hwrng: Add QRNG driver snapshot

* RNG (Random Number Generator)

Required properties:

- compatible : Should be "qcom,msm-rng"

- reg        : Offset and length of the register set for the device

Optional property:

- qcom,msm-rng-iface-clk : If the device uses iface-clk.

- qcom,no-qrng-config    : Flag to decide whether the driver do the hardware configuration or not.

Example:

	qcom,msm-rng@f9bff000 {

		compatible = "qcom,msm-rng";

		reg = <0xf9bff000 0x200>;

		qcom,msm-rng-iface-clk;

		qcom,no-qrng-config;

	};

config HW_RANDOM_MSM

	tristate "Qualcomm SoCs Random Number Generator support"

	depends on HW_RANDOM && ARCH_QCOM

	default HW_RANDOM

	---help---

	  This driver provides kernel-side support for the Random Number

	  Generator hardware found on Qualcomm SoCs.

	  If unsure, say Y.

config HW_RANDOM_MSM_LEGACY

	tristate "QTI MSM Random Number Generator support (LEGACY)"

	depends on HW_RANDOM && ARCH_QCOM

	select CRYPTO_AES

	select CRYPTO_ECB

	---help---

	  This driver provides kernel-side support for the Random Number

	  Generator hardware found on QTI MSM SoCs.

	  To compile this driver as a module, choose M here: the

	  module will be called msm_rng.

	  If unsure, say Y.

config HW_RANDOM_ST

	tristate "ST Microelectronics HW Random Number Generator support"

	depends on HW_RANDOM && ARCH_STI

obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o

obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o

obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o

obj-$(CONFIG_HW_RANDOM_MSM_LEGACY) += msm_rng.o

obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o

obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o

obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o

/*

 * Copyright (c) 2011-2013, 2015, 2017 The Linux Foundation. All rights

 * reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/device.h>

#include <linux/platform_device.h>

#include <linux/hw_random.h>

#include <linux/clk.h>

#include <linux/slab.h>

#include <linux/io.h>

#include <linux/err.h>

#include <linux/types.h>

#include <soc/qcom/socinfo.h>

#include <linux/msm-bus.h>

#include <linux/qrng.h>

#include <linux/fs.h>

#include <linux/cdev.h>

#include <linux/delay.h>

#include <linux/crypto.h>

#include <crypto/internal/rng.h>

#include <linux/platform_data/qcom_crypto_device.h>

#define DRIVER_NAME "msm_rng"

/* Device specific register offsets */

#define PRNG_DATA_OUT_OFFSET    0x0000

#define PRNG_STATUS_OFFSET	0x0004

#define PRNG_LFSR_CFG_OFFSET	0x0100

#define PRNG_CONFIG_OFFSET	0x0104

/* Device specific register masks and config values */

#define PRNG_LFSR_CFG_MASK	0xFFFF0000

#define PRNG_LFSR_CFG_CLOCKS	0x0000DDDD

#define PRNG_CONFIG_MASK	0xFFFFFFFD

#define PRNG_HW_ENABLE		0x00000002

#define MAX_HW_FIFO_DEPTH 16                     /* FIFO is 16 words deep */

#define MAX_HW_FIFO_SIZE (MAX_HW_FIFO_DEPTH * 4) /* FIFO is 32 bits wide  */

struct msm_rng_device {

	struct platform_device *pdev;

	void __iomem *base;

	struct clk *prng_clk;

	uint32_t qrng_perf_client;

	struct mutex rng_lock;

};

struct msm_rng_device msm_rng_device_info;

static struct msm_rng_device *msm_rng_dev_cached;

struct mutex cached_rng_lock;

static long msm_rng_ioctl(struct file *filp, unsigned int cmd,

				unsigned long arg)

