Commit eb428ee0 authored by Vitaly Andrianov's avatar Vitaly Andrianov Committed by Herbert Xu
Browse files

hwrng: ks-sa - add hw_random driver 



Keystone Security Accelerator module has a hardware random generator
sub-module. This commit adds the driver for this sub-module.

Signed-off-by: default avatarVitaly Andrianov <vitalya@ti.com>
[t-kristo@ti.com: dropped one unnecessary dev_err message]
Signed-off-by: default avatarTero Kristo <t-kristo@ti.com>
Signed-off-by: default avatarMurali Karicheri <m-karicheri2@ti.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 2805894c

drivers/char/hw_random/Kconfig

+7 −0
Original line number Original line Diff line number Diff line
@@ -452,3 +452,10 @@ config UML_RANDOM 
	  (check your distro, or download from

	  (check your distro, or download from

	  http://sourceforge.net/projects/gkernel/).  rngd periodically reads

	  http://sourceforge.net/projects/gkernel/).  rngd periodically reads

	  /dev/hwrng and injects the entropy into /dev/random.

	  /dev/hwrng and injects the entropy into /dev/random.



config HW_RANDOM_KEYSTONE

	depends on ARCH_KEYSTONE

	default HW_RANDOM

	tristate "TI Keystone NETCP SA Hardware random number generator"

	help

	  This option enables Keystone's hardware random generator.

drivers/char/hw_random/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -38,3 +38,4 @@ obj-$(CONFIG_HW_RANDOM_MESON) += meson-rng.o 
obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o

obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o

obj-$(CONFIG_HW_RANDOM_MTK)	+= mtk-rng.o

obj-$(CONFIG_HW_RANDOM_MTK)	+= mtk-rng.o

obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o

obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o

obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o

drivers/char/hw_random/ks-sa-rng.c

0 → 100644
+257 −0
Original line number Original line Diff line number Diff line 
/*

 * Random Number Generator driver for the Keystone SOC

 *

 * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com

 *

 * Authors:	Sandeep Nair

 *		Vitaly Andrianov

 *

 * 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.

 *

 * This program 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/hw_random.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/io.h>

#include <linux/platform_device.h>

#include <linux/clk.h>

#include <linux/pm_runtime.h>

#include <linux/err.h>

#include <linux/regmap.h>

#include <linux/mfd/syscon.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/delay.h>



#define SA_CMD_STATUS_OFS			0x8



/* TRNG enable control in SA System module*/

#define SA_CMD_STATUS_REG_TRNG_ENABLE		BIT(3)



/* TRNG start control in TRNG module */

#define TRNG_CNTL_REG_TRNG_ENABLE		BIT(10)



/* Data ready indicator in STATUS register */

#define TRNG_STATUS_REG_READY			BIT(0)



/* Data ready clear control in INTACK register */

#define TRNG_INTACK_REG_READY			BIT(0)



/*

 * Number of samples taken to gather entropy during startup.

 * If value is 0, the number of samples is 2^24 else

 * equals value times 2^8.

 */

#define TRNG_DEF_STARTUP_CYCLES			0

#define TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT	16



/*

 * Minimum number of samples taken to regenerate entropy

 * If value is 0, the number of samples is 2^24 else

 * equals value times 2^6.

 */

#define TRNG_DEF_MIN_REFILL_CYCLES		1

#define TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT	0



/*

 * Maximum number of samples taken to regenerate entropy

 * If value is 0, the number of samples is 2^24 else

 * equals value times 2^8.

 */

#define TRNG_DEF_MAX_REFILL_CYCLES		0

#define TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT	16



/* Number of CLK input cycles between samples */

#define TRNG_DEF_CLK_DIV_CYCLES			0

#define TRNG_CFG_REG_SAMPLE_DIV_SHIFT		8



/* Maximum retries to get rng data */

#define SA_MAX_RNG_DATA_RETRIES			5

/* Delay between retries (in usecs) */

#define SA_RNG_DATA_RETRY_DELAY			5



struct trng_regs {

	u32	output_l;

	u32	output_h;

	u32	status;

	u32	intmask;

	u32	intack;

	u32	control;

	u32	config;

};



struct ks_sa_rng {

	struct device	*dev;

	struct hwrng	rng;

	struct clk	*clk;

	struct regmap	*regmap_cfg;

	struct trng_regs *reg_rng;

};



static int ks_sa_rng_init(struct hwrng *rng)

{

	u32 value;

	struct device *dev = (struct device *)rng->priv;

	struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);



	/* Enable RNG module */

	regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,

			  SA_CMD_STATUS_REG_TRNG_ENABLE,

			  SA_CMD_STATUS_REG_TRNG_ENABLE);



