The dummy regulator driver does not need to create a platform device, it
only did so because it was simple to do.  Change it over to use the
faux bus instead as this is NOT a real platform device, and it makes
the code even smaller than before.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/regulator/dummy.c | 37 +++++++++----------------------------
 1 file changed, 9 insertions(+), 28 deletions(-)

diff --git a/drivers/regulator/dummy.c b/drivers/regulator/dummy.c
index 5b9b9e4e762d..163b47e25291 100644
--- a/drivers/regulator/dummy.c
+++ b/drivers/regulator/dummy.c
@@ -13,7 +13,7 @@
 
 #include <linux/err.h>
 #include <linux/export.h>
-#include <linux/platform_device.h>
+#include <linux/device/faux.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 
@@ -37,15 +37,15 @@ static const struct regulator_desc dummy_desc = {
 	.ops = &dummy_ops,
 };
 
-static int dummy_regulator_probe(struct platform_device *pdev)
+static int dummy_regulator_probe(struct faux_device *vdev)
 {
 	struct regulator_config config = { };
 	int ret;
 
-	config.dev = &pdev->dev;
+	config.dev = &vdev->dev;
 	config.init_data = &dummy_initdata;
 
-	dummy_regulator_rdev = devm_regulator_register(&pdev->dev, &dummy_desc,
+	dummy_regulator_rdev = devm_regulator_register(&vdev->dev, &dummy_desc,
 						       &config);
 	if (IS_ERR(dummy_regulator_rdev)) {
 		ret = PTR_ERR(dummy_regulator_rdev);
@@ -56,36 +56,17 @@ static int dummy_regulator_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static struct platform_driver dummy_regulator_driver = {
-	.probe		= dummy_regulator_probe,
-	.driver		= {
-		.name		= "reg-dummy",
-		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
-	},
+struct faux_driver_ops dummy_regulator_driver = {
+	.probe = dummy_regulator_probe,
 };
 
-static struct platform_device *dummy_pdev;
+static struct faux_device *dummy_fdev;
 
 void __init regulator_dummy_init(void)
 {
-	int ret;
-
-	dummy_pdev = platform_device_alloc("reg-dummy", -1);
-	if (!dummy_pdev) {
+	dummy_fdev = faux_device_create("reg-dummy", &dummy_regulator_driver);
+	if (!dummy_fdev) {
 		pr_err("Failed to allocate dummy regulator device\n");
 		return;
 	}
-
-	ret = platform_device_add(dummy_pdev);
-	if (ret != 0) {
-		pr_err("Failed to register dummy regulator device: %d\n", ret);
-		platform_device_put(dummy_pdev);
-		return;
-	}
-
-	ret = platform_driver_register(&dummy_regulator_driver);
-	if (ret != 0) {
-		pr_err("Failed to register dummy regulator driver: %d\n", ret);
-		platform_device_unregister(dummy_pdev);
-	}
 }
-- 
2.48.1

On Mon, Feb 03, 2025 at 03:25:18PM +0100, Greg Kroah-Hartman wrote:
> The dummy regulator driver does not need to create a platform device, it
> only did so because it was simple to do.  Change it over to use the
> faux bus instead as this is NOT a real platform device, and it makes
> the code even smaller than before.

No, they did this because you explicitly asked that this be done....

> -static int dummy_regulator_probe(struct platform_device *pdev)
> +static int dummy_regulator_probe(struct faux_device *vdev)

Just dev or fdev - we could just pass a struct device in here, we don't
actually care that it's a platform device at this point.  Having the
abbreviation mismatch with the device type is odd.

On Mon, Feb 03, 2025 at 03:39:06PM +0000, Mark Brown wrote:
> On Mon, Feb 03, 2025 at 03:25:18PM +0100, Greg Kroah-Hartman wrote:
> > The dummy regulator driver does not need to create a platform device, it
> > only did so because it was simple to do.  Change it over to use the
> > faux bus instead as this is NOT a real platform device, and it makes
> > the code even smaller than before.
> 
> No, they did this because you explicitly asked that this be done....

I did?  What was it attempting to be before this?  I don't remember that
at all, sorry.

> > -static int dummy_regulator_probe(struct platform_device *pdev)
> > +static int dummy_regulator_probe(struct faux_device *vdev)
> 
> Just dev or fdev - we could just pass a struct device in here, we don't
> actually care that it's a platform device at this point.  Having the
> abbreviation mismatch with the device type is odd.

Ah, that's a mistake from my first pass when this was a "struct
virtual_device" and I called this "vdev".  I'll go fix that up, thanks.

greg k-h

On Mon, Feb 03, 2025 at 04:46:02PM +0100, Greg Kroah-Hartman wrote:
> On Mon, Feb 03, 2025 at 03:39:06PM +0000, Mark Brown wrote:
> > On Mon, Feb 03, 2025 at 03:25:18PM +0100, Greg Kroah-Hartman wrote:

> > > The dummy regulator driver does not need to create a platform device, it
> > > only did so because it was simple to do.  Change it over to use the
> > > faux bus instead as this is NOT a real platform device, and it makes
> > > the code even smaller than before.

> > No, they did this because you explicitly asked that this be done....

> I did?  What was it attempting to be before this?  I don't remember that
> at all, sorry.

Yeah, there were some things where people were creating custom buses for
internal uses like this which you pushed back on due to code duplication
- you said to just use platform bus since the bus code looked identical.