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140 lines
3.1 KiB
140 lines
3.1 KiB
// 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 <[email protected]> |
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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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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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priv->base = devm_platform_ioremap_resource(pdev, 0); |
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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 = devm_hwrng_register(&pdev->dev, &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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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[] __maybe_unused = { |
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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 <[email protected]>"); |
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MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
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