Add the dw8250 uart support. This hardware is a widely used 16550A derivative that includes additional registers.
Without this specific device support, the Linux 8250_dw driver fails to probe the extended registers (UCV, CPR, etc.), which are essential for correct feature detection: [ 0.293566] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled [ 0.306929] Oops - store (or AMO) access fault [#1] [ 0.307020] Modules linked in: [ 0.307192] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.0.0 #1 PREEMPTLAZY [ 0.307250] Hardware name: Milk-V Duo (DT) [ 0.307294] epc : dw8250_setup_port+0x22/0x520 [ 0.307504] ra : dw8250_probe+0x57e/0x5b8 [ 0.307518] epc : ffffffff80708dd6 ra : ffffffff8070a49e sp : ffffffc60000b820 [ 0.307525] gp : ffffffff81a32ba8 tp : ffffffd602180cc0 t0 : 0000000000000073 [ 0.307533] t1 : 000000000000006c t2 : 0000000000000000 s0 : ffffffc60000b830 [ 0.307539] s1 : ffffffd6028c8640 a0 : ffffffc60000b848 a1 : ffffffff813162c1 [ 0.307546] a2 : ffffffff813162c0 a3 : ffffffd6028c8640 a4 : ffffffc60002d0b4 [ 0.307552] a5 : 0000000000000001 a6 : 0000000000000094 a7 : 0000000000000060 [ 0.307558] s2 : ffffffd60225d410 s3 : ffffffd60225d400 s4 : 0000000000000000 [ 0.307573] s5 : ffffffff80e31a48 s6 : 0000000000000008 s7 : 0000000000000000 [ 0.307584] s8 : 0000000000000149 s9 : 0000000000000000 s10: 0000000000000000 [ 0.307590] s11: 0000000000000000 t3 : ffffffd602007c00 t4 : ffffffff81601540 [ 0.307604] t5 : 0000000000000003 t6 : ffffffd602a42f82 ssp : 0000000000000000 [ 0.307611] status: 0000000200000120 badaddr: ffffffc60002d0b4 cause: 0000000000000007 [ 0.307652] [<ffffffff80708dd6>] dw8250_setup_port+0x22/0x520 [ 0.307695] [<ffffffff8070a49e>] dw8250_probe+0x57e/0x5b8 [ 0.307702] [<ffffffff80731f0e>] platform_probe+0x46/0x80 [ 0.307708] [<ffffffff8072f67c>] really_probe+0x84/0x22c [ 0.307715] [<ffffffff8072f880>] __driver_probe_device+0x5c/0xd4 [ 0.307721] [<ffffffff8072f9be>] driver_probe_device+0x2e/0xf4 [ 0.307727] [<ffffffff8072fbe6>] __driver_attach+0x6e/0x14c [ 0.307734] [<ffffffff8072d5f0>] bus_for_each_dev+0x60/0xb0 [ 0.307740] [<ffffffff8072f1b2>] driver_attach+0x1a/0x24 [ 0.307746] [<ffffffff8072e8da>] bus_add_driver+0xca/0x1d8 [ 0.307752] [<ffffffff80730aaa>] driver_register+0x3e/0xdc [ 0.307757] [<ffffffff80731c54>] __platform_driver_register+0x1c/0x24 [ 0.307779] [<ffffffff80c334f6>] dw8250_platform_driver_init+0x1a/0x24 [ 0.307793] [<ffffffff80011992>] do_one_initcall+0x4e/0x2a4 [ 0.307800] [<ffffffff80c01362>] kernel_init_freeable+0x226/0x2b0 [ 0.307807] [<ffffffff80bc3798>] kernel_init+0x1c/0x144 [ 0.307813] [<ffffffff8001361c>] ret_from_fork_kernel+0x18/0x164 [ 0.307820] [<ffffffff80bcefb6>] ret_from_fork_kernel_asm+0x16/0x18 [ 0.307914] Code: 3683 2085 0b63 32f7 000f 0140 6918 4785 0713 0b47 (c31c) 2583 [ 0.308041] ---[ end trace 0000000000000000 ]--- [ 0.308180] Kernel panic - not syncing: Fatal exception in interrupt [ 0.315760] ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]--- Signed-off-by: Kuan-Wei Chiu <[email protected]> --- hw/char/Kconfig | 4 ++ hw/char/dw8250.c | 118 +++++++++++++++++++++++++++++++++++++++ hw/char/meson.build | 1 + include/hw/char/dw8250.h | 27 +++++++++ 4 files changed, 150 insertions(+) create mode 100644 hw/char/dw8250.c create mode 100644 include/hw/char/dw8250.h diff --git a/hw/char/Kconfig b/hw/char/Kconfig index 020c0a84bb..418d99b757 100644 --- a/hw/char/Kconfig +++ b/hw/char/Kconfig @@ -95,3 +95,7 @@ config IP_OCTAL_232 bool default y depends on IPACK + +config DW8250 + bool + select SERIAL diff --git a/hw/char/dw8250.c b/hw/char/dw8250.c new file mode 100644 index 0000000000..4ec829ceaf --- /dev/null +++ b/hw/char/dw8250.c @@ -0,0 +1,118 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Synopsys DesignWare APB UART (DW 8250) + * + * Copyright (c) 2026 Kuan-Wei Chiu <[email protected]> + */ + +#include "qemu/osdep.h" +#include "qapi/error.h" +#include "hw/char/dw8250.h" +#include "hw/core/qdev-properties.h" +#include "hw/core/qdev-properties-system.h" + +#define DW_UART_REGION_SIZE 0x100 + +#define DW_UART_RE_EN 0xB4 /* Receiver Output Enable Register */ +#define DW_UART_DLF 0xC0 /* Divisor Latch Fraction Register */ +#define DW_UART_CPR 0xF4 /* Component Parameter Register */ +#define DW_UART_UCV 0xF8 /* UART Component Version */ +#define DW_UART_CTR 0xFC /* Component Type Register */ + +#define DW_UART_UCV_VALUE 0x3332332A /* "323*" -> v3.23a */ +#define DW_UART_CTR_VALUE 0x44570110 /* "DW" */ + +static uint64_t dw8250_ext_read(void *opaque, hwaddr addr, unsigned int size) +{ + switch (addr) { + case DW_UART_UCV: + return DW_UART_UCV_VALUE; + case DW_UART_CPR: + return 0x00000000; /* No advanced features (DMA, extra FIFOs) */ + case DW_UART_CTR: + return DW_UART_CTR_VALUE; + + case DW_UART_RE_EN: + case DW_UART_DLF: + /* + * Return 0 to indicate these optional features + * (RS485 and Fractional Divisor) are not implemented. + */ + return 0x00000000; + + default: + return 0; + } +} + +static void dw8250_ext_write(void *opaque, hwaddr addr, uint64_t val, unsigned int size) +{ +} + +static const MemoryRegionOps dw8250_ext_ops = { + .read = dw8250_ext_read, + .write = dw8250_ext_write, + .endianness = DEVICE_LITTLE_ENDIAN, + .valid.min_access_size = 4, + .valid.max_access_size = 4, +}; + +static void dw8250_instance_init(Object *obj) +{ + DW8250State *s = DW8250(obj); + + s->serial_mm = qdev_new("serial-mm"); + object_property_add_child(obj, "serial-mm", OBJECT(s->serial_mm)); + object_property_add_alias(obj, "chardev", OBJECT(s->serial_mm), "chardev"); +} + +static void dw8250_realize(DeviceState *dev, Error **errp) +{ + DW8250State *s = DW8250(dev); + SysBusDevice *sbd = SYS_BUS_DEVICE(dev); + SysBusDevice *serial_sbd = SYS_BUS_DEVICE(s->serial_mm); + + memory_region_init(&s->container, OBJECT(dev), "dw8250-container", + DW_UART_REGION_SIZE); + sysbus_init_mmio(sbd, &s->container); + + qdev_prop_set_uint8(s->serial_mm, "regshift", s->regshift); + qdev_prop_set_uint8(s->serial_mm, "endianness", DEVICE_LITTLE_ENDIAN); + sysbus_realize(serial_sbd, errp); + + memory_region_init_io(&s->ext_iomem, OBJECT(dev), &dw8250_ext_ops, s, + "dw8250-ext", DW_UART_REGION_SIZE); + memory_region_add_subregion(&s->container, 0, &s->ext_iomem); + + memory_region_add_subregion_overlap(&s->container, 0, + sysbus_mmio_get_region(serial_sbd, 0), 1); + + sysbus_pass_irq(sbd, serial_sbd); +} + +static const Property dw8250_properties[] = { + DEFINE_PROP_UINT8("regshift", DW8250State, regshift, 2), +}; + +static void dw8250_class_init(ObjectClass *klass, const void *data) +{ + DeviceClass *dc = DEVICE_CLASS(klass); + + dc->realize = dw8250_realize; + device_class_set_props(dc, dw8250_properties); +} + +static const TypeInfo dw8250_info = { + .name = TYPE_DW8250, + .parent = TYPE_SYS_BUS_DEVICE, + .instance_size = sizeof(DW8250State), + .instance_init = dw8250_instance_init, + .class_init = dw8250_class_init, +}; + +static void dw8250_register_types(void) +{ + type_register_static(&dw8250_info); +} + +type_init(dw8250_register_types) diff --git a/hw/char/meson.build b/hw/char/meson.build index fc3d7ee506..b2250ee6ae 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_DW8250', if_true: files('dw8250.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/dw8250.h b/include/hw/char/dw8250.h new file mode 100644 index 0000000000..59396ad202 --- /dev/null +++ b/include/hw/char/dw8250.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Synopsys DesignWare APB UART (DW 8250) + * + * Copyright (c) 2026 Kuan-Wei Chiu <[email protected]> + */ + +#ifndef HW_CHAR_DW8250_H +#define HW_CHAR_DW8250_H + +#include "hw/core/sysbus.h" +#include "qom/object.h" + +#define TYPE_DW8250 "dw8250" +OBJECT_DECLARE_SIMPLE_TYPE(DW8250State, DW8250) + +struct DW8250State { + SysBusDevice parent_obj; + + MemoryRegion container; + MemoryRegion ext_iomem; + DeviceState *serial_mm; + + uint8_t regshift; +}; + +#endif -- 2.54.0.563.g4f69b47b94-goog
