hw/char: Initial commit of Ibex UART

This is the initial commit of the Ibex UART device. Serial TX is
working, while RX has been implemeneted but untested.

This is based on the documentation from:
https://docs.opentitan.org/hw/ip/uart/doc/

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: LIU Zhiwei<zhiwei_liu@c-sky.com>

2 files changed, 493 insertions, 0 deletions

diff --git a/hw/char/Makefile.objs b/hw/char/Makefile.objs
index 9e9a6c1aff..633996be5b 100644
--- a/hw/char/Makefile.objs
+++ b/hw/char/Makefile.objs
@@ -12,6 +12,7 @@ common-obj-$(CONFIG_VIRTIO_SERIAL) += virtio-console.o
 common-obj-$(CONFIG_XILINX) += xilinx_uartlite.o
 common-obj-$(CONFIG_XEN) += xen_console.o
 common-obj-$(CONFIG_CADENCE) += cadence_uart.o
+common-obj-$(CONFIG_IBEX) += ibex_uart.o
 
 common-obj-$(CONFIG_EXYNOS4) += exynos4210_uart.o
 common-obj-$(CONFIG_COLDFIRE) += mcf_uart.o
diff --git a/hw/char/ibex_uart.c b/hw/char/ibex_uart.c
new file mode 100644
index 0000000000..3e0dd9968e
--- /dev/null
+++ b/hw/char/ibex_uart.c
@@ -0,0 +1,492 @@
+/*
+ * QEMU lowRISC Ibex UART device
+ *
+ * Copyright (c) 2020 Western Digital
+ *
+ * For details check the documentation here:
+ *    https://docs.opentitan.org/hw/ip/uart/doc/
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/char/ibex_uart.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+#include "migration/vmstate.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+
+static void ibex_uart_update_irqs(IbexUartState *s)
+{
+    if (s->uart_intr_state & s->uart_intr_enable & INTR_STATE_TX_WATERMARK) {
+        qemu_set_irq(s->tx_watermark, 1);
+    } else {
+        qemu_set_irq(s->tx_watermark, 0);
+    }
+
+    if (s->uart_intr_state & s->uart_intr_enable & INTR_STATE_RX_WATERMARK) {
+        qemu_set_irq(s->rx_watermark, 1);
+    } else {
+        qemu_set_irq(s->rx_watermark, 0);
+    }
+
+    if (s->uart_intr_state & s->uart_intr_enable & INTR_STATE_TX_EMPTY) {
+        qemu_set_irq(s->tx_empty, 1);
+    } else {
+        qemu_set_irq(s->tx_empty, 0);
+    }
+
+    if (s->uart_intr_state & s->uart_intr_enable & INTR_STATE_RX_OVERFLOW) {
+        qemu_set_irq(s->rx_overflow, 1);
+    } else {
+        qemu_set_irq(s->rx_overflow, 0);
+    }
+}
+
+static int ibex_uart_can_receive(void *opaque)
+{
+    IbexUartState *s = opaque;
+
+    if (s->uart_ctrl & UART_CTRL_RX_ENABLE) {
+        return 1;
+    }
+
+    return 0;
+}
+
+static void ibex_uart_receive(void *opaque, const uint8_t *buf, int size)
+{
+    IbexUartState *s = opaque;
+    uint8_t rx_fifo_level = (s->uart_fifo_ctrl & FIFO_CTRL_RXILVL)
+                            >> FIFO_CTRL_RXILVL_SHIFT;
+
+    s->uart_rdata = *buf;
+
+    s->uart_status &= ~UART_STATUS_RXIDLE;
+    s->uart_status &= ~UART_STATUS_RXEMPTY;
+
+    if (size > rx_fifo_level) {
+        s->uart_intr_state |= INTR_STATE_RX_WATERMARK;
+    }
+
+    ibex_uart_update_irqs(s);
+}
+
+static gboolean ibex_uart_xmit(GIOChannel *chan, GIOCondition cond,
+                               void *opaque)
+{
+    IbexUartState *s = opaque;
+    uint8_t tx_fifo_level = (s->uart_fifo_ctrl & FIFO_CTRL_TXILVL)
+                            >> FIFO_CTRL_TXILVL_SHIFT;
+    int ret;
+
+    /* instant drain the fifo when there's no back-end */
+    if (!qemu_chr_fe_backend_connected(&s->chr)) {
+        s->tx_level = 0;
+        return FALSE;
+    }
+
+    if (!s->tx_level) {
+        s->uart_status &= ~UART_STATUS_TXFULL;
+        s->uart_status |= UART_STATUS_TXEMPTY;
+        s->uart_intr_state |= INTR_STATE_TX_EMPTY;
+        s->uart_intr_state &= ~INTR_STATE_TX_WATERMARK;
+        ibex_uart_update_irqs(s);
+        return FALSE;
+    }
+
+    ret = qemu_chr_fe_write(&s->chr, s->tx_fifo, s->tx_level);
+
