This commit implements UART support for the MAX78000
Signed-off-by: Jackson Donaldson <jc...@duck.com>
Reviewed-by: Peter Maydell <peter.mayd...@linaro.org>
---
hw/arm/Kconfig | 1 +
hw/char/Kconfig | 3 +
hw/char/max78000_uart.c | 285 ++++++++++++++++++++++++++++++++
hw/char/meson.build | 1 +
include/hw/char/max78000_uart.h | 78 +++++++++
5 files changed, 368 insertions(+)
create mode 100644 hw/char/max78000_uart.c
create mode 100644 include/hw/char/max78000_uart.h
diff --git a/hw/arm/Kconfig b/hw/arm/Kconfig
index e3b419b468..031e0bf59e 100644
--- a/hw/arm/Kconfig
+++ b/hw/arm/Kconfig
@@ -367,6 +367,7 @@ config MAX78000_SOC
bool
select ARM_V7M
select MAX78000_ICC
+ select MAX78000_UART
config RASPI
bool
diff --git a/hw/char/Kconfig b/hw/char/Kconfig
index 9d517f3e28..020c0a84bb 100644
--- a/hw/char/Kconfig
+++ b/hw/char/Kconfig
@@ -48,6 +48,9 @@ config VIRTIO_SERIAL
default y
depends on VIRTIO
+config MAX78000_UART
+ bool
+
config STM32F2XX_USART
bool
diff --git a/hw/char/max78000_uart.c b/hw/char/max78000_uart.c
new file mode 100644
index 0000000000..19506d52ef
--- /dev/null
+++ b/hw/char/max78000_uart.c
@@ -0,0 +1,285 @@
+/*
+ * MAX78000 UART
+ *
+ * Copyright (c) 2025 Jackson Donaldson <jc...@duck.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/char/max78000_uart.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+#include "hw/qdev-properties-system.h"
+#include "qemu/log.h"
+#include "qemu/module.h"
+#include "migration/vmstate.h"
+#include "trace.h"
+
+
+static int max78000_uart_can_receive(void *opaque)
+{
+ Max78000UartState *s = opaque;
+ if (!(s->ctrl & UART_BCLKEN)) {
+ return 0;
+ }
+ return fifo8_num_free(&s->rx_fifo);
+}
+
+static void max78000_update_irq(Max78000UartState *s)
+{
+ int interrupt_level;
+
+ interrupt_level = s->int_fl & s->int_en;
+ qemu_set_irq(s->irq, interrupt_level);
+}
+
+static void max78000_uart_receive(void *opaque, const uint8_t *buf, int size)
+{
+ Max78000UartState *s = opaque;
+
+ assert(size <= fifo8_num_free(&s->rx_fifo));
+
+ fifo8_push_all(&s->rx_fifo, buf, size);
+
+ uint32_t rx_threshold = s->ctrl & 0xf;
+
+ if (fifo8_num_used(&s->rx_fifo) >= rx_threshold) {
+ s->int_fl |= UART_RX_THD;
+ }
+
+ max78000_update_irq(s);
+}
+
+static void max78000_uart_reset_hold(Object *obj, ResetType type)
+{
+ Max78000UartState *s = MAX78000_UART(obj);
+
+ s->ctrl = 0;
+ s->status = UART_TX_EM | UART_RX_EM;
+ s->int_en = 0;
+ s->int_fl = 0;
+ s->osr = 0;
+ s->txpeek = 0;
+ s->pnr = UART_RTS;
+ s->fifo = 0;
+ s->dma = 0;
+ s->wken = 0;
+ s->wkfl = 0;
+ fifo8_reset(&s->rx_fifo);
+}
+
+static uint64_t max78000_uart_read(void *opaque, hwaddr addr,
+ unsigned int size)
+{
+ Max78000UartState *s = opaque;
+ uint64_t retvalue = 0;
+ switch (addr) {
+ case UART_CTRL:
+ retvalue = s->ctrl;
+ break;
+ case UART_STATUS:
+ retvalue = (fifo8_num_used(&s->rx_fifo) << UART_RX_LVL) |
+ UART_TX_EM |
+ (fifo8_is_empty(&s->rx_fifo) ? UART_RX_EM : 0);
+ break;
+ case UART_INT_EN:
+ retvalue = s->int_en;
+ break;
+ case UART_INT_FL:
+ retvalue = s->int_fl;
+ break;
+ case UART_CLKDIV:
+ retvalue = s->clkdiv;
+ break;
+ case UART_OSR:
+ retvalue = s->osr;
+ break;
+ case UART_TXPEEK:
+ if (!fifo8_is_empty(&s->rx_fifo)) {
+ retvalue = fifo8_peek(&s->rx_fifo);
+ }
+ break;
+ case UART_PNR:
+ retvalue = s->pnr;
+ break;
+ case UART_FIFO:
+ if (!fifo8_is_empty(&s->rx_fifo)) {
