/** * Copyright (c) 2010-2012 Broadcom. All rights reserved. * Copyright (c) 2013 Lubomir Rintel * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License ("GPL") * version 2, as published by the Free Software Foundation. */ #include <linux/hw_random.h> #include <linux/io.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of_address.h> #include <linux/of_platform.h> #include <linux/platform_device.h> #include <linux/printk.h> #define RNG_CTRL 0x0 #define RNG_STATUS 0x4 #define RNG_DATA 0x8 /* enable rng */ #define RNG_RBGEN 0x1 /* the initial numbers generated are "less random" so will be discarded */ #define RNG_WARMUP_COUNT 0x40000 static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) { void __iomem *rng_base = (void __iomem *)rng->priv; while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) { if (!wait) return 0; cpu_relax(); } *(u32 *)buf = __raw_readl(rng_base + RNG_DATA); return sizeof(u32); } static struct hwrng bcm2835_rng_ops = { .name = "bcm2835", .read = bcm2835_rng_read, }; static int bcm2835_rng_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct device_node *np = dev->of_node; void __iomem *rng_base; int err; /* map peripheral */ rng_base = of_iomap(np, 0); if (!rng_base) { dev_err(dev, "failed to remap rng regs"); return -ENODEV; } bcm2835_rng_ops.priv = (unsigned long)rng_base; /* set warm-up count & enable */ __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS); __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL); /* register driver */ err = hwrng_register(&bcm2835_rng_ops); if (err) { dev_err(dev, "hwrng registration failed\n"); iounmap(rng_base); } else dev_info(dev, "hwrng registered\n"); return err; } static int bcm2835_rng_remove(struct platform_device *pdev) { void __iomem *rng_base = (void __iomem *)bcm2835_rng_ops.priv; /* disable rng hardware */ __raw_writel(0, rng_base + RNG_CTRL); /* unregister driver */ hwrng_unregister(&bcm2835_rng_ops); iounmap(rng_base); return 0; } static const struct of_device_id bcm2835_rng_of_match[] = { { .compatible = "brcm,bcm2835-rng", }, {}, }; MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match); static struct platform_driver bcm2835_rng_driver = { .driver = { .name = "bcm2835-rng", .owner = THIS_MODULE, .of_match_table = bcm2835_rng_of_match, }, .probe = bcm2835_rng_probe, .remove = bcm2835_rng_remove, }; module_platform_driver(bcm2835_rng_driver); MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver"); MODULE_LICENSE("GPL v2");