Re: [PATCH] sysreset: esp32: add driver for esp32 series chips

[Yao Zi <me@ziyao.cc>]

On Sun, Jul 12, 2026 at 03:48:16PM +0800, hehongbo918@gmail.com wrote:
> From: Honbo He <hehongbo918@gmail.com>
> 
> Add system reset driver for Espressif Gen3 and Gen4 RISC-V SoCs.
> The reset register base address, offset, and bit mask are read
> from the device tree to support different chip variants without
> code changes.
> 
> Signed-off-by: Honbo He <hehongbo918@gmail.com>
> ---
>  drivers/sysreset/Kconfig          |  9 ++++
>  drivers/sysreset/Makefile         |  1 +
>  drivers/sysreset/sysreset_esp32.c | 72 +++++++++++++++++++++++++++++++
>  3 files changed, 82 insertions(+)
>  create mode 100644 drivers/sysreset/sysreset_esp32.c

...

> diff --git a/drivers/sysreset/sysreset_esp32.c b/drivers/sysreset/sysreset_esp32.c
> new file mode 100644
> index 00000000000..3d4c619f44f
> --- /dev/null
> +++ b/drivers/sysreset/sysreset_esp32.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2026, Honbo He <hehongbo918@gmail.com>
> + *
> + * System reset driver for Espressif SoCs.
> + *
> + * Supported SoCs (Gen3/4):
> + *  ESP32-C5, ESP32-C6, ESP32-C61, ESP32-H2, ESP32-H21, ESP32-H4,
> + *  ESP32-P4, ESP32-S31
> + *
> + * On the unsupported chips(Gen1/2), the system reset logic resides inside the
> + * RTC_CNTL peripheral and is only accessible through the boot ROM function
> + * software_reset_cpu(). The register definitions are not exposed in the SoC headers,
> + * making it impractical to implement a direct register-based reset
> + * in U-Boot without reverse-engineering the ROM code.
> + */
> +
> +#include <dm.h>
> +#include <stdbool.h>

But you make no use of bool, so I guess this could be ommitted

> +#include <sysreset.h>
> +#include <wait_bit.h>

Not used, either.

> +#include <linux/io.h>
> +#include <linux/errno.h>

Could you please sort the headers, too?

> +
> +struct esp32_sysreset_priv {
> +	void __iomem *base;
> +	u32 offset;
> +	u32 mask;
> +};
> +
> +static int esp32_sysreset_request(struct udevice *dev, enum sysreset_t type)
> +{
> +	struct esp32_sysreset_priv *priv = dev_get_priv(dev);
> +
> +	setbits_le32(priv->base + priv->offset, priv->mask);

And this looks quite compatible with the generic syscon-reboot binding.
Why not re-use this driver instead?

> +
> +	return -EINPROGRESS;
> +}
> +
> +static struct sysreset_ops esp32_sysreset = {
> +	.request = esp32_sysreset_request,
> +};
> +
> +static int esp32_sysreset_probe(struct udevice *dev)
> +{
> +	struct esp32_sysreset_priv *priv = dev_get_priv(dev);
> +
> +	priv->base = dev_read_addr_ptr(dev);
> +	if (!priv->base)
> +		return -EINVAL;
> +
> +	priv->offset = dev_read_u32_default(dev, "offset", 0);
> +	priv->mask = dev_read_u32_default(dev, "mask", 0);
> +	if (priv->mask == 0)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static const struct udevice_id esp32s31_sysreset_ids[] = {
> +	{ .compatible = "esp,esp32-sysreset", },

Is the compatible documented anywhere so we could have a stable dt ABI
as reference? I searched current Linux master but got no luck.

Best regards,
Yao Zi