From: Michael <michael@videogpu.com>
Add NEORV32 UART device: CTRL/DATA registers, RX FIFO, TX to chardev.
Includes Kconfig/meson and public header.
Signed-off-by: Michael Levit <michael@videogpu.com>
---
hw/char/Kconfig | 3 +
hw/char/meson.build | 1 +
hw/char/neorv32_uart.c | 285 +++++++++++++++++++++++++++++++++
include/hw/char/neorv32_uart.h | 54 +++++++
4 files changed, 343 insertions(+)
create mode 100644 hw/char/neorv32_uart.c
create mode 100644 include/hw/char/neorv32_uart.h
diff --git a/hw/char/Kconfig b/hw/char/Kconfig
index 020c0a84bb..1fd39c2b30 100644
--- a/hw/char/Kconfig
+++ b/hw/char/Kconfig
@@ -95,3 +95,6 @@ config IP_OCTAL_232
bool
default y
depends on IPACK
+
+config NEORV32_UART
+ bool
diff --git a/hw/char/meson.build b/hw/char/meson.build
index a9e1dc26c0..2f5bf827a7 100644
--- a/hw/char/meson.build
+++ b/hw/char/meson.build
@@ -31,6 +31,7 @@ system_ss.add(when: 'CONFIG_OMAP', if_true: files('omap_uart.c'))
system_ss.add(when: 'CONFIG_RASPI', if_true: files('bcm2835_aux.c'))
system_ss.add(when: 'CONFIG_RENESAS_SCI', if_true: files('renesas_sci.c'))
system_ss.add(when: 'CONFIG_SIFIVE_UART', if_true: files('sifive_uart.c'))
+system_ss.add(when: 'CONFIG_NEORV32_UART', if_true: files('neorv32_uart.c'))
system_ss.add(when: 'CONFIG_SH_SCI', if_true: files('sh_serial.c'))
system_ss.add(when: 'CONFIG_STM32F2XX_USART', if_true: files('stm32f2xx_usart.c'))
system_ss.add(when: 'CONFIG_STM32L4X5_USART', if_true: files('stm32l4x5_usart.c'))
diff --git a/hw/char/neorv32_uart.c b/hw/char/neorv32_uart.c
new file mode 100644
index 0000000000..a21066d194
--- /dev/null
+++ b/hw/char/neorv32_uart.c
@@ -0,0 +1,285 @@
+/*
+ * Neorv32-specific UART.
+ *
+ * Copyright (c) 2025 Michael Levit
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/log.h"
+#include "migration/vmstate.h"
+#include "chardev/char.h"
+#include "chardev/char-fe.h"
+#include "hw/irq.h"
+#include "hw/char/neorv32_uart.h"
+#include "hw/qdev-properties-system.h"
+
+#define NEORV32_UART_IO_REGION_SIZE (32)
+
+static Property neorv32_uart_properties[] = {
+ DEFINE_PROP_CHR("chardev", Neorv32UARTState, chr),
+};
+
+enum {
+ NEORV32_UART_CTRL = 0, /**< offset 0: control register */
+ NEORV32_UART_DATA = 4 /**< offset 4: data register */
+};
+
+/** UART control register bits */
+enum NEORV32_UART_CTRL_enum {
+ UART_CTRL_EN = 0, /* enable */
+ UART_CTRL_SIM_MODE = 1, /* sim override */
+ UART_CTRL_HWFC_EN = 2, /* RTS/CTS */
+ UART_CTRL_PRSC_LSB = 3, /* prescaler sel LSB */
+ UART_CTRL_PRSC_MSB = 5, /* prescaler sel MSB */
+ UART_CTRL_BAUD_LSB = 6, /* baud div LSB */
+ UART_CTRL_BAUD_MSB = 15, /* baud div MSB */
+ UART_CTRL_RX_NEMPTY = 16, /* RX not empty */
+ UART_CTRL_RX_FULL = 17, /* RX full */
+ UART_CTRL_TX_EMPTY = 18, /* TX empty */
+ UART_CTRL_TX_NFULL = 19, /* TX not full */
+ UART_CTRL_IRQ_RX_NEMPTY = 20, /* IRQ on RX not empty */
+ UART_CTRL_IRQ_RX_FULL = 21, /* IRQ on RX full */
+ UART_CTRL_IRQ_TX_EMPTY = 22, /* IRQ on TX empty */
+ UART_CTRL_IRQ_TX_NFULL = 23, /* IRQ on TX not full */
+
+ UART_CTRL_RX_OVER = 30, /* RX overflow */
+ UART_CTRL_TX_BUSY = 31 /* TX busy or not empty */
+};
+
+/** bits */
+enum NEORV32_UART_DATA_enum {
+ UART_DATA_RTX_LSB = 0, /**< (r/w): UART rx/tx data, LSB */
+ UART_DATA_RTX_MSB = 7, /**< (r/w): UART rx/tx data, MSB */
+
+ UART_DATA_RX_FIFO_SIZE_LSB = 8, /**< (r/-): log2(RX FIFO size), LSB */
+ UART_DATA_RX_FIFO_SIZE_MSB = 11, /**< (r/-): log2(RX FIFO size), MSB */
