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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2010 Michael Neuling IBM Corporation4 *5 * Driver for the pseries hardware RNG for POWER7+ and above6 */7 8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt9 10#include <linux/kernel.h>11#include <linux/module.h>12#include <linux/hw_random.h>13#include <asm/vio.h>14 15 16static int pseries_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)17{18 u64 buffer[PLPAR_HCALL_BUFSIZE];19 int rc;20 21 rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer);22 if (rc != H_SUCCESS) {23 pr_err_ratelimited("H_RANDOM call failed %d\n", rc);24 return -EIO;25 }26 memcpy(data, buffer, 8);27 28 /* The hypervisor interface returns 64 bits */29 return 8;30}31 32/*33 * pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations34 *35 * This is a required function for a driver to operate in a CMO environment36 * but this device does not make use of DMA allocations, return 0.37 *38 * Return value:39 * Number of bytes of IO data the driver will need to perform well -> 040 */41static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev)42{43 return 0;44};45 46static struct hwrng pseries_rng = {47 .name = KBUILD_MODNAME,48 .read = pseries_rng_read,49};50 51static int pseries_rng_probe(struct vio_dev *dev,52 const struct vio_device_id *id)53{54 return hwrng_register(&pseries_rng);55}56 57static void pseries_rng_remove(struct vio_dev *dev)58{59 hwrng_unregister(&pseries_rng);60}61 62static const struct vio_device_id pseries_rng_driver_ids[] = {63 { "ibm,random-v1", "ibm,random"},64 { "", "" }65};66MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids);67 68static struct vio_driver pseries_rng_driver = {69 .name = KBUILD_MODNAME,70 .probe = pseries_rng_probe,71 .remove = pseries_rng_remove,72 .get_desired_dma = pseries_rng_get_desired_dma,73 .id_table = pseries_rng_driver_ids74};75 76static int __init rng_init(void)77{78 pr_info("Registering IBM pSeries RNG driver\n");79 return vio_register_driver(&pseries_rng_driver);80}81 82module_init(rng_init);83 84static void __exit rng_exit(void)85{86 vio_unregister_driver(&pseries_rng_driver);87}88module_exit(rng_exit);89 90MODULE_LICENSE("GPL");91MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>");92MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors");93