Re: [PATCH v4 7/8] soc: starfive: Add socinfo driver for JHB100 SoC

[Conor Dooley <conor@kernel.org>]

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On Sat, Aug 08, 2026 at 06:50:53PM -0700, Changhuang Liang wrote:
> Add socinfo driver for JHB100 SoC. Currently available for distinguishing
> between the two reversions, A0 and A1.
> 
> Signed-off-by: Changhuang Liang <changhuang.liang@starfivetech.com>
> ---
>  MAINTAINERS                                   |  6 ++
>  drivers/soc/Kconfig                           |  1 +
>  drivers/soc/Makefile                          |  1 +
>  drivers/soc/starfive/Kconfig                  |  6 ++
>  drivers/soc/starfive/Makefile                 |  2 +
>  drivers/soc/starfive/socinfo/Kconfig          | 11 +++
>  drivers/soc/starfive/socinfo/Makefile         |  2 +
>  drivers/soc/starfive/socinfo/jhb100-socinfo.c | 90 +++++++++++++++++++
>  8 files changed, 119 insertions(+)
>  create mode 100644 drivers/soc/starfive/Kconfig
>  create mode 100644 drivers/soc/starfive/Makefile
>  create mode 100644 drivers/soc/starfive/socinfo/Kconfig
>  create mode 100644 drivers/soc/starfive/socinfo/Makefile
>  create mode 100644 drivers/soc/starfive/socinfo/jhb100-socinfo.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cecb4f279160..90919c672d4d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -26040,6 +26040,7 @@ M:	Conor Dooley <conor@kernel.org>
>  S:	Maintained
>  T:	git https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/
>  F:	Documentation/devicetree/bindings/soc/starfive/
> +F:	drivers/soc/starfive/
>  
>  STARFIVE STARLINK PMU DRIVER
>  M:	Ji Sheng Teoh <jisheng.teoh@starfivetech.com>
> @@ -26094,6 +26095,11 @@ S:	Maintained
>  F:	drivers/reset/starfive/reset-starfive-jhb1*
>  F:	include/dt-bindings/reset/starfive,jhb1*.h
>  
> +STARFIVE JHB100 SOCINFO DRIVER
> +M:	Changhuang Liang <changhuang.liang@starfivetech.com>
> +S:	Maintained
> +F:	drivers/soc/starfive/socinfo/jhb100-socinfo.c
> +
>  STARFIVE JHB100 SYSCON
>  M:	Changhuang Liang <changhuang.liang@starfivetech.com>
>  S:	Maintained
> diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
> index a2d65adffb80..b3b01fc38139 100644
> --- a/drivers/soc/Kconfig
> +++ b/drivers/soc/Kconfig
> @@ -24,6 +24,7 @@ source "drivers/soc/renesas/Kconfig"
>  source "drivers/soc/rockchip/Kconfig"
>  source "drivers/soc/samsung/Kconfig"
>  source "drivers/soc/sophgo/Kconfig"
> +source "drivers/soc/starfive/Kconfig"
>  source "drivers/soc/sunxi/Kconfig"
>  source "drivers/soc/tegra/Kconfig"
>  source "drivers/soc/ti/Kconfig"
> diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
> index c9e689080ceb..009f85ff891a 100644
> --- a/drivers/soc/Makefile
> +++ b/drivers/soc/Makefile
> @@ -30,6 +30,7 @@ obj-y				+= renesas/
>  obj-y				+= rockchip/
>  obj-$(CONFIG_SOC_SAMSUNG)	+= samsung/
>  obj-y				+= sophgo/
> +obj-y				+= starfive/
>  obj-y				+= sunxi/
>  obj-$(CONFIG_ARCH_TEGRA)	+= tegra/
>  obj-y				+= ti/
> diff --git a/drivers/soc/starfive/Kconfig b/drivers/soc/starfive/Kconfig
> new file mode 100644
> index 000000000000..04b020083d3e
> --- /dev/null
> +++ b/drivers/soc/starfive/Kconfig
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +menu "StarFive SoC (System On Chip) specific Drivers"
> +
> +source "drivers/soc/starfive/socinfo/Kconfig"
> +
> +endmenu
> diff --git a/drivers/soc/starfive/Makefile b/drivers/soc/starfive/Makefile
> new file mode 100644
> index 000000000000..ca1e609b8104
> --- /dev/null
> +++ b/drivers/soc/starfive/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-y += socinfo/
> diff --git a/drivers/soc/starfive/socinfo/Kconfig b/drivers/soc/starfive/socinfo/Kconfig
> new file mode 100644
> index 000000000000..92bbab62895b
> --- /dev/null
> +++ b/drivers/soc/starfive/socinfo/Kconfig
> @@ -0,0 +1,11 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +config STARFIVE_JHB100_SOCINFO
> +	bool "StarFive JHB100 SoC Information"
> +	depends on ARCH_STARFIVE || COMPILE_TEST
> +	select SOC_BUS
> +	default y
> +	help
> +	  Include support for the SoC bus socinfo for the StarFive JHB100 SoC
> +	  platforms to provide information about the SoC family and variant
> +	  to user space.
> diff --git a/drivers/soc/starfive/socinfo/Makefile b/drivers/soc/starfive/socinfo/Makefile
> new file mode 100644
> index 000000000000..26c2bdf1de3b
> --- /dev/null
> +++ b/drivers/soc/starfive/socinfo/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_STARFIVE_JHB100_SOCINFO)	+= jhb100-socinfo.o
> diff --git a/drivers/soc/starfive/socinfo/jhb100-socinfo.c b/drivers/soc/starfive/socinfo/jhb100-socinfo.c
> new file mode 100644
> index 000000000000..638f81ef174c
> --- /dev/null
> +++ b/drivers/soc/starfive/socinfo/jhb100-socinfo.c
> @@ -0,0 +1,90 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2025 StarFive Technology Co., Ltd.
> + *
> + * Author: Changhuang Liang <changhuang.liang@starfivetech.com>
> + */
> +
> +#define pr_fmt(fmt) "jhb100-socinfo: " fmt
> +
> +#include <linux/bitfield.h>
> +#include <linux/init.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/sys_soc.h>
> +
> +#define JHB100_REV_ID			0x38
> +#define JHB100_REV_ID_CHAR		GENMASK(3, 2)
> +#define JHB100_REV_ID_NUM		GENMASK(1, 0)
> +
> +static int __init starfive_socinfo_init(void)
> +{
> +	struct soc_device_attribute *attrs;
> +	struct soc_device *soc_dev;
> +	const char *machine = NULL;
> +	struct device_node *np;
> +	struct regmap *regmap;
> +	char rev_char;
> +	u32 rev_id;
> +	int ret;
> +
> +	np = of_find_compatible_node(NULL, NULL, "starfive,jhb100-sys0-syscon");

