diff options
| -rw-r--r-- | hw/riscv/sifive_uart.c | 176 | ||||
| -rw-r--r-- | include/hw/riscv/sifive_uart.h | 71 |
2 files changed, 247 insertions, 0 deletions
diff --git a/hw/riscv/sifive_uart.c b/hw/riscv/sifive_uart.c new file mode 100644 index 0000000..b0c3798 --- /dev/null +++ b/hw/riscv/sifive_uart.c @@ -0,0 +1,176 @@ +/* + * QEMU model of the UART on the SiFive E300 and U500 series SOCs. + * + * Copyright (c) 2016 Stefan O'Rear + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2 or later, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include "qemu/osdep.h" +#include "qapi/error.h" +#include "hw/sysbus.h" +#include "chardev/char.h" +#include "chardev/char-fe.h" +#include "target/riscv/cpu.h" +#include "hw/riscv/sifive_uart.h" + +/* + * Not yet implemented: + * + * Transmit FIFO using "qemu/fifo8.h" + * SIFIVE_UART_IE_TXWM interrupts + * SIFIVE_UART_IE_RXWM interrupts must honor fifo watermark + * Rx FIFO watermark interrupt trigger threshold + * Tx FIFO watermark interrupt trigger threshold. + */ + +static void update_irq(SiFiveUARTState *s) +{ + int cond = 0; + if ((s->ie & SIFIVE_UART_IE_RXWM) && s->rx_fifo_len) { + cond = 1; + } + if (cond) { + qemu_irq_raise(s->irq); + } else { + qemu_irq_lower(s->irq); + } +} + +static uint64_t +uart_read(void *opaque, hwaddr addr, unsigned int size) +{ + SiFiveUARTState *s = opaque; + unsigned char r; + switch (addr) { + case SIFIVE_UART_RXFIFO: + if (s->rx_fifo_len) { + r = s->rx_fifo[0]; + memmove(s->rx_fifo, s->rx_fifo + 1, s->rx_fifo_len - 1); + s->rx_fifo_len--; + qemu_chr_fe_accept_input(&s->chr); + update_irq(s); + return r; + } + return 0x80000000; + + case SIFIVE_UART_TXFIFO: + return 0; /* Should check tx fifo */ + case SIFIVE_UART_IE: + return s->ie; + case SIFIVE_UART_IP: + return s->rx_fifo_len ? SIFIVE_UART_IP_RXWM : 0; + case SIFIVE_UART_TXCTRL: + return s->txctrl; + case SIFIVE_UART_RXCTRL: + return s->rxctrl; + case SIFIVE_UART_DIV: + return s->div; + } + + hw_error("%s: bad read: addr=0x%x\n", + __func__, (int)addr); + return 0; +} + +static void +uart_write(void *opaque, hwaddr addr, + uint64_t val64, unsigned int size) +{ + SiFiveUARTState *s = opaque; + uint32_t value = val64; + unsigned char ch = value; + + switch (addr) { + case SIFIVE_UART_TXFIFO: + qemu_chr_fe_write(&s->chr, &ch, 1); + return; + case SIFIVE_UART_IE: + s->ie = val64; + update_irq(s); + return; + case SIFIVE_UART_TXCTRL: + s->txctrl = val64; + return; + case SIFIVE_UART_RXCTRL: + s->rxctrl = val64; + return; + case SIFIVE_UART_DIV: + s->div = val64; + return; + } + hw_error("%s: bad write: addr=0x%x v=0x%x\n", + __func__, (int)addr, (int)value); +} + +static const MemoryRegionOps uart_ops = { + .read = uart_read, + .write = uart_write, + .endianness = DEVICE_NATIVE_ENDIAN, + .valid = { + .min_access_size = 4, + .max_access_size = 4 + } +}; + +static void uart_rx(void *opaque, const uint8_t *buf, int size) +{ + SiFiveUARTState *s = opaque; + + /* Got a byte. */ + if (s->rx_fifo_len >= sizeof(s->rx_fifo)) { + printf("WARNING: UART dropped char.\n"); + return; + } + s->rx_fifo[s->rx_fifo_len++] = *buf; + + update_irq(s); +} + +static int uart_can_rx(void *opaque) +{ + SiFiveUARTState *s = opaque; + + return s->rx_fifo_len < sizeof(s->rx_fifo); +} + +static void uart_event(void *opaque, int event) +{ +} + +static int uart_be_change(void *opaque) +{ + SiFiveUARTState *s = opaque; + + qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx, uart_event, + uart_be_change, s, NULL, true); + + return 0; +} + +/* + * Create UART device. + */ +SiFiveUARTState *sifive_uart_create(MemoryRegion *address_space, hwaddr base, + Chardev *chr, qemu_irq irq) +{ + SiFiveUARTState *s = g_malloc0(sizeof(SiFiveUARTState)); + s->irq = irq; + qemu_chr_fe_init(&s->chr, chr, &error_abort); + qemu_chr_fe_set_handlers(&s->chr, uart_can_rx, uart_rx, uart_event, + uart_be_change, s, NULL, true); + memory_region_init_io(&s->mmio, NULL, &uart_ops, s, + TYPE_SIFIVE_UART, SIFIVE_UART_MAX); + memory_region_add_subregion(address_space, base, &s->mmio); + return s; +} diff --git a/include/hw/riscv/sifive_uart.h b/include/hw/riscv/sifive_uart.h new file mode 100644 index 0000000..504f18a --- /dev/null +++ b/include/hw/riscv/sifive_uart.h @@ -0,0 +1,71 @@ +/* + * SiFive UART interface + * + * Copyright (c) 2016 Stefan O'Rear + * Copyright (c) 2017 SiFive, Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2 or later, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#ifndef HW_SIFIVE_UART_H +#define HW_SIFIVE_UART_H + +enum { + SIFIVE_UART_TXFIFO = 0, + SIFIVE_UART_RXFIFO = 4, + SIFIVE_UART_TXCTRL = 8, + SIFIVE_UART_TXMARK = 10, + SIFIVE_UART_RXCTRL = 12, + SIFIVE_UART_RXMARK = 14, + SIFIVE_UART_IE = 16, + SIFIVE_UART_IP = 20, + SIFIVE_UART_DIV = 24, + SIFIVE_UART_MAX = 32 +}; + +enum { + SIFIVE_UART_IE_TXWM = 1, /* Transmit watermark interrupt enable */ + SIFIVE_UART_IE_RXWM = 2 /* Receive watermark interrupt enable */ +}; + +enum { + SIFIVE_UART_IP_TXWM = 1, /* Transmit watermark interrupt pending */ + SIFIVE_UART_IP_RXWM = 2 /* Receive watermark interrupt pending */ +}; + +#define TYPE_SIFIVE_UART "riscv.sifive.uart" + +#define SIFIVE_UART(obj) \ + OBJECT_CHECK(SiFiveUARTState, (obj), TYPE_SIFIVE_UART) + +typedef struct SiFiveUARTState { + /*< private >*/ + SysBusDevice parent_obj; + + /*< public >*/ + qemu_irq irq; + MemoryRegion mmio; + CharBackend chr; + uint8_t rx_fifo[8]; + unsigned int rx_fifo_len; + uint32_t ie; + uint32_t ip; + uint32_t txctrl; + uint32_t rxctrl; + uint32_t div; +} SiFiveUARTState; + +SiFiveUARTState *sifive_uart_create(MemoryRegion *address_space, hwaddr base, + Chardev *chr, qemu_irq irq); + +#endif |