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1c6b7c21 PR |
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> |
1c6b7c21 PR |
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 */ | |
30 | static u32 (*omap3_rom_rng_call)(u32, u32, u32); | |
31 | ||
4c13ac1c | 32 | static struct delayed_work idle_work; |
1c6b7c21 PR |
33 | static int rng_idle; |
34 | static struct clk *rng_clk; | |
35 | ||
4c13ac1c | 36 | static void omap3_rom_rng_idle(struct work_struct *work) |
1c6b7c21 PR |
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 | ||
49 | static 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); |
1c6b7c21 PR |
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)); |
1c6b7c21 PR |
69 | if (r != 0) |
70 | return -EINVAL; | |
71 | return 0; | |
72 | } | |
73 | ||
161040fc | 74 | static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w) |
1c6b7c21 PR |
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 | ||
84 | static struct hwrng omap3_rom_rng_ops = { | |
85 | .name = "omap3-rom", | |
161040fc | 86 | .read = omap3_rom_rng_read, |
1c6b7c21 PR |
87 | }; |
88 | ||
89 | static 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"); |
1c6b7c21 PR |
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 | ||
113 | static int omap3_rom_rng_remove(struct platform_device *pdev) | |
114 | { | |
4c13ac1c | 115 | cancel_delayed_work_sync(&idle_work); |
1c6b7c21 PR |
116 | hwrng_unregister(&omap3_rom_rng_ops); |
117 | clk_disable_unprepare(rng_clk); | |
1c6b7c21 PR |
118 | return 0; |
119 | } | |
120 | ||
121 | static struct platform_driver omap3_rom_rng_driver = { | |
122 | .driver = { | |
123 | .name = "omap3-rom-rng", | |
1c6b7c21 PR |
124 | }, |
125 | .probe = omap3_rom_rng_probe, | |
126 | .remove = omap3_rom_rng_remove, | |
127 | }; | |
128 | ||
129 | module_platform_driver(omap3_rom_rng_driver); | |
130 | ||
131 | MODULE_ALIAS("platform:omap3-rom-rng"); | |
132 | MODULE_AUTHOR("Juha Yrjola"); | |
133 | MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>"); | |
134 | MODULE_LICENSE("GPL"); |