mirror of https://gitee.com/openkylin/qemu.git
256 lines
6.0 KiB
C
256 lines
6.0 KiB
C
/*
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* QEMU model of the Milkymist UART block.
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*
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* Copyright (c) 2010 Michael Walle <michael@walle.cc>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*
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* Specification available at:
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* http://milkymist.walle.cc/socdoc/uart.pdf
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*/
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#include "qemu/osdep.h"
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#include "hw/hw.h"
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#include "hw/sysbus.h"
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#include "trace.h"
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#include "chardev/char-fe.h"
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#include "qemu/error-report.h"
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enum {
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R_RXTX = 0,
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R_DIV,
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R_STAT,
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R_CTRL,
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R_DBG,
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R_MAX
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};
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enum {
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STAT_THRE = (1<<0),
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STAT_RX_EVT = (1<<1),
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STAT_TX_EVT = (1<<2),
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};
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enum {
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CTRL_RX_IRQ_EN = (1<<0),
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CTRL_TX_IRQ_EN = (1<<1),
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CTRL_THRU_EN = (1<<2),
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};
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enum {
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DBG_BREAK_EN = (1<<0),
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};
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#define TYPE_MILKYMIST_UART "milkymist-uart"
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#define MILKYMIST_UART(obj) \
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OBJECT_CHECK(MilkymistUartState, (obj), TYPE_MILKYMIST_UART)
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struct MilkymistUartState {
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SysBusDevice parent_obj;
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MemoryRegion regs_region;
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CharBackend chr;
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qemu_irq irq;
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uint32_t regs[R_MAX];
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};
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typedef struct MilkymistUartState MilkymistUartState;
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static void uart_update_irq(MilkymistUartState *s)
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{
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int rx_event = s->regs[R_STAT] & STAT_RX_EVT;
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int tx_event = s->regs[R_STAT] & STAT_TX_EVT;
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int rx_irq_en = s->regs[R_CTRL] & CTRL_RX_IRQ_EN;
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int tx_irq_en = s->regs[R_CTRL] & CTRL_TX_IRQ_EN;
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if ((rx_irq_en && rx_event) || (tx_irq_en && tx_event)) {
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trace_milkymist_uart_raise_irq();
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qemu_irq_raise(s->irq);
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} else {
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trace_milkymist_uart_lower_irq();
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qemu_irq_lower(s->irq);
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}
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}
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static uint64_t uart_read(void *opaque, hwaddr addr,
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unsigned size)
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{
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MilkymistUartState *s = opaque;
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uint32_t r = 0;
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addr >>= 2;
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switch (addr) {
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case R_RXTX:
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r = s->regs[addr];
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break;
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case R_DIV:
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case R_STAT:
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case R_CTRL:
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case R_DBG:
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r = s->regs[addr];
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break;
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default:
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error_report("milkymist_uart: read access to unknown register 0x"
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TARGET_FMT_plx, addr << 2);
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break;
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}
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trace_milkymist_uart_memory_read(addr << 2, r);
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return r;
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}
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static void uart_write(void *opaque, hwaddr addr, uint64_t value,
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unsigned size)
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{
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MilkymistUartState *s = opaque;
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unsigned char ch = value;
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trace_milkymist_uart_memory_write(addr, value);
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addr >>= 2;
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switch (addr) {
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case R_RXTX:
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qemu_chr_fe_write_all(&s->chr, &ch, 1);
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s->regs[R_STAT] |= STAT_TX_EVT;
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break;
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case R_DIV:
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case R_CTRL:
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case R_DBG:
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s->regs[addr] = value;
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break;
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case R_STAT:
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/* write one to clear bits */
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s->regs[addr] &= ~(value & (STAT_RX_EVT | STAT_TX_EVT));
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qemu_chr_fe_accept_input(&s->chr);
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break;
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default:
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error_report("milkymist_uart: write access to unknown register 0x"
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TARGET_FMT_plx, addr << 2);
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break;
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}
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uart_update_irq(s);
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}
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static const MemoryRegionOps uart_mmio_ops = {
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.read = uart_read,
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.write = uart_write,
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.valid = {
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.min_access_size = 4,
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.max_access_size = 4,
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},
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.endianness = DEVICE_NATIVE_ENDIAN,
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};
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static void uart_rx(void *opaque, const uint8_t *buf, int size)
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{
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MilkymistUartState *s = opaque;
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assert(!(s->regs[R_STAT] & STAT_RX_EVT));
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s->regs[R_STAT] |= STAT_RX_EVT;
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s->regs[R_RXTX] = *buf;
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uart_update_irq(s);
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}
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static int uart_can_rx(void *opaque)
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{
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MilkymistUartState *s = opaque;
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return !(s->regs[R_STAT] & STAT_RX_EVT);
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}
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static void uart_event(void *opaque, int event)
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{
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}
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static void milkymist_uart_reset(DeviceState *d)
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{
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MilkymistUartState *s = MILKYMIST_UART(d);
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int i;
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for (i = 0; i < R_MAX; i++) {
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s->regs[i] = 0;
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}
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/* THRE is always set */
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s->regs[R_STAT] = STAT_THRE;
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}
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static void milkymist_uart_realize(DeviceState *dev, Error **errp)
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{
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MilkymistUartState *s = MILKYMIST_UART(dev);
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qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx,
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uart_event, s, NULL, true);
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}
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static void milkymist_uart_init(Object *obj)
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{
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SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
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MilkymistUartState *s = MILKYMIST_UART(obj);
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sysbus_init_irq(sbd, &s->irq);
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memory_region_init_io(&s->regs_region, OBJECT(s), &uart_mmio_ops, s,
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"milkymist-uart", R_MAX * 4);
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sysbus_init_mmio(sbd, &s->regs_region);
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}
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static const VMStateDescription vmstate_milkymist_uart = {
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.name = "milkymist-uart",
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.version_id = 1,
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.minimum_version_id = 1,
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.fields = (VMStateField[]) {
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VMSTATE_UINT32_ARRAY(regs, MilkymistUartState, R_MAX),
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VMSTATE_END_OF_LIST()
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}
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};
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static Property milkymist_uart_properties[] = {
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DEFINE_PROP_CHR("chardev", MilkymistUartState, chr),
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DEFINE_PROP_END_OF_LIST(),
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};
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static void milkymist_uart_class_init(ObjectClass *klass, void *data)
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{
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DeviceClass *dc = DEVICE_CLASS(klass);
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dc->realize = milkymist_uart_realize;
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dc->reset = milkymist_uart_reset;
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dc->vmsd = &vmstate_milkymist_uart;
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dc->props = milkymist_uart_properties;
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}
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static const TypeInfo milkymist_uart_info = {
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.name = TYPE_MILKYMIST_UART,
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.parent = TYPE_SYS_BUS_DEVICE,
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.instance_size = sizeof(MilkymistUartState),
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.instance_init = milkymist_uart_init,
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.class_init = milkymist_uart_class_init,
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};
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static void milkymist_uart_register_types(void)
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{
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type_register_static(&milkymist_uart_info);
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}
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type_init(milkymist_uart_register_types)
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