drivers/char/hw_random/omap-rng.c - arm/linux - Git at Google

 /*
  * omap-rng.c - RNG driver for TI OMAP CPU family
  *
  * Author: Deepak Saxena <dsaxena@plexity.net>
  *
  * Copyright 2005 (c) MontaVista Software, Inc.
  *
  * Mostly based on original driver:
  *
  * Copyright (C) 2005 Nokia Corporation
  * Author: Juha Yrjölä <juha.yrjola@nokia.com>
  *
  * This file is licensed under  the terms of the GNU General Public
  * License version 2. This program is licensed "as is" without any
  * warranty of any kind, whether express or implied.
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/random.h>
 #include <linux/err.h>
 #include <linux/platform_device.h>
 #include <linux/hw_random.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_address.h>
 #include <linux/interrupt.h>
 #include <linux/clk.h>

 #include <asm/io.h>

 #define RNG_REG_STATUS_RDY			(1 << 0)

 #define RNG_REG_INTACK_RDY_MASK			(1 << 0)
 #define RNG_REG_INTACK_SHUTDOWN_OFLO_MASK	(1 << 1)
 #define RNG_SHUTDOWN_OFLO_MASK			(1 << 1)

 #define RNG_CONTROL_STARTUP_CYCLES_SHIFT	16
 #define RNG_CONTROL_STARTUP_CYCLES_MASK		(0xffff << 16)
 #define RNG_CONTROL_ENABLE_TRNG_SHIFT		10
 #define RNG_CONTROL_ENABLE_TRNG_MASK		(1 << 10)

 #define RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT	16
 #define RNG_CONFIG_MAX_REFIL_CYCLES_MASK	(0xffff << 16)
 #define RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT	0
 #define RNG_CONFIG_MIN_REFIL_CYCLES_MASK	(0xff << 0)

 #define RNG_CONTROL_STARTUP_CYCLES		0xff
 #define RNG_CONFIG_MIN_REFIL_CYCLES		0x21
 #define RNG_CONFIG_MAX_REFIL_CYCLES		0x22

 #define RNG_ALARMCNT_ALARM_TH_SHIFT		0x0
 #define RNG_ALARMCNT_ALARM_TH_MASK		(0xff << 0)
 #define RNG_ALARMCNT_SHUTDOWN_TH_SHIFT		16
 #define RNG_ALARMCNT_SHUTDOWN_TH_MASK		(0x1f << 16)
 #define RNG_ALARM_THRESHOLD			0xff
 #define RNG_SHUTDOWN_THRESHOLD			0x4

 #define RNG_REG_FROENABLE_MASK			0xffffff
 #define RNG_REG_FRODETUNE_MASK			0xffffff

 #define OMAP2_RNG_OUTPUT_SIZE			0x4
 #define OMAP4_RNG_OUTPUT_SIZE			0x8
 #define EIP76_RNG_OUTPUT_SIZE			0x10

 enum {
 	RNG_OUTPUT_0_REG = 0,
 	RNG_OUTPUT_1_REG,
 	RNG_OUTPUT_2_REG,
 	RNG_OUTPUT_3_REG,
 	RNG_STATUS_REG,
 	RNG_INTMASK_REG,
 	RNG_INTACK_REG,
 	RNG_CONTROL_REG,
 	RNG_CONFIG_REG,
 	RNG_ALARMCNT_REG,
 	RNG_FROENABLE_REG,
 	RNG_FRODETUNE_REG,
 	RNG_ALARMMASK_REG,
 	RNG_ALARMSTOP_REG,
 	RNG_REV_REG,
 	RNG_SYSCONFIG_REG,
 };

 static const u16 reg_map_omap2[] = {
 	[RNG_OUTPUT_0_REG]	= 0x0,
 	[RNG_STATUS_REG]	= 0x4,
 	[RNG_CONFIG_REG]	= 0x28,
 	[RNG_REV_REG]		= 0x3c,
 	[RNG_SYSCONFIG_REG]	= 0x40,
 };

 static const u16 reg_map_omap4[] = {
 	[RNG_OUTPUT_0_REG]	= 0x0,
 	[RNG_OUTPUT_1_REG]	= 0x4,
 	[RNG_STATUS_REG]	= 0x8,
 	[RNG_INTMASK_REG]	= 0xc,
 	[RNG_INTACK_REG]	= 0x10,
 	[RNG_CONTROL_REG]	= 0x14,
 	[RNG_CONFIG_REG]	= 0x18,
 	[RNG_ALARMCNT_REG]	= 0x1c,
 	[RNG_FROENABLE_REG]	= 0x20,
 	[RNG_FRODETUNE_REG]	= 0x24,
 	[RNG_ALARMMASK_REG]	= 0x28,
 	[RNG_ALARMSTOP_REG]	= 0x2c,
 	[RNG_REV_REG]		= 0x1FE0,
 	[RNG_SYSCONFIG_REG]	= 0x1FE4,
 };

