Downloading regulatory "firmware" needs a device to hang off of, and so
a platform device seemed like the simplest way to do this.  Now that we
have a faux device interface, use that instead as this "regulatory
device" is not anything resembling a platform device at all.

Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: <linux-wireless@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
v5: - rebase against 6.16-rc4 and actually cc: the relevant maintainers
      and mailing lists this time, doh!
v4: - api tweaked due to parent pointer added to faux_device create
      function.
v3: - no change
v2: - new example patch in a larger series

 net/wireless/reg.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index c1752b31734f..2524bc187a19 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -53,7 +53,7 @@
 #include <linux/list.h>
 #include <linux/ctype.h>
 #include <linux/nl80211.h>
-#include <linux/platform_device.h>
+#include <linux/device/faux.h>
 #include <linux/verification.h>
 #include <linux/moduleparam.h>
 #include <linux/firmware.h>
@@ -105,7 +105,7 @@ static struct regulatory_request __rcu *last_request =
 	(void __force __rcu *)&core_request_world;
 
 /* To trigger userspace events and load firmware */
-static struct platform_device *reg_pdev;
+static struct faux_device *reg_fdev;
 
 /*
  * Central wireless core regulatory domains, we only need two,
@@ -583,7 +583,7 @@ static int call_crda(const char *alpha2)
 	else
 		pr_debug("Calling CRDA to update world regulatory domain\n");
 
-	ret = kobject_uevent_env(&reg_pdev->dev.kobj, KOBJ_CHANGE, env);
+	ret = kobject_uevent_env(&reg_fdev->dev.kobj, KOBJ_CHANGE, env);
 	if (ret)
 		return ret;
 
@@ -779,7 +779,7 @@ static bool regdb_has_valid_signature(const u8 *data, unsigned int size)
 	const struct firmware *sig;
 	bool result;
 
-	if (request_firmware(&sig, "regulatory.db.p7s", &reg_pdev->dev))
+	if (request_firmware(&sig, "regulatory.db.p7s", &reg_fdev->dev))
 		return false;
 
 	result = verify_pkcs7_signature(data, size, sig->data, sig->size,
@@ -1061,7 +1061,7 @@ static int query_regdb_file(const char *alpha2)
 		return -ENOMEM;
 
 	err = request_firmware_nowait(THIS_MODULE, true, "regulatory.db",
-				      &reg_pdev->dev, GFP_KERNEL,
+				      &reg_fdev->dev, GFP_KERNEL,
 				      (void *)alpha2, regdb_fw_cb);
 	if (err)
 		kfree(alpha2);
@@ -1077,7 +1077,7 @@ int reg_reload_regdb(void)
 	const struct ieee80211_regdomain *current_regdomain;
 	struct regulatory_request *request;
 
-	err = request_firmware(&fw, "regulatory.db", &reg_pdev->dev);
+	err = request_firmware(&fw, "regulatory.db", &reg_fdev->dev);
 	if (err)
 		return err;
 
@@ -4300,12 +4300,12 @@ static int __init regulatory_init_db(void)
 	 * in that case, don't try to do any further work here as
 	 * it's doomed to lead to crashes.
 	 */
-	if (IS_ERR_OR_NULL(reg_pdev))
+	if (!reg_fdev)
 		return -EINVAL;
 
 	err = load_builtin_regdb_keys();
 	if (err) {
-		platform_device_unregister(reg_pdev);
+		faux_device_destroy(reg_fdev);
 		return err;
 	}
 
@@ -4313,7 +4313,7 @@ static int __init regulatory_init_db(void)
 	err = regulatory_hint_core(cfg80211_world_regdom->alpha2);
 	if (err) {
 		if (err == -ENOMEM) {
-			platform_device_unregister(reg_pdev);
+			faux_device_destroy(reg_fdev);
 			return err;
 		}
 		/*
@@ -4342,9 +4342,9 @@ late_initcall(regulatory_init_db);
 
 int __init regulatory_init(void)
 {
-	reg_pdev = platform_device_register_simple("regulatory", 0, NULL, 0);
-	if (IS_ERR(reg_pdev))
-		return PTR_ERR(reg_pdev);
+	reg_fdev = faux_device_create("regulatory", NULL, NULL);
+	if (!reg_fdev)
+		return -ENODEV;
 
 	rcu_assign_pointer(cfg80211_regdomain, cfg80211_world_regdom);
 
