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-rw-r--r--hw/riscv/sifive_uart.c176
-rw-r--r--include/hw/riscv/sifive_uart.h71
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 0000000000..b0c3798cf2
--- /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 0000000000..504f18a60f
--- /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
generated by cgit v1.2.3-55-g7522 (git 2.39.0) at 2024-12-12 08:37:06 +0100