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04dc82e116
Based on 1 normalized pattern(s): this program is free software you can distribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 24 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Armijn Hemel <armijn@tjaldur.nl> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531190115.872212424@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
144 lines
3.2 KiB
C
144 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* PIC32 RNG driver
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*
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* Joshua Henderson <joshua.henderson@microchip.com>
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* Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
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*/
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#include <linux/clk.h>
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#include <linux/clkdev.h>
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#include <linux/err.h>
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#include <linux/hw_random.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#define RNGCON 0x04
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#define TRNGEN BIT(8)
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#define PRNGEN BIT(9)
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#define PRNGCONT BIT(10)
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#define TRNGMOD BIT(11)
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#define SEEDLOAD BIT(12)
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#define RNGPOLY1 0x08
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#define RNGPOLY2 0x0C
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#define RNGNUMGEN1 0x10
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#define RNGNUMGEN2 0x14
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#define RNGSEED1 0x18
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#define RNGSEED2 0x1C
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#define RNGRCNT 0x20
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#define RCNT_MASK 0x7F
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struct pic32_rng {
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void __iomem *base;
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struct hwrng rng;
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struct clk *clk;
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};
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/*
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* The TRNG can generate up to 24Mbps. This is a timeout that should be safe
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* enough given the instructions in the loop and that the TRNG may not always
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* be at maximum rate.
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*/
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#define RNG_TIMEOUT 500
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static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
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bool wait)
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{
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struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);
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u64 *data = buf;
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u32 t;
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unsigned int timeout = RNG_TIMEOUT;
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do {
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t = readl(priv->base + RNGRCNT) & RCNT_MASK;
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if (t == 64) {
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/* TRNG value comes through the seed registers */
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*data = ((u64)readl(priv->base + RNGSEED2) << 32) +
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readl(priv->base + RNGSEED1);
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return 8;
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}
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} while (wait && --timeout);
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return -EIO;
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}
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static int pic32_rng_probe(struct platform_device *pdev)
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{
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struct pic32_rng *priv;
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struct resource *res;
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u32 v;
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int ret;
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priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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priv->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(priv->base))
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return PTR_ERR(priv->base);
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priv->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(priv->clk))
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return PTR_ERR(priv->clk);
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ret = clk_prepare_enable(priv->clk);
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if (ret)
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return ret;
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/* enable TRNG in enhanced mode */
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v = TRNGEN | TRNGMOD;
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writel(v, priv->base + RNGCON);
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priv->rng.name = pdev->name;
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priv->rng.read = pic32_rng_read;
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ret = hwrng_register(&priv->rng);
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if (ret)
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goto err_register;
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platform_set_drvdata(pdev, priv);
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return 0;
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err_register:
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clk_disable_unprepare(priv->clk);
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return ret;
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}
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static int pic32_rng_remove(struct platform_device *pdev)
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{
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struct pic32_rng *rng = platform_get_drvdata(pdev);
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hwrng_unregister(&rng->rng);
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writel(0, rng->base + RNGCON);
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clk_disable_unprepare(rng->clk);
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return 0;
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}
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static const struct of_device_id pic32_rng_of_match[] = {
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{ .compatible = "microchip,pic32mzda-rng", },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
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static struct platform_driver pic32_rng_driver = {
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.probe = pic32_rng_probe,
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.remove = pic32_rng_remove,
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.driver = {
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.name = "pic32-rng",
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.of_match_table = of_match_ptr(pic32_rng_of_match),
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},
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};
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module_platform_driver(pic32_rng_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
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MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
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