{

	long ret = 0;

	switch (cmd) {

	case QRNG_IOCTL_RESET_BUS_BANDWIDTH:

		pr_info("calling msm_rng_bus_scale(LOW)\n");

		ret = msm_bus_scale_client_update_request(

				msm_rng_device_info.qrng_perf_client, 0);

		if (ret)

			pr_err("failed qrng_reset_bus_bw, ret = %ld\n", ret);

		break;

	default:

		pr_err("Unsupported IOCTL call");

		break;

	}

	return ret;

}

/*

 *

 *  This function calls hardware random bit generator directory and retuns it

 *  back to caller

 *

 */

static int msm_rng_direct_read(struct msm_rng_device *msm_rng_dev,

					void *data, size_t max)

{

	struct platform_device *pdev;

	void __iomem *base;

	size_t currsize = 0;

	u32 val;

	u32 *retdata = data;

	int ret;

	int failed = 0;

	pdev = msm_rng_dev->pdev;

	base = msm_rng_dev->base;

	/* no room for word data */

	if (max < 4)

		return 0;

	mutex_lock(&msm_rng_dev->rng_lock);

	if (msm_rng_dev->qrng_perf_client) {

		ret = msm_bus_scale_client_update_request(

				msm_rng_dev->qrng_perf_client, 1);

		if (ret)

			pr_err("bus_scale_client_update_req failed!\n");

	}

	/* enable PRNG clock */

	ret = clk_prepare_enable(msm_rng_dev->prng_clk);

	if (ret) {

		dev_err(&pdev->dev, "failed to enable clock in callback\n");

		goto err;

	}

	/* read random data from h/w */

	do {

		/* check status bit if data is available */

		while (!(readl_relaxed(base + PRNG_STATUS_OFFSET)

				& 0x00000001)) {

			if (failed == 10) {

				pr_err("Data not available after retry\n");

				break;

			}

			pr_err("msm_rng:Data not available!\n");

			msleep_interruptible(10);

			failed++;

		}

		/* read FIFO */

		val = readl_relaxed(base + PRNG_DATA_OUT_OFFSET);

		if (!val)

			break;	/* no data to read so just bail */

		/* write data back to callers pointer */

		*(retdata++) = val;

		currsize += 4;

		/* make sure we stay on 32bit boundary */

		if ((max - currsize) < 4)

			break;

	} while (currsize < max);

	/* vote to turn off clock */

	clk_disable_unprepare(msm_rng_dev->prng_clk);

err:

	if (msm_rng_dev->qrng_perf_client) {

		ret = msm_bus_scale_client_update_request(

				msm_rng_dev->qrng_perf_client, 0);

		if (ret)

			pr_err("bus_scale_client_update_req failed!\n");

	}

	mutex_unlock(&msm_rng_dev->rng_lock);

	val = 0L;

	return currsize;

}

static int msm_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)

{

	struct msm_rng_device *msm_rng_dev;

	int rv = 0;

	msm_rng_dev = (struct msm_rng_device *)rng->priv;

	rv = msm_rng_direct_read(msm_rng_dev, data, max);

	return rv;

}

static struct hwrng msm_rng = {

	.name = DRIVER_NAME,

	.read = msm_rng_read,

	.quality = 700,

};

static int msm_rng_enable_hw(struct msm_rng_device *msm_rng_dev)

{

	unsigned long val = 0;

	unsigned long reg_val = 0;

	int ret = 0;

	if (msm_rng_dev->qrng_perf_client) {

		ret = msm_bus_scale_client_update_request(

				msm_rng_dev->qrng_perf_client, 1);

		if (ret)

			pr_err("bus_scale_client_update_req failed!\n");

	}

	/* Enable the PRNG CLK */

	ret = clk_prepare_enable(msm_rng_dev->prng_clk);

	if (ret) {

		dev_err(&(msm_rng_dev->pdev)->dev,

				"failed to enable clock in probe\n");

		return -EPERM;

	}

	/* Enable PRNG h/w only if it is NOT ON */

	val = readl_relaxed(msm_rng_dev->base + PRNG_CONFIG_OFFSET) &

					PRNG_HW_ENABLE;

