/* * Nomadik RNG support * Copyright 2009 Alessandro Rubini * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h> #include <linux/device.h> #include <linux/amba/bus.h> #include <linux/hw_random.h> #include <linux/io.h> static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) { void __iomem *base = (void __iomem *)rng->priv; /* * The register is 32 bits and gives 16 random bits (low half). * A subsequent read will delay the core for 400ns, so we just read * once and accept the very unlikely very small delay, even if wait==0. */ *(u16 *)data = __raw_readl(base + 8) & 0xffff; return 2; } /* we have at most one RNG per machine, granted */ static struct hwrng nmk_rng = { .name = "nomadik", .read = nmk_rng_read, }; static int nmk_rng_probe(struct amba_device *dev, struct amba_id *id) { void __iomem *base; int ret; ret = amba_request_regions(dev, dev->dev.init_name); if (ret) return ret; ret = -ENOMEM; base = ioremap(dev->res.start, resource_size(&dev->res)); if (!base) goto out_release; nmk_rng.priv = (unsigned long)base; ret = hwrng_register(&nmk_rng); if (ret) goto out_unmap; return 0; out_unmap: iounmap(base); out_release: amba_release_regions(dev); return ret; } static int nmk_rng_remove(struct amba_device *dev) { void __iomem *base = (void __iomem *)nmk_rng.priv; hwrng_unregister(&nmk_rng); iounmap(base); amba_release_regions(dev); return 0; } static struct amba_id nmk_rng_ids[] = { { .id = 0x000805e1, .mask = 0x000fffff, /* top bits are rev and cfg: accept all */ }, {0, 0}, }; static struct amba_driver nmk_rng_driver = { .drv = { .owner = THIS_MODULE, .name = "rng", }, .probe = nmk_rng_probe, .remove = nmk_rng_remove, .id_table = nmk_rng_ids, }; static int __init nmk_rng_init(void) { return amba_driver_register(&nmk_rng_driver); } static void __devexit nmk_rng_exit(void) { amba_driver_unregister(&nmk_rng_driver); } module_init(nmk_rng_init); module_exit(nmk_rng_exit); MODULE_LICENSE("GPL");