hwrng: pixocell - add support for picoxcell TRNG (5efb94ee) · Commits · e / devices / android_kernel_fairphone_FP3

drivers/char/hw_random/Kconfig

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		@@ -198,3 +198,15 @@ config HW_RANDOM_NOMADIK
		module will be called nomadik-rng.

		If unsure, say Y.

		config HW_RANDOM_PICOXCELL
		tristate "Picochip picoXcell true random number generator support"
		depends on HW_RANDOM && ARCH_PICOXCELL && PICOXCELL_PC3X3
		---help---
		This driver provides kernel-side support for the Random Number
		Generator hardware found on Picochip PC3x3 and later devices.

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

		If unsure, say Y.

drivers/char/hw_random/Makefile

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		@@ -19,3 +19,4 @@ obj-$(CONFIG_HW_RANDOM_TX4939) += tx4939-rng.o
		obj-$(CONFIG_HW_RANDOM_MXC_RNGA) += mxc-rnga.o
		obj-$(CONFIG_HW_RANDOM_OCTEON) += octeon-rng.o
		obj-$(CONFIG_HW_RANDOM_NOMADIK) += nomadik-rng.o
		obj-$(CONFIG_HW_RANDOM_PICOXCELL) += picoxcell-rng.o

drivers/char/hw_random/picoxcell-rng.c

0 → 100644

+208 −0

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		/*
		* Copyright (c) 2010-2011 Picochip Ltd., Jamie Iles
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 as
		* published by the Free Software Foundation.
		*
		* All enquiries to support@picochip.com
		*/
		#include <linux/clk.h>
		#include <linux/delay.h>
		#include <linux/err.h>
		#include <linux/hw_random.h>
		#include <linux/io.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/platform_device.h>

		#define DATA_REG_OFFSET 0x0200
		#define CSR_REG_OFFSET 0x0278
		#define CSR_OUT_EMPTY_MASK (1 << 24)
		#define CSR_FAULT_MASK (1 << 1)
		#define TRNG_BLOCK_RESET_MASK (1 << 0)
		#define TAI_REG_OFFSET 0x0380

		/*
		* The maximum amount of time in microseconds to spend waiting for data if the
		* core wants us to wait. The TRNG should generate 32 bits every 320ns so a
		* timeout of 20us seems reasonable. The TRNG does builtin tests of the data
		* for randomness so we can't always assume there is data present.
		*/
		#define PICO_TRNG_TIMEOUT 20

		static void __iomem *rng_base;
		static struct clk *rng_clk;
		struct device *rng_dev;

		static inline u32 picoxcell_trng_read_csr(void)
		{
		return __raw_readl(rng_base + CSR_REG_OFFSET);
		}

		static inline bool picoxcell_trng_is_empty(void)
		{
		return picoxcell_trng_read_csr() & CSR_OUT_EMPTY_MASK;
		}

		/*
		* Take the random number generator out of reset and make sure the interrupts
		* are masked. We shouldn't need to get large amounts of random bytes so just
		* poll the status register. The hardware generates 32 bits every 320ns so we
		* shouldn't have to wait long enough to warrant waiting for an IRQ.
		*/
		static void picoxcell_trng_start(void)
		{
		__raw_writel(0, rng_base + TAI_REG_OFFSET);
		__raw_writel(0, rng_base + CSR_REG_OFFSET);
		}

		static void picoxcell_trng_reset(void)
		{
		__raw_writel(TRNG_BLOCK_RESET_MASK, rng_base + CSR_REG_OFFSET);
		__raw_writel(TRNG_BLOCK_RESET_MASK, rng_base + TAI_REG_OFFSET);
		picoxcell_trng_start();
		}

		/*
		* Get some random data from the random number generator. The hw_random core
		* layer provides us with locking.
		*/
		static int picoxcell_trng_read(struct hwrng rng, void buf, size_t max,
		bool wait)
		{
		int i;

		/* Wait for some data to become available. */
		for (i = 0; i < PICO_TRNG_TIMEOUT && picoxcell_trng_is_empty(); ++i) {
		if (!wait)
		return 0;

		udelay(1);
		}

		if (picoxcell_trng_read_csr() & CSR_FAULT_MASK) {
		dev_err(rng_dev, "fault detected, resetting TRNG\n");
		picoxcell_trng_reset();
		return -EIO;
		}

		if (i == PICO_TRNG_TIMEOUT)
		return 0;

		(u32 )buf = __raw_readl(rng_base + DATA_REG_OFFSET);
		return sizeof(u32);
		}

		static struct hwrng picoxcell_trng = {
		.name = "picoxcell",
		.read = picoxcell_trng_read,
		};

		static int picoxcell_trng_probe(struct platform_device *pdev)
		{
		int ret;
		struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);

		if (!mem) {
		dev_warn(&pdev->dev, "no memory resource\n");
		return -ENOMEM;
		}

		if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
		"picoxcell_trng")) {
		dev_warn(&pdev->dev, "unable to request io mem\n");
		return -EBUSY;
		}

		rng_base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
		if (!rng_base) {
		dev_warn(&pdev->dev, "unable to remap io mem\n");
		return -ENOMEM;
		}

		rng_clk = clk_get(&pdev->dev, NULL);
		if (IS_ERR(rng_clk)) {
		dev_warn(&pdev->dev, "no clk\n");
		return PTR_ERR(rng_clk);
		}

		ret = clk_enable(rng_clk);
		if (ret) {
		dev_warn(&pdev->dev, "unable to enable clk\n");
		goto err_enable;
		}

		picoxcell_trng_start();
		ret = hwrng_register(&picoxcell_trng);
		if (ret)
		goto err_register;

		rng_dev = &pdev->dev;
		dev_info(&pdev->dev, "pixoxcell random number generator active\n");

		return 0;

		err_register:
		clk_disable(rng_clk);
		err_enable:
		clk_put(rng_clk);

		return ret;
		}

		static int __devexit picoxcell_trng_remove(struct platform_device *pdev)
		{
		hwrng_unregister(&picoxcell_trng);
		clk_disable(rng_clk);
		clk_put(rng_clk);

		return 0;
		}

		#ifdef CONFIG_PM
		static int picoxcell_trng_suspend(struct device *dev)
		{
		clk_disable(rng_clk);

		return 0;
		}

		static int picoxcell_trng_resume(struct device *dev)
		{
		return clk_enable(rng_clk);
		}

		static const struct dev_pm_ops picoxcell_trng_pm_ops = {
		.suspend = picoxcell_trng_suspend,
		.resume = picoxcell_trng_resume,
		};
		#endif /* CONFIG_PM */

		static struct platform_driver picoxcell_trng_driver = {
		.probe = picoxcell_trng_probe,
		.remove = __devexit_p(picoxcell_trng_remove),
		.driver = {
		.name = "picoxcell-trng",
		.owner = THIS_MODULE,
		#ifdef CONFIG_PM
		.pm = &picoxcell_trng_pm_ops,
		#endif /* CONFIG_PM */
		},
		};

		static int __init picoxcell_trng_init(void)
		{
		return platform_driver_register(&picoxcell_trng_driver);
		}
		module_init(picoxcell_trng_init);

		static void __exit picoxcell_trng_exit(void)
		{
		platform_driver_unregister(&picoxcell_trng_driver);
		}
		module_exit(picoxcell_trng_exit);

		MODULE_LICENSE("GPL");
		MODULE_AUTHOR("Jamie Iles");
		MODULE_DESCRIPTION("Picochip picoXcell TRNG driver");