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

[Jori Koolstra]

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/

Suggested-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Jori Koolstra <jkools...@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;
 
        rc = alloc_chrdev_region(&coproc_device.devt, 1, 1, name);
        if (rc) {
@@ -619,13 +638,12 @@ int vas_register_coproc_api(struct module *mod, enum 
vas_cop_type cop_type,
        pr_devel("%s device allocated, dev [%i,%i]\n", name,
                        MAJOR(coproc_device.devt), MINOR(coproc_device.devt));
 
-       coproc_device.class = class_create(name);
-       if (IS_ERR(coproc_device.class)) {
-               rc = PTR_ERR(coproc_device.class);
-               pr_err("Unable to create %s class %d\n", name, rc);
+       rc = class_register(class);
+       if (rc) {
+               pr_err("Unable to register %s class %d\n", name, rc);
                goto err_class;
        }
-       coproc_device.class->devnode = coproc_devnode;
+       coproc_device.class = class;
        coproc_device.cop_type = cop_type;
        coproc_device.vops = vops;
 
@@ -654,7 +672,7 @@ int vas_register_coproc_api(struct module *mod, enum 
vas_cop_type cop_type,
 err:
        cdev_del(&coproc_device.cdev);
 err_cdev:
-       class_destroy(coproc_device.class);
+       class_unregister(coproc_device.class);
 err_class:
        unregister_chrdev_region(coproc_device.devt, 1);
        return rc;
@@ -668,6 +686,6 @@ void vas_unregister_coproc_api(void)
        devno = MKDEV(MAJOR(coproc_device.devt), 0);
        device_destroy(coproc_device.class, devno);
 
-       class_destroy(coproc_device.class);
+       class_unregister(coproc_device.class);
        unregister_chrdev_region(coproc_device.devt, 1);
 }

base-commit: d466c332e106fe666d1e2f5a24d08e308bebbfa1
-- 
2.53.0