@@ -4372,9 +4372,9 @@ void regulatory_exit(void)
 	reset_regdomains(true, NULL);
 	rtnl_unlock();
 
-	dev_set_uevent_suppress(&reg_pdev->dev, true);
+	dev_set_uevent_suppress(&reg_fdev->dev, true);
 
-	platform_device_unregister(reg_pdev);
+	faux_device_destroy(reg_fdev);
 
 	list_for_each_entry_safe(reg_beacon, btmp, &reg_pending_beacons, list) {
 		list_del(&reg_beacon->list);
-- 
2.50.0

On Tue, 2025-07-01 at 12:56 +0200, Greg Kroah-Hartman wrote:
> Downloading regulatory "firmware" needs a device to hang off of, and so
> a platform device seemed like the simplest way to do this.  Now that we
> have a faux device interface, use that instead as this "regulatory
> device" is not anything resembling a platform device at all.
> 
> Cc: Johannes Berg <johannes@sipsolutions.net>
> Cc: <linux-wireless@vger.kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> v5: - rebase against 6.16-rc4 and actually cc: the relevant maintainers
>       and mailing lists this time, doh!

I did wonder for a second why it's v5 and I never saw it ;-)

>  int __init regulatory_init(void)
>  {
> -	reg_pdev = platform_device_register_simple("regulatory", 0, NULL, 0);
> -	if (IS_ERR(reg_pdev))
> -		return PTR_ERR(reg_pdev);
> +	reg_fdev = faux_device_create("regulatory", NULL, NULL);
> +	if (!reg_fdev)
> +		return -ENODEV;

Is that really -ENODEV rather than say -ENOMEM? Having a hard time
imagining how a faux device creation would end up failing in any other
case, there's no underlying device to bind to, after all? :)

Anyway, that's not really all that relevant. I assume you want me to
merge it through wireless-next, since we have faux.h in the tree now?

johannes

On Tue, Jul 01, 2025 at 01:06:46PM +0200, Johannes Berg wrote:
> On Tue, 2025-07-01 at 12:56 +0200, Greg Kroah-Hartman wrote:
> > Downloading regulatory "firmware" needs a device to hang off of, and so
> > a platform device seemed like the simplest way to do this.  Now that we
> > have a faux device interface, use that instead as this "regulatory
> > device" is not anything resembling a platform device at all.
> > 
> > Cc: Johannes Berg <johannes@sipsolutions.net>
> > Cc: <linux-wireless@vger.kernel.org>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > ---
> > v5: - rebase against 6.16-rc4 and actually cc: the relevant maintainers
> >       and mailing lists this time, doh!
> 
> I did wonder for a second why it's v5 and I never saw it ;-)
> 
> >  int __init regulatory_init(void)
> >  {
> > -	reg_pdev = platform_device_register_simple("regulatory", 0, NULL, 0);
> > -	if (IS_ERR(reg_pdev))
> > -		return PTR_ERR(reg_pdev);
> > +	reg_fdev = faux_device_create("regulatory", NULL, NULL);
> > +	if (!reg_fdev)
> > +		return -ENODEV;
> 
> Is that really -ENODEV rather than say -ENOMEM? Having a hard time
> imagining how a faux device creation would end up failing in any other
> case, there's no underlying device to bind to, after all? :)

There are some low-level functions that could fail, but the error that
I thought should be told to init would be "no device" as the device was
not created which is what really matters :)

> Anyway, that's not really all that relevant. I assume you want me to
> merge it through wireless-next, since we have faux.h in the tree now?

Please do, thanks!

greg k-h