1 /* 2 * RNG driver for AMD 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/module.h> 28 #include <linux/kernel.h> 29 #include <linux/pci.h> 30 #include <linux/hw_random.h> 31 #include <linux/delay.h> 32 #include <asm/io.h> 33 34 35 #define PFX KBUILD_MODNAME ": " 36 37 38 /* 39 * Data for PCI driver interface 40 * 41 * This data only exists for exporting the supported 42 * PCI ids via MODULE_DEVICE_TABLE. We do not actually 43 * register a pci_driver, because someone else might one day 44 * want to register another driver on the same PCI id. 45 */ 46 static const struct pci_device_id pci_tbl[] = { 47 { PCI_VDEVICE(AMD, 0x7443), 0, }, 48 { PCI_VDEVICE(AMD, 0x746b), 0, }, 49 { 0, }, /* terminate list */ 50 }; 51 MODULE_DEVICE_TABLE(pci, pci_tbl); 52 53 static struct pci_dev *amd_pdev; 54 55 56 static int amd_rng_data_present(struct hwrng *rng, int wait) 57 { 58 u32 pmbase = (u32)rng->priv; 59 int data, i; 60 61 for (i = 0; i < 20; i++) { 62 data = !!(inl(pmbase + 0xF4) & 1); 63 if (data || !wait) 64 break; 65 udelay(10); 66 } 67 return data; 68 } 69 70 static int amd_rng_data_read(struct hwrng *rng, u32 *data) 71 { 72 u32 pmbase = (u32)rng->priv; 73 74 *data = inl(pmbase + 0xF0); 75 76 return 4; 77 } 78 79 static int amd_rng_init(struct hwrng *rng) 80 { 81 u8 rnen; 82 83 pci_read_config_byte(amd_pdev, 0x40, &rnen); 84 rnen |= (1 << 7); /* RNG on */ 85 pci_write_config_byte(amd_pdev, 0x40, rnen); 86 87 pci_read_config_byte(amd_pdev, 0x41, &rnen); 88 rnen |= (1 << 7); /* PMIO enable */ 89 pci_write_config_byte(amd_pdev, 0x41, rnen); 90 91 return 0; 92 } 93 94 static void amd_rng_cleanup(struct hwrng *rng) 95 { 96 u8 rnen; 97 98 pci_read_config_byte(amd_pdev, 0x40, &rnen); 99 rnen &= ~(1 << 7); /* RNG off */ 100 pci_write_config_byte(amd_pdev, 0x40, rnen); 101 } 102 103 104 static struct hwrng amd_rng = { 105 .name = "amd", 106 .init = amd_rng_init, 107 .cleanup = amd_rng_cleanup, 108 .data_present = amd_rng_data_present, 109 .data_read = amd_rng_data_read, 110 }; 111 112 113 static int __init mod_init(void) 114 { 115 int err = -ENODEV; 116 struct pci_dev *pdev = NULL; 117 const struct pci_device_id *ent; 118 u32 pmbase; 119 120 for_each_pci_dev(pdev) { 121 ent = pci_match_id(pci_tbl, pdev); 122 if (ent) 123 goto found; 124 } 125 /* Device not found. */ 126 goto out; 127 128 found: 129 err = pci_read_config_dword(pdev, 0x58, &pmbase); 130 if (err) 131 goto out; 132 err = -EIO; 133 pmbase &= 0x0000FF00; 134 if (pmbase == 0) 135 goto out; 136 if (!request_region(pmbase + 0xF0, 8, "AMD HWRNG")) { 137 dev_err(&pdev->dev, "AMD HWRNG region 0x%x already in use!\n", 138 pmbase + 0xF0); 139 err = -EBUSY; 140 goto out; 141 } 142 amd_rng.priv = (unsigned long)pmbase; 143 amd_pdev = pdev; 144 145 pr_info("AMD768 RNG detected\n"); 146 err = hwrng_register(&amd_rng); 147 if (err) { 148 pr_err(PFX "RNG registering failed (%d)\n", 149 err); 150 release_region(pmbase + 0xF0, 8); 151 goto out; 152 } 153 out: 154 return err; 155 } 156 157 static void __exit mod_exit(void) 158 { 159 u32 pmbase = (unsigned long)amd_rng.priv; 160 release_region(pmbase + 0xF0, 8); 161 hwrng_unregister(&amd_rng); 162 } 163 164 module_init(mod_init); 165 module_exit(mod_exit); 166 167 MODULE_AUTHOR("The Linux Kernel team"); 168 MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets"); 169 MODULE_LICENSE("GPL"); 170