Implement a K230 SoC DesignWare 8250-compatible UART controller model for
QEMU, capable of running the Linux 8250_dw driver and providing an
interactive shell.
Implemented:
- Standard 16550 registers (RBR/THR/DLL, IER/DLH, IIR/FCR, LCR, MCR,
LSR, MSR, SCR) and DesignWare-specific registers (USR, TFL, RFL, SRR,
SRTS, SBCR, SDMAM, SFE, SRT, STET, HTX, CPR, UCV, CTR)
- DLAB switching; 32-byte TX/RX FIFO; synchronous transmit with
backpressure handling
- Loopback mode; chardev BREAK routed to LSR.BI/FE via CHR_EVENT_BREAK
- Four-level prioritized interrupt scheme (ELSI / RX Data / Timeout /
THRE), with edge-triggered THRE
- RX Character Timeout interrupt (IID=0xc) with 4-char-time timer that
tracks the programmed divisor latch
- Busy Detect interrupt (IID=0x7): LCR (and its shadow SBCR) writes
while USR.BUSY=1 are rejected and raise IID=0x7, cleared by reading
USR; USR.BUSY reflects TX-not-empty / RX-data-ready
- Shadow registers alias their underlying fields
- SRR (UR/RFR/XFR) self-clearing software reset
Not implemented:
- RS485 transceiver control (TCR/DE_EN/RE_EN/DET/TAT)
- 9-bit multidrop (LCR_EXT/RAR/TAR)
- Fractional baud rate (DLF)
- Auto Flow Control (MCR.AFCE)
- IrDA SIR mode (MCR.SIRE)
- Low-power divisor latch (LPDLL/LPDLH)
- FIFO access test mode (FAR/TFR/RFW)
- DMA Software Acknowledge (DMASA)
Signed-off-by: zhenbaii <[email protected]>
---
hw/char/Kconfig | 3 +
hw/char/k230_uart.c | 840 ++++++++++++++++++++++++++++++++++++++++++++
hw/char/meson.build | 1 +
include/hw/char/k230_uart.h | 180 ++++++++++
4 files changed, 1024 insertions(+)
diff --git a/hw/char/Kconfig b/hw/char/Kconfig
index
020c0a84bb6e5f11cc7d532a7999ade23505a1ba..bd000f7127e7881dabac191c81b2bcf66f549250
100644
--- a/hw/char/Kconfig
+++ b/hw/char/Kconfig
@@ -91,6 +91,9 @@ config GOLDFISH_TTY
config SHAKTI_UART
bool
+config K230_UART
+ bool
+
config IP_OCTAL_232
bool
default y
diff --git a/hw/char/k230_uart.c b/hw/char/k230_uart.c
new file mode 100644
index
0000000000000000000000000000000000000000..358c8ff8d5ab0b265e7d7f429860ac6dc3186e31
--- /dev/null
+++ b/hw/char/k230_uart.c
@@ -0,0 +1,840 @@
+/*
+ * K230 UART
+ *
+ * Copyright (c) 2026 zhenbaii <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/char/k230_uart.h"
+#include "hw/core/irq.h"
+#include "hw/core/qdev-properties-system.h"
+#include "migration/vmstate.h"
+#include "qemu/module.h"
+#include "qemu/timer.h"
+#include "qemu/host-utils.h"
+#include "system/memory.h"
+
+/* Serial clock from the K230 DT "clock-frequency" property (50 MHz). */
+#define K230_UART_SCLK_HZ 50000000ull
+
+static void k230_uart_xmit(K230UartState *s);
+static void k230_uart_update_all(K230UartState *s);
+static uint64_t k230_uart_read_rbr(K230UartState *s);
+static void k230_uart_push_rx_byte(K230UartState *s, uint8_t ch);
+static void k230_uart_reset_hold(Object *obj, ResetType type);
+
+/* ---- interrupt line ---- */
+
+/*
+ * RX FIFO trigger level. When rx_count reaches this,
+ * the RX Data Available interrupt (IID=0x4) fires.
+ */
+static uint32_t k230_uart_rx_trigger_level(const K230UartState *s)
+{
+ if (!FIELD_EX32(s->fcr, FCR, FIFOE)) {
+ return 1; /* non-FIFO mode: 1 byte */
+ }
+ switch (FIELD_EX32(s->fcr, FCR, RT)) {
+ case 0: return 1;
+ case 1: return K230_UART_FIFO_DEPTH / 4;
+ case 2: return K230_UART_FIFO_DEPTH / 2;
+ case 3: return K230_UART_FIFO_DEPTH - 2;
+ default: return 1;
+ }
+}
+
+static void k230_uart_update_irq(K230UartState *s)
+{
+ bool irq = false;
+ uint32_t rx_itl = k230_uart_rx_trigger_level(s);
+
+ /* RX trigger level > 1 */
+ if (FIELD_EX32(s->ier, IER, ERBFI) &&
+ (s->rx_count >= rx_itl || s->timeout_ipending)) {
+ irq = true;
+ }
+ /* Transmit Holding Register Empty Interrupt */
+ if (FIELD_EX32(s->ier, IER, ETBEI) && s->thr_ipending) {
+ irq = true;
+ }
+ /* Receiver Line Status Interrupt */
+ if (FIELD_EX32(s->ier, IER, ELSI) &&
+ (FIELD_EX32(s->lsr, LSR, OE) || FIELD_EX32(s->lsr, LSR, PE) ||
+ FIELD_EX32(s->lsr, LSR, FE) || FIELD_EX32(s->lsr, LSR, BI))) {
+ irq = true;
+ }
+ /* Busy detect interrupt (DW-specific, no IER gate). */
+ if (s->busy_ipending) {
+ irq = true;
+ }
+ qemu_set_irq(s->irq, irq ? 1 : 0);
+}
+
+/* ---- FIFO reset ---- */
+
+static void k230_uart_fifo_reset(K230UartState *s, bool rx, bool tx)
+{
+ if (rx) {
+ s->rx_head = s->rx_tail = s->rx_count = 0;
+ s->lsr = FIELD_DP32(s->lsr, LSR, DR, 0);
+ s->timeout_ipending = 0;
+ timer_del(&s->rx_timeout);
+ }
+ if (tx) {
+ s->tx_head = s->tx_tail = s->tx_count = 0;
+ s->lsr = FIELD_DP32(s->lsr, LSR, THRE, 1);
+ s->lsr = FIELD_DP32(s->lsr, LSR, TEMT, 1);
+ s->thr_ipending = 1;
+ }
+ k230_uart_update_all(s);
+}
+
+/* ---- transmit ---- */
+
+static gboolean k230_uart_chr_can_write(void *do_not_use, GIOCondition cond,
+ void *opaque)
+{
+ K230UartState *s = K230_UART(opaque);
+ if (!s->htx) {
+ k230_uart_xmit(s);
+ }
+ return G_SOURCE_REMOVE;
+}
+
+/* ---- baud / char-transmit time ---- */
+
+/*
+ * Recompute the per-character transmit time from the current divisor latch:
+ *
+ * baud = sclk / (16 * divisor)
+ * char_ns = 10 * 16 * divisor * 1e9 / sclk (10 = 8N1 start+data+stop)
+ *
+ * Drives the RX timeout interrupt (IID=0xc), which fires after 4 char times.