 static const u16 reg_map_eip76[] = {
 	[RNG_OUTPUT_0_REG]	= 0x0,
 	[RNG_OUTPUT_1_REG]	= 0x4,
 	[RNG_OUTPUT_2_REG]	= 0x8,
 	[RNG_OUTPUT_3_REG]	= 0xc,
 	[RNG_STATUS_REG]	= 0x10,
 	[RNG_INTACK_REG]	= 0x10,
 	[RNG_CONTROL_REG]	= 0x14,
 	[RNG_CONFIG_REG]	= 0x18,
 	[RNG_ALARMCNT_REG]	= 0x1c,
 	[RNG_FROENABLE_REG]	= 0x20,
 	[RNG_FRODETUNE_REG]	= 0x24,
 	[RNG_ALARMMASK_REG]	= 0x28,
 	[RNG_ALARMSTOP_REG]	= 0x2c,
 	[RNG_REV_REG]		= 0x7c,
 };

 struct omap_rng_dev;
 /**
  * struct omap_rng_pdata - RNG IP block-specific data
  * @regs: Pointer to the register offsets structure.
  * @data_size: No. of bytes in RNG output.
  * @data_present: Callback to determine if data is available.
  * @init: Callback for IP specific initialization sequence.
  * @cleanup: Callback for IP specific cleanup sequence.
  */
 struct omap_rng_pdata {
 	u16	*regs;
 	u32	data_size;
 	u32	(*data_present)(struct omap_rng_dev *priv);
 	int	(*init)(struct omap_rng_dev *priv);
 	void	(*cleanup)(struct omap_rng_dev *priv);
 };

 struct omap_rng_dev {
 	void __iomem			*base;
 	struct device			*dev;
 	const struct omap_rng_pdata	*pdata;
 	struct hwrng rng;
 	struct clk 			*clk;
 };

 static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
 {
 	return __raw_readl(priv->base + priv->pdata->regs[reg]);
 }

 static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
 				      u32 val)
 {
 	__raw_writel(val, priv->base + priv->pdata->regs[reg]);
 }


 static int omap_rng_do_read(struct hwrng *rng, void *data, size_t max,
 			    bool wait)
 {
 	struct omap_rng_dev *priv;
 	int i, present;

 	priv = (struct omap_rng_dev *)rng->priv;

 	if (max < priv->pdata->data_size)
 		return 0;

 	for (i = 0; i < 20; i++) {
 		present = priv->pdata->data_present(priv);
 		if (present || !wait)
 			break;

 		udelay(10);
 	}
 	if (!present)
 		return 0;

 	memcpy_fromio(data, priv->base + priv->pdata->regs[RNG_OUTPUT_0_REG],
 		      priv->pdata->data_size);

 	if (priv->pdata->regs[RNG_INTACK_REG])
 		omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);

 	return priv->pdata->data_size;
 }

 static int omap_rng_init(struct hwrng *rng)
 {
 	struct omap_rng_dev *priv;

 	priv = (struct omap_rng_dev *)rng->priv;
 	return priv->pdata->init(priv);
 }

 static void omap_rng_cleanup(struct hwrng *rng)
 {
 	struct omap_rng_dev *priv;

 	priv = (struct omap_rng_dev *)rng->priv;
 	priv->pdata->cleanup(priv);
 }


 static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
 {
 	return omap_rng_read(priv, RNG_STATUS_REG) ? 0 : 1;
 }

 static int omap2_rng_init(struct omap_rng_dev *priv)
 {
 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x1);
 	return 0;
 }

 static void omap2_rng_cleanup(struct omap_rng_dev *priv)
 {
 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x0);
 }

 static struct omap_rng_pdata omap2_rng_pdata = {
 	.regs		= (u16 *)reg_map_omap2,
 	.data_size	= OMAP2_RNG_OUTPUT_SIZE,
 	.data_present	= omap2_rng_data_present,
 	.init		= omap2_rng_init,
 	.cleanup	= omap2_rng_cleanup,
 };

 #if defined(CONFIG_OF)
 static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
 {
 	return omap_rng_read(priv, RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
 }

 static int eip76_rng_init(struct omap_rng_dev *priv)
 {
 	u32 val;

 	/* Return if RNG is already running. */
 	if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
 		return 0;

 	/*  Number of 512 bit blocks of raw Noise Source output data that must
 	 *  be processed by either the Conditioning Function or the
 	 *  SP 800-90 DRBG ‘BC_DF’ functionality to yield a ‘full entropy’
 	 *  output value.
 	 */
 	val = 0x5 << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;