+    if (ret >= 0) {
+        s->tx_level -= ret;
+        memmove(s->tx_fifo, s->tx_fifo + ret, s->tx_level);
+    }
+
+    if (s->tx_level) {
+        guint r = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
+                                        ibex_uart_xmit, s);
+        if (!r) {
+            s->tx_level = 0;
+            return FALSE;
+        }
+    }
+
+    /* Clear the TX Full bit */
+    if (s->tx_level != IBEX_UART_TX_FIFO_SIZE) {
+        s->uart_status &= ~UART_STATUS_TXFULL;
+    }
+
+    /* Disable the TX_WATERMARK IRQ */
+    if (s->tx_level < tx_fifo_level) {
+        s->uart_intr_state &= ~INTR_STATE_TX_WATERMARK;
+    }
+
+    /* Set TX empty */
+    if (s->tx_level == 0) {
+        s->uart_status |= UART_STATUS_TXEMPTY;
+        s->uart_intr_state |= INTR_STATE_TX_EMPTY;
+    }
+
+    ibex_uart_update_irqs(s);
+    return FALSE;
+}
+
+static void uart_write_tx_fifo(IbexUartState *s, const uint8_t *buf,
+                               int size)
+{
+    uint64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    uint8_t tx_fifo_level = (s->uart_fifo_ctrl & FIFO_CTRL_TXILVL)
+                            >> FIFO_CTRL_TXILVL_SHIFT;
+
+    if (size > IBEX_UART_TX_FIFO_SIZE - s->tx_level) {
+        size = IBEX_UART_TX_FIFO_SIZE - s->tx_level;
+        qemu_log_mask(LOG_GUEST_ERROR, "ibex_uart: TX FIFO overflow");
+    }
+
+    memcpy(s->tx_fifo + s->tx_level, buf, size);
+    s->tx_level += size;
+
+    if (s->tx_level > 0) {
+        s->uart_status &= ~UART_STATUS_TXEMPTY;
+    }
+
+    if (s->tx_level >= tx_fifo_level) {
+        s->uart_intr_state |= INTR_STATE_TX_WATERMARK;
+        ibex_uart_update_irqs(s);
+    }
+
+    if (s->tx_level == IBEX_UART_TX_FIFO_SIZE) {
+        s->uart_status |= UART_STATUS_TXFULL;
+    }
+
+    timer_mod(s->fifo_trigger_handle, current_time +
+              (s->char_tx_time * 4));
+}
+
+static void ibex_uart_reset(DeviceState *dev)
+{
+    IbexUartState *s = IBEX_UART(dev);
+
+    s->uart_intr_state = 0x00000000;
+    s->uart_intr_state = 0x00000000;
+    s->uart_intr_enable = 0x00000000;
+    s->uart_ctrl = 0x00000000;
+    s->uart_status = 0x0000003c;
+    s->uart_rdata = 0x00000000;
+    s->uart_fifo_ctrl = 0x00000000;
+    s->uart_fifo_status = 0x00000000;
+    s->uart_ovrd = 0x00000000;
+    s->uart_val = 0x00000000;
+    s->uart_timeout_ctrl = 0x00000000;
+
+    s->tx_level = 0;
+
+    s->char_tx_time = (NANOSECONDS_PER_SECOND / 230400) * 10;
+
+    ibex_uart_update_irqs(s);
+}
+
+static uint64_t ibex_uart_read(void *opaque, hwaddr addr,
+                                       unsigned int size)
+{
+    IbexUartState *s = opaque;
+    uint64_t retvalue = 0;
+
+    switch (addr) {
+    case IBEX_UART_INTR_STATE:
+        retvalue = s->uart_intr_state;
+        break;
+    case IBEX_UART_INTR_ENABLE:
+        retvalue = s->uart_intr_enable;
+        break;
+    case IBEX_UART_INTR_TEST:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: wdata is write only\n", __func__);
+        break;
+
+    case IBEX_UART_CTRL:
+        retvalue = s->uart_ctrl;
+        break;
+    case IBEX_UART_STATUS:
+        retvalue = s->uart_status;
+        break;
+
+    case IBEX_UART_RDATA:
+        retvalue = s->uart_rdata;
+        if (s->uart_ctrl & UART_CTRL_RX_ENABLE) {
+            qemu_chr_fe_accept_input(&s->chr);
+
+            s->uart_status |= UART_STATUS_RXIDLE;
+            s->uart_status |= UART_STATUS_RXEMPTY;
+        }
+        break;
+    case IBEX_UART_WDATA:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: wdata is write only\n", __func__);
+        break;
+
+    case IBEX_UART_FIFO_CTRL:
+        retvalue = s->uart_fifo_ctrl;
+        break;
+    case IBEX_UART_FIFO_STATUS:
