[PATCH] drm: amdkfd: Replace (un)register_chrdev() by (unregister/alloc)_chrdev_region()

[Salah Triki]

Replace (un)register_chrdev() by (unregister/alloc)_chrdev_region() as
they are deprecated since kernel 2.6. alloc_chrdev_region() generates a
dev_t value, so replace the kfd_char_dev_major int variable by the
kfd_char_dev_id dev_t variable and drop the MKDEV() call. Initialize a
cdev structure and add it to the device driver model as register_chrdev()
used to do and since alloc_chrdev_region() does not do it. Drop the
iminor() call since alloc_chrdev_region() allocates only one minor number.
On error and in the module exit function, remove the cdev structure from
the device driver model as unregister_chrdev() used to do.

Signed-off-by: Salah Triki <salah.tr...@gmail.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 35 ++++++++++++++++--------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 065d87841459..55c74466d2c5 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -37,6 +37,8 @@
 #include <linux/ptrace.h>
 #include <linux/dma-buf.h>
 #include <linux/processor.h>
+#include <linux/cdev.h>
+
 #include "kfd_priv.h"
 #include "kfd_device_queue_manager.h"
 #include "kfd_svm.h"
@@ -61,12 +63,14 @@ static const struct file_operations kfd_fops = {
        .mmap = kfd_mmap,
 };
 
-static int kfd_char_dev_major = -1;
+static dev_t kfd_char_dev_id;
 struct device *kfd_device;
 static const struct class kfd_class = {
        .name = kfd_dev_name,
 };
 
+static struct cdev kfd_cdev;
+
 static inline struct kfd_process_device *kfd_lock_pdd_by_id(struct kfd_process 
*p, __u32 gpu_id)
 {
        struct kfd_process_device *pdd;
@@ -90,17 +94,24 @@ int kfd_chardev_init(void)
 {
        int err = 0;
 
-       kfd_char_dev_major = register_chrdev(0, kfd_dev_name, &kfd_fops);
-       err = kfd_char_dev_major;
+       err = alloc_chrdev_region(&kfd_char_dev_id, 0, 1, kfd_dev_name);
+
        if (err < 0)
-               goto err_register_chrdev;
+               goto err_alloc_chrdev_region;
+
+       cdev_init(&kfd_cdev, &kfd_fops);
+       kfd_cdev.owner = THIS_MODULE;
+
+       err = cdev_add(&kfd_cdev, kfd_char_dev_id, 1);
+       if (err)
+               goto err_cdev_add;
 
        err = class_register(&kfd_class);
        if (err)
                goto err_class_create;
 
        kfd_device = device_create(&kfd_class, NULL,
-                                  MKDEV(kfd_char_dev_major, 0),
+                                  kfd_char_dev_id,
                                   NULL, kfd_dev_name);
        err = PTR_ERR(kfd_device);
        if (IS_ERR(kfd_device))
@@ -111,16 +122,19 @@ int kfd_chardev_init(void)
 err_device_create:
        class_unregister(&kfd_class);
 err_class_create:
-       unregister_chrdev(kfd_char_dev_major, kfd_dev_name);
-err_register_chrdev:
+       cdev_del(&kfd_cdev);
+err_cdev_add:
+       unregister_chrdev_region(kfd_char_dev_id, 1);
+err_alloc_chrdev_region:
        return err;
 }
 
 void kfd_chardev_exit(void)
 {
-       device_destroy(&kfd_class, MKDEV(kfd_char_dev_major, 0));
+       device_destroy(&kfd_class, kfd_char_dev_id);
        class_unregister(&kfd_class);
-       unregister_chrdev(kfd_char_dev_major, kfd_dev_name);
+       cdev_del(&kfd_cdev);
+       unregister_chrdev_region(kfd_char_dev_id, 1);
        kfd_device = NULL;
 }
 
@@ -130,9 +144,6 @@ static int kfd_open(struct inode *inode, struct file *filep)
        struct kfd_process *process;
        bool is_32bit_user_mode;
 
-       if (iminor(inode) != 0)
-               return -ENODEV;
-
        is_32bit_user_mode = in_compat_syscall();
 
        if (is_32bit_user_mode) {
-- 
2.34.1