tpm-chip: utilize new cdev_device_add helper function

Replace the open coded registration of the cdev and dev with the
new device_add_cdev() helper. The helper replaces a common pattern by
taking the proper reference against the parent device and adding both
the cdev and the device.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/tpm/tpm-chip.c

@@ -187,7 +187,6 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
 
 	cdev_init(&chip->cdev, &tpm_fops);
 	chip->cdev.owner = THIS_MODULE;
-	chip->cdev.kobj.parent = &chip->dev.kobj;
 
 	return chip;
 
@@ -230,27 +229,16 @@ static int tpm_add_char_device(struct tpm_chip *chip)
 {
 	int rc;
 
-	rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
+	rc = cdev_device_add(&chip->cdev, &chip->dev);
 	if (rc) {
 		dev_err(&chip->dev,
-			"unable to cdev_add() %s, major %d, minor %d, err=%d\n",
+			"unable to cdev_device_add() %s, major %d, minor %d, err=%d\n",
 			dev_name(&chip->dev), MAJOR(chip->dev.devt),
 			MINOR(chip->dev.devt), rc);
 
 		return rc;
 	}
 
-	rc = device_add(&chip->dev);
-	if (rc) {
-		dev_err(&chip->dev,
-			"unable to device_register() %s, major %d, minor %d, err=%d\n",
-			dev_name(&chip->dev), MAJOR(chip->dev.devt),
-			MINOR(chip->dev.devt), rc);
-
-		cdev_del(&chip->cdev);
-		return rc;
-	}
-
 	/* Make the chip available. */
 	mutex_lock(&idr_lock);
 	idr_replace(&dev_nums_idr, chip, chip->dev_num);
@@ -261,8 +249,7 @@ static int tpm_add_char_device(struct tpm_chip *chip)
 
 static void tpm_del_char_device(struct tpm_chip *chip)
 {
-	cdev_del(&chip->cdev);
-	device_del(&chip->dev);
+	cdev_device_del(&chip->cdev, &chip->dev);
 
 	/* Make the chip unavailable. */
 	mutex_lock(&idr_lock);