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| 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 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 |
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