NACK: [SRU][O][PATCH 01/13] gpio: introduce utilities for synchronous fake device creation

[Koichiro Den]

On Fri, Apr 11, 2025 at 04:26:23PM GMT, Koichiro Den wrote:
> BugLink: https://bugs.launchpad.net/bugs/2103496
> 
> Both gpio-sim and gpio-virtuser share a mechanism to instantiate a
> platform device, wait for probe completion, and retrieve the probe
> success or error status synchronously. With gpio-aggregator planned to
> adopt this approach for its configfs interface, it's time to factor
> out the common code.
> 
> Add dev-sync-probe.[ch] to house helper functions used by all such
> implementations.
> 
> No functional change.
> 
> Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
> Link: https://lore.kernel.org/r/20250221133501.2203897-2-koichiro.den@canonical.com
> (cherry picked from commit eb5ab6ffb4ca2d28121455dd7452061367ed5588)
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski at linaro.org>

This is an error, SOB must be mine.
The same applies to [SRU][N/J][PATCH 01/12].

> ---
>  drivers/gpio/Kconfig          |  3 ++
>  drivers/gpio/Makefile         |  3 ++
>  drivers/gpio/dev-sync-probe.c | 97 +++++++++++++++++++++++++++++++++++
>  drivers/gpio/dev-sync-probe.h | 25 +++++++++
>  4 files changed, 128 insertions(+)
>  create mode 100644 drivers/gpio/dev-sync-probe.c
>  create mode 100644 drivers/gpio/dev-sync-probe.h
> 
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 2be612f9ce55..21ac40bde9c4 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1935,3 +1935,6 @@ config GPIO_VIRTUSER
>  endmenu
>  
>  endif
> +
> +config DEV_SYNC_PROBE
> +	tristate
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index e6b6355c66d4..a18cf557eca6 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -19,6 +19,9 @@ obj-$(CONFIG_GPIO_GENERIC)	+= gpio-generic.o
>  # directly supported by gpio-generic
>  gpio-generic-$(CONFIG_GPIO_GENERIC)	+= gpio-mmio.o
>  
> +# Utilities for drivers that need synchronous fake device creation
> +obj-$(CONFIG_DEV_SYNC_PROBE)		+= dev-sync-probe.o
> +
>  obj-$(CONFIG_GPIO_104_DIO_48E)		+= gpio-104-dio-48e.o
>  obj-$(CONFIG_GPIO_104_IDI_48)		+= gpio-104-idi-48.o
>  obj-$(CONFIG_GPIO_104_IDIO_16)		+= gpio-104-idio-16.o
> diff --git a/drivers/gpio/dev-sync-probe.c b/drivers/gpio/dev-sync-probe.c
> new file mode 100644
> index 000000000000..9ea733b863b2
> --- /dev/null
> +++ b/drivers/gpio/dev-sync-probe.c
> @@ -0,0 +1,97 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Common code for drivers creating fake platform devices.
> + *
> + * Provides synchronous device creation: waits for probe completion and
> + * returns the probe success or error status to the device creator.
> + *
> + * Copyright (C) 2021 Bartosz Golaszewski <brgl at bgdev.pl>
> + * Copyright (C) 2025 Koichiro Den <koichiro.den at canonical.com>
> + */
> +
> +#include <linux/device.h>
> +#include <linux/slab.h>
> +
> +#include "dev-sync-probe.h"
> +
> +static int dev_sync_probe_notifier_call(struct notifier_block *nb,
> +					unsigned long action, void *data)
> +{
> +	struct dev_sync_probe_data *pdata;
> +	struct device *dev = data;
> +
> +	pdata = container_of(nb, struct dev_sync_probe_data, bus_notifier);
> +	if (!device_match_name(dev, pdata->name))
> +		return NOTIFY_DONE;
> +
> +	switch (action) {
> +	case BUS_NOTIFY_BOUND_DRIVER:
> +		pdata->driver_bound = true;
> +		break;
> +	case BUS_NOTIFY_DRIVER_NOT_BOUND:
> +		pdata->driver_bound = false;
> +		break;
> +	default:
> +		return NOTIFY_DONE;
> +	}
> +
> +	complete(&pdata->probe_completion);
> +	return NOTIFY_OK;
> +}
> +
> +void dev_sync_probe_init(struct dev_sync_probe_data *data)
> +{
> +	memset(data, 0, sizeof(*data));
> +	init_completion(&data->probe_completion);
> +	data->bus_notifier.notifier_call = dev_sync_probe_notifier_call;
> +}
> +EXPORT_SYMBOL_GPL(dev_sync_probe_init);
> +
> +int dev_sync_probe_register(struct dev_sync_probe_data *data,
> +			    struct platform_device_info *pdevinfo)
> +{
> +	struct platform_device *pdev;
> +	char *name;
> +
> +	name = kasprintf(GFP_KERNEL, "%s.%d", pdevinfo->name, pdevinfo->id);
> +	if (!name)
> +		return -ENOMEM;
> +
> +	data->driver_bound = false;
> +	data->name = name;
> +	reinit_completion(&data->probe_completion);
> +	bus_register_notifier(&platform_bus_type, &data->bus_notifier);
> +
> +	pdev = platform_device_register_full(pdevinfo);
> +	if (IS_ERR(pdev)) {
> +		bus_unregister_notifier(&platform_bus_type, &data->bus_notifier);
> +		kfree(data->name);
> +		return PTR_ERR(pdev);
> +	}
> +
> +	wait_for_completion(&data->probe_completion);
> +	bus_unregister_notifier(&platform_bus_type, &data->bus_notifier);
> +
> +	if (!data->driver_bound) {
> +		platform_device_unregister(pdev);
> +		kfree(data->name);
> +		return -ENXIO;
> +	}
> +
> +	data->pdev = pdev;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(dev_sync_probe_register);
> +
> +void dev_sync_probe_unregister(struct dev_sync_probe_data *data)
> +{
> +	platform_device_unregister(data->pdev);
> +	kfree(data->name);
> +	data->pdev = NULL;
> +}
> +EXPORT_SYMBOL_GPL(dev_sync_probe_unregister);
> +
> +MODULE_AUTHOR("Bartosz Golaszewski <brgl at bgdev.pl>");
> +MODULE_AUTHOR("Koichiro Den <koichiro.den at canonical.com>");
> +MODULE_DESCRIPTION("Utilities for synchronous fake device creation");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/gpio/dev-sync-probe.h b/drivers/gpio/dev-sync-probe.h
> new file mode 100644
> index 000000000000..4b3d52b70519
> --- /dev/null
> +++ b/drivers/gpio/dev-sync-probe.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef DEV_SYNC_PROBE_H
> +#define DEV_SYNC_PROBE_H
> +
> +#include <linux/completion.h>
> +#include <linux/notifier.h>
> +#include <linux/platform_device.h>
> +
> +struct dev_sync_probe_data {
> +	struct platform_device *pdev;
> +	const char *name;
> +
> +	/* Synchronize with probe */
> +	struct notifier_block bus_notifier;
> +	struct completion probe_completion;
> +	bool driver_bound;
> +};
> +
> +void dev_sync_probe_init(struct dev_sync_probe_data *data);
> +int dev_sync_probe_register(struct dev_sync_probe_data *data,
> +			    struct platform_device_info *pdevinfo);
> +void dev_sync_probe_unregister(struct dev_sync_probe_data *data);
> +
> +#endif /* DEV_SYNC_PROBE_H */
> -- 
> 2.45.2
>