	/* Configure RNG module */

	writel(0, &ks_sa_rng->reg_rng->control);

	value = TRNG_DEF_STARTUP_CYCLES << TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT;

	writel(value, &ks_sa_rng->reg_rng->control);



	value =	(TRNG_DEF_MIN_REFILL_CYCLES <<

		 TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT) |

		(TRNG_DEF_MAX_REFILL_CYCLES <<

		 TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT) |

		(TRNG_DEF_CLK_DIV_CYCLES <<

		 TRNG_CFG_REG_SAMPLE_DIV_SHIFT);



	writel(value, &ks_sa_rng->reg_rng->config);



	/* Disable all interrupts from TRNG */

	writel(0, &ks_sa_rng->reg_rng->intmask);



	/* Enable RNG */

	value = readl(&ks_sa_rng->reg_rng->control);

	value |= TRNG_CNTL_REG_TRNG_ENABLE;

	writel(value, &ks_sa_rng->reg_rng->control);



	return 0;

}



static void ks_sa_rng_cleanup(struct hwrng *rng)

{

	struct device *dev = (struct device *)rng->priv;

	struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);



	/* Disable RNG */

	writel(0, &ks_sa_rng->reg_rng->control);

	regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,

			  SA_CMD_STATUS_REG_TRNG_ENABLE, 0);

}



static int ks_sa_rng_data_read(struct hwrng *rng, u32 *data)

{

	struct device *dev = (struct device *)rng->priv;

	struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);



	/* Read random data */

	data[0] = readl(&ks_sa_rng->reg_rng->output_l);

	data[1] = readl(&ks_sa_rng->reg_rng->output_h);



	writel(TRNG_INTACK_REG_READY, &ks_sa_rng->reg_rng->intack);



	return sizeof(u32) * 2;

}



static int ks_sa_rng_data_present(struct hwrng *rng, int wait)

{

	struct device *dev = (struct device *)rng->priv;

	struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);



	u32	ready;

	int	j;



	for (j = 0; j < SA_MAX_RNG_DATA_RETRIES; j++) {

		ready = readl(&ks_sa_rng->reg_rng->status);

		ready &= TRNG_STATUS_REG_READY;



		if (ready || !wait)

			break;



		udelay(SA_RNG_DATA_RETRY_DELAY);

	}



	return ready;

}



static int ks_sa_rng_probe(struct platform_device *pdev)

{

	struct ks_sa_rng	*ks_sa_rng;

	struct device		*dev = &pdev->dev;

	int			ret;

	struct resource		*mem;



	ks_sa_rng = devm_kzalloc(dev, sizeof(*ks_sa_rng), GFP_KERNEL);

	if (!ks_sa_rng)

		return -ENOMEM;



	ks_sa_rng->dev = dev;

	ks_sa_rng->rng = (struct hwrng) {

		.name = "ks_sa_hwrng",

		.init = ks_sa_rng_init,

		.data_read = ks_sa_rng_data_read,

		.data_present = ks_sa_rng_data_present,

		.cleanup = ks_sa_rng_cleanup,

	};

	ks_sa_rng->rng.priv = (unsigned long)dev;



	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	ks_sa_rng->reg_rng = devm_ioremap_resource(dev, mem);

	if (IS_ERR(ks_sa_rng->reg_rng))

		return PTR_ERR(ks_sa_rng->reg_rng);



	ks_sa_rng->regmap_cfg =

		syscon_regmap_lookup_by_phandle(dev->of_node,

						"ti,syscon-sa-cfg");



	if (IS_ERR(ks_sa_rng->regmap_cfg)) {

		dev_err(dev, "syscon_node_to_regmap failed\n");

		return -EINVAL;

	}



	pm_runtime_enable(dev);

	ret = pm_runtime_get_sync(dev);

	if (ret < 0) {

		dev_err(dev, "Failed to enable SA power-domain\n");

		pm_runtime_disable(dev);

		return ret;

	}



	platform_set_drvdata(pdev, ks_sa_rng);



	return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng);

}



static int ks_sa_rng_remove(struct platform_device *pdev)

{

	pm_runtime_put_sync(&pdev->dev);

	pm_runtime_disable(&pdev->dev);



	return 0;

}



static const struct of_device_id ks_sa_rng_dt_match[] = {

	{

		.compatible = "ti,keystone-rng",

	},

	{ },

};

MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);



static struct platform_driver ks_sa_rng_driver = {

	.driver		= {

		.name	= "ks-sa-rng",

		.of_match_table = ks_sa_rng_dt_match,

	},

	.probe		= ks_sa_rng_probe,

	.remove		= ks_sa_rng_remove,

};



module_platform_driver(ks_sa_rng_driver);



MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");

MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");

MODULE_LICENSE("GPL");

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