+ retvalue = fifo8_pop(&s->rx_fifo);
+ max78000_update_irq(s);
+ }
+ break;
+ case UART_DMA:
+ /* DMA not implemented */
+ retvalue = s->dma;
+ break;
+ case UART_WKEN:
+ retvalue = s->wken;
+ break;
+ case UART_WKFL:
+ retvalue = s->wkfl;
+ break;
+ default:
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "%s: Bad offset 0x%"HWADDR_PRIx"\n", __func__, addr);
+ break;
+ }
+
+ return retvalue;
+}
+
+static void max78000_uart_write(void *opaque, hwaddr addr,
+ uint64_t val64, unsigned int size)
+{
+ Max78000UartState *s = opaque;
+
+ uint32_t value = val64;
+ uint8_t data;
+
+ switch (addr) {
+ case UART_CTRL:
+ if (value & UART_FLUSH_RX) {
+ fifo8_reset(&s->rx_fifo);
+ }
+ if (value & UART_BCLKEN) {
+ value = value | UART_BCLKRDY;
+ }
+ s->ctrl = value & ~(UART_FLUSH_RX | UART_FLUSH_TX);
+
+ /*
+ * Software can manage UART flow control manually by setting hfc_en
+ * in UART_CTRL. This would require emulating uart at a lower level,
+ * and is currently unimplemented.
+ */
+
+ return;
+ case UART_STATUS:
+ /* UART_STATUS is read only */
+ return;
+ case UART_INT_EN:
+ s->int_en = value;
+ return;
+ case UART_INT_FL:
+ s->int_fl = s->int_fl & ~(value);
+ max78000_update_irq(s);
+ return;
+ case UART_CLKDIV:
+ s->clkdiv = value;
+ return;
+ case UART_OSR:
+ s->osr = value;
+ return;
+ case UART_PNR:
+ s->pnr = value;
+ return;
+ case UART_FIFO:
+ data = value & 0xff;
+ /*
+ * XXX this blocks entire thread. Rewrite to use
+ * qemu_chr_fe_write and background I/O callbacks
+ */
+ qemu_chr_fe_write_all(&s->chr, &data, 1);
+
+ /* TX is always empty */
+ s->int_fl |= UART_TX_HE;
+ max78000_update_irq(s);
+
+ return;
+ case UART_DMA:
+ /* DMA not implemented */
+ s->dma = value;
+ return;
+ case UART_WKEN:
+ s->wken = value;
+ return;
+ case UART_WKFL:
+ s->wkfl = value;
+ return;
+ default:
+ qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%"
+ HWADDR_PRIx "\n", __func__, addr);
+ }
+}
+
+static const MemoryRegionOps max78000_uart_ops = {
+ .read = max78000_uart_read,
+ .write = max78000_uart_write,
+ .endianness = DEVICE_LITTLE_ENDIAN,
+ .valid.min_access_size = 4,
+ .valid.max_access_size = 4,
+};
+
+static const Property max78000_uart_properties[] = {
+ DEFINE_PROP_CHR("chardev", Max78000UartState, chr),
+};
+
+static const VMStateDescription max78000_uart_vmstate = {
+ .name = TYPE_MAX78000_UART,
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .fields = (VMStateField[]) {
+ VMSTATE_UINT32(ctrl, Max78000UartState),
+ VMSTATE_UINT32(status, Max78000UartState),
+ VMSTATE_UINT32(int_en, Max78000UartState),
+ VMSTATE_UINT32(int_fl, Max78000UartState),
+ VMSTATE_UINT32(clkdiv, Max78000UartState),
+ VMSTATE_UINT32(osr, Max78000UartState),
+ VMSTATE_UINT32(txpeek, Max78000UartState),
+ VMSTATE_UINT32(pnr, Max78000UartState),
+ VMSTATE_UINT32(fifo, Max78000UartState),
+ VMSTATE_UINT32(dma, Max78000UartState),
+ VMSTATE_UINT32(wken, Max78000UartState),
+ VMSTATE_UINT32(wkfl, Max78000UartState),
+ VMSTATE_FIFO8(rx_fifo, Max78000UartState),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static void max78000_uart_init(Object *obj)
+{
+ Max78000UartState *s = MAX78000_UART(obj);
+ fifo8_create(&s->rx_fifo, 8);
+
+ sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->irq);
+
+ memory_region_init_io(&s->mmio, obj, &max78000_uart_ops, s,
+ TYPE_MAX78000_UART, 0x400);
+ sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
