Re: [PATCH v2 1/6] hw/gpio/aspeed_sgpio: Add basic device model for Aspeed SGPIO

["Cédric Le Goater" <clg@kaod.org>]

On 12/9/25 01:01, Yubin Zou wrote:
> This initial implementation includes the basic device structure,
> memory-mapped register definitions, and read/write handlers for the
> SGPIO control registers.
> 
> Signed-off-by: Yubin Zou <yubinz@google.com>
> ---
>   hw/gpio/aspeed_sgpio.c         | 154 +++++++++++++++++++++++++++++++++++++++++
>   hw/gpio/meson.build            |   1 +
>   include/hw/gpio/aspeed_sgpio.h |  66 ++++++++++++++++++
>   3 files changed, 221 insertions(+)

Please add to your .git/config :

   [diff]
     orderFile = /path/to/qemu/scripts/git.orderfile

It is easier to review if the changes in header files are first.


> diff --git a/hw/gpio/aspeed_sgpio.c b/hw/gpio/aspeed_sgpio.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..8676fa7ced134f1f62dc9e30b42c5fe6db3de268
> --- /dev/null
> +++ b/hw/gpio/aspeed_sgpio.c
> @@ -0,0 +1,154 @@
> +/*
> + * ASPEED Serial GPIO Controller
> + *
> + * Copyright 2025 Google LLC.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/host-utils.h"
> +#include "qemu/log.h"
> +#include "qemu/error-report.h"
> +#include "qapi/error.h"
> +#include "qapi/visitor.h"
> +#include "hw/qdev-properties.h"
> +#include "hw/gpio/aspeed_sgpio.h"
> +
> +static uint64_t aspeed_sgpio_2700_read_int_status_reg(AspeedSGPIOState *s,
> +                                uint32_t reg)
> +{
> +    return 0;
> +}
> +
> +static uint64_t aspeed_sgpio_2700_read_control_reg(AspeedSGPIOState *s,
> +                                uint32_t reg)
> +{
> +    AspeedSGPIOClass *agc = ASPEED_SGPIO_GET_CLASS(s);
> +    uint32_t idx = reg - R_SGPIO_0_CONTROL;
> +    if (idx >= agc->nr_sgpio_pin_pairs) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: pin index: %d, out of bounds\n",
> +                      __func__, idx);
> +        return 0;
> +    }
> +    return s->ctrl_regs[idx];
> +}
> +
> +static void aspeed_sgpio_2700_write_control_reg(AspeedSGPIOState *s,
> +                                uint32_t reg, uint64_t data)
> +{
> +    AspeedSGPIOClass *agc = ASPEED_SGPIO_GET_CLASS(s);
> +    uint32_t idx = reg - R_SGPIO_0_CONTROL;
> +    if (idx >= agc->nr_sgpio_pin_pairs) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: pin index: %d, out of bounds\n",
> +                      __func__, idx);
> +        return;
> +    }
> +    s->ctrl_regs[idx] = data;
> +}
> +
> +static uint64_t aspeed_sgpio_2700_read(void *opaque, hwaddr offset,
> +                                uint32_t size)
> +{
> +    AspeedSGPIOState *s = ASPEED_SGPIO(opaque);
> +    uint64_t value = 0;
> +    uint64_t reg;
> +
> +    reg = offset >> 2;
> +
> +    switch (reg) {
> +    case R_SGPIO_INT_STATUS_0 ... R_SGPIO_INT_STATUS_7:
> +        aspeed_sgpio_2700_read_int_status_reg(s, reg);
> +        break;
> +    case R_SGPIO_0_CONTROL ... R_SGPIO_255_CONTROL:
> +        value = aspeed_sgpio_2700_read_control_reg(s, reg);
