| Lubomir Rintel | 8c4196a | 2013-03-28 07:19:38 +0100 | [diff] [blame] | 1 | /** |
| 2 | * Copyright (c) 2010-2012 Broadcom. All rights reserved. |
| 3 | * Copyright (c) 2013 Lubomir Rintel |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU General Public License ("GPL") |
| 7 | * version 2, as published by the Free Software Foundation. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/hw_random.h> |
| 11 | #include <linux/init.h> |
| 12 | #include <linux/io.h> |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/of_address.h> |
| 16 | #include <linux/of_platform.h> |
| 17 | #include <linux/platform_device.h> |
| 18 | #include <linux/printk.h> |
| 19 | |
| 20 | #define RNG_CTRL 0x0 |
| 21 | #define RNG_STATUS 0x4 |
| 22 | #define RNG_DATA 0x8 |
| 23 | |
| 24 | /* enable rng */ |
| 25 | #define RNG_RBGEN 0x1 |
| 26 | |
| 27 | /* the initial numbers generated are "less random" so will be discarded */ |
| 28 | #define RNG_WARMUP_COUNT 0x40000 |
| 29 | |
| 30 | static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, |
| 31 | bool wait) |
| 32 | { |
| 33 | void __iomem *rng_base = (void __iomem *)rng->priv; |
| 34 | |
| 35 | while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) { |
| 36 | if (!wait) |
| 37 | return 0; |
| 38 | cpu_relax(); |
| 39 | } |
| 40 | |
| 41 | *(u32 *)buf = __raw_readl(rng_base + RNG_DATA); |
| 42 | return sizeof(u32); |
| 43 | } |
| 44 | |
| 45 | static struct hwrng bcm2835_rng_ops = { |
| 46 | .name = "bcm2835", |
| 47 | .read = bcm2835_rng_read, |
| 48 | }; |
| 49 | |
| 50 | static int bcm2835_rng_probe(struct platform_device *pdev) |
| 51 | { |
| 52 | struct device *dev = &pdev->dev; |
| 53 | struct device_node *np = dev->of_node; |
| 54 | void __iomem *rng_base; |
| 55 | int err; |
| 56 | |
| 57 | /* map peripheral */ |
| 58 | rng_base = of_iomap(np, 0); |
| 59 | if (!rng_base) { |
| 60 | dev_err(dev, "failed to remap rng regs"); |
| 61 | return -ENODEV; |
| 62 | } |
| 63 | bcm2835_rng_ops.priv = (unsigned long)rng_base; |
| 64 | |
| 65 | /* register driver */ |
| 66 | err = hwrng_register(&bcm2835_rng_ops); |
| 67 | if (err) { |
| 68 | dev_err(dev, "hwrng registration failed\n"); |
| 69 | iounmap(rng_base); |
| 70 | } else { |
| 71 | dev_info(dev, "hwrng registered\n"); |
| 72 | |
| 73 | /* set warm-up count & enable */ |
| 74 | __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS); |
| 75 | __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL); |
| 76 | } |
| 77 | return err; |
| 78 | } |
| 79 | |
| 80 | static int bcm2835_rng_remove(struct platform_device *pdev) |
| 81 | { |
| 82 | void __iomem *rng_base = (void __iomem *)bcm2835_rng_ops.priv; |
| 83 | |
| 84 | /* disable rng hardware */ |
| 85 | __raw_writel(0, rng_base + RNG_CTRL); |
| 86 | |
| 87 | /* unregister driver */ |
| 88 | hwrng_unregister(&bcm2835_rng_ops); |
| 89 | iounmap(rng_base); |
| 90 | |
| 91 | return 0; |
| 92 | } |
| 93 | |
| 94 | static const struct of_device_id bcm2835_rng_of_match[] = { |
| 95 | { .compatible = "brcm,bcm2835-rng", }, |
| 96 | {}, |
| 97 | }; |
| 98 | MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match); |
| 99 | |
| 100 | static struct platform_driver bcm2835_rng_driver = { |
| 101 | .driver = { |
| 102 | .name = "bcm2835-rng", |
| 103 | .owner = THIS_MODULE, |
| 104 | .of_match_table = bcm2835_rng_of_match, |
| 105 | }, |
| 106 | .probe = bcm2835_rng_probe, |
| 107 | .remove = bcm2835_rng_remove, |
| 108 | }; |
| 109 | module_platform_driver(bcm2835_rng_driver); |
| 110 | |
| 111 | MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); |
| 112 | MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver"); |
| 113 | MODULE_LICENSE("GPLv2"); |