1 /* 2 * Copyright (C) 2006-2007 PA Semi, Inc 3 * 4 * Maintained by: Olof Johansson <olof@lixom.net> 5 * 6 * Driver for the PWRficient onchip rng 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 22 #include <linux/module.h> 23 #include <linux/kernel.h> 24 #include <linux/platform_device.h> 25 #include <linux/hw_random.h> 26 #include <asm/of_platform.h> 27 #include <asm/io.h> 28 29 #define SDCRNG_CTL_REG 0x00 30 #define SDCRNG_CTL_FVLD_M 0x0000f000 31 #define SDCRNG_CTL_FVLD_S 12 32 #define SDCRNG_CTL_KSZ 0x00000800 33 #define SDCRNG_CTL_RSRC_CRG 0x00000010 34 #define SDCRNG_CTL_RSRC_RRG 0x00000000 35 #define SDCRNG_CTL_CE 0x00000004 36 #define SDCRNG_CTL_RE 0x00000002 37 #define SDCRNG_CTL_DR 0x00000001 38 #define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG) 39 #define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG) 40 #define SDCRNG_VAL_REG 0x20 41 42 #define MODULE_NAME "pasemi_rng" 43 44 static int pasemi_rng_data_present(struct hwrng *rng) 45 { 46 void __iomem *rng_regs = (void __iomem *)rng->priv; 47 48 return (in_le32(rng_regs + SDCRNG_CTL_REG) 49 & SDCRNG_CTL_FVLD_M) ? 1 : 0; 50 } 51 52 static int pasemi_rng_data_read(struct hwrng *rng, u32 *data) 53 { 54 void __iomem *rng_regs = (void __iomem *)rng->priv; 55 *data = in_le32(rng_regs + SDCRNG_VAL_REG); 56 return 4; 57 } 58 59 static int pasemi_rng_init(struct hwrng *rng) 60 { 61 void __iomem *rng_regs = (void __iomem *)rng->priv; 62 u32 ctl; 63 64 ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ; 65 out_le32(rng_regs + SDCRNG_CTL_REG, ctl); 66 out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR); 67 68 return 0; 69 } 70 71 static void pasemi_rng_cleanup(struct hwrng *rng) 72 { 73 void __iomem *rng_regs = (void __iomem *)rng->priv; 74 u32 ctl; 75 76 ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE; 77 out_le32(rng_regs + SDCRNG_CTL_REG, 78 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl); 79 } 80 81 static struct hwrng pasemi_rng = { 82 .name = MODULE_NAME, 83 .init = pasemi_rng_init, 84 .cleanup = pasemi_rng_cleanup, 85 .data_present = pasemi_rng_data_present, 86 .data_read = pasemi_rng_data_read, 87 }; 88 89 static int __devinit rng_probe(struct of_device *ofdev, 90 const struct of_device_id *match) 91 { 92 void __iomem *rng_regs; 93 struct device_node *rng_np = ofdev->node; 94 struct resource res; 95 int err = 0; 96 97 err = of_address_to_resource(rng_np, 0, &res); 98 if (err) 99 return -ENODEV; 100 101 rng_regs = ioremap(res.start, 0x100); 102 103 if (!rng_regs) 104 return -ENOMEM; 105 106 pasemi_rng.priv = (unsigned long)rng_regs; 107 108 printk(KERN_INFO "Registering PA Semi RNG\n"); 109 110 err = hwrng_register(&pasemi_rng); 111 112 if (err) 113 iounmap(rng_regs); 114 115 return err; 116 } 117 118 static int __devexit rng_remove(struct of_device *dev) 119 { 120 void __iomem *rng_regs = (void __iomem *)pasemi_rng.priv; 121 122 hwrng_unregister(&pasemi_rng); 123 iounmap(rng_regs); 124 125 return 0; 126 } 127 128 static struct of_device_id rng_match[] = { 129 { 130 .compatible = "1682m-rng", 131 }, 132 {}, 133 }; 134 135 static struct of_platform_driver rng_driver = { 136 .name = "pasemi-rng", 137 .match_table = rng_match, 138 .probe = rng_probe, 139 .remove = rng_remove, 140 }; 141 142 static int __init rng_init(void) 143 { 144 return of_register_platform_driver(&rng_driver); 145 } 146 module_init(rng_init); 147 148 static void __exit rng_exit(void) 149 { 150 of_unregister_platform_driver(&rng_driver); 151 } 152 module_exit(rng_exit); 153 154 MODULE_LICENSE("GPL"); 155 MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>"); 156 MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor"); 157