Re: [PATCH v2] powerpc: vas-api: constify dynamic struct class in coproc api register

The class_create() call has been deprecated in favor of class_register()
as the driver core now allows for a struct class to be in read-only
memory.

In vas_register_coproc_api() the dynamic allocation of the struct class
corresonding to the coprocessor type (right now only nx-gzip) is
replaced by calling

	static const struct class* cop_to_class(enum vas_cop_type cop)

which links the coprocessor type to the appropriate static const struct
class.

Compile tested only.

Link: https://lore.kernel.org/all/2023040244-duffel-pushpin-f738@gregkh/ (local)

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
---
v2: undo whitespace removal

 arch/powerpc/platforms/book3s/vas-api.c | 34 +++++++++++++++++++------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
index ea4ffa63f043..e377981fd533 100644
--- a/arch/powerpc/platforms/book3s/vas-api.c
+++ b/arch/powerpc/platforms/book3s/vas-api.c

@@ -45,7 +45,7 @@ static struct coproc_dev {
 	struct device *device;
 	char *name;
 	dev_t devt;
-	struct class *class;
+	const struct class *class;
 	enum vas_cop_type cop_type;
 	const struct vas_user_win_ops *vops;
 } coproc_device;

@@ -599,6 +599,21 @@ static struct file_operations coproc_fops = {
 	.unlocked_ioctl = coproc_ioctl,
 };
 
+static const struct class nx_gzip_class = {
+	.name		= "nx-gzip",
+	.devnode	= coproc_devnode
+};
+
+static const struct class* cop_to_class(enum vas_cop_type cop)
+{
+	switch (cop) {
+	case VAS_COP_TYPE_GZIP:		return &nx_gzip_class;
+	default:
+		pr_err("No device class defined for cop type %d\n", cop);
+		return NULL;
+	}
+}
+
 /*
  * Supporting only nx-gzip coprocessor type now, but this API code
  * extended to other coprocessor types later.

@@ -609,6 +624,10 @@ int vas_register_coproc_api(struct module *mod, enum vas_cop_type cop_type,
 {
 	int rc = -EINVAL;
 	dev_t devno;
+	const struct class* class = cop_to_class(cop_type);
+
+	if (!class)
+		return rc;