const TypeInfo bcm2835_aux_info = {
     .name          = TYPE_BCM2835_AUX,
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_size = sizeof(BCM2835AuxState),
     .instance_init = bcm2835_aux_init,
     .class_init    = bcm2835_aux_class_init,
 };

 static void bcm2835_aux_register_types(void)
 {
     type_register_static(&bcm2835_aux_info);
 }

 type_init(bcm2835_aux_register_types)
	/*
	* BCM2835 (Raspberry Pi / Pi 2) Aux block (mini UART and SPI).
	* Copyright (c) 2015, Microsoft
	* Written by Andrew Baumann
	* Based on pl011.c, copyright terms below:
	*
	* Arm PrimeCell PL011 UART
	*
	* Copyright (c) 2006 CodeSourcery.
	* Written by Paul Brook
	*
	* This code is licensed under the GPL.
	*
	* At present only the core UART functions (data path for tx/rx) are
	* implemented. The following features/registers are unimplemented:
	* - Line/modem control
	* - Scratch register
	* - Extra control
	* - Baudrate
	* - SPI interfaces
	*/

	#include "qemu/osdep.h"
	#include "hw/char/bcm2835_aux.h"
	#include "qemu/log.h"

	#define AUX_IRQ 0x0
	#define AUX_ENABLES 0x4
	#define AUX_MU_IO_REG 0x40
	#define AUX_MU_IER_REG 0x44
	#define AUX_MU_IIR_REG 0x48
	#define AUX_MU_LCR_REG 0x4c
	#define AUX_MU_MCR_REG 0x50
	#define AUX_MU_LSR_REG 0x54
	#define AUX_MU_MSR_REG 0x58
	#define AUX_MU_SCRATCH 0x5c
	#define AUX_MU_CNTL_REG 0x60
	#define AUX_MU_STAT_REG 0x64
	#define AUX_MU_BAUD_REG 0x68

	/* bits in IER/IIR registers */
	#define TX_INT 0x1
	#define RX_INT 0x2

	static void bcm2835_aux_update(BCM2835AuxState *s)
	{
	/* signal an interrupt if either:
	* 1. rx interrupt is enabled and we have a non-empty rx fifo, or
	* 2. the tx interrupt is enabled (since we instantly drain the tx fifo)
	*/
	s->iir = 0;
	if ((s->ier & RX_INT) && s->read_count != 0) {
	s->iir \|= RX_INT;
	}
	if (s->ier & TX_INT) {
	s->iir \|= TX_INT;
	}
	qemu_set_irq(s->irq, s->iir != 0);
	}

	static uint64_t bcm2835_aux_read(void *opaque, hwaddr offset, unsigned size)
	{
	BCM2835AuxState *s = opaque;
	uint32_t c, res;

	switch (offset) {
	case AUX_IRQ:
	return s->iir != 0;

	case AUX_ENABLES:
	return 1; /* mini UART permanently enabled */

	case AUX_MU_IO_REG:
	/* "DLAB bit set means access baudrate register" is NYI */
	c = s->read_fifo[s->read_pos];
	if (s->read_count > 0) {
	s->read_count--;
	if (++s->read_pos == BCM2835_AUX_RX_FIFO_LEN) {
	s->read_pos = 0;
	}
	}
	qemu_chr_fe_accept_input(&s->chr);
	bcm2835_aux_update(s);
	return c;

	case AUX_MU_IER_REG:
	/* "DLAB bit set means access baudrate register" is NYI */
	return 0xc0 \| s->ier; /* FIFO enables always read 1 */

	case AUX_MU_IIR_REG:
	res = 0xc0; /* FIFO enables */
	/* The spec is unclear on what happens when both tx and rx
	* interrupts are active, besides that this cannot occur. At
	* present, we choose to prioritise the rx interrupt, since
	* the tx fifo is always empty. */
	if (s->read_count != 0) {
	res \|= 0x4;
	} else {
	res \|= 0x2;
	}
	if (s->iir == 0) {
	res \|= 0x1;
	}
	return res;

	case AUX_MU_LCR_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
	return 0;

	case AUX_MU_MCR_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
	return 0;

	case AUX_MU_LSR_REG:
	res = 0x60; /* tx idle, empty */
	if (s->read_count != 0) {
	res \|= 0x1;
	}
	return res;

	case AUX_MU_MSR_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MSR_REG unsupported\n", __func__);
	return 0;

	case AUX_MU_SCRATCH:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
	return 0;

	case AUX_MU_CNTL_REG:
	return 0x3; /* tx, rx enabled */

	case AUX_MU_STAT_REG:
	res = 0x30e; /* space in the output buffer, empty tx fifo, idle tx/rx */
	if (s->read_count > 0) {
	res \|= 0x1; /* data in input buffer */
	assert(s->read_count < BCM2835_AUX_RX_FIFO_LEN);
	res \|= ((uint32_t)s->read_count) << 16; /* rx fifo fill level */
	}
	return res;

	case AUX_MU_BAUD_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
	return 0;

	default:
	qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
	__func__, offset);
	return 0;
	}
	}

	static void bcm2835_aux_write(void *opaque, hwaddr offset, uint64_t value,
	unsigned size)
	{
	BCM2835AuxState *s = opaque;
	unsigned char ch;