+ * divisor == 0 means "unprogrammed": keep the previous (reset default) value.
+ */
+static void k230_uart_update_char_time(K230UartState *s)
+{
+ uint32_t divisor = ((uint32_t)s->dlh << 8) | s->dll;
+ if (divisor == 0) {
+ return;
+ }
+ s->char_transmit_time = muldiv64(10ull * 16 * divisor,
+ NANOSECONDS_PER_SECOND,
+ K230_UART_SCLK_HZ);
+}
+
+/* Send all characters in THR or TX-FIFO into char backend */
+static void k230_uart_xmit(K230UartState *s)
+{
+ int ret;
+
+ if (s->tx_count == 0 || s->htx) {
+ return;
+ }
+
+ while (s->tx_count > 0) {
+ uint8_t ch = (uint8_t)s->tx_fifo[s->tx_tail];
+
+ if (FIELD_EX32(s->mcr, MCR, LOOPBACK)) {
+ /* Go to RX fifo */
+ k230_uart_push_rx_byte(s, ch);
+ ret = 1;
+ } else {
+ /* Go to char backend */
+ ret = qemu_chr_fe_write(&s->chr, &ch, 1);
+ }
+ if (ret < 0) {
+ /* Wait for backend to be accessible then call the callback */
+ qemu_chr_fe_add_watch(&s->chr, G_IO_OUT,
+ k230_uart_chr_can_write, s);
+ break;
+ }
+
+ s->tx_tail = (s->tx_tail + 1) % K230_UART_FIFO_DEPTH;
+ s->tx_count--;
+ }
+
+ s->lsr = FIELD_DP32(s->lsr, LSR, TEMT, (s->tx_count == 0) ? 1 : 0);
+ k230_uart_update_all(s);
+}
+
+/* ---- RX timeout ---- */
+
+/* Character timeout callback */
+static void k230_uart_rx_timeout(void *opaque)
+{
+ K230UartState *s = K230_UART(opaque);
+ if (s->rx_count > 0) {
+ s->timeout_ipending = 1;
+ k230_uart_update_all(s);
+ }
+}
+
+/* ---- receive ---- */
+
+/* Push a byte to rxfifo(when FIFO_EN is set) or RBR(FIFO_EN not set). */
+static void k230_uart_push_rx_byte(K230UartState *s, uint8_t ch)
+{
+ bool fifo_en = FIELD_EX32(s->fcr, FCR, FIFOE);
+ uint16_t capacity = fifo_en ? K230_UART_FIFO_DEPTH : 1;
+
+ if (s->rx_count < capacity) {
+ s->rx_fifo[s->rx_head] = ch;
+ s->rx_head = (s->rx_head + 1) % K230_UART_FIFO_DEPTH;
+ s->rx_count++;
+ s->lsr = FIELD_DP32(s->lsr, LSR, DR, 1);
+ timer_mod(&s->rx_timeout,
+ qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)
+ + 4 * s->char_transmit_time);
+ } else {
+ s->lsr = FIELD_DP32(s->lsr, LSR, OE, 1);
+ }
+ k230_uart_update_all(s);
+}
+
+/* ---- derived register recomputation ---- */
+
+static void k230_uart_update_thre(K230UartState *s)
+{
+ bool should_set = (s->tx_count == 0);
+#if K230_UART_THRE_MODE
+ if (FIELD_EX32(s->ier, IER, PTIME)
+ && FIELD_EX32(s->fcr, FCR, FIFOE)) {
+ uint8_t tet = FIELD_EX32(s->fcr, FCR, TET);
+ uint16_t threshold;
+ switch (tet) {
+ case 0x0:
+ threshold = 0;
+ break;
+ case 0x1:
+ threshold = 2;
+ break;
+ case 0x2:
+ threshold = K230_UART_FIFO_DEPTH / 4;
+ break;
+ case 0x3:
+ threshold = K230_UART_FIFO_DEPTH / 2;
+ break;
+ default:
+ threshold = 0;
+ break;
+ }
+ should_set = (s->tx_count <= threshold);
+ }
+#endif
+
+ uint8_t old_thre = FIELD_EX32(s->lsr, LSR, THRE);
+ s->lsr = FIELD_DP32(s->lsr, LSR, THRE, should_set ? 1 : 0);
+
+ /* Edge trigger */
+ if (should_set && !old_thre) {
+ s->thr_ipending = 1;
+ }
+}
+
+static bool k230_uart_is_busy(const K230UartState *s)
+{
+ return !FIELD_EX32(s->lsr, LSR, TEMT) || FIELD_EX32(s->lsr, LSR, DR);
+}
+
+static void k230_uart_update_usr(K230UartState *s)
+{
+ bool fifo_en = FIELD_EX32(s->fcr, FCR, FIFOE);
+ uint16_t capacity = fifo_en ? K230_UART_FIFO_DEPTH : 1;
+
+ s->usr = 0;
+#if !K230_UART_16550_COMPATIBLE
+ if (k230_uart_is_busy(s)) {