 	/* Number of FRO samples that are XOR-ed together into one bit to be
 	 * shifted into the main shift register
 	 */
 	val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
 	omap_rng_write(priv, RNG_CONFIG_REG, val);

 	/* Enable all available FROs */
 	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
 	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);

 	/* Enable TRNG */
 	val = RNG_CONTROL_ENABLE_TRNG_MASK;
 	omap_rng_write(priv, RNG_CONTROL_REG, val);

 	return 0;
 }

 static int omap4_rng_init(struct omap_rng_dev *priv)
 {
 	u32 val;

 	/* Return if RNG is already running. */
 	if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
 		return 0;

 	val = RNG_CONFIG_MIN_REFIL_CYCLES << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
 	val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
 	omap_rng_write(priv, RNG_CONFIG_REG, val);

 	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
 	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
 	val = RNG_ALARM_THRESHOLD << RNG_ALARMCNT_ALARM_TH_SHIFT;
 	val |= RNG_SHUTDOWN_THRESHOLD << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT;
 	omap_rng_write(priv, RNG_ALARMCNT_REG, val);

 	val = RNG_CONTROL_STARTUP_CYCLES << RNG_CONTROL_STARTUP_CYCLES_SHIFT;
 	val |= RNG_CONTROL_ENABLE_TRNG_MASK;
 	omap_rng_write(priv, RNG_CONTROL_REG, val);

 	return 0;
 }

 static void omap4_rng_cleanup(struct omap_rng_dev *priv)
 {
 	int val;

 	val = omap_rng_read(priv, RNG_CONTROL_REG);
 	val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
 	omap_rng_write(priv, RNG_CONTROL_REG, val);
 }

 static irqreturn_t omap4_rng_irq(int irq, void *dev_id)
 {
 	struct omap_rng_dev *priv = dev_id;
 	u32 fro_detune, fro_enable;

 	/*
 	 * Interrupt raised by a fro shutdown threshold, do the following:
 	 * 1. Clear the alarm events.
 	 * 2. De tune the FROs which are shutdown.
 	 * 3. Re enable the shutdown FROs.
 	 */
 	omap_rng_write(priv, RNG_ALARMMASK_REG, 0x0);
 	omap_rng_write(priv, RNG_ALARMSTOP_REG, 0x0);

 	fro_enable = omap_rng_read(priv, RNG_FROENABLE_REG);
 	fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
 	fro_detune = fro_detune | omap_rng_read(priv, RNG_FRODETUNE_REG);
 	fro_enable = RNG_REG_FROENABLE_MASK;

 	omap_rng_write(priv, RNG_FRODETUNE_REG, fro_detune);
 	omap_rng_write(priv, RNG_FROENABLE_REG, fro_enable);

 	omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);

 	return IRQ_HANDLED;
 }

 static struct omap_rng_pdata omap4_rng_pdata = {
 	.regs		= (u16 *)reg_map_omap4,
 	.data_size	= OMAP4_RNG_OUTPUT_SIZE,
 	.data_present	= omap4_rng_data_present,
 	.init		= omap4_rng_init,
 	.cleanup	= omap4_rng_cleanup,
 };

 static struct omap_rng_pdata eip76_rng_pdata = {
 	.regs		= (u16 *)reg_map_eip76,
 	.data_size	= EIP76_RNG_OUTPUT_SIZE,
 	.data_present	= omap4_rng_data_present,
 	.init		= eip76_rng_init,
 	.cleanup	= omap4_rng_cleanup,
 };

 static const struct of_device_id omap_rng_of_match[] = {
 		{
 			.compatible	= "ti,omap2-rng",
 			.data		= &omap2_rng_pdata,
 		},
 		{
 			.compatible	= "ti,omap4-rng",
 			.data		= &omap4_rng_pdata,
 		},
 		{
 			.compatible	= "inside-secure,safexcel-eip76",
 			.data		= &eip76_rng_pdata,
 		},
 		{},
 };
 MODULE_DEVICE_TABLE(of, omap_rng_of_match);

 static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
 					  struct platform_device *pdev)
 {
 	const struct of_device_id *match;
 	struct device *dev = &pdev->dev;
 	int irq, err;

 	match = of_match_device(of_match_ptr(omap_rng_of_match), dev);
 	if (!match) {
 		dev_err(dev, "no compatible OF match\n");
 		return -EINVAL;
 	}
 	priv->pdata = match->data;

 	if (of_device_is_compatible(dev->of_node, "ti,omap4-rng") ||
 	    of_device_is_compatible(dev->of_node, "inside-secure,safexcel-eip76")) {
 		irq = platform_get_irq(pdev, 0);
 		if (irq < 0) {
 			dev_err(dev, "%s: error getting IRQ resource - %d\n",
 				__func__, irq);
 			return irq;
 		}

 		err = devm_request_irq(dev, irq, omap4_rng_irq,
 				       IRQF_TRIGGER_NONE, dev_name(dev), priv);
 		if (err) {
 			dev_err(dev, "unable to request irq %d, err = %d\n",
 				irq, err);
 			return err;
 		}

