1 /* 2 * RNG driver for AMD Geode RNGs 3 * 4 * Copyright 2005 (c) MontaVista Software, Inc. 5 * 6 * with the majority of the code coming from: 7 * 8 * Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG) 9 * (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com> 10 * 11 * derived from 12 * 13 * Hardware driver for the AMD 768 Random Number Generator (RNG) 14 * (c) Copyright 2001 Red Hat Inc 15 * 16 * derived from 17 * 18 * Hardware driver for Intel i810 Random Number Generator (RNG) 19 * Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com> 20 * Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> 21 * 22 * This file is licensed under the terms of the GNU General Public 23 * License version 2. This program is licensed "as is" without any 24 * warranty of any kind, whether express or implied. 25 */ 26 27 #include <linux/delay.h> 28 #include <linux/hw_random.h> 29 #include <linux/io.h> 30 #include <linux/kernel.h> 31 #include <linux/module.h> 32 #include <linux/pci.h> 33 34 35 #define PFX KBUILD_MODNAME ": " 36 37 #define GEODE_RNG_DATA_REG 0x50 38 #define GEODE_RNG_STATUS_REG 0x54 39 40 /* 41 * Data for PCI driver interface 42 * 43 * This data only exists for exporting the supported 44 * PCI ids via MODULE_DEVICE_TABLE. We do not actually 45 * register a pci_driver, because someone else might one day 46 * want to register another driver on the same PCI id. 47 */ 48 static const struct pci_device_id pci_tbl[] = { 49 { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), 0, }, 50 { 0, }, /* terminate list */ 51 }; 52 MODULE_DEVICE_TABLE(pci, pci_tbl); 53 54 55 static int geode_rng_data_read(struct hwrng *rng, u32 *data) 56 { 57 void __iomem *mem = (void __iomem *)rng->priv; 58 59 *data = readl(mem + GEODE_RNG_DATA_REG); 60 61 return 4; 62 } 63 64 static int geode_rng_data_present(struct hwrng *rng, int wait) 65 { 66 void __iomem *mem = (void __iomem *)rng->priv; 67 int data, i; 68 69 for (i = 0; i < 20; i++) { 70 data = !!(readl(mem + GEODE_RNG_STATUS_REG)); 71 if (data || !wait) 72 break; 73 udelay(10); 74 } 75 return data; 76 } 77 78 79 static struct hwrng geode_rng = { 80 .name = "geode", 81 .data_present = geode_rng_data_present, 82 .data_read = geode_rng_data_read, 83 }; 84 85 86 static int __init geode_rng_init(void) 87 { 88 int err = -ENODEV; 89 struct pci_dev *pdev = NULL; 90 const struct pci_device_id *ent; 91 void __iomem *mem; 92 unsigned long rng_base; 93 94 for_each_pci_dev(pdev) { 95 ent = pci_match_id(pci_tbl, pdev); 96 if (ent) 97 goto found; 98 } 99 /* Device not found. */ 100 goto out; 101 102 found: 103 rng_base = pci_resource_start(pdev, 0); 104 if (rng_base == 0) 105 goto out; 106 err = -ENOMEM; 107 mem = ioremap(rng_base, 0x58); 108 if (!mem) 109 goto out; 110 geode_rng.priv = (unsigned long)mem; 111 112 pr_info("AMD Geode RNG detected\n"); 113 err = hwrng_register(&geode_rng); 114 if (err) { 115 pr_err(PFX "RNG registering failed (%d)\n", 116 err); 117 goto err_unmap; 118 } 119 out: 120 return err; 121 122 err_unmap: 123 iounmap(mem); 124 goto out; 125 } 126 127 static void __exit geode_rng_exit(void) 128 { 129 void __iomem *mem = (void __iomem *)geode_rng.priv; 130 131 hwrng_unregister(&geode_rng); 132 iounmap(mem); 133 } 134 135 module_init(geode_rng_init); 136 module_exit(geode_rng_exit); 137 138 MODULE_DESCRIPTION("H/W RNG driver for AMD Geode LX CPUs"); 139 MODULE_LICENSE("GPL"); 140