+ s->usr = FIELD_DP32(s->usr, USR, BUSY, 1);
+ }
+#endif
+#if K230_UART_FIFO_STAT && K230_UART_FIFO_MODE
+ s->usr = FIELD_DP32(s->usr, USR, TFNF, s->tx_count < capacity ? 1 : 0);
+ s->usr = FIELD_DP32(s->usr, USR, TFE, s->tx_count == 0 ? 1 : 0);
+ s->usr = FIELD_DP32(s->usr, USR, RFNE, s->rx_count != 0 ? 1 : 0);
+ s->usr = FIELD_DP32(s->usr, USR, RFF, s->rx_count == capacity ? 1 : 0);
+#endif
+}
+
+static void k230_uart_update_iir(K230UartState *s)
+{
+ s->iir = 0;
+ /* Indicate whether FIFO is enabled or not */
+ if (FIELD_EX32(s->fcr, FCR, FIFOE)) {
+ s->iir = FIELD_DP32(s->iir, IIR, FIFOSE, 0x3);
+ }
+
+ if (FIELD_EX32(s->ier, IER, ELSI) &&
+ (FIELD_EX32(s->lsr, LSR, OE) || FIELD_EX32(s->lsr, LSR, PE) ||
+ FIELD_EX32(s->lsr, LSR, FE) || FIELD_EX32(s->lsr, LSR, BI))) {
+ /* Receiver Line Status Interrupt */
+ s->iir = FIELD_DP32(s->iir, IIR, IID, 0x6);
+ } else if (FIELD_EX32(s->ier, IER, ERBFI) &&
+ (s->rx_count >= k230_uart_rx_trigger_level(s))) {
+ /* Receiver Data Available Interrupt */
+ s->iir = FIELD_DP32(s->iir, IIR, IID, 0x4);
+ } else if (FIELD_EX32(s->ier, IER, ERBFI) && s->timeout_ipending) {
+ /* Character timeout interrupt */
+ s->iir = FIELD_DP32(s->iir, IIR, IID, 0xc);
+ } else if (FIELD_EX32(s->ier, IER, ETBEI) && s->thr_ipending) {
+ /* THR Empty Interrupt */
+ s->iir = FIELD_DP32(s->iir, IIR, IID, 0x2);
+ } else if (s->busy_ipending) {
+ /* Busy detect: LCR written while USR.BUSY=1 (DW-specific) */
+ s->iir = FIELD_DP32(s->iir, IIR, IID, 0x7);
+ } else {
+ s->iir = FIELD_DP32(s->iir, IIR, IID, 0x1);
+ }
+}
+
+
+static void k230_uart_update_msr(K230UartState *s)
+{
+ uint8_t old_status = s->msr & 0xf0;
+ uint8_t new_status;
+
+ if (FIELD_EX32(s->mcr, MCR, LOOPBACK)) {
+ /*
+ * Standard 16550 loopback mapping:
+ * DTR -> DSR, RTS -> CTS, OUT1 -> RI, OUT2 -> DCD
+ */
+ new_status = 0;
+ if (FIELD_EX32(s->mcr, MCR, RTS)) {
+ new_status |= 0x10; /* CTS */
+ }
+ if (FIELD_EX32(s->mcr, MCR, DTR)) {
+ new_status |= 0x20; /* DSR */
+ }
+ if (FIELD_EX32(s->mcr, MCR, OUT1)) {
+ new_status |= 0x40; /* RI */
+ }
+ if (FIELD_EX32(s->mcr, MCR, OUT2)) {
+ new_status |= 0x80; /* DCD */
+ }
+ } else {
+ /* No real modem: report CTS/DSR/DCD as active (ready) */
+ new_status = 0xb0; /* CTS | DSR | DCD */
+ }
+
+ /* Accumulate delta bits on status changes */
+ uint8_t deltas = s->msr & 0x0f;
+ uint8_t changes = old_status ^ new_status;
+ if (changes & 0x10) {
+ deltas |= 0x01; /* DCTS */
+ }
+ if (changes & 0x20) {
+ deltas |= 0x02; /* DDSR */
+ }
+ if ((old_status & 0x40) && !(new_status & 0x40)) {
+ deltas |= 0x04; /* TERI */
+ }
+ if (changes & 0x80) {
+ deltas |= 0x08; /* DDCD */
+ }
+
+ s->msr = new_status | deltas;
+}
+
+static void k230_uart_update_all(K230UartState *s)
+{
+ k230_uart_update_thre(s);
+ k230_uart_update_usr(s);
+ k230_uart_update_iir(s);
+ k230_uart_update_irq(s);
+}
+
+/* ---- MMIO read ---- */
+
+static uint64_t k230_uart_read_rbr(K230UartState *s)
+{
+ uint64_t ret = 0;
+
+ if (s->rx_count > 0) {
+ ret = s->rx_fifo[s->rx_tail];
+ s->rx_tail = (s->rx_tail + 1) % K230_UART_FIFO_DEPTH;
+ s->rx_count--;
+ s->timeout_ipending = 0;
+ if (s->rx_count == 0) {
+ s->lsr = FIELD_DP32(s->lsr, LSR, DR, 0);
+ timer_del(&s->rx_timeout);
+ } else {
+ timer_mod(&s->rx_timeout,
+ qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)
