2 * omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family
4 * Copyright (C) 2009 Nokia Corporation
5 * Author: Juha Yrjola <juha.yrjola@solidboot.com>
7 * Copyright (C) 2013 Pali Rohár <pali.rohar@gmail.com>
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.
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
25 #define RNG_RESET 0x01
26 #define RNG_GEN_PRNG_HW_INIT 0x02
27 #define RNG_GEN_HW 0x08
29 /* param1: ptr, param2: count, param3: flag */
30 static u32 (*omap3_rom_rng_call
)(u32
, u32
, u32
);
32 static struct timer_list idle_timer
;
34 static struct clk
*rng_clk
;
36 static void omap3_rom_rng_idle(unsigned long data
)
40 r
= omap3_rom_rng_call(0, 0, RNG_RESET
);
42 pr_err("reset failed: %d\n", r
);
45 clk_disable_unprepare(rng_clk
);
49 static int omap3_rom_rng_get_random(void *buf
, unsigned int count
)
54 del_timer_sync(&idle_timer
);
56 clk_prepare_enable(rng_clk
);
57 r
= omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT
);
59 clk_disable_unprepare(rng_clk
);
60 pr_err("HW init failed: %d\n", r
);
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));
74 static int omap3_rom_rng_data_present(struct hwrng
*rng
, int wait
)
79 static int omap3_rom_rng_data_read(struct hwrng
*rng
, u32
*data
)
83 r
= omap3_rom_rng_get_random(data
, 4);
89 static struct hwrng omap3_rom_rng_ops
= {
91 .data_present
= omap3_rom_rng_data_present
,
92 .data_read
= omap3_rom_rng_data_read
,
95 static int omap3_rom_rng_probe(struct platform_device
*pdev
)
97 pr_info("initializing\n");
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");
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
);
112 /* Leave the RNG in reset state. */
113 clk_prepare_enable(rng_clk
);
114 omap3_rom_rng_idle(0);
116 return hwrng_register(&omap3_rom_rng_ops
);
119 static int omap3_rom_rng_remove(struct platform_device
*pdev
)
121 hwrng_unregister(&omap3_rom_rng_ops
);
122 clk_disable_unprepare(rng_clk
);
126 static struct platform_driver omap3_rom_rng_driver
= {
128 .name
= "omap3-rom-rng",
130 .probe
= omap3_rom_rng_probe
,
131 .remove
= omap3_rom_rng_remove
,
134 module_platform_driver(omap3_rom_rng_driver
);
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");