+
+ UART_DATA_TX_FIFO_SIZE_LSB = 12, /**< (r/-): log2(RX FIFO size), LSB */
+ UART_DATA_TX_FIFO_SIZE_MSB = 15, /**< (r/-): log2(RX FIFO size), MSB */
+};
+/**@}*/
+
+static void neorv32_uart_update_irq(Neorv32UARTState *s)
+{
+ int cond = 0;
+ if ((s->ie & NEORV32_UART_IE_TXWM) ||
+ ((s->ie & NEORV32_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
+neorv32_uart_read(void *opaque, hwaddr addr, unsigned int size)
+{
+ Neorv32UARTState *s = opaque;
+ unsigned char r;
+
+ switch (addr) {
+ case NEORV32_UART_CTRL:
+ if (s->rx_fifo_len) {
+ s->CTRL |= (1 << UART_CTRL_RX_NEMPTY); /* set data available */
+ } else {
+ s->CTRL &= ~(1 << UART_CTRL_RX_NEMPTY); /* clear data available */
+ }
+ /* TODO: assuming here TX is always avalable, fix it. */
+ s->CTRL |= (1 << UART_CTRL_TX_NFULL); /* set TX not full */
+
+ return s->CTRL;
+
+ case NEORV32_UART_DATA:
+ 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);
+ s->DATA = r;
+
+ neorv32_uart_update_irq(s); /* TODO: check if need to call */
+ return r;
+ }
+ }
+
+ qemu_log_mask(LOG_GUEST_ERROR, "%s: bad read: addr = 0x%x\n",
+ __func__, (int)addr);
+ return 0;
+}
+
+
+
+static void
+neorv32_uart_write(void *opaque, hwaddr addr, uint64_t val64, unsigned int size)
+{
+ Neorv32UARTState *s = opaque;
+ uint32_t value = val64;
+ unsigned char ch = value;
+
+ /* TODO: check if need to update data and control bits */
+ switch (addr) {
+ case NEORV32_UART_CTRL:
+ s->CTRL = value;
+ /* TODO: check if need to call, depending on IRQ flags */
+ /* neorv32_uart_update_irq(s); */
+ return;
+ case NEORV32_UART_DATA:
+ s->DATA = value;
+ qemu_chr_fe_write(&s->chr, &ch, 1);
+ /* neorv32_uart_update_irq(s); TODO: check if need to call */
+ 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 neorv32_uart_ops = {
+ .read = neorv32_uart_read,
+ .write = neorv32_uart_write,
+ .endianness = DEVICE_NATIVE_ENDIAN,
+ .valid = {
+ .min_access_size = 4,
+ .max_access_size = 4
+ }
+};
+
+static void neorv32_uart_init(Object *obj)
+{
+ SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+ Neorv32UARTState *s = NEORV32_UART(obj);
+
+ memory_region_init_io(&s->mmio, OBJECT(s), &neorv32_uart_ops, s,
+ TYPE_NEORV32_UART, NEORV32_UART_IO_REGION_SIZE);
+ sysbus_init_mmio(sbd, &s->mmio);
+ sysbus_init_irq(sbd, &s->irq);
+}
+
+
+static void neorv32_uart_rx(void *opaque, const uint8_t *buf, int size)
+{
+ Neorv32UARTState *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;
+
+ neorv32_uart_update_irq(s);
+}
+
+static int neorv32_uart_can_rx(void *opaque)
+{
+ Neorv32UARTState *s = opaque;
+
+ return s->rx_fifo_len < sizeof(s->rx_fifo);
+}
+
+static void neorv32_uart_event(void *opaque, QEMUChrEvent event)
+{
+}
+
+static int neorv32_uart_be_change(void *opaque)
+{
+ Neorv32UARTState *s = opaque;
+
+ qemu_chr_fe_set_handlers(&s->chr, neorv32_uart_can_rx, neorv32_uart_rx,
+ neorv32_uart_event, neorv32_uart_be_change, s,
+ NULL, true);
+
+ return 0;
+}
+
+static void neorv32_uart_realize(DeviceState *dev, Error **errp)
+{
+ Neorv32UARTState *s = NEORV32_UART(dev);
+
+ qemu_chr_fe_set_handlers(&s->chr, neorv32_uart_can_rx, neorv32_uart_rx,
+ neorv32_uart_event, neorv32_uart_be_change, s,
+ NULL, true);
+}
+
+static const VMStateDescription vmstate_neorv32_uart = {
+ .name = TYPE_NEORV32_UART,
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .fields = (VMStateField[]) {
+ VMSTATE_UINT8_ARRAY(rx_fifo, Neorv32UARTState,
