Alessandro Rubini | bc85b25 | 2009-12-19 19:45:43 +0800 | [diff] [blame] | 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> |
Srinidhi Kasagar | 1944cc8 | 2010-05-19 06:49:13 +0100 | [diff] [blame] | 18 | #include <linux/clk.h> |
| 19 | #include <linux/err.h> |
| 20 | |
| 21 | static struct clk *rng_clk; |
Alessandro Rubini | bc85b25 | 2009-12-19 19:45:43 +0800 | [diff] [blame] | 22 | |
| 23 | static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) |
| 24 | { |
| 25 | void __iomem *base = (void __iomem *)rng->priv; |
| 26 | |
| 27 | /* |
| 28 | * The register is 32 bits and gives 16 random bits (low half). |
| 29 | * A subsequent read will delay the core for 400ns, so we just read |
| 30 | * once and accept the very unlikely very small delay, even if wait==0. |
| 31 | */ |
| 32 | *(u16 *)data = __raw_readl(base + 8) & 0xffff; |
| 33 | return 2; |
| 34 | } |
| 35 | |
| 36 | /* we have at most one RNG per machine, granted */ |
| 37 | static struct hwrng nmk_rng = { |
| 38 | .name = "nomadik", |
| 39 | .read = nmk_rng_read, |
| 40 | }; |
| 41 | |
Russell King | aa25afa | 2011-02-19 15:55:00 +0000 | [diff] [blame] | 42 | static int nmk_rng_probe(struct amba_device *dev, const struct amba_id *id) |
Alessandro Rubini | bc85b25 | 2009-12-19 19:45:43 +0800 | [diff] [blame] | 43 | { |
| 44 | void __iomem *base; |
| 45 | int ret; |
| 46 | |
Srinidhi Kasagar | 1944cc8 | 2010-05-19 06:49:13 +0100 | [diff] [blame] | 47 | rng_clk = clk_get(&dev->dev, NULL); |
| 48 | if (IS_ERR(rng_clk)) { |
| 49 | dev_err(&dev->dev, "could not get rng clock\n"); |
| 50 | ret = PTR_ERR(rng_clk); |
| 51 | return ret; |
| 52 | } |
| 53 | |
| 54 | clk_enable(rng_clk); |
| 55 | |
Alessandro Rubini | bc85b25 | 2009-12-19 19:45:43 +0800 | [diff] [blame] | 56 | ret = amba_request_regions(dev, dev->dev.init_name); |
| 57 | if (ret) |
Julia Lawall | 2725ae1 | 2011-06-08 21:00:55 +0800 | [diff] [blame] | 58 | goto out_clk; |
Alessandro Rubini | bc85b25 | 2009-12-19 19:45:43 +0800 | [diff] [blame] | 59 | ret = -ENOMEM; |
| 60 | base = ioremap(dev->res.start, resource_size(&dev->res)); |
| 61 | if (!base) |
| 62 | goto out_release; |
| 63 | nmk_rng.priv = (unsigned long)base; |
| 64 | ret = hwrng_register(&nmk_rng); |
| 65 | if (ret) |
| 66 | goto out_unmap; |
| 67 | return 0; |
| 68 | |
| 69 | out_unmap: |
| 70 | iounmap(base); |
| 71 | out_release: |
| 72 | amba_release_regions(dev); |
Julia Lawall | 2725ae1 | 2011-06-08 21:00:55 +0800 | [diff] [blame] | 73 | out_clk: |
Srinidhi Kasagar | 1944cc8 | 2010-05-19 06:49:13 +0100 | [diff] [blame] | 74 | clk_disable(rng_clk); |
| 75 | clk_put(rng_clk); |
Alessandro Rubini | bc85b25 | 2009-12-19 19:45:43 +0800 | [diff] [blame] | 76 | return ret; |
| 77 | } |
| 78 | |
| 79 | static int nmk_rng_remove(struct amba_device *dev) |
| 80 | { |
| 81 | void __iomem *base = (void __iomem *)nmk_rng.priv; |
| 82 | hwrng_unregister(&nmk_rng); |
| 83 | iounmap(base); |
| 84 | amba_release_regions(dev); |
Srinidhi Kasagar | 1944cc8 | 2010-05-19 06:49:13 +0100 | [diff] [blame] | 85 | clk_disable(rng_clk); |
| 86 | clk_put(rng_clk); |
Alessandro Rubini | bc85b25 | 2009-12-19 19:45:43 +0800 | [diff] [blame] | 87 | return 0; |
| 88 | } |
| 89 | |
| 90 | static struct amba_id nmk_rng_ids[] = { |
| 91 | { |
| 92 | .id = 0x000805e1, |
| 93 | .mask = 0x000fffff, /* top bits are rev and cfg: accept all */ |
| 94 | }, |
| 95 | {0, 0}, |
| 96 | }; |
| 97 | |
| 98 | static struct amba_driver nmk_rng_driver = { |
| 99 | .drv = { |
| 100 | .owner = THIS_MODULE, |
| 101 | .name = "rng", |
| 102 | }, |
| 103 | .probe = nmk_rng_probe, |
| 104 | .remove = nmk_rng_remove, |
| 105 | .id_table = nmk_rng_ids, |
| 106 | }; |
| 107 | |
| 108 | static int __init nmk_rng_init(void) |
| 109 | { |
| 110 | return amba_driver_register(&nmk_rng_driver); |
| 111 | } |
| 112 | |
| 113 | static void __devexit nmk_rng_exit(void) |
| 114 | { |
| 115 | amba_driver_unregister(&nmk_rng_driver); |
| 116 | } |
| 117 | |
| 118 | module_init(nmk_rng_init); |
| 119 | module_exit(nmk_rng_exit); |
| 120 | |
| 121 | MODULE_LICENSE("GPL"); |