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/*
* nRF51 SoC UART emulation
*
* See nRF51 Series Reference Manual, "29 Universal Asynchronous
* Receiver/Transmitter" for hardware specifications:
* http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.pdf
*
* Copyright (c) 2018 Julia Suvorova <jusual@mail.ru>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 or
* (at your option) any later version.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include "hw/char/nrf51_uart.h"
#include "hw/irq.h"
#include "hw/qdev-properties.h"
#include "hw/qdev-properties-system.h"
#include "migration/vmstate.h"
#include "trace.h"
static void nrf51_uart_update_irq(NRF51UARTState *s)
{
bool irq = false;
irq |= (s->reg[R_UART_RXDRDY] &&
(s->reg[R_UART_INTEN] & R_UART_INTEN_RXDRDY_MASK));
irq |= (s->reg[R_UART_TXDRDY] &&
(s->reg[R_UART_INTEN] & R_UART_INTEN_TXDRDY_MASK));
irq |= (s->reg[R_UART_ERROR] &&
(s->reg[R_UART_INTEN] & R_UART_INTEN_ERROR_MASK));
irq |= (s->reg[R_UART_RXTO] &&
(s->reg[R_UART_INTEN] & R_UART_INTEN_RXTO_MASK));
qemu_set_irq(s->irq, irq);
}
static uint64_t uart_read(void *opaque, hwaddr addr, unsigned int size)
{
NRF51UARTState *s = NRF51_UART(opaque);
uint64_t r;
if (!s->enabled) {
return 0;
}
switch (addr) {
case A_UART_RXD:
r = s->rx_fifo[s->rx_fifo_pos];
if (s->rx_started && s->rx_fifo_len) {
s->rx_fifo_pos = (s->rx_fifo_pos + 1) % UART_FIFO_LENGTH;
s->rx_fifo_len--;
if (s->rx_fifo_len) {
s->reg[R_UART_RXDRDY] = 1;
nrf51_uart_update_irq(s);
}
qemu_chr_fe_accept_input(&s->chr);
}
break;
case A_UART_INTENSET:
case A_UART_INTENCLR:
case A_UART_INTEN:
r = s->reg[R_UART_INTEN];
break;
default:
r = s->reg[addr / 4];
break;
}
trace_nrf51_uart_read(addr, r, size);
return r;
}
static gboolean uart_transmit(void *do_not_use, GIOCondition cond, void *opaque)
{
NRF51UARTState *s = NRF51_UART(opaque);
int r;
uint8_t c = s->reg[R_UART_TXD];
s->watch_tag = 0;
r = qemu_chr_fe_write(&s->chr, &c, 1);
if (r <= 0) {
s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
uart_transmit, s);
if (!s->watch_tag) {
/* The hardware has no transmit error reporting,
* so silently drop the byte
*/
goto buffer_drained;
}
return G_SOURCE_REMOVE;
}
buffer_drained:
s->reg[R_UART_TXDRDY] = 1;
s->pending_tx_byte = false;
return G_SOURCE_REMOVE;
}
static void uart_cancel_transmit(NRF51UARTState *s)
{
if (s->watch_tag) {
g_source_remove(s->watch_tag);
s->watch_tag = 0;
}
}
static void uart_write(void *opaque, hwaddr addr,
uint64_t value, unsigned int size)
{
NRF51UARTState *s = NRF51_UART(opaque);
trace_nrf51_uart_write(addr, value, size);
if (!s->enabled && (addr != A_UART_ENABLE)) {
return;
}
switch (addr) {
case A_UART_TXD:
if (!s->pending_tx_byte && s->tx_started) {
s->reg[R_UART_TXD] = value;
s->pending_tx_byte = true;
uart_transmit(NULL, G_IO_OUT, s);
}
break;
case A_UART_INTEN:
s->reg[R_UART_INTEN] = value;
break;
case A_UART_INTENSET:
s->reg[R_UART_INTEN] |= value;
break;
case A_UART_INTENCLR:
s->reg[R_UART_INTEN] &= ~value;
break;
case A_UART_TXDRDY ... A_UART_RXTO:
s->reg[addr / 4] = value;
break;
case A_UART_ERRORSRC:
s->reg[addr / 4] &= ~value;
break;
case A_UART_RXD:
break;
case A_UART_RXDRDY:
if (value == 0) {
s->reg[R_UART_RXDRDY] = 0;
}
break;
case A_UART_STARTTX:
if (value == 1) {
s->tx_started = true;
}
break;
case A_UART_STARTRX:
if (value == 1) {
s->rx_started = true;
}
break;
case A_UART_ENABLE:
if (value) {
if (value == 4) {
s->enabled = true;
}
break;
}
s->enabled = false;
value = 1;
/* fall through */
case A_UART_SUSPEND:
case A_UART_STOPTX:
if (value == 1) {
s->tx_started = false;
