Re: [PATCH v2 3/3] sysreset: cv1800b: Use the RTC device node for register access

[Hiago De Franco <hfranco@baylibre.com>]

On Tue, Oct 06, 2026 at 11:45:08PM +0800, Zhuxu Ran wrote:
> The CV1800B system reset driver uses hard-coded RTC register
> addresses. Initialize a register map from the RTC node shared with
> its parent device instead, and propagate register access errors.
> Require the RTC driver that binds the sysreset child. Preserve the
> existing reset requests, including the warm-reset sequence used for
> SYSRESET_COLD.
> 
> Signed-off-by: Zhuxu Ran <zhuxu_ran@zohomail.com>
> ---
>  drivers/sysreset/Kconfig            |  6 ++-
>  drivers/sysreset/sysreset_cv1800b.c | 90 +++++++++++++++++++++++--------------
>  2 files changed, 60 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/sysreset/Kconfig b/drivers/sysreset/Kconfig
> index 16ef434a8d9..c9f2a552b47 100644
> --- a/drivers/sysreset/Kconfig
> +++ b/drivers/sysreset/Kconfig
> @@ -60,9 +60,11 @@ config SYSRESET_CMD_POWEROFF
>  endif
>  
>  config SYSRESET_CV1800B
> -	bool "Enable support for Sophgo cv1800b System Reset"
> +	bool "Enable support for Sophgo CV1800B system reset"
> +	depends on RTC_CV1800B
>  	help
> -	  Enable system reset support for Sophgo cv1800b SoC.
> +	  Enable system reset and power control through the RTC subsystem
> +	  found on Sophgo CV1800 series SoCs.
>  
>  config POWEROFF_GPIO
>  	bool "Enable support for GPIO poweroff driver"
> diff --git a/drivers/sysreset/sysreset_cv1800b.c b/drivers/sysreset/sysreset_cv1800b.c
> index 9cd62772ef4..fa76c8cf38e 100644
> --- a/drivers/sysreset/sysreset_cv1800b.c
> +++ b/drivers/sysreset/sysreset_cv1800b.c
> @@ -1,64 +1,86 @@
>  // SPDX-License-Identifier: GPL-2.0
>  /*
>   * Copyright (c) 2024, Kongyang Liu <seashell11234455@gmail.com>
> + * Copyright (c) 2026, Zhuxu Ran <zhuxu_ran@zohomail.com>
>   */
>  
>  #include <dm.h>
> -#include <stdbool.h>
> +#include <regmap.h>
>  #include <sysreset.h>
> -#include <wait_bit.h>
> -#include <linux/io.h>
> +#include <linux/bitops.h>
> +#include <linux/err.h>
>  #include <linux/errno.h>
>  
> -#define REG_RTC_BASE             (void *)0x05026000
> -#define REG_RTC_CTRL_BASE        (void *)0x05025000
> -#define REG_RTC_EN_SHDN_REQ      (REG_RTC_BASE + 0xc0)
> -#define REG_RTC_EN_PWR_CYC_REQ   (REG_RTC_BASE + 0xc8)
> -#define REG_RTC_EN_WARM_RST_REQ  (REG_RTC_BASE + 0xcc)
> -#define REG_RTC_CTRL_UNLOCKKEY   (REG_RTC_CTRL_BASE + 0x4)
> -#define REG_RTC_CTRL             (REG_RTC_CTRL_BASE + 0x8)
> +#define RTC_CTRL_UNLOCKKEY	0x0004
> +#define RTC_CTRL		0x0008
> +#define RTC_EN_SHDN_REQ		0x10c0

Looks like the tabs for 0x10c0 are not correct.

> +#define RTC_EN_PWR_CYC_REQ	0x10c8
> +#define RTC_EN_WARM_RST_REQ	0x10cc
>  
> -#define CTRL_UNLOCKKEY_MAGIC     0xAB18
> +#define CTRL_UNLOCKKEY_MAGIC	0xab18

This line change is purely cosmetic. I think it is fine since you are
changing all the other addresses, but I just wanted to highligth it. 

