hwrng: stm32 - add support for STM32 HW RNG (c6a97c42) · Commits · e / devices / android_kernel_samsung_universal8895

drivers/char/hw_random/Kconfig

+12 −0

Original line number	Original line	Diff line number	Diff line
	@@ -369,6 +369,18 @@ config HW_RANDOM_XGENE

	If unsure, say Y.		If unsure, say Y.

			config HW_RANDOM_STM32
			tristate "STMicroelectronics STM32 random number generator"
			depends on HW_RANDOM && (ARCH_STM32 \|\| COMPILE_TEST)
			help
			This driver provides kernel-side support for the Random Number
			Generator hardware found on STM32 microcontrollers.

			To compile this driver as a module, choose M here: the
			module will be called stm32-rng.

			If unsure, say N.

	endif # HW_RANDOM		endif # HW_RANDOM

	config UML_RANDOM		config UML_RANDOM

drivers/char/hw_random/Makefile

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -32,3 +32,4 @@ obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
	obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o		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

drivers/char/hw_random/stm32-rng.c

0 → 100644

+202 −0

Original line number	Original line	Diff line number	Diff line
			/*
			* Copyright (c) 2015, Daniel Thompson
			*
			* This file is free software; you can redistribute it and/or
			* modify it under the terms of the GNU General Public License
			* as published by the Free Software Foundation; either version 2
			* of the License, or (at your option) any later version.
			*
			* This file is distributed in the hope that 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/delay.h>
			#include <linux/hw_random.h>
			#include <linux/io.h>
			#include <linux/kernel.h>
			#include <linux/module.h>
			#include <linux/of_address.h>
			#include <linux/of_platform.h>
			#include <linux/pm_runtime.h>
			#include <linux/slab.h>

			#define RNG_CR 0x00
			#define RNG_CR_RNGEN BIT(2)

			#define RNG_SR 0x04
			#define RNG_SR_SEIS BIT(6)
			#define RNG_SR_CEIS BIT(5)
			#define RNG_SR_DRDY BIT(0)

			#define RNG_DR 0x08

			/*
			* It takes 40 cycles @ 48MHz to generate each random number (e.g. <1us).
			* At the time of writing STM32 parts max out at ~200MHz meaning a timeout
			* of 500 leaves us a very comfortable margin for error. The loop to which
			* the timeout applies takes at least 4 instructions per iteration so the
			* timeout is enough to take us up to multi-GHz parts!
			*/
			#define RNG_TIMEOUT 500

			struct stm32_rng_private {
			struct hwrng rng;
			void __iomem *base;
			struct clk *clk;
			};

			static int stm32_rng_read(struct hwrng rng, void data, size_t max, bool wait)
			{
			struct stm32_rng_private *priv =
			container_of(rng, struct stm32_rng_private, rng);
			u32 sr;
			int retval = 0;

			pm_runtime_get_sync((struct device *) priv->rng.priv);

			while (max > sizeof(u32)) {
			sr = readl_relaxed(priv->base + RNG_SR);
			if (!sr && wait) {
			unsigned int timeout = RNG_TIMEOUT;

			do {
			cpu_relax();
			sr = readl_relaxed(priv->base + RNG_SR);
			} while (!sr && --timeout);
			}

			/* If error detected or data not ready... */
			if (sr != RNG_SR_DRDY)
			break;

			(u32 )data = readl_relaxed(priv->base + RNG_DR);

			retval += sizeof(u32);
			data += sizeof(u32);
			max -= sizeof(u32);
			}

			if (WARN_ONCE(sr & (RNG_SR_SEIS \| RNG_SR_CEIS),
			"bad RNG status - %x\n", sr))
			writel_relaxed(0, priv->base + RNG_SR);

			pm_runtime_mark_last_busy((struct device *) priv->rng.priv);
			pm_runtime_put_sync_autosuspend((struct device *) priv->rng.priv);

			return retval \|\| !wait ? retval : -EIO;
			}

			static int stm32_rng_init(struct hwrng *rng)
			{
			struct stm32_rng_private *priv =
			container_of(rng, struct stm32_rng_private, rng);
			int err;

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

			writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR);

			/* clear error indicators */
			writel_relaxed(0, priv->base + RNG_SR);

			return 0;
			}

			static void stm32_rng_cleanup(struct hwrng *rng)
			{
			struct stm32_rng_private *priv =
			container_of(rng, struct stm32_rng_private, rng);

			writel_relaxed(0, priv->base + RNG_CR);
			clk_disable_unprepare(priv->clk);
			}

			static int stm32_rng_probe(struct platform_device *ofdev)
			{
			struct device *dev = &ofdev->dev;
			struct device_node *np = ofdev->dev.of_node;
			struct stm32_rng_private *priv;
			struct resource res;
			int err;

			priv = devm_kzalloc(dev, sizeof(struct stm32_rng_private), GFP_KERNEL);
			if (!priv)
			return -ENOMEM;

			err = of_address_to_resource(np, 0, &res);
			if (err)
			return err;

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

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

			dev_set_drvdata(dev, priv);

			priv->rng.name = dev_driver_string(dev),
			#ifndef CONFIG_PM
			priv->rng.init = stm32_rng_init,
			priv->rng.cleanup = stm32_rng_cleanup,
			#endif
			priv->rng.read = stm32_rng_read,
			priv->rng.priv = (unsigned long) dev;

			pm_runtime_set_autosuspend_delay(dev, 100);
			pm_runtime_use_autosuspend(dev);
			pm_runtime_enable(dev);

			return devm_hwrng_register(dev, &priv->rng);
			}

			#ifdef CONFIG_PM
			static int stm32_rng_runtime_suspend(struct device *dev)
			{
			struct stm32_rng_private *priv = dev_get_drvdata(pdev);

			stm32_rng_cleanup(&priv->rng);

			return 0;
			}

			static int stm32_rng_runtime_resume(struct device *dev)
			{
			struct stm32_rng_private *priv = dev_get_drvdata(pdev);

			return stm32_rng_init(&priv->rng);
			}
			#endif

			static UNIVERSAL_DEV_PM_OPS(stm32_rng_pm_ops, stm32_rng_runtime_suspend,
			stm32_rng_runtime_resume, NULL);

			static const struct of_device_id stm32_rng_match[] = {
			{
			.compatible = "st,stm32-rng",
			},
			{},
			};
			MODULE_DEVICE_TABLE(of, stm32_rng_match);

			static struct platform_driver stm32_rng_driver = {
			.driver = {
			.name = "stm32-rng",
			.pm = &stm32_rng_pm_ops,
			.of_match_table = stm32_rng_match,
			},
			.probe = stm32_rng_probe,
			};

			module_platform_driver(stm32_rng_driver);

			MODULE_LICENSE("GPL");
			MODULE_AUTHOR("Daniel Thompson <daniel.thompson@linaro.org>");
			MODULE_DESCRIPTION("STMicroelectronics STM32 RNG device driver");