Remind me again why this is not just probed as an mfd cell from the syscon
driver?

(Hint: please put this info in the commit message).

Cheers
Conor.

> +	if (!of_device_is_available(np)) {
> +		of_node_put(np);
> +		return -ENODEV;
> +	}
> +
> +	regmap = syscon_node_to_regmap(np);
> +	if (IS_ERR(regmap)) {
> +		of_node_put(np);
> +		return PTR_ERR(regmap);
> +	}
> +
> +	ret = regmap_read(regmap, JHB100_REV_ID, &rev_id);
> +	if (ret) {
> +		of_node_put(np);
> +		return ret;
> +	}
> +
> +	of_node_put(np);
> +
> +	rev_char = (char)FIELD_GET(JHB100_REV_ID_CHAR, rev_id) + 'A';
> +	rev_id = (u32)FIELD_GET(JHB100_REV_ID_NUM, rev_id);
> +
> +	attrs = kzalloc_obj(*attrs);
> +	if (!attrs)
> +		return -ENOMEM;
> +
> +	np = of_find_node_by_path("/");
> +	of_property_read_string(np, "model", &machine);
> +	if (machine)
> +		attrs->machine = kstrdup(machine, GFP_KERNEL);
> +	of_node_put(np);
> +
> +	attrs->revision = kasprintf(GFP_KERNEL, "%c%u", rev_char, rev_id);
> +	if (!attrs->revision) {
> +		kfree(attrs->machine);
> +		kfree(attrs);
> +		return -ENOMEM;
> +	}
> +
> +	attrs->family = "JH";
> +	attrs->soc_id = "JHB100";
> +
> +	soc_dev = soc_device_register(attrs);
> +	if (IS_ERR(soc_dev)) {
> +		kfree(attrs->revision);
> +		kfree(attrs->machine);
> +		kfree(attrs);
> +		return PTR_ERR(soc_dev);
> +	}
> +
> +	pr_info("StarFive %s SoC rev(%s)\n", attrs->soc_id, attrs->revision);
> +
> +	return 0;
> +}
> +
> +subsys_initcall(starfive_socinfo_init);
> -- 
> 2.25.1
> 

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