+ NEORV32_UART_RX_FIFO_SIZE),
+ VMSTATE_UINT8(rx_fifo_len, Neorv32UARTState),
+ VMSTATE_UINT32(ie, Neorv32UARTState),
+ VMSTATE_END_OF_LIST()
+ },
+};
+
+static void neorv32_uart_reset_enter(Object *obj, ResetType type)
+{
+ Neorv32UARTState *s = NEORV32_UART(obj);
+ s->rx_fifo_len = 0;
+ s->ie = 0;
+}
+
+static void neorv32_uart_reset_hold(Object *obj, ResetType type)
+{
+ Neorv32UARTState *s = NEORV32_UART(obj);
+ qemu_irq_lower(s->irq);
+}
+
+static void neorv32_uart_class_init(ObjectClass *oc, const void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(oc);
+ ResettableClass *rc = RESETTABLE_CLASS(oc);
+
+ dc->realize = neorv32_uart_realize;
+ dc->vmsd = &vmstate_neorv32_uart;
+ rc->phases.enter = neorv32_uart_reset_enter;
+ rc->phases.hold = neorv32_uart_reset_hold;
+ device_class_set_props(dc, neorv32_uart_properties);
+ set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
+}
+
+static const TypeInfo neorv32_uart_info = {
+ .name = TYPE_NEORV32_UART,
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(Neorv32UARTState),
+ .instance_init = neorv32_uart_init,
+ .class_init = neorv32_uart_class_init,
+};
+
+static void neorv32_uart_register_types(void)
+{
+ type_register_static(&neorv32_uart_info);
+}
+
+type_init(neorv32_uart_register_types)
+/*
+ * Create UART device.
+ */
+Neorv32UARTState *neorv32_uart_create(MemoryRegion *address_space, hwaddr base,
+ Chardev *chr)
+{
+ DeviceState *dev;
+ SysBusDevice *s;
+ bool succed = false;
+
+ dev = qdev_new("riscv.neorv32.uart");
+
+ qdev_prop_set_chr(dev, "chardev", chr);
+ s = SYS_BUS_DEVICE(dev);
+ succed = sysbus_realize_and_unref(s, &error_fatal);
+
+ if (succed) {
+ memory_region_add_subregion(address_space, base,
+ sysbus_mmio_get_region(s, 0));
+ return NEORV32_UART(dev);
+ } else {
+ return NULL;
+ }
+} /* neorv32_uart_create */
diff --git a/include/hw/char/neorv32_uart.h b/include/hw/char/neorv32_uart.h
new file mode 100644
index 0000000000..fa33906724
--- /dev/null
+++ b/include/hw/char/neorv32_uart.h
@@ -0,0 +1,54 @@
+/*
+ * Neorv32-specific UART.
+ *
+ * Copyright (c) 2025 Michael Levit
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef HW_NEORV32_UART_H
+#define HW_NEORV32_UART_H
+
+#include "chardev/char-fe.h"
+#include "hw/qdev-properties.h"
+#include "hw/sysbus.h"
+#include "qom/object.h"
+
+#define TYPE_NEORV32_UART "riscv.neorv32.uart"
+OBJECT_DECLARE_SIMPLE_TYPE(Neorv32UARTState, NEORV32_UART)
+
+#define QEMU_UART_DATA_RX_FIFO_SIZE_LSB 8 /* log2 RX FIFO size LSB */
+#define QEMU_UART_DATA_RX_FIFO_SIZE_MSB 11 /* log2 RX FIFO size MSB */
+
+#define NEORV32_UART_RX_FIFO_SIZE 32 /* in HW it is 2048 + 256 = _MSB + _LSB */
+
+enum {
+ NEORV32_UART_IE_TXWM = 1, /* Transmit watermark interrupt enable */
+ NEORV32_UART_IE_RXWM = 2 /* Receive watermark interrupt enable */
+};
+
+enum {
+ NEORV32_UART_IP_TXWM = 1, /* Transmit watermark interrupt pending */
+ NEORV32_UART_IP_RXWM = 2 /* Receive watermark interrupt pending */
+};
+
+
+
+struct Neorv32UARTState {
+ /*< private >*/
+ SysBusDevice parent_obj;
+
+ /*< public >*/
+ qemu_irq irq;
+ MemoryRegion mmio;
+ CharFrontend chr;
+ uint8_t rx_fifo[NEORV32_UART_RX_FIFO_SIZE];
+ uint8_t rx_fifo_len;
+ uint32_t ie; /* interrupt enable */
+ uint32_t CTRL;
+ uint32_t DATA;
+};
+
+Neorv32UARTState *neorv32_uart_create(MemoryRegion *address_space, hwaddr base,
+ Chardev *chr);
+
+#endif /* HW_NEORV32_UART_H */
--
2.51.1© 2016 - 2025 Red Hat, Inc.