 		/*
 		 * On OMAP4, enabling the shutdown_oflo interrupt is
 		 * done in the interrupt mask register. There is no
 		 * such register on EIP76, and it's enabled by the
 		 * same bit in the control register
 		 */
 		if (priv->pdata->regs[RNG_INTMASK_REG])
 			omap_rng_write(priv, RNG_INTMASK_REG,
 				       RNG_SHUTDOWN_OFLO_MASK);
 		else
 			omap_rng_write(priv, RNG_CONTROL_REG,
 				       RNG_SHUTDOWN_OFLO_MASK);
 	}
 	return 0;
 }
 #else
 static int of_get_omap_rng_device_details(struct omap_rng_dev *omap_rng,
 					  struct platform_device *pdev)
 {
 	return -EINVAL;
 }
 #endif

 static int get_omap_rng_device_details(struct omap_rng_dev *omap_rng)
 {
 	/* Only OMAP2/3 can be non-DT */
 	omap_rng->pdata = &omap2_rng_pdata;
 	return 0;
 }

 static int omap_rng_probe(struct platform_device *pdev)
 {
 	struct omap_rng_dev *priv;
 	struct resource *res;
 	struct device *dev = &pdev->dev;
 	int ret;

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

 	priv->rng.read = omap_rng_do_read;
 	priv->rng.init = omap_rng_init;
 	priv->rng.cleanup = omap_rng_cleanup;

 	priv->rng.priv = (unsigned long)priv;
 	platform_set_drvdata(pdev, priv);
 	priv->dev = dev;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	priv->base = devm_ioremap_resource(dev, res);
 	if (IS_ERR(priv->base)) {
 		ret = PTR_ERR(priv->base);
 		goto err_ioremap;
 	}

 	priv->rng.name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
 	if (!priv->rng.name) {
 		ret = -ENOMEM;
 		goto err_ioremap;
 	}

 	pm_runtime_enable(&pdev->dev);
 	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Failed to runtime_get device: %d\n", ret);
 		pm_runtime_put_noidle(&pdev->dev);
 		goto err_ioremap;
 	}

 	priv->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -EPROBE_DEFER)
 		return -EPROBE_DEFER;
 	if (!IS_ERR(priv->clk)) {
 		ret = clk_prepare_enable(priv->clk);
 		if (ret) {
 			dev_err(&pdev->dev,
 				"Unable to enable the clk: %d\n", ret);
 			goto err_register;
 		}
 	}

 	ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
 				get_omap_rng_device_details(priv);
 	if (ret)
 		goto err_register;

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

 	dev_info(&pdev->dev, "Random Number Generator ver. %02x\n",
 		 omap_rng_read(priv, RNG_REV_REG));

 	return 0;

 err_register:
 	priv->base = NULL;
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);

 	if (!IS_ERR(priv->clk))
 		clk_disable_unprepare(priv->clk);
 err_ioremap:
 	dev_err(dev, "initialization failed.\n");
 	return ret;
 }

 static int omap_rng_remove(struct platform_device *pdev)
 {
 	struct omap_rng_dev *priv = platform_get_drvdata(pdev);

 	hwrng_unregister(&priv->rng);

 	priv->pdata->cleanup(priv);

 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);

 	if (!IS_ERR(priv->clk))
 		clk_disable_unprepare(priv->clk);

 	return 0;
 }

 static int __maybe_unused omap_rng_suspend(struct device *dev)
 {
 	struct omap_rng_dev *priv = dev_get_drvdata(dev);

 	priv->pdata->cleanup(priv);
 	pm_runtime_put_sync(dev);

 	return 0;
 }

 static int __maybe_unused omap_rng_resume(struct device *dev)
 {
 	struct omap_rng_dev *priv = dev_get_drvdata(dev);
 	int ret;