+ + 4 * s->char_transmit_time);
+ }
+ qemu_chr_fe_accept_input(&s->chr);
+ }
+
+ if (!FIELD_EX32(s->ier, IER, ELCOLR)) {
+ s->lsr = FIELD_DP32(s->lsr, LSR, OE, 0);
+ s->lsr = FIELD_DP32(s->lsr, LSR, PE, 0);
+ s->lsr = FIELD_DP32(s->lsr, LSR, FE, 0);
+ s->lsr = FIELD_DP32(s->lsr, LSR, BI, 0);
+ }
+
+ k230_uart_update_all(s);
+ return ret;
+}
+
+static uint64_t k230_uart_read(void *opaque, hwaddr addr, unsigned int size)
+{
+ K230UartState *s = K230_UART(opaque);
+ uint64_t ret = 0;
+
+ switch (addr >> 2) {
+ case R_RBR_DLL_THR:
+ if (FIELD_EX32(s->lcr, LCR, DLAB)) {
+ /* DLL accessible only when not busy. */
+ ret = (K230_UART_16550_COMPATIBLE || !k230_uart_is_busy(s))
+ ? s->dll : 0;
+ } else {
+ ret = k230_uart_read_rbr(s);
+ }
+ break;
+ case R_IER_DLH:
+ if (FIELD_EX32(s->lcr, LCR, DLAB)) {
+ /* DLH accessible only when not busy. */
+ ret = (K230_UART_16550_COMPATIBLE || !k230_uart_is_busy(s))
+ ? s->dlh : 0;
+ } else {
+ /* IER */
+ ret = s->ier;
+ }
+ break;
+ case R_IIR:
+ ret = s->iir;
+ if (FIELD_EX32(s->iir, IIR, IID) == 0x2) {
+ s->thr_ipending = 0;
+ k230_uart_update_all(s);
+ }
+ break;
+ case R_LCR:
+ ret = s->lcr;
+ break;
+ case R_LSR:
+ ret = s->lsr;
+ /* Clear OE PE FE and Break Interrupt status bits */
+ s->lsr = FIELD_DP32(s->lsr, LSR, OE, 0);
+ s->lsr = FIELD_DP32(s->lsr, LSR, PE, 0);
+ s->lsr = FIELD_DP32(s->lsr, LSR, FE, 0);
+ s->lsr = FIELD_DP32(s->lsr, LSR, BI, 0);
+ k230_uart_update_all(s);
+ break;
+ case R_MCR:
+ ret = s->mcr;
+ break;
+ case R_MSR:
+ ret = s->msr;
+ s->msr &= 0xf0; /* clear delta bits on read */
+ break;
+ case R_SCR:
+ ret = s->scr;
+ break;
+
+ /* Shadow registers: aliases of standard registers. */
+ case R_SRTS:
+ ret = FIELD_EX32(s->mcr, MCR, RTS);
+ break;
+ case R_SBCR:
+ ret = FIELD_EX32(s->lcr, LCR, BC);
+ break;
+ case R_SDMAM:
+ ret = FIELD_EX32(s->fcr, FCR, DMAM);
+ break;
+ case R_SFE:
+ ret = FIELD_EX32(s->fcr, FCR, FIFOE);
+ break;
+ case R_SRT:
+ ret = FIELD_EX32(s->fcr, FCR, RT);
+ break;
+ case R_STET:
+ ret = FIELD_EX32(s->fcr, FCR, TET);
+ break;
+ case R_HTX:
+ ret = s->htx;
+ break;
+
+ case R_CPR:
+ ret = (K230_UART_APB_DATA_WIDTH << 0) |
+ (K230_UART_AFCE_MODE << 4) |
+ (K230_UART_THRE_MODE << 5) |
+ (K230_UART_SIR_MODE << 6) |
+ (K230_UART_SIR_LP_MODE << 7) |
+ (K230_UART_ADDITIONAL_FEATURES << 8) |
+ (K230_UART_FIFO_ACCESS << 9) |
+ (K230_UART_FIFO_STAT << 10) |
+ (K230_UART_SHADOW << 11) |
+ (K230_UART_ADD_ENCODED_PARAMS << 12) |
+ (K230_UART_DMA_EXTRA << 13) |
+ (K230_UART_FIFO_MODE << 16);
+ break;
+ case R_UCV:
+ /* Version */
+ ret = 0x342e3061;
+ break;
+ case R_DLF:
+ ret = 0;
+ break;
+ case R_USR:
+ ret = s->usr;
+ /* Reading USR clears the busy-detect interrupt. */
+ if (s->busy_ipending) {
+ s->busy_ipending = 0;
+ k230_uart_update_all(s);
+ }
+ break;
+ case R_TFL:
+ /* Transmit FIFO Level: number of bytes in TX FIFO. */
+ ret = s->tx_count;
+ break;
+ case R_RFL:
+ /* Receive FIFO Level: number of bytes in RX FIFO. */
+ ret = s->rx_count;
+ break;
+ case R_CTR:
+ /* Component Type Register: fixed ID. */
+ ret = K230_UART_CTR_VALUE;
+ break;
+ default:
+ ret = 0;
+ break;
+ }
+ return ret;
+}
+
+/* ---- MMIO write ---- */
+
+static void k230_uart_write(void *opaque, hwaddr addr,
+ uint64_t val64, unsigned int size)
+{
+ K230UartState *s = K230_UART(opaque);