+}
+
+static void max78000_uart_realize(DeviceState *dev, Error **errp)
+{
+ Max78000UartState *s = MAX78000_UART(dev);
+
+ qemu_chr_fe_set_handlers(&s->chr, max78000_uart_can_receive,
+ max78000_uart_receive, NULL, NULL,
+ s, NULL, true);
+}
+
+static void max78000_uart_class_init(ObjectClass *klass, const void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+ ResettableClass *rc = RESETTABLE_CLASS(klass);
+
+ rc->phases.hold = max78000_uart_reset_hold;
+
+ device_class_set_props(dc, max78000_uart_properties);
+ dc->realize = max78000_uart_realize;
+
+ dc->vmsd = &max78000_uart_vmstate;
+}
+
+static const TypeInfo max78000_uart_info = {
+ .name = TYPE_MAX78000_UART,
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(Max78000UartState),
+ .instance_init = max78000_uart_init,
+ .class_init = max78000_uart_class_init,
+};
+
+static void max78000_uart_register_types(void)
+{
+ type_register_static(&max78000_uart_info);
+}
+
+type_init(max78000_uart_register_types)
diff --git a/hw/char/meson.build b/hw/char/meson.build
index 4e439da8b9..a9e1dc26c0 100644
--- a/hw/char/meson.build
+++ b/hw/char/meson.build
@@ -26,6 +26,7 @@ system_ss.add(when: 'CONFIG_AVR_USART', if_true:
files('avr_usart.c'))
system_ss.add(when: 'CONFIG_COLDFIRE', if_true: files('mcf_uart.c'))
system_ss.add(when: 'CONFIG_DIGIC', if_true: files('digic-uart.c'))
system_ss.add(when: 'CONFIG_EXYNOS4', if_true: files('exynos4210_uart.c'))
+system_ss.add(when: 'CONFIG_MAX78000_UART', if_true: files('max78000_uart.c'))
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'))
diff --git a/include/hw/char/max78000_uart.h b/include/hw/char/max78000_uart.h
new file mode 100644
index 0000000000..cf90d51dbf
--- /dev/null
+++ b/include/hw/char/max78000_uart.h
@@ -0,0 +1,78 @@
+/*
+ * MAX78000 UART
+ *
+ * Copyright (c) 2025 Jackson Donaldson <jc...@duck.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef HW_MAX78000_UART_H
+#define HW_MAX78000_UART_H
+
+#include "hw/sysbus.h"
+#include "chardev/char-fe.h"
+#include "qemu/fifo8.h"
+#include "qom/object.h"
+
+#define UART_CTRL 0x0
+#define UART_STATUS 0x4
+#define UART_INT_EN 0x8
+#define UART_INT_FL 0xc
+#define UART_CLKDIV 0x10
+#define UART_OSR 0x14
+#define UART_TXPEEK 0x18
+#define UART_PNR 0x1c
+#define UART_FIFO 0x20
+#define UART_DMA 0x30
+#define UART_WKEN 0x34
+#define UART_WKFL 0x38
+
+/* CTRL */
+#define UART_CTF_DIS (1 << 7)
+#define UART_FLUSH_TX (1 << 8)
+#define UART_FLUSH_RX (1 << 9)
+#define UART_BCLKEN (1 << 15)
+#define UART_BCLKRDY (1 << 19)
+
+/* STATUS */
+#define UART_RX_LVL 8
+#define UART_TX_EM (1 << 6)
+#define UART_RX_FULL (1 << 5)
+#define UART_RX_EM (1 << 4)
+
+/* PNR (Pin Control Register) */
+#define UART_CTS 1
+#define UART_RTS (1 << 1)
+
+/* INT_EN / INT_FL */
+#define UART_RX_THD (1 << 4)
+#define UART_TX_HE (1 << 6)
+
+#define UART_RXBUFLEN 0x100
+#define TYPE_MAX78000_UART "max78000-uart"
+OBJECT_DECLARE_SIMPLE_TYPE(Max78000UartState, MAX78000_UART)
+
+struct Max78000UartState {
+ SysBusDevice parent_obj;
+
+ MemoryRegion mmio;
+
+ uint32_t ctrl;
+ uint32_t status;
+ uint32_t int_en;
+ uint32_t int_fl;
+ uint32_t clkdiv;
+ uint32_t osr;
+ uint32_t txpeek;
+ uint32_t pnr;
+ uint32_t fifo;
+ uint32_t dma;
+ uint32_t wken;
+ uint32_t wkfl;
+
+ Fifo8 rx_fifo;
+
+ CharBackend chr;
+ qemu_irq irq;
+};
+#endif /* HW_STM32F2XX_USART_H */
--
2.34.1
