projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| bc85b25e AR |
1 | /* |
| 2 | * Nomadik RNG support | |
| 3 | * Copyright 2009 Alessandro Rubini | |
| 4 | * | |
| 5 | * This program is free software; you can redistribute it and/or modify | |
| 6 | * it under the terms of the GNU General Public License as published by | |
| 7 | * the Free Software Foundation; either version 2 of the License, or | |
| 8 | * (at your option) any later version. | |
| 9 | */ | |
| 10 | ||
| 11 | #include <linux/kernel.h> | |
| 12 | #include <linux/module.h> | |
| 13 | #include <linux/init.h> | |
| 14 | #include <linux/device.h> | |
| 15 | #include <linux/amba/bus.h> | |
| 16 | #include <linux/hw_random.h> | |
| 17 | #include <linux/io.h> | |
| 18 | ||
| 19 | static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) | |
| 20 | { | |
| 21 | void __iomem *base = (void __iomem *)rng->priv; | |
| 22 | ||
| 23 | /* | |
| 24 | * The register is 32 bits and gives 16 random bits (low half). | |
| 25 | * A subsequent read will delay the core for 400ns, so we just read | |
| 26 | * once and accept the very unlikely very small delay, even if wait==0. | |
| 27 | */ | |
| 28 | *(u16 *)data = __raw_readl(base + 8) & 0xffff; | |
| 29 | return 2; | |
| 30 | } | |
| 31 | ||
| 32 | /* we have at most one RNG per machine, granted */ | |
| 33 | static struct hwrng nmk_rng = { | |
| 34 | .name = "nomadik", | |
| 35 | .read = nmk_rng_read, | |
| 36 | }; | |
| 37 | ||
| 38 | static int nmk_rng_probe(struct amba_device *dev, struct amba_id *id) | |
| 39 | { | |
| 40 | void __iomem *base; | |
| 41 | int ret; | |
| 42 | ||
| 43 | ret = amba_request_regions(dev, dev->dev.init_name); | |
| 44 | if (ret) | |
| 45 | return ret; | |
| 46 | ret = -ENOMEM; | |
| 47 | base = ioremap(dev->res.start, resource_size(&dev->res)); | |
| 48 | if (!base) | |
| 49 | goto out_release; | |
| 50 | nmk_rng.priv = (unsigned long)base; | |
| 51 | ret = hwrng_register(&nmk_rng); | |
| 52 | if (ret) | |
| 53 | goto out_unmap; | |
| 54 | return 0; | |
| 55 | ||
| 56 | out_unmap: | |
| 57 | iounmap(base); | |
| 58 | out_release: | |
| 59 | amba_release_regions(dev); | |
| 60 | return ret; | |
| 61 | } | |
| 62 | ||
| 63 | static int nmk_rng_remove(struct amba_device *dev) | |
| 64 | { | |
| 65 | void __iomem *base = (void __iomem *)nmk_rng.priv; | |
| 66 | hwrng_unregister(&nmk_rng); | |
| 67 | iounmap(base); | |
| 68 | amba_release_regions(dev); | |
| 69 | return 0; | |
| 70 | } | |
| 71 | ||
| 72 | static struct amba_id nmk_rng_ids[] = { | |
| 73 | { | |
| 74 | .id = 0x000805e1, | |
| 75 | .mask = 0x000fffff, /* top bits are rev and cfg: accept all */ | |
| 76 | }, | |
| 77 | {0, 0}, | |
| 78 | }; | |
| 79 | ||
| 80 | static struct amba_driver nmk_rng_driver = { | |
| 81 | .drv = { | |
| 82 | .owner = THIS_MODULE, | |
| 83 | .name = "rng", | |
| 84 | }, | |
| 85 | .probe = nmk_rng_probe, | |
| 86 | .remove = nmk_rng_remove, | |
| 87 | .id_table = nmk_rng_ids, | |
| 88 | }; | |
| 89 | ||
| 90 | static int __init nmk_rng_init(void) | |
| 91 | { | |
| 92 | return amba_driver_register(&nmk_rng_driver); | |
| 93 | } | |
| 94 | ||
| 95 | static void __devexit nmk_rng_exit(void) | |
| 96 | { | |
| 97 | amba_driver_unregister(&nmk_rng_driver); | |
| 98 | } | |
| 99 | ||
| 100 | module_init(nmk_rng_init); | |
| 101 | module_exit(nmk_rng_exit); | |
| 102 | ||
| 103 | MODULE_LICENSE("GPL"); |