+ uint32_t val = (uint32_t)val64;
+ uint32_t offset = addr >> 2;
+
+ switch (offset) {
+ case R_RBR_DLL_THR:
+ if (FIELD_EX32(s->lcr, LCR, DLAB)) {
+ /* DLL writable only when not busy. */
+ if (K230_UART_16550_COMPATIBLE || !k230_uart_is_busy(s)) {
+ s->dll = val & 0xff;
+ k230_uart_update_char_time(s);
+ }
+ } else {
+ bool fifo_en = FIELD_EX32(s->fcr, FCR, FIFOE);
+ uint16_t capacity = fifo_en ? K230_UART_FIFO_DEPTH : 1;
+ if (s->tx_count < capacity) {
+ s->tx_fifo[s->tx_head] = val & 0xff;
+ s->tx_head = (s->tx_head + 1) % K230_UART_FIFO_DEPTH;
+ s->tx_count++;
+ } else if (!fifo_en) {
+ s->tx_fifo[s->tx_tail] = val & 0xff;
+ }
+ s->lsr = FIELD_DP32(s->lsr, LSR, THRE, 0);
+ s->thr_ipending = 0;
+ s->lsr = FIELD_DP32(s->lsr, LSR, TEMT, 0);
+ k230_uart_xmit(s);
+ }
+ break;
+ case R_IER_DLH:
+ if (FIELD_EX32(s->lcr, LCR, DLAB)) {
+ /* DLH writable only when not busy. */
+ if (K230_UART_16550_COMPATIBLE || !k230_uart_is_busy(s)) {
+ s->dlh = val & 0xff;
+ k230_uart_update_char_time(s);
+ }
+ } else {
+ uint8_t old_etbei = FIELD_EX32(s->ier, IER, ETBEI);
+ s->ier = FIELD_DP32(s->ier, IER, ERBFI,
+ FIELD_EX32(val, IER, ERBFI));
+ s->ier = FIELD_DP32(s->ier, IER, ETBEI,
+ FIELD_EX32(val, IER, ETBEI));
+ s->ier = FIELD_DP32(s->ier, IER, ELSI,
+ FIELD_EX32(val, IER, ELSI));
+ s->ier = FIELD_DP32(s->ier, IER, EDSSI,
+ FIELD_EX32(val, IER, EDSSI));
+ s->ier = FIELD_DP32(s->ier, IER, ELCOLR,
+ FIELD_EX32(val, IER, ELCOLR));
+#if K230_UART_THRE_MODE
+ s->ier = FIELD_DP32(s->ier, IER, PTIME,
+ FIELD_EX32(val, IER, PTIME));
+#endif
+ if (!old_etbei && FIELD_EX32(s->ier, IER, ETBEI)
+ && FIELD_EX32(s->lsr, LSR, THRE)) {
+ s->thr_ipending = 1;
+ }
+ }
+ break;
+ case R_FCR:
+ if ((val ^ s->fcr) & R_FCR_FIFOE_MASK) {
+ val |= R_FCR_RFIFOR_MASK | R_FCR_XFIFOR_MASK;
+ }
+ s->fcr = FIELD_DP32(s->fcr, FCR, FIFOE,
+ FIELD_EX32(val, FCR, FIFOE));
+ s->fcr = FIELD_DP32(s->fcr, FCR, DMAM,
+ FIELD_EX32(val, FCR, DMAM));
+ s->fcr = FIELD_DP32(s->fcr, FCR, RT,
+ FIELD_EX32(val, FCR, RT));
+#if K230_UART_THRE_MODE
+ s->fcr = FIELD_DP32(s->fcr, FCR, TET,
+ FIELD_EX32(val, FCR, TET));
+#endif
+ if (FIELD_EX32(val, FCR, RFIFOR)) {
+ k230_uart_fifo_reset(s, true, false);
+ }
+ if (FIELD_EX32(val, FCR, XFIFOR)) {
+ k230_uart_fifo_reset(s, false, true);
+ }
+ break;
+ case R_LCR:
+ /*
+ * When UART_16550_COMPATIBLE == NO (the K230 case),
+ * LCR is writable only when USR.BUSY == 0. A write while busy is
+ * ignored and triggers the busy-detect interrupt (IID=0x7), which is
+ * cleared by reading USR. The 8250_dw driver detects this via
+ * dw8250_check_lcr() and retries after draining the FIFOs.
+ */
+ if (!K230_UART_16550_COMPATIBLE && k230_uart_is_busy(s)) {
+ s->busy_ipending = 1;
+ } else {
+ s->lcr = val & 0xff;
+ }
+ break;
+ case R_MCR:
+ /*
+ * K230 advertises AFCE_MODE=0 and SIR_MODE=0 in CPR, so MCR[5:6]
+ * (AFCE/SIRE) are read-only 0. MCR[7] is reserved and also 0.
+ */
+ s->mcr = val & 0x1f;
+ k230_uart_update_msr(s);
+ break;
+ case R_SCR:
+ s->scr = val & 0xff;
+ break;
+
+ /*
+ * Shadow registers: aliases of standard register fields.
+ * They let software update a single bit without read-modify-write on the
+ * original register. SBCR shadows LCR[6] (BC), which is gated by the
+ * busy-detect logic just like a direct LCR write.
