Re: [PATCH v2 1/2] mfd: rohm-bd71828: Use software nodes for gpio-keys

[Matti Vaittinen <mazziesaccount@gmail.com>]

On 23/03/2026 03:37, Dmitry Torokhov wrote:
> Refactor the rohm-bd71828 MFD driver to use software nodes for
> instantiating the gpio-keys child device, replacing the old
> platform_data mechanism.
> 
> The power key's properties are now defined using software nodes and
> property entries. The IRQ is passed as a resource attached to the
> platform device.
> 
> This will allow dropping support for using platform data for configuring
> gpio-keys in the future.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks a lot Dmitry for converting this to the swnodes. I like the idea 
very much :) A few minor, (mostly styling related as I am a bit 
old-fashioned) comments.

> ---
>   drivers/mfd/rohm-bd71828.c | 117 ++++++++++++++++++++++++++++++++-------------
>   1 file changed, 85 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/mfd/rohm-bd71828.c b/drivers/mfd/rohm-bd71828.c
> index a79f354bf5cb..20b7910e7f63 100644
> --- a/drivers/mfd/rohm-bd71828.c
> +++ b/drivers/mfd/rohm-bd71828.c
> @@ -5,7 +5,8 @@
>    * ROHM BD718[15/28/79] and BD72720 PMIC driver
>    */
>   
> -#include <linux/gpio_keys.h>
> +#include <linux/device/devres.h>
> +#include <linux/gfp_types.h>
>   #include <linux/i2c.h>
>   #include <linux/input.h>
>   #include <linux/interrupt.h>
> @@ -18,6 +19,7 @@
>   #include <linux/mfd/rohm-generic.h>
>   #include <linux/module.h>
>   #include <linux/of.h>
> +#include <linux/property.h>
>   #include <linux/regmap.h>
>   #include <linux/types.h>
>   
> @@ -37,19 +39,6 @@
>   		},							   \
>   	}
>   
> -static struct gpio_keys_button button = {
> -	.code = KEY_POWER,
> -	.gpio = -1,
> -	.type = EV_KEY,
> -	.wakeup = 1,
> -};
> -
> -static const struct gpio_keys_platform_data bd71828_powerkey_data = {
> -	.buttons = &button,
> -	.nbuttons = 1,
> -	.name = "bd71828-pwrkey",
> -};
> -
>   static const struct resource bd71815_rtc_irqs[] = {
>   	DEFINE_RES_IRQ_NAMED(BD71815_INT_RTC0, "bd70528-rtc-alm-0"),
>   	DEFINE_RES_IRQ_NAMED(BD71815_INT_RTC1, "bd70528-rtc-alm-1"),
> @@ -174,11 +163,8 @@ static struct mfd_cell bd71828_mfd_cells[] = {
>   		.name = "bd71828-rtc",
>   		.resources = bd71828_rtc_irqs,
>   		.num_resources = ARRAY_SIZE(bd71828_rtc_irqs),
> -	}, {
> -		.name = "gpio-keys",
> -		.platform_data = &bd71828_powerkey_data,
> -		.pdata_size = sizeof(bd71828_powerkey_data),
>   	},
> +	/* Power button is registered separately */
>   };
>   
>   static const struct resource bd72720_power_irqs[] = {
> @@ -242,11 +228,8 @@ static const struct mfd_cell bd72720_mfd_cells[] = {
>   		.name = "bd72720-rtc",
>   		.resources = bd72720_rtc_irqs,
>   		.num_resources = ARRAY_SIZE(bd72720_rtc_irqs),
> -	}, {
> -		.name = "gpio-keys",
> -		.platform_data = &bd71828_powerkey_data,
> -		.pdata_size = sizeof(bd71828_powerkey_data),
>   	},
> +	/* Power button is registered separately */
>   };
>   
>   static const struct regmap_range bd71815_volatile_ranges[] = {
> @@ -877,6 +860,75 @@ static int set_clk_mode(struct device *dev, struct regmap *regmap,
>   				  OUT32K_MODE_CMOS);
>   }
>   
> +static void bd71828_i2c_unregister_swnodes(void *data)
> +{
> +	const struct software_node *nodes = data;
> +
> +	software_node_unregister_node_group((const struct software_node *[]){
> +		&nodes[0],
> +		&nodes[1],
> +		NULL
> +	});

Perhaps it was possible to use a temporary variable for the 
software_node pointer array? It would allow also old-school fellows like 
me to pick the meaning by a glance :)

