Re: [PATCH 4/9] rtc: efi: Transition to the faux device interface

Greg Kroah-Hartman
2025-03-17T13:08:39Z

On Mon, Mar 17, 2025 at 10:13:16AM +0000, Sudeep Holla wrote:
> The EFI RTC driver does not require the creation of a platform device.
> Originally, this approach was chosen for simplicity when the driver was
> first implemented.
>
> With the introduction of the lightweight faux device interface, we now
> have a more appropriate alternative. Migrate the driver to utilize the
> faux bus, given that the platform device it previously created was not
> a real one anyway. This will simplify the code, reducing its footprint
> while maintaining functionality.
>
> Cc: Ard Biesheuvel <ardb@kernel.org>
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: linux-rtc@vger.kernel.org
> Cc: linux-efi@vger.kernel.org
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
> drivers/firmware/efi/efi.c | 3 ---
> drivers/rtc/rtc-efi.c | 31 ++++++++++++++++++++++---------
> 2 files changed, 22 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index eec173cb1f398d3b4f28b42c917e50e1728dc277..18deb2d212ce6944927f5e3a9a40bb6754e7ffa9 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -427,9 +427,6 @@ static int __init efisubsys_init(void)
> }
> }
>
> - if (efi_rt_services_supported(EFI_RT_SUPPORTED_TIME_SERVICES))
> - platform_device_register_simple("rtc-efi", 0, NULL, 0);
> -
> /* We register the efi directory at /sys/firmware/efi */
> efi_kobj = kobject_create_and_add("efi", firmware_kobj);
> if (!efi_kobj) {
> diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
> index fa8bf82df9488e7d1c23c058b4a3032dde74bc6e..3d21a470e8ff9777c5eeb991f3aa9170f6351930 100644
> --- a/drivers/rtc/rtc-efi.c
> +++ b/drivers/rtc/rtc-efi.c
> @@ -14,7 +14,7 @@
> #include <linux/module.h>
> #include <linux/stringify.h>
> #include <linux/time.h>
> -#include <linux/platform_device.h>
> +#include <linux/device/faux.h>
> #include <linux/rtc.h>
> #include <linux/efi.h>
>
> @@ -254,7 +254,7 @@ static const struct rtc_class_ops efi_rtc_ops = {
> .proc = efi_procfs,
> };
>
> -static int __init efi_rtc_probe(struct platform_device *dev)
> +static int __init efi_rtc_probe(struct faux_device *dev)
> {
> struct rtc_device *rtc;
> efi_time_t eft;
> @@ -268,7 +268,7 @@ static int __init efi_rtc_probe(struct platform_device *dev)
> if (IS_ERR(rtc))
> return PTR_ERR(rtc);
>
> - platform_set_drvdata(dev, rtc);
> + faux_device_set_drvdata(dev, rtc);
>
> rtc->ops = &efi_rtc_ops;
> clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
> @@ -282,15 +282,28 @@ static int __init efi_rtc_probe(struct platform_device *dev)
> return devm_rtc_register_device(rtc);
> }
>
> -static struct platform_driver efi_rtc_driver = {
> - .driver = {
> - .name = "rtc-efi",
> - },
> +static struct faux_device_ops efi_rtc_fdev_ops = {
> + .probe = efi_rtc_probe,
> };
>
> -module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
> +static int __init rtc_efi_init(void)
> +{
> + struct faux_device *fdev;
> +
> + if (!efi_rt_services_supported(EFI_RT_SUPPORTED_TIME_SERVICES))
> + return 0;
> +
> + fdev = faux_device_create("rtc-efi", NULL, &efi_rtc_fdev_ops);
> + if (!fdev) {
> + pr_err("rtc-efi: could not create the device\n");
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +device_initcall(rtc_efi_init);
>
> MODULE_AUTHOR("dann frazier <dannf@dannf.org>");
> MODULE_LICENSE("GPL");
> MODULE_DESCRIPTION("EFI RTC driver");
> -MODULE_ALIAS("platform:rtc-efi");
> +MODULE_ALIAS("faux:rtc-efi");

No alias please.