+ */
+ case R_SRTS:
+ s->mcr = FIELD_DP32(s->mcr, MCR, RTS, val & 0x1);
+ k230_uart_update_msr(s);
+ break;
+ case R_SBCR:
+ if (!K230_UART_16550_COMPATIBLE && k230_uart_is_busy(s)) {
+ s->busy_ipending = 1;
+ } else {
+ s->lcr = FIELD_DP32(s->lcr, LCR, BC, val & 0x1);
+ }
+ break;
+ case R_SDMAM:
+ s->fcr = FIELD_DP32(s->fcr, FCR, DMAM, val & 0x1);
+ break;
+ case R_SFE:
+ /* Shadow of FCR[0]; changing FIFOE resets both FIFOs */
+ if ((s->fcr ^ val) & R_FCR_FIFOE_MASK) {
+ k230_uart_fifo_reset(s, true, true);
+ }
+ s->fcr = FIELD_DP32(s->fcr, FCR, FIFOE, val & 0x1);
+ break;
+ case R_SRT:
+ s->fcr = FIELD_DP32(s->fcr, FCR, RT, val & 0x3);
+ break;
+ case R_STET:
+#if K230_UART_THRE_MODE
+ s->fcr = FIELD_DP32(s->fcr, FCR, TET, val & 0x3);
+#endif
+ break;
+ case R_HTX:
+ s->htx = val & 0x1;
+ /* Clearing HTX resumes transmission of any buffered TX data. */
+ if (!s->htx) {
+ k230_uart_xmit(s);
+ }
+ break;
+
+ case R_SRR:
+ if (FIELD_EX32(val, SRR, UR)) {
+ device_cold_reset(DEVICE(s));
+ return;
+ }
+ if (FIELD_EX32(val, SRR, RFR)) {
+ k230_uart_fifo_reset(s, true, false);
+ }
+ if (FIELD_EX32(val, SRR, XFR)) {
+ k230_uart_fifo_reset(s, false, true);
+ }
+ break;
+
+ default:
+ break;
+ }
+ k230_uart_update_all(s);
+}
+
+/* ---- device lifecycle ---- */
+
+static const MemoryRegionOps k230_uart_ops = {
+ .read = k230_uart_read,
+ .write = k230_uart_write,
+ .endianness = DEVICE_LITTLE_ENDIAN,
+ .impl.min_access_size = 4,
+ .impl.max_access_size = 4,
+};
+
+static void k230_uart_init(Object *obj)
+{
+ K230UartState *s = K230_UART(obj);
+ SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+
+ memory_region_init_io(&s->mmio, OBJECT(s), &k230_uart_ops, s,
+ TYPE_K230_UART, 0x100);
+ sysbus_init_mmio(sbd, &s->mmio);
+ sysbus_init_irq(sbd, &s->irq);
+}
+
+static int k230_uart_can_receive(void *opaque)
+{
+ K230UartState *s = K230_UART(opaque);
+ return K230_UART_FIFO_DEPTH - s->rx_count;
+}
+
+static void k230_uart_receive(void *opaque, const uint8_t *buf, int size)
+{
+ K230UartState *s = K230_UART(opaque);
+ for (int i = 0; i < size; i++) {
+ k230_uart_push_rx_byte(s, buf[i]);
+ }
+}
+
+static void k230_uart_event(void *opaque, QEMUChrEvent event)
+{
+ K230UartState *s = K230_UART(opaque);
+
+ if (event == CHR_EVENT_BREAK) {
+ k230_uart_push_rx_byte(s, 0);
+ s->lsr = FIELD_DP32(s->lsr, LSR, BI, 1);
+ s->lsr = FIELD_DP32(s->lsr, LSR, FE, 1);
+ k230_uart_update_all(s);
+ }
+}
+
+static void k230_uart_reset_hold(Object *obj, ResetType type)
+{
+ K230UartState *s = K230_UART(obj);
+ s->lcr = 0;
+ s->fcr = 0;
+ s->ier = 0;
+ s->mcr = 0;
+ s->scr = 0;
+ s->dll = 0;
+ s->dlh = 0;
+ s->lsr = 0x60;
+ s->msr = 0xb0;
+
+ s->rx_head = s->rx_tail = s->rx_count = 0;
+ s->tx_head = s->tx_tail = s->tx_count = 0;
+ s->htx = 0;
+
+ qemu_set_irq(s->irq, 0);
+
+ s->thr_ipending = 0;
+ s->timeout_ipending = 0;
+ s->busy_ipending = 0;
+ timer_del(&s->rx_timeout);
+ /* Default to 115200 baud until the driver programs the divisor latch. */
+ s->char_transmit_time = (NANOSECONDS_PER_SECOND / 115200) * 10;
+
+ k230_uart_update_all(s);
+}
+
+static void k230_uart_realize(DeviceState *dev, Error **errp)
+{
+ K230UartState *s = K230_UART(dev);
+ qemu_chr_fe_set_handlers(&s->chr, k230_uart_can_receive,
+ k230_uart_receive, k230_uart_event,
+ NULL, s, NULL, true);
+
+ timer_init_ns(&s->rx_timeout, QEMU_CLOCK_VIRTUAL,
+ k230_uart_rx_timeout, s);
+}
+
+static int k230_uart_post_load(void *opaque, int version_id)
+{
+ K230UartState *s = K230_UART(opaque);
+
+ /*
+ * iir and usr are derived from the saved state; recompute them after
+ * migration so the device is consistent.
