[PATCH] lib: utils/reset: Add litex SoC reset driver

[Anup Patel]

On Fri, May 29, 2026 at 3:03 PM Inochi Amaoto <inochiama at gmail.com> wrote:
>
> Litex SoC controller supports reboot function by toggling the first
> bit of the ctrl register. Add a reset driver so other software can
> use it.
>
> Signed-off-by: Inochi Amaoto <inochiama at gmail.com>

LGTM.

Reviewed-by: Anup Patel <anup at brainfault.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

> ---
>  lib/utils/reset/Kconfig            |  5 +++
>  lib/utils/reset/fdt_reset_litex.c  | 66 ++++++++++++++++++++++++++++++
>  lib/utils/reset/objects.mk         |  3 ++
>  platform/generic/configs/defconfig |  1 +
>  4 files changed, 75 insertions(+)
>  create mode 100644 lib/utils/reset/fdt_reset_litex.c
>
> diff --git a/lib/utils/reset/Kconfig b/lib/utils/reset/Kconfig
> index f98926e5..b2ac120e 100644
> --- a/lib/utils/reset/Kconfig
> +++ b/lib/utils/reset/Kconfig
> @@ -24,6 +24,11 @@ config FDT_RESET_HTIF
>         select SYS_HTIF
>         default n
>
> +config FDT_RESET_LITEX
> +       bool "LITEX SoC reset driver"
> +       depends on FDT_GPIO
> +       default n
> +
>  config FDT_RESET_RPMI
>         bool "RPMI FDT reset driver"
>         depends on FDT_MAILBOX && RPMI_MAILBOX
> diff --git a/lib/utils/reset/fdt_reset_litex.c b/lib/utils/reset/fdt_reset_litex.c
> new file mode 100644
> index 00000000..287745f0
> --- /dev/null
> +++ b/lib/utils/reset/fdt_reset_litex.c
> @@ -0,0 +1,66 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2026 Inochi Amaoto <inochiama at gmail.com>
> + */
> +
> +#include <libfdt.h>
> +#include <sbi/riscv_io.h>
> +#include <sbi/sbi_error.h>
> +#include <sbi/sbi_system.h>
> +#include <sbi_utils/fdt/fdt_driver.h>
> +#include <sbi_utils/fdt/fdt_helper.h>
> +
> +#define RESET_CTRL                     0x0
> +
> +static volatile u32 *litex_soc_base;
> +
> +static int litex_reset_check(u32 type, u32 reason)
> +{
> +       switch (type) {
> +       case SBI_SRST_RESET_TYPE_COLD_REBOOT:
> +       case SBI_SRST_RESET_TYPE_WARM_REBOOT:
> +               return 255;
> +       }
> +
> +       return 0;
> +}
> +
> +static void litex_do_reset(u32 type, u32 reason)
> +{
> +       writel_relaxed(0x1, litex_soc_base + RESET_CTRL);
> +}
> +
> +static struct sbi_system_reset_device litex_reset = {
> +       .name = "litex-reset",
> +       .system_reset_check = litex_reset_check,
> +       .system_reset = litex_do_reset
> +};
> +
> +static int litex_reset_init(const void *fdt, int nodeoff,
> +                           const struct fdt_match *match)
> +{
> +       uint64_t reg_addr;
> +       int rc;
> +
> +       rc = fdt_get_node_addr_size(fdt, nodeoff, 0, &reg_addr, NULL);
> +       if (rc < 0 || !reg_addr)
> +               return SBI_ENODEV;
> +
> +
> +       litex_soc_base = (volatile u32 *)(unsigned long)reg_addr;
> +
> +       sbi_system_reset_add_device(&litex_reset);
> +
> +       return 0;
> +}
> +
> +static const struct fdt_match litex_reset_match[] = {
> +       { .compatible = "litex,soc-controller" },
> +       { },
> +};
> +
> +const struct fdt_driver fdt_reset_litex = {
> +       .match_table = litex_reset_match,
> +       .init = litex_reset_init,
> +};
> diff --git a/lib/utils/reset/objects.mk b/lib/utils/reset/objects.mk
> index 3c681c27..38b4e306 100644
> --- a/lib/utils/reset/objects.mk
> +++ b/lib/utils/reset/objects.mk
> @@ -17,6 +17,9 @@ libsbiutils-objs-$(CONFIG_FDT_RESET_GPIO) += reset/fdt_reset_gpio.o
>  carray-fdt_early_drivers-$(CONFIG_FDT_RESET_HTIF) += fdt_reset_htif
>  libsbiutils-objs-$(CONFIG_FDT_RESET_HTIF) += reset/fdt_reset_htif.o
>
> +carray-fdt_early_drivers-$(CONFIG_FDT_RESET_LITEX) += fdt_reset_litex
> +libsbiutils-objs-$(CONFIG_FDT_RESET_LITEX) += reset/fdt_reset_litex.o
> +
>  carray-fdt_early_drivers-$(CONFIG_FDT_RESET_SG2042_HWMON_MCU) += fdt_reset_sg2042_mcu
>  libsbiutils-objs-$(CONFIG_FDT_RESET_SG2042_HWMON_MCU) += reset/fdt_reset_sg2042_hwmon_mcu.o
>
> diff --git a/platform/generic/configs/defconfig b/platform/generic/configs/defconfig
> index 818b71f4..969639e3 100644
> --- a/platform/generic/configs/defconfig
> +++ b/platform/generic/configs/defconfig
> @@ -49,6 +49,7 @@ CONFIG_FDT_REGMAP_SYSCON=y
>  CONFIG_FDT_RESET=y
>  CONFIG_FDT_RESET_ATCWDT200=y
>  CONFIG_FDT_RESET_GPIO=y
> +CONFIG_FDT_RESET_LITEX=y
>  CONFIG_FDT_RESET_HTIF=y
>  CONFIG_FDT_RESET_RPMI=y
>  CONFIG_FDT_RESET_SG2042_HWMON_MCU=y
> --
> 2.54.0
>
>
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