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: no getter for offset 0x%"
> +                      PRIx64"\n", __func__, offset);
> +        return 0;
> +    }
> +
> +    return value;
> +}
> +
> +static void aspeed_sgpio_2700_write(void *opaque, hwaddr offset, uint64_t data,
> +                                uint32_t size)
> +{
> +    AspeedSGPIOState *s = ASPEED_SGPIO(opaque);
> +    uint64_t reg;
> +
> +    reg = offset >> 2;
> +
> +    switch (reg) {
> +    case R_SGPIO_0_CONTROL ... R_SGPIO_255_CONTROL:
> +        aspeed_sgpio_2700_write_control_reg(s, reg, data);
> +        break;
> +    default:
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: no setter for offset 0x%"
> +                      PRIx64"\n", __func__, offset);
> +        return;
> +    }
> +}
> +
> +static const MemoryRegionOps aspeed_gpio_2700_ops = {
> +  .read       = aspeed_sgpio_2700_read,
> +  .write      = aspeed_sgpio_2700_write,
> +  .endianness = DEVICE_LITTLE_ENDIAN,
> +  .valid.min_access_size = 4,
> +  .valid.max_access_size = 4,
> +};
> +
> +static void aspeed_sgpio_realize(DeviceState *dev, Error **errp)
> +{
> +    AspeedSGPIOState *s = ASPEED_SGPIO(dev);
> +    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
> +    AspeedSGPIOClass *agc = ASPEED_SGPIO_GET_CLASS(s);
> +
> +    /* Interrupt parent line */
> +    sysbus_init_irq(sbd, &s->irq);
> +
> +    memory_region_init_io(&s->iomem, OBJECT(s), agc->reg_ops, s,
> +                          TYPE_ASPEED_SGPIO, agc->mem_size);
> +
> +    sysbus_init_mmio(sbd, &s->iomem);
> +}
> +
> +static void aspeed_sgpio_class_init(ObjectClass *klass, const void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->realize = aspeed_sgpio_realize;
> +    dc->desc = "Aspeed SGPIO Controller";
> +}
> +
> +static void aspeed_sgpio_2700_class_init(ObjectClass *klass, const void *data)
> +{
> +    AspeedSGPIOClass *agc = ASPEED_SGPIO_CLASS(klass);
> +    agc->nr_sgpio_pin_pairs = 256;
> +    agc->mem_size = 0x1000;
> +    agc->reg_ops = &aspeed_gpio_2700_ops;
> +}
> +
> +static const TypeInfo aspeed_sgpio_info = {
> +    .name           = TYPE_ASPEED_SGPIO,
> +    .parent         = TYPE_SYS_BUS_DEVICE,
> +    .instance_size  = sizeof(AspeedSGPIOState),
> +    .class_size     = sizeof(AspeedSGPIOClass),
> +    .class_init     = aspeed_sgpio_class_init,
> +    .abstract       = true,
> +};
> +
> +static const TypeInfo aspeed_sgpio_ast2700_info = {
> +  .name           = TYPE_ASPEED_SGPIO "-ast2700",
> +  .parent         = TYPE_ASPEED_SGPIO,
> +  .class_init     = aspeed_sgpio_2700_class_init,
> +};
> +
> +static void aspeed_sgpio_register_types(void)
> +{
> +    type_register_static(&aspeed_sgpio_info);
> +    type_register_static(&aspeed_sgpio_ast2700_info);
> +}
> +
> +type_init(aspeed_sgpio_register_types);
> diff --git a/hw/gpio/meson.build b/hw/gpio/meson.build
> index 74840619c01bf4d9a02c058c434c3ec9d2a55bee..6a67ee958faace69ffd3fe08e8ade31ced0faf7e 100644