 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0) {
 		dev_err(dev, "Failed to runtime_get device: %d\n", ret);
 		pm_runtime_put_noidle(dev);
 		return ret;
 	}

 	priv->pdata->init(priv);

 	return 0;
 }

 static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);

 static struct platform_driver omap_rng_driver = {
 	.driver = {
 		.name		= "omap_rng",
 		.pm		= &omap_rng_pm,
 		.of_match_table = of_match_ptr(omap_rng_of_match),
 	},
 	.probe		= omap_rng_probe,
 	.remove		= omap_rng_remove,
 };

 module_platform_driver(omap_rng_driver);
 MODULE_ALIAS("platform:omap_rng");
 MODULE_AUTHOR("Deepak Saxena (and others)");
 MODULE_LICENSE("GPL");
	/*
	* omap-rng.c - RNG driver for TI OMAP CPU family
	*
	* Author: Deepak Saxena <dsaxena@plexity.net>
	*
	* Copyright 2005 (c) MontaVista Software, Inc.
	*
	* Mostly based on original driver:
	*
	* Copyright (C) 2005 Nokia Corporation
	* Author: Juha Yrjölä <juha.yrjola@nokia.com>
	*
	* This file is licensed under the terms of the GNU General Public
	* License version 2. This program is licensed "as is" without any
	* warranty of any kind, whether express or implied.
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/random.h>
	#include <linux/err.h>
	#include <linux/platform_device.h>
	#include <linux/hw_random.h>
	#include <linux/delay.h>
	#include <linux/slab.h>
	#include <linux/pm_runtime.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/of_address.h>
	#include <linux/interrupt.h>
	#include <linux/clk.h>

	#include <asm/io.h>

	#define RNG_REG_STATUS_RDY (1 << 0)

	#define RNG_REG_INTACK_RDY_MASK (1 << 0)
	#define RNG_REG_INTACK_SHUTDOWN_OFLO_MASK (1 << 1)
	#define RNG_SHUTDOWN_OFLO_MASK (1 << 1)

	#define RNG_CONTROL_STARTUP_CYCLES_SHIFT 16
	#define RNG_CONTROL_STARTUP_CYCLES_MASK (0xffff << 16)
	#define RNG_CONTROL_ENABLE_TRNG_SHIFT 10
	#define RNG_CONTROL_ENABLE_TRNG_MASK (1 << 10)

	#define RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT 16
	#define RNG_CONFIG_MAX_REFIL_CYCLES_MASK (0xffff << 16)
	#define RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT 0
	#define RNG_CONFIG_MIN_REFIL_CYCLES_MASK (0xff << 0)

	#define RNG_CONTROL_STARTUP_CYCLES 0xff
	#define RNG_CONFIG_MIN_REFIL_CYCLES 0x21
	#define RNG_CONFIG_MAX_REFIL_CYCLES 0x22

	#define RNG_ALARMCNT_ALARM_TH_SHIFT 0x0
	#define RNG_ALARMCNT_ALARM_TH_MASK (0xff << 0)
	#define RNG_ALARMCNT_SHUTDOWN_TH_SHIFT 16
	#define RNG_ALARMCNT_SHUTDOWN_TH_MASK (0x1f << 16)
	#define RNG_ALARM_THRESHOLD 0xff
	#define RNG_SHUTDOWN_THRESHOLD 0x4

	#define RNG_REG_FROENABLE_MASK 0xffffff
	#define RNG_REG_FRODETUNE_MASK 0xffffff

	#define OMAP2_RNG_OUTPUT_SIZE 0x4
	#define OMAP4_RNG_OUTPUT_SIZE 0x8
	#define EIP76_RNG_OUTPUT_SIZE 0x10

	enum {
	RNG_OUTPUT_0_REG = 0,
	RNG_OUTPUT_1_REG,
	RNG_OUTPUT_2_REG,
	RNG_OUTPUT_3_REG,
	RNG_STATUS_REG,
	RNG_INTMASK_REG,
	RNG_INTACK_REG,
	RNG_CONTROL_REG,
	RNG_CONFIG_REG,
	RNG_ALARMCNT_REG,
	RNG_FROENABLE_REG,
	RNG_FRODETUNE_REG,
	RNG_ALARMMASK_REG,
	RNG_ALARMSTOP_REG,
	RNG_REV_REG,
	RNG_SYSCONFIG_REG,
	};

	static const u16 reg_map_omap2[] = {
	[RNG_OUTPUT_0_REG] = 0x0,
	[RNG_STATUS_REG] = 0x4,
	[RNG_CONFIG_REG] = 0x28,
	[RNG_REV_REG] = 0x3c,
	[RNG_SYSCONFIG_REG] = 0x40,
	};