}
/* fall through */
case A_UART_STOPRX:
if (addr != A_UART_STOPTX && value == 1) {
s->rx_started = false;
s->reg[R_UART_RXTO] = 1;
}
break;
default:
s->reg[addr / 4] = value;
break;
}
nrf51_uart_update_irq(s);
}
static const MemoryRegionOps uart_ops = {
.read = uart_read,
.write = uart_write,
.endianness = DEVICE_LITTLE_ENDIAN,
};
static void nrf51_uart_reset(DeviceState *dev)
{
NRF51UARTState *s = NRF51_UART(dev);
s->pending_tx_byte = 0;
uart_cancel_transmit(s);
memset(s->reg, 0, sizeof(s->reg));
s->reg[R_UART_PSELRTS] = 0xFFFFFFFF;
s->reg[R_UART_PSELTXD] = 0xFFFFFFFF;
s->reg[R_UART_PSELCTS] = 0xFFFFFFFF;
s->reg[R_UART_PSELRXD] = 0xFFFFFFFF;
s->reg[R_UART_BAUDRATE] = 0x4000000;
s->rx_fifo_len = 0;
s->rx_fifo_pos = 0;
s->rx_started = false;
s->tx_started = false;
s->enabled = false;
}
static void uart_receive(void *opaque, const uint8_t *buf, int size)
{
NRF51UARTState *s = NRF51_UART(opaque);
int i;
if (size == 0 || s->rx_fifo_len >= UART_FIFO_LENGTH) {
return;
}
for (i = 0; i < size; i++) {
uint32_t pos = (s->rx_fifo_pos + s->rx_fifo_len) % UART_FIFO_LENGTH;
s->rx_fifo[pos] = buf[i];
s->rx_fifo_len++;
}
s->reg[R_UART_RXDRDY] = 1;
nrf51_uart_update_irq(s);
}
static int uart_can_receive(void *opaque)
{
NRF51UARTState *s = NRF51_UART(opaque);
return s->rx_started ? (UART_FIFO_LENGTH - s->rx_fifo_len) : 0;
}
static void uart_event(void *opaque, QEMUChrEvent event)
{
NRF51UARTState *s = NRF51_UART(opaque);
if (event == CHR_EVENT_BREAK) {
s->reg[R_UART_ERRORSRC] |= 3;
s->reg[R_UART_ERROR] = 1;
nrf51_uart_update_irq(s);
}
}
static void nrf51_uart_realize(DeviceState *dev, Error **errp)
{
NRF51UARTState *s = NRF51_UART(dev);
qemu_chr_fe_set_handlers(&s->chr, uart_can_receive, uart_receive,
uart_event, NULL, s, NULL, true);
}
static void nrf51_uart_init(Object *obj)
{
NRF51UARTState *s = NRF51_UART(obj);
SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
memory_region_init_io(&s->iomem, obj, &uart_ops, s,
"nrf51_soc.uart", UART_SIZE);
sysbus_init_mmio(sbd, &s->iomem);
sysbus_init_irq(sbd, &s->irq);
}
static int nrf51_uart_post_load(void *opaque, int version_id)
{
NRF51UARTState *s = NRF51_UART(opaque);
if (s->pending_tx_byte) {
s->watch_tag = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
uart_transmit, s);
}
return 0;
}
static const VMStateDescription nrf51_uart_vmstate = {
.name = "nrf51_soc.uart",
.post_load = nrf51_uart_post_load,
.fields = (const VMStateField[]) {
VMSTATE_UINT32_ARRAY(reg, NRF51UARTState, 0x56C),
VMSTATE_UINT8_ARRAY(rx_fifo, NRF51UARTState, UART_FIFO_LENGTH),
VMSTATE_UINT32(rx_fifo_pos, NRF51UARTState),
VMSTATE_UINT32(rx_fifo_len, NRF51UARTState),
VMSTATE_BOOL(rx_started, NRF51UARTState),
VMSTATE_BOOL(tx_started, NRF51UARTState),
VMSTATE_BOOL(pending_tx_byte, NRF51UARTState),
VMSTATE_BOOL(enabled, NRF51UARTState),
VMSTATE_END_OF_LIST()
}
};
static const Property nrf51_uart_properties[] = {
DEFINE_PROP_CHR("chardev", NRF51UARTState, chr),
};
static void nrf51_uart_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
device_class_set_legacy_reset(dc, nrf51_uart_reset);
dc->realize = nrf51_uart_realize;
device_class_set_props(dc, nrf51_uart_properties);
dc->vmsd = &nrf51_uart_vmstate;
}
static const TypeInfo nrf51_uart_info = {
.name = TYPE_NRF51_UART,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(NRF51UARTState),
.instance_init = nrf51_uart_init,
.class_init = nrf51_uart_class_init
};
static void nrf51_uart_register_types(void)
{
type_register_static(&nrf51_uart_info);
}
type_init(nrf51_uart_register_types)
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