+ */
+ k230_uart_update_all(s);
+ return 0;
+}
+
+static const VMStateDescription vmstate_k230_uart = {
+ .name = "k230.uart",
+ .version_id = 2,
+ .minimum_version_id = 1,
+ .post_load = k230_uart_post_load,
+ .fields = (const VMStateField[]) {
+ VMSTATE_UINT8(lcr, K230UartState),
+ VMSTATE_UINT8(fcr, K230UartState),
+ VMSTATE_UINT8(ier, K230UartState),
+ VMSTATE_UINT8(dll, K230UartState),
+ VMSTATE_UINT8(dlh, K230UartState),
+ VMSTATE_UINT8(mcr, K230UartState),
+ VMSTATE_UINT8(lsr, K230UartState),
+ VMSTATE_UINT8(msr, K230UartState),
+ VMSTATE_UINT8(scr, K230UartState),
+ VMSTATE_UINT8(htx, K230UartState),
+ VMSTATE_UINT16_ARRAY(rx_fifo, K230UartState,
+ K230_UART_FIFO_DEPTH),
+ VMSTATE_UINT16_ARRAY(tx_fifo, K230UartState,
+ K230_UART_FIFO_DEPTH),
+ VMSTATE_UINT32(rx_head, K230UartState),
+ VMSTATE_UINT32(rx_tail, K230UartState),
+ VMSTATE_UINT32(rx_count, K230UartState),
+ VMSTATE_UINT32(tx_head, K230UartState),
+ VMSTATE_UINT32(tx_tail, K230UartState),
+ VMSTATE_UINT32(tx_count, K230UartState),
+ VMSTATE_UINT8(thr_ipending, K230UartState),
+ VMSTATE_UINT8(timeout_ipending, K230UartState),
+ VMSTATE_UINT8(busy_ipending, K230UartState),
+ VMSTATE_UINT64(char_transmit_time, K230UartState),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static const Property k230_uart_properties[] = {
+ DEFINE_PROP_CHR("chardev", K230UartState, chr),
+};
+
+static void k230_uart_class_init(ObjectClass *klass, const void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+ ResettableClass *rc = RESETTABLE_CLASS(klass);
+
+ dc->realize = k230_uart_realize;
+ rc->phases.hold = k230_uart_reset_hold;
+ dc->vmsd = &vmstate_k230_uart;
+ dc->desc = "K230 UART (16550-compatible)";
+ device_class_set_props(dc, k230_uart_properties);
+}
+
+static const TypeInfo k230_uart_info = {
+ .name = TYPE_K230_UART,
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(K230UartState),
+ .instance_init = k230_uart_init,
+ .class_init = k230_uart_class_init
+};
+
+static void k230_uart_register_types(void)
+{
+ type_register_static(&k230_uart_info);
+}
+
+type_init(k230_uart_register_types)
diff --git a/hw/char/meson.build b/hw/char/meson.build
index
fc3d7ee506fcf8eb1219f6af9689fd90573861c9..23d8ede3f031f80d1b519bf49beac9d23502e2cb
100644
--- a/hw/char/meson.build
+++ b/hw/char/meson.build
@@ -38,6 +38,7 @@ system_ss.add(when: 'CONFIG_STM32L4X5_USART', if_true:
files('stm32l4x5_usart.c'
system_ss.add(when: 'CONFIG_MCHP_PFSOC_MMUART', if_true:
files('mchp_pfsoc_mmuart.c'))
system_ss.add(when: 'CONFIG_HTIF', if_true: files('riscv_htif.c'))
system_ss.add(when: 'CONFIG_GOLDFISH_TTY', if_true: files('goldfish_tty.c'))
+system_ss.add(when: 'CONFIG_K230', if_true: files('k230_uart.c'))
specific_ss.add(when: 'CONFIG_TERMINAL3270', if_true: files('terminal3270.c'))
specific_ss.add(when: 'CONFIG_PSERIES', if_true: files('spapr_vty.c'))
diff --git a/include/hw/char/k230_uart.h b/include/hw/char/k230_uart.h
new file mode 100644
index
0000000000000000000000000000000000000000..60e39101c00c73d0167fcff47bc1e56fe4cf0b19
--- /dev/null
+++ b/include/hw/char/k230_uart.h
@@ -0,0 +1,180 @@
+/*
+ * K230 UART device
+ *
+ * K230 Technical Reference Manual V0.3.1 (2024-11-18):
+ *
https://github.com/revyos/external-docs/blob/master/K230/en-us/K230_Technical_Reference_Manual_V0.3.1_20241118.pdf
+ *
+ * Register semantics cross-checked against the SDK Linux driver
+ * src/little/linux/drivers/tty/serial/8250/8250_dw.c in
+ * https://github.com/kendryte/k230_sdk (compatible "snps,dw-apb-uart").
+ *
+ * Copyright (c) 2026 zhenbaii <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef HW_K230_UART_H
+#define HW_K230_UART_H
+
+#include "hw/core/sysbus.h"
+#include "chardev/char-fe.h"
+#include "hw/core/registerfields.h"
+#include "qom/object.h"
+
+REG32(RBR_DLL_THR, 0x00)
+REG32(IER_DLH, 0x04)
+REG32(IER, 0x04)
+ FIELD(IER, ERBFI, 0, 1)
+ FIELD(IER, ETBEI, 1, 1)
+ FIELD(IER, ELSI, 2, 1)
+ FIELD(IER, EDSSI, 3, 1)
+ FIELD(IER, ELCOLR, 4, 1)
+ FIELD(IER, PTIME, 7, 1)
+REG32(FCR, 0x08)
+ FIELD(FCR, FIFOE, 0, 1)
+ FIELD(FCR, RFIFOR, 1, 1)
+ FIELD(FCR, XFIFOR, 2, 1)
+ FIELD(FCR, DMAM, 3, 1)
+ FIELD(FCR, TET, 4, 2)
