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

Sudeep Holla
2025-03-17T10:13:57Z

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");

--
2.34.1