Merge remote-tracking branch 'omap_dss2/for-next'
[deliverable/linux.git] / drivers / char / hw_random / omap3-rom-rng.c
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1/*
2 * omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family
3 *
4 * Copyright (C) 2009 Nokia Corporation
5 * Author: Juha Yrjola <juha.yrjola@solidboot.com>
6 *
7 * Copyright (C) 2013 Pali Rohár <pali.rohar@gmail.com>
8 *
9 * This file is licensed under the terms of the GNU General Public
10 * License version 2. This program is licensed "as is" without any
11 * warranty of any kind, whether express or implied.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/module.h>
17#include <linux/init.h>
18#include <linux/random.h>
19#include <linux/hw_random.h>
4c13ac1c 20#include <linux/workqueue.h>
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21#include <linux/clk.h>
22#include <linux/err.h>
23#include <linux/platform_device.h>
24
25#define RNG_RESET 0x01
26#define RNG_GEN_PRNG_HW_INIT 0x02
27#define RNG_GEN_HW 0x08
28
29/* param1: ptr, param2: count, param3: flag */
30static u32 (*omap3_rom_rng_call)(u32, u32, u32);
31
4c13ac1c 32static struct delayed_work idle_work;
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33static int rng_idle;
34static struct clk *rng_clk;
35
4c13ac1c 36static void omap3_rom_rng_idle(struct work_struct *work)
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37{
38 int r;
39
40 r = omap3_rom_rng_call(0, 0, RNG_RESET);
41 if (r != 0) {
42 pr_err("reset failed: %d\n", r);
43 return;
44 }
45 clk_disable_unprepare(rng_clk);
46 rng_idle = 1;
47}
48
49static int omap3_rom_rng_get_random(void *buf, unsigned int count)
50{
51 u32 r;
52 u32 ptr;
53
4c13ac1c 54 cancel_delayed_work_sync(&idle_work);
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55 if (rng_idle) {
56 clk_prepare_enable(rng_clk);
57 r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
58 if (r != 0) {
59 clk_disable_unprepare(rng_clk);
60 pr_err("HW init failed: %d\n", r);
61 return -EIO;
62 }
63 rng_idle = 0;
64 }
65
66 ptr = virt_to_phys(buf);
67 r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW);
4c13ac1c 68 schedule_delayed_work(&idle_work, msecs_to_jiffies(500));
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69 if (r != 0)
70 return -EINVAL;
71 return 0;
72}
73
161040fc 74static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w)
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75{
76 int r;
77
78 r = omap3_rom_rng_get_random(data, 4);
79 if (r < 0)
80 return r;
81 return 4;
82}
83
84static struct hwrng omap3_rom_rng_ops = {
85 .name = "omap3-rom",
161040fc 86 .read = omap3_rom_rng_read,
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87};
88
89static int omap3_rom_rng_probe(struct platform_device *pdev)
90{
91 pr_info("initializing\n");
92
93 omap3_rom_rng_call = pdev->dev.platform_data;
94 if (!omap3_rom_rng_call) {
95 pr_err("omap3_rom_rng_call is NULL\n");
96 return -EINVAL;
97 }
98
4c13ac1c 99 INIT_DELAYED_WORK(&idle_work, omap3_rom_rng_idle);
0574bce9 100 rng_clk = devm_clk_get(&pdev->dev, "ick");
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101 if (IS_ERR(rng_clk)) {
102 pr_err("unable to get RNG clock\n");
103 return PTR_ERR(rng_clk);
104 }
105
106 /* Leave the RNG in reset state. */
107 clk_prepare_enable(rng_clk);
108 omap3_rom_rng_idle(0);
109
110 return hwrng_register(&omap3_rom_rng_ops);
111}
112
113static int omap3_rom_rng_remove(struct platform_device *pdev)
114{
4c13ac1c 115 cancel_delayed_work_sync(&idle_work);
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116 hwrng_unregister(&omap3_rom_rng_ops);
117 clk_disable_unprepare(rng_clk);
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118 return 0;
119}
120
121static struct platform_driver omap3_rom_rng_driver = {
122 .driver = {
123 .name = "omap3-rom-rng",
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124 },
125 .probe = omap3_rom_rng_probe,
126 .remove = omap3_rom_rng_remove,
127};
128
129module_platform_driver(omap3_rom_rng_driver);
130
131MODULE_ALIAS("platform:omap3-rom-rng");
132MODULE_AUTHOR("Juha Yrjola");
133MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
134MODULE_LICENSE("GPL");
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