Re: [PATCH v3 1/3] hw/char: add K230 DW 8250-compatible UART
Daniel Henrique Barboza <[email protected]>
| Newsgroups | gmane.comp.emulators.qemu |
|---|---|
| Message-ID | <[email protected]> |
On 8/7/2026 11:32 PM, WX Chen wrote: > 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: WX Chen <[email protected]> > --- Reviewed-by: Daniel Henrique Barboza <[email protected]> > hw/char/Kconfig | 3 + > hw/char/k230_uart.c | 816 ++++++++++++++++++++++++++++++++++++++++++++ > hw/char/meson.build | 1 + > include/hw/char/k230_uart.h | 198 +++++++++++ > 4 files changed, 1018 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..7d83a04aaf3129f2908ea97adb805cfca9f13095 > --- /dev/null > +++ b/hw/char/k230_uart.c > @@ -0,0 +1,816 @@ > +/* > + * K230 UART > + * > + * Copyright (c) 2026 WX Chen <[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 bool k230_uart_rx_line_status_int(const K230UartState *s) > +{ > + return 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)); > +} > + > +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 (k230_uart_rx_line_status_int(s)) { > + 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 (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); > + } > + > + 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_is_busy(s)) { > + s->usr = FIELD_DP32(s->usr, USR, BUSY, 1); > + } > + 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); > +} > + > +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 (k230_uart_rx_line_status_int(s)) { > + /* 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_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_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_R_CPR; > + break; > + case R_UCV: > + ret = K230_UART_R_UCV; > + 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_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_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)); > + s->ier = FIELD_DP32(s->ier, IER, PTIME, > + FIELD_EX32(val, IER, PTIME)); > + 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)); > + s->fcr = FIELD_DP32(s->fcr, FCR, TET, > + FIELD_EX32(val, FCR, TET)); > + 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: > + /* > + * 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_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_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: > + s->fcr = FIELD_DP32(s->fcr, FCR, TET, val & 0x3); > + 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..049dcd341d3e81c861ce50bf68195d3c0e12cb40 > --- /dev/null > +++ b/include/hw/char/k230_uart.h > @@ -0,0 +1,198 @@ > +/* > + * 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 WX Chen <[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 */ > + > +/* CPR read-only value, assembled from the fields above. */ > +#define K230_UART_R_CPR \ > + ((uint32_t)(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)) > + > +/* UCV: ASCII "4.0a" = 0x34 0x2e 0x30 0x61 */ > +#define K230_UART_R_UCV 0x342e3061u > + > +#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 >