Re: [PATCH v2 1/3] hw/misc/k230_iomux: add Kendryte K230 IOMUX model

On Tue, Jul 14, 2026 at 06:22:00PM +0800, Kangjie Huang wrote:
> Add a SysBus model for the 64 K230 Function IO configuration
> registers documented by the K230 Technical Reference Manual.
> 
> Preserve the writable configuration fields across aligned 32-bit
> accesses, apply the documented reset values, and ignore writes to
> read-only and reserved fields. Offsets outside the documented register
> list read as zero and ignore writes.
> 
> This provides the register behavior used by the Kendryte SDK U-Boot
> pinctrl-single driver and Linux IOMUX configuration code.
> 
> Signed-off-by: Kangjie Huang <[email protected]>
> ---
>  hw/misc/Kconfig              |   3 +
>  hw/misc/k230_iomux.c         | 124 +++++++++++++++++++++++++++++++++++
hw/misc/k230_iomux.c needs to be added to MAINTAINERS.

>  hw/misc/meson.build          |   2 +
>  hw/misc/trace-events         |   4 ++
>  include/hw/misc/k230_iomux.h |  34 ++++++++++
>  5 files changed, 167 insertions(+)
>  create mode 100644 hw/misc/k230_iomux.c
>  create mode 100644 include/hw/misc/k230_iomux.h
> 
> diff --git a/hw/misc/Kconfig b/hw/misc/Kconfig
> index 1543ee6653..573d24a9df 100644
> --- a/hw/misc/Kconfig
> +++ b/hw/misc/Kconfig
> @@ -257,4 +257,7 @@ config XLNX_VERSAL_TRNG
>  config XLNX_ZYNQ_DDRC
>      bool
>  
> +config K230_IOMUX
> +    bool
> +
>  source macio/Kconfig
> diff --git a/hw/misc/k230_iomux.c b/hw/misc/k230_iomux.c
> new file mode 100644
> index 0000000000..cc40dc8ae4
> --- /dev/null
> +++ b/hw/misc/k230_iomux.c
> @@ -0,0 +1,124 @@
> +/*
> + * Kendryte K230 IOMUX
> + *
> + * Copyright (c) 2026 Kangjie Huang <[email protected]>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * Provides the Function IO configuration registers documented by the K230
> + * Technical Reference Manual.
> + *
> + * 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
> + *
> + * For more information, see <https://www.kendryte.com/en/proDetail/230>
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/misc/k230_iomux.h"
> +#include "migration/vmstate.h"
> +#include "qemu/module.h"
> +#include "trace.h"
> +
> +/* TRM V0.3.1 section 12.9.2.1 Function IO register list. */
> +static const uint32_t k230_iomux_reset_values[K230_IOMUX_NUM_REGS] = {
> +    0x944, 0x944, 0x929, 0x908, 0x888, 0x908, 0x948, 0x890,
> +    0x890, 0x890, 0x910, 0x890, 0x890, 0x8a9, 0xa9e, 0xabf,
> +    0xb9e, 0xb9e, 0xb9e, 0xb9e, 0xb9e, 0xb9e, 0xb9e, 0xb9e,
> +    0xb1e, 0xa90, 0xabf, 0xb9e, 0xb9e, 0xb9e, 0xb9e, 0xb9e,
> +    0xbd0, 0xbd0, 0xbd0, 0xbd0, 0xbd0, 0xbd0, 0x890, 0x910,
> +    0x890, 0x910, 0x890, 0x910, 0x890, 0x910, 0x890, 0x910,
> +    0x890, 0x910, 0x890, 0x910, 0x890, 0x910, 0x89e, 0x89f,
> +    0x99e, 0x99e, 0x99e, 0x99e, 0x890, 0x890, 0x8a9, 0x8a9,
> +};
> +
> +static void k230_iomux_reset(DeviceState *dev)
> +{
> +    K230IomuxState *s = K230_IOMUX(dev);
> +
> +    memcpy(s->regs, k230_iomux_reset_values,
> +           sizeof(k230_iomux_reset_values));
> +}
> +
> +static uint64_t k230_iomux_read(void *opaque, hwaddr offset, unsigned size)
> +{
> +    K230IomuxState *s = K230_IOMUX(opaque);
> +    uint32_t value = 0;
> +
> +    if (offset < K230_IOMUX_REGS_SIZE) {
> +        value = s->regs[offset >> 2];
> +    }
> +
> +    trace_k230_iomux_read(offset, value);
> +    return value;
> +}
> +
> +static void k230_iomux_write(void *opaque, hwaddr offset,
> +                             uint64_t value, unsigned size)
> +{
> +    K230IomuxState *s = K230_IOMUX(opaque);
> +
> +    trace_k230_iomux_write(offset, value);
> +    if (offset < K230_IOMUX_REGS_SIZE) {
> +        s->regs[offset >> 2] = value & K230_IOMUX_WRITABLE_MASK;
According to the K230 Manual, Section 12.9.2.2, IOMUX register bit 31 (DI)
is a read-only field described as “Input data from outside the Chip to the PAD”:

  > bits: 31
  > Field Name: DI
  > Access: RO
  > Field Description: Input data from outside the Chip to the PAD

We don't need to simulate external input here, but I suggest adding a
comment explaining that this is set to zero.

