1 /* 2 * Copyright (C) 2010 Michael Neuling IBM Corporation 3 * 4 * Driver for the pseries hardware RNG for POWER7+ and above 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 */ 19 20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 21 22 #include <linux/kernel.h> 23 #include <linux/module.h> 24 #include <linux/hw_random.h> 25 #include <asm/vio.h> 26 27 28 static int pseries_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) 29 { 30 u64 buffer[PLPAR_HCALL_BUFSIZE]; 31 size_t size = max < 8 ? max : 8; 32 int rc; 33 34 rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer); 35 if (rc != H_SUCCESS) { 36 pr_err_ratelimited("H_RANDOM call failed %d\n", rc); 37 return -EIO; 38 } 39 memcpy(data, buffer, size); 40 41 /* The hypervisor interface returns 64 bits */ 42 return size; 43 } 44 45 /** 46 * pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations 47 * 48 * This is a required function for a driver to operate in a CMO environment 49 * but this device does not make use of DMA allocations, return 0. 50 * 51 * Return value: 52 * Number of bytes of IO data the driver will need to perform well -> 0 53 */ 54 static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev) 55 { 56 return 0; 57 }; 58 59 static struct hwrng pseries_rng = { 60 .name = KBUILD_MODNAME, 61 .read = pseries_rng_read, 62 }; 63 64 static int pseries_rng_probe(struct vio_dev *dev, 65 const struct vio_device_id *id) 66 { 67 return hwrng_register(&pseries_rng); 68 } 69 70 static int pseries_rng_remove(struct vio_dev *dev) 71 { 72 hwrng_unregister(&pseries_rng); 73 return 0; 74 } 75 76 static struct vio_device_id pseries_rng_driver_ids[] = { 77 { "ibm,random-v1", "ibm,random"}, 78 { "", "" } 79 }; 80 MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids); 81 82 static struct vio_driver pseries_rng_driver = { 83 .name = KBUILD_MODNAME, 84 .probe = pseries_rng_probe, 85 .remove = pseries_rng_remove, 86 .get_desired_dma = pseries_rng_get_desired_dma, 87 .id_table = pseries_rng_driver_ids 88 }; 89 90 static int __init rng_init(void) 91 { 92 pr_info("Registering IBM pSeries RNG driver\n"); 93 return vio_register_driver(&pseries_rng_driver); 94 } 95 96 module_init(rng_init); 97 98 static void __exit rng_exit(void) 99 { 100 vio_unregister_driver(&pseries_rng_driver); 101 } 102 module_exit(rng_exit); 103 104 MODULE_LICENSE("GPL"); 105 MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>"); 106 MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors"); 107