+        retvalue = s->uart_fifo_status;
+
+        retvalue |= s->tx_level & 0x1F;
+
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: RX fifos are not supported\n", __func__);
+        break;
+
+    case IBEX_UART_OVRD:
+        retvalue = s->uart_ovrd;
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: ovrd is not supported\n", __func__);
+        break;
+    case IBEX_UART_VAL:
+        retvalue = s->uart_val;
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: val is not supported\n", __func__);
+        break;
+    case IBEX_UART_TIMEOUT_CTRL:
+        retvalue = s->uart_timeout_ctrl;
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: timeout_ctrl is not supported\n", __func__);
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
+        return 0;
+    }
+
+    return retvalue;
+}
+
+static void ibex_uart_write(void *opaque, hwaddr addr,
+                                  uint64_t val64, unsigned int size)
+{
+    IbexUartState *s = opaque;
+    uint32_t value = val64;
+
+    switch (addr) {
+    case IBEX_UART_INTR_STATE:
+        /* Write 1 clear */
+        s->uart_intr_state &= ~value;
+        ibex_uart_update_irqs(s);
+        break;
+    case IBEX_UART_INTR_ENABLE:
+        s->uart_intr_enable = value;
+        ibex_uart_update_irqs(s);
+        break;
+    case IBEX_UART_INTR_TEST:
+        s->uart_intr_state |= value;
+        ibex_uart_update_irqs(s);
+        break;
+
+    case IBEX_UART_CTRL:
+        s->uart_ctrl = value;
+
+        if (value & UART_CTRL_NF) {
+            qemu_log_mask(LOG_UNIMP,
+                          "%s: UART_CTRL_NF is not supported\n", __func__);
+        }
+        if (value & UART_CTRL_SLPBK) {
+            qemu_log_mask(LOG_UNIMP,
+                          "%s: UART_CTRL_SLPBK is not supported\n", __func__);
+        }
+        if (value & UART_CTRL_LLPBK) {
+            qemu_log_mask(LOG_UNIMP,
+                          "%s: UART_CTRL_LLPBK is not supported\n", __func__);
+        }
+        if (value & UART_CTRL_PARITY_EN) {
+            qemu_log_mask(LOG_UNIMP,
+                          "%s: UART_CTRL_PARITY_EN is not supported\n",
+                          __func__);
+        }
+        if (value & UART_CTRL_PARITY_ODD) {
+            qemu_log_mask(LOG_UNIMP,
+                          "%s: UART_CTRL_PARITY_ODD is not supported\n",
+                          __func__);
+        }
+        if (value & UART_CTRL_RXBLVL) {
+            qemu_log_mask(LOG_UNIMP,
+                          "%s: UART_CTRL_RXBLVL is not supported\n", __func__);
+        }
+        if (value & UART_CTRL_NCO) {
+            uint64_t baud = ((value & UART_CTRL_NCO) >> 16);
+            baud *= 1000;
+            baud /= 2 ^ 20;
+
+            s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10;
+        }
+        break;
+    case IBEX_UART_STATUS:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: status is read only\n", __func__);
+        break;
+
+    case IBEX_UART_RDATA:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: rdata is read only\n", __func__);
+        break;
+    case IBEX_UART_WDATA:
+        uart_write_tx_fifo(s, (uint8_t *) &value, 1);
+        break;
+
+    case IBEX_UART_FIFO_CTRL:
+        s->uart_fifo_ctrl = value;
+
+        if (value & FIFO_CTRL_RXRST) {
+            qemu_log_mask(LOG_UNIMP,
+                          "%s: RX fifos are not supported\n", __func__);
+        }
+        if (value & FIFO_CTRL_TXRST) {
+            s->tx_level = 0;
+        }
+        break;
+    case IBEX_UART_FIFO_STATUS:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: fifo_status is read only\n", __func__);
+        break;
+
+    case IBEX_UART_OVRD:
+        s->uart_ovrd = value;
