mirror of https://gitee.com/openkylin/qemu.git
193 lines
4.7 KiB
C
193 lines
4.7 KiB
C
/*
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* QEMU model of the UART on the SiFive E300 and U500 series SOCs.
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*
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* Copyright (c) 2016 Stefan O'Rear
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2 or later, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "hw/sysbus.h"
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#include "chardev/char.h"
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#include "chardev/char-fe.h"
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#include "target/riscv/cpu.h"
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#include "hw/riscv/sifive_uart.h"
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/*
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* Not yet implemented:
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*
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* Transmit FIFO using "qemu/fifo8.h"
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*/
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/* Returns the state of the IP (interrupt pending) register */
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static uint64_t uart_ip(SiFiveUARTState *s)
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{
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uint64_t ret = 0;
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uint64_t txcnt = SIFIVE_UART_GET_TXCNT(s->txctrl);
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uint64_t rxcnt = SIFIVE_UART_GET_RXCNT(s->rxctrl);
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if (txcnt != 0) {
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ret |= SIFIVE_UART_IP_TXWM;
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}
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if (s->rx_fifo_len > rxcnt) {
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ret |= SIFIVE_UART_IP_RXWM;
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}
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return ret;
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}
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static void update_irq(SiFiveUARTState *s)
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{
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int cond = 0;
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if ((s->ie & SIFIVE_UART_IE_TXWM) ||
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((s->ie & SIFIVE_UART_IE_RXWM) && s->rx_fifo_len)) {
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cond = 1;
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}
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if (cond) {
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qemu_irq_raise(s->irq);
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} else {
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qemu_irq_lower(s->irq);
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}
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}
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static uint64_t
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uart_read(void *opaque, hwaddr addr, unsigned int size)
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{
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SiFiveUARTState *s = opaque;
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unsigned char r;
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switch (addr) {
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case SIFIVE_UART_RXFIFO:
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if (s->rx_fifo_len) {
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r = s->rx_fifo[0];
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memmove(s->rx_fifo, s->rx_fifo + 1, s->rx_fifo_len - 1);
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s->rx_fifo_len--;
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qemu_chr_fe_accept_input(&s->chr);
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update_irq(s);
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return r;
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}
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return 0x80000000;
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case SIFIVE_UART_TXFIFO:
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return 0; /* Should check tx fifo */
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case SIFIVE_UART_IE:
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return s->ie;
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case SIFIVE_UART_IP:
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return uart_ip(s);
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case SIFIVE_UART_TXCTRL:
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return s->txctrl;
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case SIFIVE_UART_RXCTRL:
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return s->rxctrl;
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case SIFIVE_UART_DIV:
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return s->div;
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}
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hw_error("%s: bad read: addr=0x%x\n",
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__func__, (int)addr);
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return 0;
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}
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static void
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uart_write(void *opaque, hwaddr addr,
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uint64_t val64, unsigned int size)
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{
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SiFiveUARTState *s = opaque;
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uint32_t value = val64;
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unsigned char ch = value;
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switch (addr) {
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case SIFIVE_UART_TXFIFO:
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qemu_chr_fe_write(&s->chr, &ch, 1);
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update_irq(s);
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return;
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case SIFIVE_UART_IE:
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s->ie = val64;
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update_irq(s);
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return;
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case SIFIVE_UART_TXCTRL:
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s->txctrl = val64;
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return;
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case SIFIVE_UART_RXCTRL:
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s->rxctrl = val64;
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return;
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case SIFIVE_UART_DIV:
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s->div = val64;
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return;
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}
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hw_error("%s: bad write: addr=0x%x v=0x%x\n",
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__func__, (int)addr, (int)value);
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}
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static const MemoryRegionOps uart_ops = {
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.read = uart_read,
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.write = uart_write,
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.endianness = DEVICE_NATIVE_ENDIAN,
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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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};
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static void uart_rx(void *opaque, const uint8_t *buf, int size)
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{
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SiFiveUARTState *s = opaque;
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/* Got a byte. */
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if (s->rx_fifo_len >= sizeof(s->rx_fifo)) {
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printf("WARNING: UART dropped char.\n");
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return;
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}
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s->rx_fifo[s->rx_fifo_len++] = *buf;
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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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SiFiveUARTState *s = opaque;
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return s->rx_fifo_len < sizeof(s->rx_fifo);
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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 int uart_be_change(void *opaque)
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{
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SiFiveUARTState *s = opaque;
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qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx, uart_event,
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uart_be_change, s, NULL, true);
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return 0;
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}
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/*
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* Create UART device.
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*/
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SiFiveUARTState *sifive_uart_create(MemoryRegion *address_space, hwaddr base,
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Chardev *chr, qemu_irq irq)
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{
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SiFiveUARTState *s = g_malloc0(sizeof(SiFiveUARTState));
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s->irq = irq;
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qemu_chr_fe_init(&s->chr, chr, &error_abort);
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qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx, uart_event,
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uart_be_change, s, NULL, true);
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memory_region_init_io(&s->mmio, NULL, &uart_ops, s,
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TYPE_SIFIVE_UART, SIFIVE_UART_MAX);
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memory_region_add_subregion(address_space, base, &s->mmio);
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return s;
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}
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