> +}
> +
> +static int bd71828_i2c_register_pwrbutton(struct device *dev, int button_irq,
> +					  struct irq_domain *irq_domain)
> +{
> +	static const struct property_entry bd71828_powerkey_parent_props[] = {
> +		PROPERTY_ENTRY_STRING("label", "bd71828-pwrkey"),
> +		{ }
> +	};
> +	static const struct property_entry bd71828_powerkey_props[] = {
> +		PROPERTY_ENTRY_U32("linux,code", KEY_POWER),
> +		PROPERTY_ENTRY_BOOL("wakeup-source"),
> +		{ }
> +	};
> +	struct software_node *nodes;
> +	int error;
> +
> +	nodes = devm_kcalloc(dev, 2, sizeof(*nodes), GFP_KERNEL);
> +	if (!nodes)
> +		return -ENOMEM;
> +
> +	/* Node corresponding to gpio-keys device itself */
> +	nodes[0].name = devm_kasprintf(dev, GFP_KERNEL, "%s-power-key", dev_name(dev));
> +	if (!nodes[0].name)
> +		return -ENOMEM;
> +
> +	nodes[0].properties = bd71828_powerkey_parent_props;
> +
> +	/* Node representing power button within gpio-keys device */
> +	nodes[1].parent = &nodes[0];
> +	nodes[1].properties = bd71828_powerkey_props;
> +
> +	error = software_node_register_node_group((const struct software_node *[]){
> +		&nodes[0],
> +		&nodes[1],
> +		NULL
> +	});

I think having a temporary variable might make this to look more familiar.

> +	if (error)
> +		return error;
> +
> +	error = devm_add_action_or_reset(dev, bd71828_i2c_unregister_swnodes, nodes);
> +	if (error)
> +		return error;
> +
> +	const struct mfd_cell gpio_keys_cell = {
> +		.name = "gpio-keys",
> +		.resources = (const struct resource[]) {
> +			DEFINE_RES_IRQ_NAMED(button_irq, "bd71828-pwrkey"),
> +		},
> +		.num_resources = 1,
> +		.swnode = &nodes[0],
> +	};

I don't really love seeing variables declared in the middle of a block. 
Perhaps consider splitting the software-node preparation in own function 
and doing something like (completely untested thought):

ret = alloc_and_prepare_the_swnode_stuff(...);
if (!ret) {
	const struct software_node *nodes[] = { ... };
	const struct mfd_cell gpio_keys_cell = { ... };
	
	...
}

or alternatively, split the software-node and MFD device registration 
into own function? Do you think it would work?

> +	error = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, &gpio_keys_cell, 1,
> +				     NULL, 0, irq_domain);
> +	if (error)
> +		return dev_err_probe(dev, error, "Failed to create power button subdevice");
> +
> +	return 0;
> +}
> +
>   static struct i2c_client *bd71828_dev;
>   static void bd71828_power_off(void)
>   {
> @@ -929,6 +981,7 @@ static struct regmap *bd72720_do_regmaps(struct i2c_client *i2c)
>   static int bd71828_i2c_probe(struct i2c_client *i2c)
>   {
>   	struct regmap_irq_chip_data *irq_data;
> +	struct irq_domain *irq_domain;
>   	int ret;
>   	struct regmap *regmap = NULL;
>   	const struct regmap_config *regmap_config;
> @@ -1008,6 +1061,8 @@ static int bd71828_i2c_probe(struct i2c_client *i2c)
>   	dev_dbg(&i2c->dev, "Registered %d IRQs for chip\n",
>   		irqchip->num_irqs);
>   
> +	irq_domain = regmap_irq_get_domain(irq_data);

nit: Maybe move this call closer to where the irq_domain is actually 
needed for the first time.

> +
>   	/*
>   	 * On some ICs the main IRQ register has corresponding mask register.
>   	 * This is not handled by the regmap IRQ. Let's enable all the main
> @@ -1022,23 +1077,21 @@ static int bd71828_i2c_probe(struct i2c_client *i2c)
>   					"Failed to enable main level IRQs\n");
>   		}
>   	}
> -	if (button_irq) {
> -		ret = regmap_irq_get_virq(irq_data, button_irq);
> -		if (ret < 0)
> -			return dev_err_probe(&i2c->dev, ret,
> -					     "Failed to get the power-key IRQ\n");
> -
> -		button.irq = ret;
> -	}
>   
>   	ret = set_clk_mode(&i2c->dev, regmap, clkmode_reg);
>   	if (ret)
>   		return ret;
>   
>   	ret = devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_AUTO, mfd, cells,
> -				   NULL, 0, regmap_irq_get_domain(irq_data));
> +				   NULL, 0, irq_domain);
>   	if (ret)
> -		return	dev_err_probe(&i2c->dev, ret, "Failed to create subdevices\n");
> +		return dev_err_probe(&i2c->dev, ret, "Failed to create subdevices\n");
> +
> +	if (button_irq) {
> +		ret = bd71828_i2c_register_pwrbutton(&i2c->dev, button_irq, irq_domain);
> +		if (ret)
> +			return ret;
> +	}
>   
>   	if (of_device_is_system_power_controller(i2c->dev.of_node) &&
>   	    chip_type == ROHM_CHIP_TYPE_BD71828) {
> 


-- 
---
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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