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>
20 #include <linux/timer.h>
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
32 static struct timer_list idle_timer;
33 static int rng_idle;
34 static struct clk *rng_clk;
35
omap3_rom_rng_idle(unsigned long data)36 static void omap3_rom_rng_idle(unsigned long data)
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
omap3_rom_rng_get_random(void * buf,unsigned int count)49 static int omap3_rom_rng_get_random(void *buf, unsigned int count)
50 {
51 u32 r;
52 u32 ptr;
53
54 del_timer_sync(&idle_timer);
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);
68 mod_timer(&idle_timer, jiffies + msecs_to_jiffies(500));
69 if (r != 0)
70 return -EINVAL;
71 return 0;
72 }
73
omap3_rom_rng_data_present(struct hwrng * rng,int wait)74 static int omap3_rom_rng_data_present(struct hwrng *rng, int wait)
75 {
76 return 1;
77 }
78
omap3_rom_rng_data_read(struct hwrng * rng,u32 * data)79 static int omap3_rom_rng_data_read(struct hwrng *rng, u32 *data)
80 {
81 int r;
82
83 r = omap3_rom_rng_get_random(data, 4);
84 if (r < 0)
85 return r;
86 return 4;
87 }
88
89 static struct hwrng omap3_rom_rng_ops = {
90 .name = "omap3-rom",
91 .data_present = omap3_rom_rng_data_present,
92 .data_read = omap3_rom_rng_data_read,
93 };
94
omap3_rom_rng_probe(struct platform_device * pdev)95 static int omap3_rom_rng_probe(struct platform_device *pdev)
96 {
97 pr_info("initializing\n");
98
99 omap3_rom_rng_call = pdev->dev.platform_data;
100 if (!omap3_rom_rng_call) {
101 pr_err("omap3_rom_rng_call is NULL\n");
102 return -EINVAL;
103 }
104
105 setup_timer(&idle_timer, omap3_rom_rng_idle, 0);
106 rng_clk = devm_clk_get(&pdev->dev, "ick");
107 if (IS_ERR(rng_clk)) {
108 pr_err("unable to get RNG clock\n");
109 return PTR_ERR(rng_clk);
110 }
111
112 /* Leave the RNG in reset state. */
113 clk_prepare_enable(rng_clk);
114 omap3_rom_rng_idle(0);
115
116 return hwrng_register(&omap3_rom_rng_ops);
117 }
118
omap3_rom_rng_remove(struct platform_device * pdev)119 static int omap3_rom_rng_remove(struct platform_device *pdev)
120 {
121 hwrng_unregister(&omap3_rom_rng_ops);
122 clk_disable_unprepare(rng_clk);
123 return 0;
124 }
125
126 static struct platform_driver omap3_rom_rng_driver = {
127 .driver = {
128 .name = "omap3-rom-rng",
129 },
130 .probe = omap3_rom_rng_probe,
131 .remove = omap3_rom_rng_remove,
132 };
133
134 module_platform_driver(omap3_rom_rng_driver);
135
136 MODULE_ALIAS("platform:omap3-rom-rng");
137 MODULE_AUTHOR("Juha Yrjola");
138 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
139 MODULE_LICENSE("GPL");
140