+ FIELD(FCR, RT, 6, 2)
+REG32(IIR, 0x08)
+ FIELD(IIR, IID, 0, 4)
+ FIELD(IIR, FIFOSE, 6, 2)
+REG32(LCR, 0x0c)
+ FIELD(LCR, DLS, 0, 2)
+ FIELD(LCR, STOP, 2, 1)
+ FIELD(LCR, PEN, 3, 1)
+ FIELD(LCR, EPS, 4, 1)
+ FIELD(LCR, SP, 5, 1)
+ FIELD(LCR, BC, 6, 1)
+ FIELD(LCR, DLAB, 7, 1)
+REG32(MCR, 0x10)
+ FIELD(MCR, DTR, 0, 1)
+ FIELD(MCR, RTS, 1, 1)
+ FIELD(MCR, OUT1, 2, 1)
+ FIELD(MCR, OUT2, 3, 1)
+ FIELD(MCR, LOOPBACK, 4, 1)
+ FIELD(MCR, AFCE, 5, 1)
+ FIELD(MCR, SIRE, 6, 1)
+REG32(LSR, 0x14)
+ FIELD(LSR, DR, 0, 1)
+ FIELD(LSR, OE, 1, 1)
+ FIELD(LSR, PE, 2, 1)
+ FIELD(LSR, FE, 3, 1)
+ FIELD(LSR, BI, 4, 1)
+ FIELD(LSR, THRE, 5, 1)
+ FIELD(LSR, TEMT, 6, 1)
+ FIELD(LSR, RFE, 7, 1)
+ FIELD(LSR, ADDR_RSVD, 8, 1)
+REG32(MSR, 0x18)
+ FIELD(MSR, DCTS, 0, 1)
+ FIELD(MSR, DDSR, 1, 1)
+ FIELD(MSR, TERI, 2, 1)
+ FIELD(MSR, DDCD, 3, 1)
+ FIELD(MSR, CTS, 4, 1)
+ FIELD(MSR, DSR, 5, 1)
+ FIELD(MSR, RI, 6, 1)
+ FIELD(MSR, DCD, 7, 1)
+REG32(RFW, 0x78)
+ FIELD(RFW, RFWD, 0, 8)
+ FIELD(RFW, RFPE, 8, 1)
+ FIELD(RFW, RFFE, 9, 1)
+REG32(USR, 0x7c)
+ FIELD(USR, BUSY, 0, 1)
+ FIELD(USR, TFNF, 1, 1)
+ FIELD(USR, TFE, 2, 1)
+ FIELD(USR, RFNE, 3, 1)
+ FIELD(USR, RFF, 4, 1)
+REG32(TFL, 0x80)
+ FIELD(TFL, TFL, 0, 5)
+REG32(RFL, 0x84)
+ FIELD(RFL, RFL, 0, 5)
+REG32(SRR, 0x88)
+ FIELD(SRR, UR, 0, 1)
+ FIELD(SRR, RFR, 1, 1)
+ FIELD(SRR, XFR, 2, 1)
+REG32(SRTS, 0x8c)
+ FIELD(SRTS, SRTS, 0, 1)
+REG32(SBCR, 0x90)
+ FIELD(SBCR, SBCB, 0, 1)
+REG32(SDMAM, 0x94)
+ FIELD(SDMAM, SDMAM, 0, 1)
+REG32(SFE, 0x98)
+ FIELD(SFE, SFE, 0, 1)
+REG32(SRT, 0x9c)
+ FIELD(SRT, SRT, 0, 2)
+REG32(STET, 0xa0)
+ FIELD(STET, STET, 0, 2)
+REG32(HTX, 0xa4)
+ FIELD(HTX, HTX, 0, 1)
+REG32(TCR, 0xac)
+ FIELD(TCR, RS485_EN, 0, 1)
+ FIELD(TCR, RE_POL, 1, 1)
+ FIELD(TCR, DE_POL, 2, 1)
+ FIELD(TCR, XFER_MODE, 3, 2)
+REG32(SCR, 0x1c)
+REG32(DLF, 0xc0)
+REG32(CPR, 0xf4)
+REG32(UCV, 0xf8)
+REG32(CTR, 0xfc)
+
+/* peripheral ID 0x44570110 ("DW\x01\x10"). Read-only. */
+#define K230_UART_CTR_VALUE 0x44570110u
+#define K230_UART_16550_COMPATIBLE 0
+#define K230_UART_FIFO_DEPTH 32
+
+/* CPR */
+#define K230_UART_APB_DATA_WIDTH 2 /* CPR[1:0] - 32-bit APB */
+#define K230_UART_AFCE_MODE 0 /* CPR[4] - not implemented */
+#define K230_UART_THRE_MODE 1 /* CPR[5] - implemented */
+#define K230_UART_SIR_MODE 0 /* CPR[6] - not implemented */
+#define K230_UART_SIR_LP_MODE 0 /* CPR[7] - not implemented */
+#define K230_UART_ADDITIONAL_FEATURES 1 /* CPR[8] - UCV/CTR present */
+#define K230_UART_FIFO_ACCESS 0 /* CPR[9] - not implemented */
+#define K230_UART_FIFO_STAT 1 /* CPR[10] - TFL/RFL present */
+#define K230_UART_SHADOW 1 /* CPR[11] - shadow regs */
+#define K230_UART_ADD_ENCODED_PARAMS 1 /* CPR[12] - CPR present */
+#define K230_UART_DMA_EXTRA 0 /* CPR[13] - not implemented */
+#define K230_UART_FIFO_MODE 0x2 /* CPR[23:16] - 32-byte FIFO */
+
+#define TYPE_K230_UART "k230-uart"
+OBJECT_DECLARE_SIMPLE_TYPE(K230UartState, K230_UART)
+struct K230UartState {
+ SysBusDevice parent_obj;
+ MemoryRegion mmio;
+
+ /* Standard 16550 registers */
+ uint8_t dll; /* Divisor Latch Low, offset 0x00 */
+ uint8_t ier; /* Interrupt Enable, offset 0x04 */
+ uint8_t dlh; /* Divisor Latch High, offset 0x04 */
+ uint8_t fcr; /* FIFO Control, offset 0x08 */
+ uint8_t iir; /* Interrupt Identification, offset 0x08 */
+ uint8_t lcr; /* Line Control, offset 0x0c */
+ uint8_t mcr; /* Modem Control, offset 0x10 */
+ uint8_t lsr; /* Line Status, offset 0x14 */
+ uint8_t msr; /* Modem Status, offset 0x18 */
+ uint8_t scr; /* Scratchpad, offset 0x1c */
+
+ /* DesignWare-specific registers */
+ uint8_t usr; /* UART Status, offset 0x7c */
+ uint8_t htx; /* Halt TX, offset 0xa4 */
+
+ /* Internal interrupt state. */
+ uint8_t thr_ipending; /* THR empty (IID=0x2) pending */
+ uint8_t timeout_ipending; /* RX FIFO timeout (IID=0xc) */
+ uint8_t busy_ipending; /* busy detect (IID=0x7) pending */
+
+ /* FIFO */
+ uint16_t rx_fifo[K230_UART_FIFO_DEPTH];
+ uint32_t rx_head, rx_tail, rx_count;
+ uint16_t tx_fifo[K230_UART_FIFO_DEPTH];
+ uint32_t tx_head, tx_tail, tx_count;
+
+ uint64_t char_transmit_time;
+
+ CharFrontend chr;
+ qemu_irq irq;
+ QEMUTimer rx_timeout;
+};
+
+#endif
--
2.48.1