	static const u16 reg_map_omap4[] = {
	[RNG_OUTPUT_0_REG] = 0x0,
	[RNG_OUTPUT_1_REG] = 0x4,
	[RNG_STATUS_REG] = 0x8,
	[RNG_INTMASK_REG] = 0xc,
	[RNG_INTACK_REG] = 0x10,
	[RNG_CONTROL_REG] = 0x14,
	[RNG_CONFIG_REG] = 0x18,
	[RNG_ALARMCNT_REG] = 0x1c,
	[RNG_FROENABLE_REG] = 0x20,
	[RNG_FRODETUNE_REG] = 0x24,
	[RNG_ALARMMASK_REG] = 0x28,
	[RNG_ALARMSTOP_REG] = 0x2c,
	[RNG_REV_REG] = 0x1FE0,
	[RNG_SYSCONFIG_REG] = 0x1FE4,
	};

	static const u16 reg_map_eip76[] = {
	[RNG_OUTPUT_0_REG] = 0x0,
	[RNG_OUTPUT_1_REG] = 0x4,
	[RNG_OUTPUT_2_REG] = 0x8,
	[RNG_OUTPUT_3_REG] = 0xc,
	[RNG_STATUS_REG] = 0x10,
	[RNG_INTACK_REG] = 0x10,
	[RNG_CONTROL_REG] = 0x14,
	[RNG_CONFIG_REG] = 0x18,
	[RNG_ALARMCNT_REG] = 0x1c,
	[RNG_FROENABLE_REG] = 0x20,
	[RNG_FRODETUNE_REG] = 0x24,
	[RNG_ALARMMASK_REG] = 0x28,
	[RNG_ALARMSTOP_REG] = 0x2c,
	[RNG_REV_REG] = 0x7c,
	};

	struct omap_rng_dev;
	/**
	* struct omap_rng_pdata - RNG IP block-specific data
	* @regs: Pointer to the register offsets structure.
	* @data_size: No. of bytes in RNG output.
	* @data_present: Callback to determine if data is available.
	* @init: Callback for IP specific initialization sequence.
	* @cleanup: Callback for IP specific cleanup sequence.
	*/
	struct omap_rng_pdata {
	u16 *regs;
	u32 data_size;
	u32 (data_present)(struct omap_rng_dev priv);
	int (init)(struct omap_rng_dev priv);
	void (cleanup)(struct omap_rng_dev priv);
	};

	struct omap_rng_dev {
	void __iomem *base;
	struct device *dev;
	const struct omap_rng_pdata *pdata;
	struct hwrng rng;
	struct clk *clk;
	};

	static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
	{
	return __raw_readl(priv->base + priv->pdata->regs[reg]);
	}

	static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
	u32 val)
	{
	__raw_writel(val, priv->base + priv->pdata->regs[reg]);
	}


	static int omap_rng_do_read(struct hwrng rng, void data, size_t max,
	bool wait)
	{
	struct omap_rng_dev *priv;
	int i, present;

	priv = (struct omap_rng_dev *)rng->priv;

	if (max < priv->pdata->data_size)
	return 0;

	for (i = 0; i < 20; i++) {
	present = priv->pdata->data_present(priv);
	if (present \|\| !wait)
	break;

	udelay(10);
	}
	if (!present)
	return 0;

	memcpy_fromio(data, priv->base + priv->pdata->regs[RNG_OUTPUT_0_REG],
	priv->pdata->data_size);

	if (priv->pdata->regs[RNG_INTACK_REG])
	omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);

	return priv->pdata->data_size;
	}

	static int omap_rng_init(struct hwrng *rng)
	{
	struct omap_rng_dev *priv;

	priv = (struct omap_rng_dev *)rng->priv;
	return priv->pdata->init(priv);
	}

	static void omap_rng_cleanup(struct hwrng *rng)
	{
	struct omap_rng_dev *priv;

	priv = (struct omap_rng_dev *)rng->priv;
	priv->pdata->cleanup(priv);
	}


	static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
	{
	return omap_rng_read(priv, RNG_STATUS_REG) ? 0 : 1;
	}

	static int omap2_rng_init(struct omap_rng_dev *priv)
	{
	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x1);
	return 0;
	}

	static void omap2_rng_cleanup(struct omap_rng_dev *priv)
	{
	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x0);
	}

	static struct omap_rng_pdata omap2_rng_pdata = {
	.regs = (u16 *)reg_map_omap2,
	.data_size = OMAP2_RNG_OUTPUT_SIZE,
	.data_present = omap2_rng_data_present,
	.init = omap2_rng_init,
	.cleanup = omap2_rng_cleanup,
	};

	#if defined(CONFIG_OF)
	static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
	{
	return omap_rng_read(priv, RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
	}

	static int eip76_rng_init(struct omap_rng_dev *priv)
	{
	u32 val;

	/* Return if RNG is already running. */
	if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
	return 0;

