136 lines
3.0 KiB
C
136 lines
3.0 KiB
C
/*
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* omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family
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*
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* Copyright (C) 2009 Nokia Corporation
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* Author: Juha Yrjola <juha.yrjola@solidboot.com>
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*
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* Copyright (C) 2013 Pali Rohár <pali.rohar@gmail.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/random.h>
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#include <linux/hw_random.h>
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#include <linux/workqueue.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/platform_device.h>
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#define RNG_RESET 0x01
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#define RNG_GEN_PRNG_HW_INIT 0x02
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#define RNG_GEN_HW 0x08
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/* param1: ptr, param2: count, param3: flag */
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static u32 (*omap3_rom_rng_call)(u32, u32, u32);
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static struct delayed_work idle_work;
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static int rng_idle;
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static struct clk *rng_clk;
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static void omap3_rom_rng_idle(struct work_struct *work)
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{
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int r;
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r = omap3_rom_rng_call(0, 0, RNG_RESET);
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if (r != 0) {
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pr_err("reset failed: %d\n", r);
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return;
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}
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clk_disable_unprepare(rng_clk);
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rng_idle = 1;
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}
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static int omap3_rom_rng_get_random(void *buf, unsigned int count)
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{
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u32 r;
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u32 ptr;
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cancel_delayed_work_sync(&idle_work);
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if (rng_idle) {
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clk_prepare_enable(rng_clk);
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r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
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if (r != 0) {
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clk_disable_unprepare(rng_clk);
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pr_err("HW init failed: %d\n", r);
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return -EIO;
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}
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rng_idle = 0;
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}
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ptr = virt_to_phys(buf);
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r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW);
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schedule_delayed_work(&idle_work, msecs_to_jiffies(500));
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if (r != 0)
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return -EINVAL;
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return 0;
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}
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static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w)
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{
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int r;
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r = omap3_rom_rng_get_random(data, 4);
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if (r < 0)
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return r;
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return 4;
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}
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static struct hwrng omap3_rom_rng_ops = {
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.name = "omap3-rom",
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.read = omap3_rom_rng_read,
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};
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static int omap3_rom_rng_probe(struct platform_device *pdev)
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{
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pr_info("initializing\n");
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omap3_rom_rng_call = pdev->dev.platform_data;
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if (!omap3_rom_rng_call) {
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pr_err("omap3_rom_rng_call is NULL\n");
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return -EINVAL;
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}
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INIT_DELAYED_WORK(&idle_work, omap3_rom_rng_idle);
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rng_clk = devm_clk_get(&pdev->dev, "ick");
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if (IS_ERR(rng_clk)) {
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pr_err("unable to get RNG clock\n");
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return PTR_ERR(rng_clk);
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}
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/* Leave the RNG in reset state. */
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clk_prepare_enable(rng_clk);
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omap3_rom_rng_idle(0);
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return hwrng_register(&omap3_rom_rng_ops);
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}
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static int omap3_rom_rng_remove(struct platform_device *pdev)
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{
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cancel_delayed_work_sync(&idle_work);
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hwrng_unregister(&omap3_rom_rng_ops);
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if (!rng_idle)
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clk_disable_unprepare(rng_clk);
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return 0;
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}
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static struct platform_driver omap3_rom_rng_driver = {
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.driver = {
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.name = "omap3-rom-rng",
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},
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.probe = omap3_rom_rng_probe,
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.remove = omap3_rom_rng_remove,
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};
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module_platform_driver(omap3_rom_rng_driver);
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MODULE_ALIAS("platform:omap3-rom-rng");
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MODULE_AUTHOR("Juha Yrjola");
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MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
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MODULE_LICENSE("GPL");
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