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qemu-e2k/hw/char/bcm2835_aux.c
Andrew Baumann 97398d900c bcm2835_aux: add emulation of BCM2835 AUX (aka UART1) block 
At present only the core UART functions (data path for tx/rx) are
implemented, which is enough for UEFI to boot. The following
features/registers are unimplemented:
  * Line/modem control
  * Scratch register
  * Extra control
  * Baudrate
  * SPI interfaces

Signed-off-by: Andrew Baumann <Andrew.Baumann@microsoft.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1457467526-8840-3-git-send-email-Andrew.Baumann@microsoft.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2016-03-16 17:42:18 +00:00

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/*
* 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"
#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;
}
}
if (s->chr) {
qemu_chr_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;
if (s->chr) {
qemu_chr_fe_write(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);
if (s->chr) {
qemu_chr_add_handlers(s->chr, bcm2835_aux_can_receive,
bcm2835_aux_receive, NULL, s);
}
}
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)
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