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 { 99 void __iomem *rng_regs; 100 struct device_node *rng_np = ofdev->dev.of_node; 101 struct resource res; 102 int err = 0; 103 104 err = of_address_to_resource(rng_np, 0, &res); 105 if (err) 106 return -ENODEV; 107 108 rng_regs = ioremap(res.start, 0x100); 109 110 if (!rng_regs) 111 return -ENOMEM; 112 113 pasemi_rng.priv = (unsigned long)rng_regs; 114 115 printk(KERN_INFO "Registering PA Semi RNG\n"); 116 117 err = hwrng_register(&pasemi_rng); 118 119 if (err) 120 iounmap(rng_regs); 121 122 return err; 123 } 124 125 static int rng_remove(struct platform_device *dev) 126 { 127 void __iomem *rng_regs = (void __iomem *)pasemi_rng.priv; 128 129 hwrng_unregister(&pasemi_rng); 130 iounmap(rng_regs); 131 132 return 0; 133 } 134 135 static struct of_device_id rng_match[] = { 136 { .compatible = "1682m-rng", }, 137 { .compatible = "pasemi,pwrficient-rng", }, 138 { }, 139 }; 140 141 static struct platform_driver rng_driver = { 142 .driver = { 143 .name = "pasemi-rng", 144 .owner = THIS_MODULE, 145 .of_match_table = rng_match, 146 }, 147 .probe = rng_probe, 148 .remove = rng_remove, 149 }; 150 151 module_platform_driver(rng_driver); 152 153 MODULE_LICENSE("GPL"); 154 MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>"); 155 MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor"); 156