LXR linux/drivers/char/hw_random/omap3-rom-rng.c

   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 */
  30static u32 (*omap3_rom_rng_call)(u32, u32, u32);
  31
  32static struct timer_list idle_timer;
  33static int rng_idle;
  34static struct clk *rng_clk;
  35
  36static 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
  49static 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
  74static int omap3_rom_rng_data_present(struct hwrng *rng, int wait)
  75{
  76        return 1;
  77}
  78
  79static 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
  89static 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
  95static 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
 119static 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
 126static 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
 134module_platform_driver(omap3_rom_rng_driver);
 135
 136MODULE_ALIAS("platform:omap3-rom-rng");
 137MODULE_AUTHOR("Juha Yrjola");
 138MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
 139MODULE_LICENSE("GPL");
 140