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 <linux/delay.h> 27 #include <linux/of_platform.h> 28 #include <asm/io.h> 29 30 #define SDCRNG_CTL_REG 0x00 31 #define SDCRNG_CTL_FVLD_M 0x0000f000 32 #define SDCRNG_CTL_FVLD_S 12 33 #define SDCRNG_CTL_KSZ 0x00000800 34 #define SDCRNG_CTL_RSRC_CRG 0x00000010 35 #define SDCRNG_CTL_RSRC_RRG 0x00000000 36 #define SDCRNG_CTL_CE 0x00000004 37 #define SDCRNG_CTL_RE 0x00000002 38 #define SDCRNG_CTL_DR 0x00000001 39 #define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG) 40 #define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG) 41 #define SDCRNG_VAL_REG 0x20 42 43 #define MODULE_NAME "pasemi_rng" 44 45 static int pasemi_rng_data_present(struct hwrng *rng, int wait) 46 { 47 void __iomem *rng_regs = (void __iomem *)rng->priv; 48 int data, i; 49 50 for (i = 0; i < 20; i++) { 51 data = (in_le32(rng_regs + SDCRNG_CTL_REG) 52 & SDCRNG_CTL_FVLD_M) ? 1 : 0; 53 if (data || !wait) 54 break; 55 udelay(10); 56 } 57 return data; 58 } 59 60 static int pasemi_rng_data_read(struct hwrng *rng, u32 *data) 61 { 62 void __iomem *rng_regs = (void __iomem *)rng->priv; 63 *data = in_le32(rng_regs + SDCRNG_VAL_REG); 64 return 4; 65 } 66 67 static int pasemi_rng_init(struct hwrng *rng) 68 { 69 void __iomem *rng_regs = (void __iomem *)rng->priv; 70 u32 ctl; 71 72 ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ; 73 out_le32(rng_regs + SDCRNG_CTL_REG, ctl); 74 out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR); 75 76 return 0; 77 } 78 79 static void pasemi_rng_cleanup(struct hwrng *rng) 80 { 81 void __iomem *rng_regs = (void __iomem *)rng->priv; 82 u32 ctl; 83 84 ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE; 85 out_le32(rng_regs + SDCRNG_CTL_REG, 86 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl); 87 } 88 89 static struct hwrng pasemi_rng = { 90 .name = MODULE_NAME, 91 .init = pasemi_rng_init, 92 .cleanup = pasemi_rng_cleanup, 93 .data_present = pasemi_rng_data_present, 94 .data_read = pasemi_rng_data_read, 95 }; 96 97 static int __devinit rng_probe(struct platform_device *ofdev, 98 const struct of_device_id *match) 99 { 100 void __iomem *rng_regs; 101 struct device_node *rng_np = ofdev->dev.of_node; 102 struct resource res; 103 int err = 0; 104 105 err = of_address_to_resource(rng_np, 0, &res); 106 if (err) 107 return -ENODEV; 108 109 rng_regs = ioremap(res.start, 0x100); 110 111 if (!rng_regs) 112 return -ENOMEM; 113 114 pasemi_rng.priv = (unsigned long)rng_regs; 115 116 printk(KERN_INFO "Registering PA Semi RNG\n"); 117 118 err = hwrng_register(&pasemi_rng); 119 120 if (err) 121 iounmap(rng_regs); 122 123 return err; 124 } 125 126 static int __devexit rng_remove(struct platform_device *dev) 127 { 128 void __iomem *rng_regs = (void __iomem *)pasemi_rng.priv; 129 130 hwrng_unregister(&pasemi_rng); 131 iounmap(rng_regs); 132 133 return 0; 134 } 135 136 static struct of_device_id rng_match[] = { 137 { .compatible = "1682m-rng", }, 138 { .compatible = "pasemi,pwrficient-rng", }, 139 { }, 140 }; 141 142 static struct of_platform_driver rng_driver = { 143 .driver = { 144 .name = "pasemi-rng", 145 .owner = THIS_MODULE, 146 .of_match_table = rng_match, 147 }, 148 .probe = rng_probe, 149 .remove = rng_remove, 150 }; 151 152 static int __init rng_init(void) 153 { 154 return of_register_platform_driver(&rng_driver); 155 } 156 module_init(rng_init); 157 158 static void __exit rng_exit(void) 159 { 160 of_unregister_platform_driver(&rng_driver); 161 } 162 module_exit(rng_exit); 163 164 MODULE_LICENSE("GPL"); 165 MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>"); 166 MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor"); 167