TPM_NUM_DEVICES
rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
rc = alloc_chrdev_region(&tpm_devt, 0, 2*TPM_NUM_DEVICES, "tpm");
unregister_chrdev_region(tpm_devt, 2 * TPM_NUM_DEVICES);
unregister_chrdev_region(tpm_devt, 2*TPM_NUM_DEVICES);
chip->devs.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);