	/* Number of 512 bit blocks of raw Noise Source output data that must
	* be processed by either the Conditioning Function or the
	* SP 800-90 DRBG ‘BC_DF’ functionality to yield a ‘full entropy’
	* output value.
	*/
	val = 0x5 << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;

	/* Number of FRO samples that are XOR-ed together into one bit to be
	* shifted into the main shift register
	*/
	val \|= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
	omap_rng_write(priv, RNG_CONFIG_REG, val);

	/* Enable all available FROs */
	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);

	/* Enable TRNG */
	val = RNG_CONTROL_ENABLE_TRNG_MASK;
	omap_rng_write(priv, RNG_CONTROL_REG, val);

	return 0;
	}

	static int omap4_rng_init(struct omap_rng_dev *priv)
	{
	u32 val;

	/* Return if RNG is already running. */
	if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
	return 0;

	val = RNG_CONFIG_MIN_REFIL_CYCLES << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
	val \|= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
	omap_rng_write(priv, RNG_CONFIG_REG, val);

	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
	val = RNG_ALARM_THRESHOLD << RNG_ALARMCNT_ALARM_TH_SHIFT;
	val \|= RNG_SHUTDOWN_THRESHOLD << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT;
	omap_rng_write(priv, RNG_ALARMCNT_REG, val);

	val = RNG_CONTROL_STARTUP_CYCLES << RNG_CONTROL_STARTUP_CYCLES_SHIFT;
	val \|= RNG_CONTROL_ENABLE_TRNG_MASK;
	omap_rng_write(priv, RNG_CONTROL_REG, val);

	return 0;
	}

	static void omap4_rng_cleanup(struct omap_rng_dev *priv)
	{
	int val;

	val = omap_rng_read(priv, RNG_CONTROL_REG);
	val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
	omap_rng_write(priv, RNG_CONTROL_REG, val);
	}

	static irqreturn_t omap4_rng_irq(int irq, void *dev_id)
	{
	struct omap_rng_dev *priv = dev_id;
	u32 fro_detune, fro_enable;

	/*
	* Interrupt raised by a fro shutdown threshold, do the following:
	* 1. Clear the alarm events.
	* 2. De tune the FROs which are shutdown.
	* 3. Re enable the shutdown FROs.
	*/
	omap_rng_write(priv, RNG_ALARMMASK_REG, 0x0);
	omap_rng_write(priv, RNG_ALARMSTOP_REG, 0x0);

	fro_enable = omap_rng_read(priv, RNG_FROENABLE_REG);
	fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
	fro_detune = fro_detune \| omap_rng_read(priv, RNG_FRODETUNE_REG);
	fro_enable = RNG_REG_FROENABLE_MASK;

	omap_rng_write(priv, RNG_FRODETUNE_REG, fro_detune);
	omap_rng_write(priv, RNG_FROENABLE_REG, fro_enable);

	omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);

	return IRQ_HANDLED;
	}

	static struct omap_rng_pdata omap4_rng_pdata = {
	.regs = (u16 *)reg_map_omap4,
	.data_size = OMAP4_RNG_OUTPUT_SIZE,
	.data_present = omap4_rng_data_present,
	.init = omap4_rng_init,
	.cleanup = omap4_rng_cleanup,
	};

	static struct omap_rng_pdata eip76_rng_pdata = {
	.regs = (u16 *)reg_map_eip76,
	.data_size = EIP76_RNG_OUTPUT_SIZE,
	.data_present = omap4_rng_data_present,
	.init = eip76_rng_init,
	.cleanup = omap4_rng_cleanup,
	};

	static const struct of_device_id omap_rng_of_match[] = {
	{
	.compatible = "ti,omap2-rng",
	.data = &omap2_rng_pdata,
	},
	{
	.compatible = "ti,omap4-rng",
	.data = &omap4_rng_pdata,
	},
	{
	.compatible = "inside-secure,safexcel-eip76",
	.data = &eip76_rng_pdata,
	},
	{},
	};
	MODULE_DEVICE_TABLE(of, omap_rng_of_match);

	static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
	struct platform_device *pdev)
	{
	const struct of_device_id *match;
	struct device *dev = &pdev->dev;
	int irq, err;

	match = of_match_device(of_match_ptr(omap_rng_of_match), dev);
	if (!match) {
	dev_err(dev, "no compatible OF match\n");
	return -EINVAL;
	}
	priv->pdata = match->data;

	if (of_device_is_compatible(dev->of_node, "ti,omap4-rng") \|\|
	of_device_is_compatible(dev->of_node, "inside-secure,safexcel-eip76")) {
	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_err(dev, "%s: error getting IRQ resource - %d\n",
	__func__, irq);
	return irq;
	}

	err = devm_request_irq(dev, irq, omap4_rng_irq,
	IRQF_TRIGGER_NONE, dev_name(dev), priv);
	if (err) {
	dev_err(dev, "unable to request irq %d, err = %d\n",
	irq, err);
	return err;
	}