	switch (offset) {
	case AUX_ENABLES:
	if (value != 1) {
	qemu_log_mask(LOG_UNIMP, "%s: unsupported attempt to enable SPI "
	"or disable UART\n", __func__);
	}
	break;

	case AUX_MU_IO_REG:
	/* "DLAB bit set means access baudrate register" is NYI */
	ch = value;
	/* XXX this blocks entire thread. Rewrite to use
	* qemu_chr_fe_write and background I/O callbacks */
	qemu_chr_fe_write_all(&s->chr, &ch, 1);
	break;

	case AUX_MU_IER_REG:
	/* "DLAB bit set means access baudrate register" is NYI */
	s->ier = value & (TX_INT \| RX_INT);
	bcm2835_aux_update(s);
	break;

	case AUX_MU_IIR_REG:
	if (value & 0x2) {
	s->read_count = 0;
	}
	break;

	case AUX_MU_LCR_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_LCR_REG unsupported\n", __func__);
	break;

	case AUX_MU_MCR_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_MCR_REG unsupported\n", __func__);
	break;

	case AUX_MU_SCRATCH:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_SCRATCH unsupported\n", __func__);
	break;

	case AUX_MU_CNTL_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_CNTL_REG unsupported\n", __func__);
	break;

	case AUX_MU_BAUD_REG:
	qemu_log_mask(LOG_UNIMP, "%s: AUX_MU_BAUD_REG unsupported\n", __func__);
	break;

	default:
	qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset %"HWADDR_PRIx"\n",
	__func__, offset);
	}

	bcm2835_aux_update(s);
	}

	static int bcm2835_aux_can_receive(void *opaque)
	{
	BCM2835AuxState *s = opaque;

	return s->read_count < BCM2835_AUX_RX_FIFO_LEN;
	}

	static void bcm2835_aux_put_fifo(void *opaque, uint8_t value)
	{
	BCM2835AuxState *s = opaque;
	int slot;

	slot = s->read_pos + s->read_count;
	if (slot >= BCM2835_AUX_RX_FIFO_LEN) {
	slot -= BCM2835_AUX_RX_FIFO_LEN;
	}
	s->read_fifo[slot] = value;
	s->read_count++;
	if (s->read_count == BCM2835_AUX_RX_FIFO_LEN) {
	/* buffer full */
	}
	bcm2835_aux_update(s);
	}

	static void bcm2835_aux_receive(void opaque, const uint8_t buf, int size)
	{
	bcm2835_aux_put_fifo(opaque, *buf);
	}

	static const MemoryRegionOps bcm2835_aux_ops = {
	.read = bcm2835_aux_read,
	.write = bcm2835_aux_write,
	.endianness = DEVICE_NATIVE_ENDIAN,
	.valid.min_access_size = 4,
	.valid.max_access_size = 4,
	};

	static const VMStateDescription vmstate_bcm2835_aux = {
	.name = TYPE_BCM2835_AUX,
	.version_id = 1,
	.minimum_version_id = 1,
	.fields = (VMStateField[]) {
	VMSTATE_UINT8_ARRAY(read_fifo, BCM2835AuxState,
	BCM2835_AUX_RX_FIFO_LEN),
	VMSTATE_UINT8(read_pos, BCM2835AuxState),
	VMSTATE_UINT8(read_count, BCM2835AuxState),
	VMSTATE_UINT8(ier, BCM2835AuxState),
	VMSTATE_UINT8(iir, BCM2835AuxState),
	VMSTATE_END_OF_LIST()
	}
	};

	static void bcm2835_aux_init(Object *obj)
	{
	SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
	BCM2835AuxState *s = BCM2835_AUX(obj);

	memory_region_init_io(&s->iomem, OBJECT(s), &bcm2835_aux_ops, s,
	TYPE_BCM2835_AUX, 0x100);
	sysbus_init_mmio(sbd, &s->iomem);
	sysbus_init_irq(sbd, &s->irq);
	}

	static void bcm2835_aux_realize(DeviceState dev, Error *errp)
	{
	BCM2835AuxState *s = BCM2835_AUX(dev);

	qemu_chr_fe_set_handlers(&s->chr, bcm2835_aux_can_receive,
	bcm2835_aux_receive, NULL, NULL, s, NULL, true);
	}

	static Property bcm2835_aux_props[] = {
	DEFINE_PROP_CHR("chardev", BCM2835AuxState, chr),
	DEFINE_PROP_END_OF_LIST(),
	};

	static void bcm2835_aux_class_init(ObjectClass oc, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(oc);

	dc->realize = bcm2835_aux_realize;
	dc->vmsd = &vmstate_bcm2835_aux;
	set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
	dc->props = bcm2835_aux_props;
	}

	static const TypeInfo bcm2835_aux_info = {
	.name = TYPE_BCM2835_AUX,
	.parent = TYPE_SYS_BUS_DEVICE,
	.instance_size = sizeof(BCM2835AuxState),
	.instance_init = bcm2835_aux_init,
	.class_init = bcm2835_aux_class_init,
	};

	static void bcm2835_aux_register_types(void)
	{
	type_register_static(&bcm2835_aux_info);
	}

	type_init(bcm2835_aux_register_types)