hw/riscv: Move sifive_uart model to hw/char

This is an effort to clean up the hw/riscv directory. Ideally it
should only contain the RISC-V SoC / machine codes plus generic
codes. Let's move sifive_uart model to hw/char directory.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <1599129623-68957-9-git-send-email-bmeng.cn@gmail.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

3 files changed, 198 insertions, 0 deletions

diff --git a/hw/char/Kconfig b/hw/char/Kconfig
index 91da92f..939bc44 100644
--- a/hw/char/Kconfig
+++ b/hw/char/Kconfig
@@ -58,3 +58,6 @@ config AVR_USART
 
 config MCHP_PFSOC_MMUART
     bool
+
+config SIFIVE_UART
+    bool
diff --git a/hw/char/meson.build b/hw/char/meson.build
index 3db623e..196ac91 100644
--- a/hw/char/meson.build
+++ b/hw/char/meson.build
@@ -30,6 +30,7 @@ softmmu_ss.add(when: 'CONFIG_EXYNOS4', if_true: files('exynos4210_uart.c'))
 softmmu_ss.add(when: 'CONFIG_OMAP', if_true: files('omap_uart.c'))
 softmmu_ss.add(when: 'CONFIG_RASPI', if_true: files('bcm2835_aux.c'))
 softmmu_ss.add(when: 'CONFIG_RENESAS_SCI', if_true: files('renesas_sci.c'))
+softmmu_ss.add(when: 'CONFIG_SIFIVE_UART', if_true: files('sifive_uart.c'))
 softmmu_ss.add(when: 'CONFIG_SH4', if_true: files('sh_serial.c'))
 softmmu_ss.add(when: 'CONFIG_STM32F2XX_USART', if_true: files('stm32f2xx_usart.c'))
 softmmu_ss.add(when: 'CONFIG_MCHP_PFSOC_MMUART', if_true: files('mchp_pfsoc_mmuart.c'))
diff --git a/hw/char/sifive_uart.c b/hw/char/sifive_uart.c
new file mode 100644
index 0000000..3a00ba7
--- /dev/null
+++ b/hw/char/sifive_uart.c
@@ -0,0 +1,194 @@
+/*
+ * 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 "qemu/log.h"
+#include "hw/sysbus.h"
+#include "chardev/char.h"
+#include "chardev/char-fe.h"
+#include "hw/hw.h"
+#include "hw/irq.h"
+#include "hw/char/sifive_uart.h"
+
+/*
+ * Not yet implemented:
+ *
+ * Transmit FIFO using "qemu/fifo8.h"
+ */
+
+/* Returns the state of the IP (interrupt pending) register */
+static uint64_t uart_ip(SiFiveUARTState *s)
+{
+    uint64_t ret = 0;
+
+    uint64_t txcnt = SIFIVE_UART_GET_TXCNT(s->txctrl);
+    uint64_t rxcnt = SIFIVE_UART_GET_RXCNT(s->rxctrl);
+
+    if (txcnt != 0) {
+        ret |= SIFIVE_UART_IP_TXWM;
+    }
+    if (s->rx_fifo_len > rxcnt) {
+        ret |= SIFIVE_UART_IP_RXWM;
+    }
+
+    return ret;
+}
+
+static void update_irq(SiFiveUARTState *s)
+{
+    int cond = 0;
+    if ((s->ie & SIFIVE_UART_IE_TXWM) ||
+        ((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 uart_ip(s);
+    case SIFIVE_UART_TXCTRL:
+        return s->txctrl;
+    case SIFIVE_UART_RXCTRL:
+        return s->rxctrl;
+    case SIFIVE_UART_DIV:
+        return s->div;
+    }
+
+    qemu_log_mask(LOG_GUEST_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);
+        update_irq(s);
+        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;
+    }
+    qemu_log_mask(LOG_GUEST_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, QEMUChrEvent 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;
+}