	/*
	* On OMAP4, enabling the shutdown_oflo interrupt is
	* done in the interrupt mask register. There is no
	* such register on EIP76, and it's enabled by the
	* same bit in the control register
	*/
	if (priv->pdata->regs[RNG_INTMASK_REG])
	omap_rng_write(priv, RNG_INTMASK_REG,
	RNG_SHUTDOWN_OFLO_MASK);
	else
	omap_rng_write(priv, RNG_CONTROL_REG,
	RNG_SHUTDOWN_OFLO_MASK);
	}
	return 0;
	}
	#else
	static int of_get_omap_rng_device_details(struct omap_rng_dev *omap_rng,
	struct platform_device *pdev)
	{
	return -EINVAL;
	}
	#endif

	static int get_omap_rng_device_details(struct omap_rng_dev *omap_rng)
	{
	/* Only OMAP2/3 can be non-DT */
	omap_rng->pdata = &omap2_rng_pdata;
	return 0;
	}

	static int omap_rng_probe(struct platform_device *pdev)
	{
	struct omap_rng_dev *priv;
	struct resource *res;
	struct device *dev = &pdev->dev;
	int ret;

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

	priv->rng.read = omap_rng_do_read;
	priv->rng.init = omap_rng_init;
	priv->rng.cleanup = omap_rng_cleanup;

	priv->rng.priv = (unsigned long)priv;
	platform_set_drvdata(pdev, priv);
	priv->dev = dev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	priv->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(priv->base)) {
	ret = PTR_ERR(priv->base);
	goto err_ioremap;
	}

	priv->rng.name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
	if (!priv->rng.name) {
	ret = -ENOMEM;
	goto err_ioremap;
	}

	pm_runtime_enable(&pdev->dev);
	ret = pm_runtime_get_sync(&pdev->dev);
	if (ret < 0) {
	dev_err(&pdev->dev, "Failed to runtime_get device: %d\n", ret);
	pm_runtime_put_noidle(&pdev->dev);
	goto err_ioremap;
	}

	priv->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -EPROBE_DEFER)
	return -EPROBE_DEFER;
	if (!IS_ERR(priv->clk)) {
	ret = clk_prepare_enable(priv->clk);
	if (ret) {
	dev_err(&pdev->dev,
	"Unable to enable the clk: %d\n", ret);
	goto err_register;
	}
	}

	ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
	get_omap_rng_device_details(priv);
	if (ret)
	goto err_register;

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

	dev_info(&pdev->dev, "Random Number Generator ver. %02x\n",
	omap_rng_read(priv, RNG_REV_REG));

	return 0;

	err_register:
	priv->base = NULL;
	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);

	if (!IS_ERR(priv->clk))
	clk_disable_unprepare(priv->clk);
	err_ioremap:
	dev_err(dev, "initialization failed.\n");
	return ret;
	}

	static int omap_rng_remove(struct platform_device *pdev)
	{
	struct omap_rng_dev *priv = platform_get_drvdata(pdev);

	hwrng_unregister(&priv->rng);

	priv->pdata->cleanup(priv);

	pm_runtime_put_sync(&pdev->dev);
	pm_runtime_disable(&pdev->dev);

	if (!IS_ERR(priv->clk))
	clk_disable_unprepare(priv->clk);

	return 0;
	}

	static int __maybe_unused omap_rng_suspend(struct device *dev)
	{
	struct omap_rng_dev *priv = dev_get_drvdata(dev);

	priv->pdata->cleanup(priv);
	pm_runtime_put_sync(dev);

	return 0;
	}

	static int __maybe_unused omap_rng_resume(struct device *dev)
	{
	struct omap_rng_dev *priv = dev_get_drvdata(dev);
	int ret;

	ret = pm_runtime_get_sync(dev);
	if (ret < 0) {
	dev_err(dev, "Failed to runtime_get device: %d\n", ret);
	pm_runtime_put_noidle(dev);
	return ret;
	}

	priv->pdata->init(priv);

	return 0;
	}

	static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);

	static struct platform_driver omap_rng_driver = {
	.driver = {
	.name = "omap_rng",
	.pm = &omap_rng_pm,
	.of_match_table = of_match_ptr(omap_rng_of_match),
	},
	.probe = omap_rng_probe,
	.remove = omap_rng_remove,
	};

	module_platform_driver(omap_rng_driver);
	MODULE_ALIAS("platform:omap_rng");
	MODULE_AUTHOR("Deepak Saxena (and others)");
	MODULE_LICENSE("GPL");