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: ovrd is not supported\n", __func__);
+        break;
+    case IBEX_UART_VAL:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: val is read only\n", __func__);
+        break;
+    case IBEX_UART_TIMEOUT_CTRL:
+        s->uart_timeout_ctrl = value;
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: timeout_ctrl is not supported\n", __func__);
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
+    }
+}
+
+static void fifo_trigger_update(void *opaque)
+{
+    IbexUartState *s = opaque;
+
+    if (s->uart_ctrl & UART_CTRL_TX_ENABLE) {
+        ibex_uart_xmit(NULL, G_IO_OUT, s);
+    }
+}
+
+static const MemoryRegionOps ibex_uart_ops = {
+    .read = ibex_uart_read,
+    .write = ibex_uart_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
+};
+
+static int ibex_uart_post_load(void *opaque, int version_id)
+{
+    IbexUartState *s = opaque;
+
+    ibex_uart_update_irqs(s);
+    return 0;
+}
+
+static const VMStateDescription vmstate_ibex_uart = {
+    .name = TYPE_IBEX_UART,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .post_load = ibex_uart_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8_ARRAY(tx_fifo, IbexUartState,
+                            IBEX_UART_TX_FIFO_SIZE),
+        VMSTATE_UINT32(tx_level, IbexUartState),
+        VMSTATE_UINT64(char_tx_time, IbexUartState),
+        VMSTATE_TIMER_PTR(fifo_trigger_handle, IbexUartState),
+        VMSTATE_UINT32(uart_intr_state, IbexUartState),
+        VMSTATE_UINT32(uart_intr_enable, IbexUartState),
+        VMSTATE_UINT32(uart_ctrl, IbexUartState),
+        VMSTATE_UINT32(uart_status, IbexUartState),
+        VMSTATE_UINT32(uart_rdata, IbexUartState),
+        VMSTATE_UINT32(uart_fifo_ctrl, IbexUartState),
+        VMSTATE_UINT32(uart_fifo_status, IbexUartState),
+        VMSTATE_UINT32(uart_ovrd, IbexUartState),
+        VMSTATE_UINT32(uart_val, IbexUartState),
+        VMSTATE_UINT32(uart_timeout_ctrl, IbexUartState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static Property ibex_uart_properties[] = {
+    DEFINE_PROP_CHR("chardev", IbexUartState, chr),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void ibex_uart_init(Object *obj)
+{
+    IbexUartState *s = IBEX_UART(obj);
+
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_watermark);
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_watermark);
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_empty);
+    sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_overflow);
+
+    memory_region_init_io(&s->mmio, obj, &ibex_uart_ops, s,
+                          TYPE_IBEX_UART, 0x400);
+    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
+}
+
+static void ibex_uart_realize(DeviceState *dev, Error **errp)
+{
+    IbexUartState *s = IBEX_UART(dev);
+
+    s->fifo_trigger_handle = timer_new_ns(QEMU_CLOCK_VIRTUAL,
+                                          fifo_trigger_update, s);
+
+    qemu_chr_fe_set_handlers(&s->chr, ibex_uart_can_receive,
+                             ibex_uart_receive, NULL, NULL,
+                             s, NULL, true);
+}
+
+static void ibex_uart_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->reset = ibex_uart_reset;
+    dc->realize = ibex_uart_realize;
+    dc->vmsd = &vmstate_ibex_uart;
+    device_class_set_props(dc, ibex_uart_properties);
+}
+
+static const TypeInfo ibex_uart_info = {
+    .name          = TYPE_IBEX_UART,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(IbexUartState),
+    .instance_init = ibex_uart_init,
+    .class_init    = ibex_uart_class_init,
+};
+
+static void ibex_uart_register_types(void)
+{
+    type_register_static(&ibex_uart_info);
+}
+
+type_init(ibex_uart_register_types)