1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2010 Michael Neuling IBM Corporation 4 * 5 * Driver for the pseries hardware RNG for POWER7+ and above 6 */ 7 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <linux/kernel.h> 11 #include <linux/module.h> 12 #include <linux/hw_random.h> 13 #include <asm/vio.h> 14 15 16 static 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 operations 34 * 35 * This is a required function for a driver to operate in a CMO environment 36 * 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 -> 0 40 */ 41 static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev) 42 { 43 return 0; 44 }; 45 46 static struct hwrng pseries_rng = { 47 .name = KBUILD_MODNAME, 48 .read = pseries_rng_read, 49 }; 50 51 static int pseries_rng_probe(struct vio_dev *dev, 52 const struct vio_device_id *id) 53 { 54 return hwrng_register(&pseries_rng); 55 } 56 57 static void pseries_rng_remove(struct vio_dev *dev) 58 { 59 hwrng_unregister(&pseries_rng); 60 } 61 62 static const struct vio_device_id pseries_rng_driver_ids[] = { 63 { "ibm,random-v1", "ibm,random"}, 64 { "", "" } 65 }; 66 MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids); 67 68 static 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_ids 74 }; 75 76 static 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 82 module_init(rng_init); 83 84 static void __exit rng_exit(void) 85 { 86 vio_unregister_driver(&pseries_rng_driver); 87 } 88 module_exit(rng_exit); 89 90 MODULE_LICENSE("GPL"); 91 MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>"); 92 MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors"); 93