hwrng: pic32 - Add PIC32 RNG hardware driver (730d02e2) · Commits · e / devices / android_kernel_xiaomi_nabu

drivers/char/hw_random/Kconfig

+13 −0

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	@@ -381,6 +381,19 @@ config HW_RANDOM_STM32

	If unsure, say N.		If unsure, say N.

			config HW_RANDOM_PIC32
			tristate "Microchip PIC32 Random Number Generator support"
			depends on HW_RANDOM && MACH_PIC32
			default y
			---help---
			This driver provides kernel-side support for the Random Number
			Generator hardware found on a PIC32.

			To compile this driver as a module, choose M here. the
			module will be called pic32-rng.

			If unsure, say Y.

	endif # HW_RANDOM		endif # HW_RANDOM

	config UML_RANDOM		config UML_RANDOM

drivers/char/hw_random/Makefile

+1 −0

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	@@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
	obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o		obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
	obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o		obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
	obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o		obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
			obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o

drivers/char/hw_random/pic32-rng.c

0 → 100644

+155 −0

Original line number	Original line	Diff line number	Diff line
			/*
			* PIC32 RNG driver
			*
			* Joshua Henderson <joshua.henderson@microchip.com>
			* Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
			*
			* 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.
			*/

			#include <linux/clk.h>
			#include <linux/clkdev.h>
			#include <linux/err.h>
			#include <linux/hw_random.h>
			#include <linux/io.h>
			#include <linux/kernel.h>
			#include <linux/module.h>
			#include <linux/of.h>
			#include <linux/of_device.h>
			#include <linux/platform_device.h>
			#include <linux/slab.h>

			#define RNGCON 0x04
			#define TRNGEN BIT(8)
			#define PRNGEN BIT(9)
			#define PRNGCONT BIT(10)
			#define TRNGMOD BIT(11)
			#define SEEDLOAD BIT(12)
			#define RNGPOLY1 0x08
			#define RNGPOLY2 0x0C
			#define RNGNUMGEN1 0x10
			#define RNGNUMGEN2 0x14
			#define RNGSEED1 0x18
			#define RNGSEED2 0x1C
			#define RNGRCNT 0x20
			#define RCNT_MASK 0x7F

			struct pic32_rng {
			void __iomem *base;
			struct hwrng rng;
			struct clk *clk;
			};

			/*
			* The TRNG can generate up to 24Mbps. This is a timeout that should be safe
			* enough given the instructions in the loop and that the TRNG may not always
			* be at maximum rate.
			*/
			#define RNG_TIMEOUT 500

			static int pic32_rng_read(struct hwrng rng, void buf, size_t max,
			bool wait)
			{
			struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);
			u64 *data = buf;
			u32 t;
			unsigned int timeout = RNG_TIMEOUT;

			if (max < 8)
			return 0;

			do {
			t = readl(priv->base + RNGRCNT) & RCNT_MASK;
			if (t == 64) {
			/* TRNG value comes through the seed registers */
			*data = ((u64)readl(priv->base + RNGSEED2) << 32) +
			readl(priv->base + RNGSEED1);
			return 8;
			}
			} while (wait && --timeout);

			return -EIO;
			}

			static int pic32_rng_probe(struct platform_device *pdev)
			{
			struct pic32_rng *priv;
			struct resource *res;
			u32 v;
			int ret;

			priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
			if (!priv)
			return -ENOMEM;

			res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
			priv->base = devm_ioremap_resource(&pdev->dev, res);
			if (IS_ERR(priv->base))
			return PTR_ERR(priv->base);

			priv->clk = devm_clk_get(&pdev->dev, NULL);
			if (IS_ERR(priv->clk))
			return PTR_ERR(priv->clk);

			ret = clk_prepare_enable(priv->clk);
			if (ret)
			return ret;

			/* enable TRNG in enhanced mode */
			v = TRNGEN \| TRNGMOD;
			writel(v, priv->base + RNGCON);

			priv->rng.name = pdev->name;
			priv->rng.read = pic32_rng_read;

			ret = hwrng_register(&priv->rng);
			if (ret)
			goto err_register;

			platform_set_drvdata(pdev, priv);

			return 0;

			err_register:
			clk_disable_unprepare(priv->clk);
			return ret;
			}

			static int pic32_rng_remove(struct platform_device *pdev)
			{
			struct pic32_rng *rng = platform_get_drvdata(pdev);

			hwrng_unregister(&rng->rng);
			writel(0, rng->base + RNGCON);
			clk_disable_unprepare(rng->clk);
			return 0;
			}

			static const struct of_device_id pic32_rng_of_match[] = {
			{ .compatible = "microchip,pic32mzda-rng", },
			{ /* sentinel */ }
			};
			MODULE_DEVICE_TABLE(of, pic32_rng_of_match);

			static struct platform_driver pic32_rng_driver = {
			.probe = pic32_rng_probe,
			.remove = pic32_rng_remove,
			.driver = {
			.name = "pic32-rng",
			.owner = THIS_MODULE,
			.of_match_table = of_match_ptr(pic32_rng_of_match),
			},
			};

			module_platform_driver(pic32_rng_driver);

			MODULE_LICENSE("GPL");
			MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
			MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");