>  
> -/* REG_RTC_CTRL */
> -#define BIT_REQ_SHDN       BIT(0)
> -#define BIT_REQ_PWR_CYC    BIT(3)
> -#define BIT_REQ_WARM_RST   BIT(4)
> +#define BIT_REQ_SHDN	  BIT(0)
> +#define BIT_REQ_PWR_CYC	  BIT(3)

Same here, looks like the tabs for BIT(3) are not correct.

> +#define BIT_REQ_WARM_RST	BIT(4)
>  
> -static struct {
> -	void *pre_req_reg;
> +struct cv1800b_sysreset_priv {
> +	struct regmap *regmap;
> +};
> +
> +static const struct {
> +	u32 pre_req_reg;
>  	u32 req_bit;
>  } reset_info[SYSRESET_COUNT] = {
> -	[SYSRESET_WARM]      = { REG_RTC_EN_WARM_RST_REQ, BIT_REQ_WARM_RST },
> -	[SYSRESET_COLD]      = { REG_RTC_EN_WARM_RST_REQ, BIT_REQ_WARM_RST },
> -	[SYSRESET_POWER]     = { REG_RTC_EN_PWR_CYC_REQ, BIT_REQ_PWR_CYC },
> -	[SYSRESET_POWER_OFF] = { REG_RTC_EN_SHDN_REQ, BIT_REQ_SHDN },
> +	[SYSRESET_WARM]      = { RTC_EN_WARM_RST_REQ, BIT_REQ_WARM_RST },
> +	[SYSRESET_COLD]      = { RTC_EN_WARM_RST_REQ, BIT_REQ_WARM_RST },
> +	[SYSRESET_POWER]     = { RTC_EN_PWR_CYC_REQ, BIT_REQ_PWR_CYC },
> +	[SYSRESET_POWER_OFF] = { RTC_EN_SHDN_REQ, BIT_REQ_SHDN },
>  };
>  
>  static int cv1800b_sysreset_request(struct udevice *dev, enum sysreset_t type)
>  {
> -	u32 reg;
> +	struct cv1800b_sysreset_priv *priv = dev_get_priv(dev);
> +	int ret;
> +
> +	if (type >= SYSRESET_COUNT)
> +		return -EINVAL;
>  
> -	writel(1, reset_info[type].pre_req_reg);
> -	writel(CTRL_UNLOCKKEY_MAGIC, REG_RTC_CTRL_UNLOCKKEY);
> -	reg = readl(REG_RTC_CTRL);
> -	writel(0xFFFF0800 | reset_info[type].req_bit, REG_RTC_CTRL);
> +	ret = regmap_write(priv->regmap, reset_info[type].pre_req_reg, 1);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(priv->regmap, RTC_CTRL_UNLOCKKEY,
> +			   CTRL_UNLOCKKEY_MAGIC);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(priv->regmap, RTC_CTRL,
> +			   0xffff0800 | reset_info[type].req_bit);
> +	if (ret)
> +		return ret;
>  
>  	return -EINPROGRESS;
>  }
>  
> +static int cv1800b_sysreset_probe(struct udevice *dev)
> +{
> +	struct cv1800b_sysreset_priv *priv = dev_get_priv(dev);
> +
> +	priv->regmap = devm_regmap_init(dev, NULL, NULL, NULL);
> +	if (IS_ERR(priv->regmap))
> +		return PTR_ERR(priv->regmap);
> +
> +	return 0;
> +}
> +
>  static struct sysreset_ops cv1800b_sysreset = {
>  	.request = cv1800b_sysreset_request,
>  };
>  
> -static const struct udevice_id cv1800b_sysreset_ids[] = {
> -	{ .compatible = "sophgo,cv1800b-sysreset", },
> -	{},
> -};
> -
>  U_BOOT_DRIVER(sysreset_cv1800b) = {
>  	.name = "cv1800b_sysreset",
> -	.id	  = UCLASS_SYSRESET,
> -	.ops  = &cv1800b_sysreset,
> -	.of_match = cv1800b_sysreset_ids
> +	.id = UCLASS_SYSRESET,
> +	.probe = cv1800b_sysreset_probe,
> +	.ops = &cv1800b_sysreset,
> +	.priv_auto = sizeof(struct cv1800b_sysreset_priv),
>  };
> 
> -- 
> 2.55.0
> 

Best regards,
-- 
Hiago