> --- a/hw/gpio/meson.build
> +++ b/hw/gpio/meson.build
> @@ -16,5 +16,6 @@ system_ss.add(when: 'CONFIG_RASPI', if_true: files(
>   ))
>   system_ss.add(when: 'CONFIG_STM32L4X5_SOC', if_true: files('stm32l4x5_gpio.c'))
>   system_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: files('aspeed_gpio.c'))
> +system_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: files('aspeed_sgpio.c'))
>   system_ss.add(when: 'CONFIG_SIFIVE_GPIO', if_true: files('sifive_gpio.c'))
>   system_ss.add(when: 'CONFIG_PCF8574', if_true: files('pcf8574.c'))
> diff --git a/include/hw/gpio/aspeed_sgpio.h b/include/hw/gpio/aspeed_sgpio.h
> new file mode 100644
> index 0000000000000000000000000000000000000000..ffdc54a112da8962a7bc5773d524f1d86eb85d39
> --- /dev/null
> +++ b/include/hw/gpio/aspeed_sgpio.h
> @@ -0,0 +1,66 @@
> +/*
> + * ASPEED Serial GPIO Controller
> + *
> + * Copyright 2025 Google LLC.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +#ifndef ASPEED_SGPIO_H
> +#define ASPEED_SGPIO_H
> +
> +#include "hw/sysbus.h"
> +#include "qom/object.h"
> +#include "hw/registerfields.h"
> +
> +#define TYPE_ASPEED_SGPIO "aspeed.sgpio"
> +OBJECT_DECLARE_TYPE(AspeedSGPIOState, AspeedSGPIOClass, ASPEED_SGPIO)
> +
> +#define ASPEED_SGPIO_MAX_PIN_PAIR 256
> +#define ASPEED_SGPIO_MAX_INT 8
> +
> +/* AST2700 SGPIO Register Address Offsets */
> +REG32(SGPIO_INT_STATUS_0, 0x40)
> +REG32(SGPIO_INT_STATUS_1, 0x44)
> +REG32(SGPIO_INT_STATUS_2, 0x48)
> +REG32(SGPIO_INT_STATUS_3, 0x4C)
> +REG32(SGPIO_INT_STATUS_4, 0x50)
> +REG32(SGPIO_INT_STATUS_5, 0x54)
> +REG32(SGPIO_INT_STATUS_6, 0x58)
> +REG32(SGPIO_INT_STATUS_7, 0x5C)
> +/* AST2700 SGPIO_0 - SGPIO_255 Control Register */
> +REG32(SGPIO_0_CONTROL, 0x80)
> +    SHARED_FIELD(SGPIO_SERIAL_OUT_VAL, 0, 1)
> +    SHARED_FIELD(SGPIO_PARALLEL_OUT_VAL, 1, 1)
> +    SHARED_FIELD(SGPIO_INT_EN, 2, 1)
> +    SHARED_FIELD(SGPIO_INT_TYPE, 3, 3)
> +    SHARED_FIELD(SGPIO_RESET_POLARITY, 6, 1)
> +    SHARED_FIELD(SGPIO_RESERVED_1, 7, 2)
> +    SHARED_FIELD(SGPIO_INPUT_MASK, 9, 1)
> +    SHARED_FIELD(SGPIO_PARALLEL_EN, 10, 1)
> +    SHARED_FIELD(SGPIO_PARALLEL_IN_MODE, 11, 1)
> +    SHARED_FIELD(SGPIO_INT_STATUS, 12, 1)
> +    SHARED_FIELD(SGPIO_SERIAL_IN_VAL, 13, 1)
> +    SHARED_FIELD(SGPIO_PARALLEL_IN_VAL, 14, 1)
> +    SHARED_FIELD(SGPIO_RESERVED_2, 15, 12)
> +    SHARED_FIELD(SGPIO_WRITE_PROTECT, 31, 1)
> +REG32(SGPIO_255_CONTROL, 0x47C)
> +
> +struct AspeedSGPIOClass {
> +    SysBusDevice parent_obj;
> +    uint32_t nr_sgpio_pin_pairs;
> +    uint64_t mem_size;
> +    const MemoryRegionOps *reg_ops;
> +};


I don't see any need of an AspeedSGPIOClass for now. Do you have plans
for future models ?

Thanks,

C.


> +
> +struct AspeedSGPIOState {
> +  /* <private> */
> +  SysBusDevice parent;
> +
> +  /*< public >*/
> +  MemoryRegion iomem;
> +  qemu_irq irq;
> +  uint32_t ctrl_regs[ASPEED_SGPIO_MAX_PIN_PAIR];
> +  uint32_t int_regs[ASPEED_SGPIO_MAX_INT];
> +};
> +
> +#endif /* ASPEED_SGPIO_H */
>