I checked the K230 SDK and there are no dependencies on this part,
but from the standpoint of modeling completeness, it's worth noting.

Thanks,
Chao
> +    }
> +}
> +
> +static const MemoryRegionOps k230_iomux_ops = {
> +    .read = k230_iomux_read,
> +    .write = k230_iomux_write,
> +    .endianness = DEVICE_LITTLE_ENDIAN,
> +    .valid = {
> +        .min_access_size = 4,
> +        .max_access_size = 4,
> +        .unaligned = false,
> +    },
> +    .impl = {
> +        .min_access_size = 4,
> +        .max_access_size = 4,
> +        .unaligned = false,
> +    },
> +};
> +
> +static void k230_iomux_init(Object *obj)
> +{
> +    K230IomuxState *s = K230_IOMUX(obj);
> +
> +    memory_region_init_io(&s->mmio, obj, &k230_iomux_ops, s,
> +                          TYPE_K230_IOMUX, K230_IOMUX_MMIO_SIZE);
> +    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
> +}
> +
> +static const VMStateDescription vmstate_k230_iomux = {
> +    .name = "k230.iomux",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (const VMStateField[]) {
> +        VMSTATE_UINT32_ARRAY(regs, K230IomuxState, K230_IOMUX_NUM_REGS),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static void k230_iomux_class_init(ObjectClass *klass, const void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->desc = "Kendryte K230 IOMUX";
> +    dc->vmsd = &vmstate_k230_iomux;
> +    device_class_set_legacy_reset(dc, k230_iomux_reset);
> +}
> +
> +static const TypeInfo k230_iomux_info = {
> +    .name          = TYPE_K230_IOMUX,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(K230IomuxState),
> +    .instance_init = k230_iomux_init,
> +    .class_init    = k230_iomux_class_init,
> +};
> +
> +static void k230_iomux_register_types(void)
> +{
> +    type_register_static(&k230_iomux_info);
> +}
> +
> +type_init(k230_iomux_register_types)
> diff --git a/hw/misc/meson.build b/hw/misc/meson.build
> index 23265f6035..31e5145a35 100644
> --- a/hw/misc/meson.build
> +++ b/hw/misc/meson.build
> @@ -168,3 +168,5 @@ system_ss.add(when: 'CONFIG_SBSA_REF', if_true: files('sbsa_ec.c'))
>  
>  # HPPA devices
>  system_ss.add(when: 'CONFIG_LASI', if_true: files('lasi.c'))
> +
> +system_ss.add(when: 'CONFIG_K230_IOMUX', if_true: files('k230_iomux.c'))
> diff --git a/hw/misc/trace-events b/hw/misc/trace-events
> index c9a868b3ef..388967c9e1 100644
> --- a/hw/misc/trace-events
> +++ b/hw/misc/trace-events
> @@ -405,6 +405,10 @@ djmemc_write(int reg, uint64_t value, unsigned int size) "reg=0x%x value=0x%"PRI
>  iosb_read(int reg, uint64_t value, unsigned int size) "reg=0x%x value=0x%"PRIx64" size=%u"
>  iosb_write(int reg, uint64_t value, unsigned int size) "reg=0x%x value=0x%"PRIx64" size=%u"
>  
> +# k230_iomux.c
> +k230_iomux_read(uint64_t offset, uint32_t value) "offset=0x%" PRIx64 " value=0x%" PRIx32
> +k230_iomux_write(uint64_t offset, uint64_t value) "offset=0x%" PRIx64 " value=0x%" PRIx64
> +
>  # aspeed_sli.c
>  aspeed_sli_write(uint64_t offset, unsigned int size, uint32_t data) "To 0x%" PRIx64 " of size %u: 0x%" PRIx32
>  aspeed_sli_read(uint64_t offset, unsigned int size, uint32_t data) "To 0x%" PRIx64 " of size %u: 0x%" PRIx32
> diff --git a/include/hw/misc/k230_iomux.h b/include/hw/misc/k230_iomux.h
> new file mode 100644
> index 0000000000..15a16ef4de
> --- /dev/null
> +++ b/include/hw/misc/k230_iomux.h
> @@ -0,0 +1,34 @@
> +/*
> + * Kendryte K230 IOMUX
> + *
> + * 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
> + *
> + * Copyright (c) 2026 Kangjie Huang <[email protected]>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#ifndef HW_MISC_K230_IOMUX_H
> +#define HW_MISC_K230_IOMUX_H
> +
> +#include "hw/core/sysbus.h"
> +#include "qom/object.h"
> +
> +#define TYPE_K230_IOMUX "riscv.k230.iomux"
> +OBJECT_DECLARE_SIMPLE_TYPE(K230IomuxState, K230_IOMUX)
> +
> +#define K230_IOMUX_MMIO_SIZE 0x800
> +#define K230_IOMUX_NUM_REGS 64
> +#define K230_IOMUX_REGS_SIZE \
> +    (K230_IOMUX_NUM_REGS * sizeof(uint32_t))
> +#define K230_IOMUX_WRITABLE_MASK 0x00003fff
> +
> +struct K230IomuxState {
> +    SysBusDevice parent_obj;
> +
> +    MemoryRegion mmio;
> +    uint32_t regs[K230_IOMUX_NUM_REGS];
> +};
> +
> +#endif /* HW_MISC_K230_IOMUX_H */
> -- 
> 2.43.0
>