	/* PRNG H/W is not ON */

	if (val != PRNG_HW_ENABLE) {

		val = readl_relaxed(msm_rng_dev->base + PRNG_LFSR_CFG_OFFSET);

		val &= PRNG_LFSR_CFG_MASK;

		val |= PRNG_LFSR_CFG_CLOCKS;

		writel_relaxed(val, msm_rng_dev->base + PRNG_LFSR_CFG_OFFSET);

		/* The PRNG CONFIG register should be first written */

		mb();

		reg_val = readl_relaxed(msm_rng_dev->base + PRNG_CONFIG_OFFSET)

						& PRNG_CONFIG_MASK;

		reg_val |= PRNG_HW_ENABLE;

		writel_relaxed(reg_val, msm_rng_dev->base + PRNG_CONFIG_OFFSET);

		/* The PRNG clk should be disabled only after we enable the

		 * PRNG h/w by writing to the PRNG CONFIG register.

		 */

		mb();

	}

	clk_disable_unprepare(msm_rng_dev->prng_clk);

	if (msm_rng_dev->qrng_perf_client) {

		ret = msm_bus_scale_client_update_request(

				msm_rng_dev->qrng_perf_client, 0);

		if (ret)

			pr_err("bus_scale_client_update_req failed!\n");

	}

	return 0;

}

static const struct file_operations msm_rng_fops = {

	.unlocked_ioctl = msm_rng_ioctl,

};

static struct class *msm_rng_class;

static struct cdev msm_rng_cdev;

static int msm_rng_probe(struct platform_device *pdev)

{

	struct resource *res;

	struct msm_rng_device *msm_rng_dev = NULL;

	void __iomem *base = NULL;

	bool configure_qrng = true;

	int error = 0;

	int ret = 0;

	struct device *dev;

	struct msm_bus_scale_pdata *qrng_platform_support = NULL;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (res == NULL) {

		dev_err(&pdev->dev, "invalid address\n");

		error = -EFAULT;

		goto err_exit;

	}

	msm_rng_dev = kzalloc(sizeof(struct msm_rng_device), GFP_KERNEL);

	if (!msm_rng_dev) {

		error = -ENOMEM;

		goto err_exit;

	}

	base = ioremap(res->start, resource_size(res));

	if (!base) {

		dev_err(&pdev->dev, "ioremap failed\n");

		error = -ENOMEM;

		goto err_iomap;

	}

	msm_rng_dev->base = base;

	/* create a handle for clock control */

	if ((pdev->dev.of_node) && (of_property_read_bool(pdev->dev.of_node,

					"qcom,msm-rng-iface-clk")))

		msm_rng_dev->prng_clk = clk_get(&pdev->dev,

							"iface_clk");

	else

		msm_rng_dev->prng_clk = clk_get(&pdev->dev, "core_clk");

	if (IS_ERR(msm_rng_dev->prng_clk)) {

		dev_err(&pdev->dev, "failed to register clock source\n");

		error = -EPERM;

		goto err_clk_get;

	}

	/* save away pdev and register driver data */

	msm_rng_dev->pdev = pdev;

	platform_set_drvdata(pdev, msm_rng_dev);

	if (pdev->dev.of_node) {

		/* Register bus client */

		qrng_platform_support = msm_bus_cl_get_pdata(pdev);

		msm_rng_dev->qrng_perf_client = msm_bus_scale_register_client(

						qrng_platform_support);

		msm_rng_device_info.qrng_perf_client =

					msm_rng_dev->qrng_perf_client;

		if (!msm_rng_dev->qrng_perf_client)

			pr_err("Unable to register bus client\n");

	}

	/* Enable rng h/w for the targets which can access the entire

	 * address space of PRNG.

	 */

	if ((pdev->dev.of_node) && (of_property_read_bool(pdev->dev.of_node,

					"qcom,no-qrng-config")))

		configure_qrng = false;

	if (configure_qrng) {

		error = msm_rng_enable_hw(msm_rng_dev);

		if (error)

			goto rollback_clk;

	}

	mutex_init(&msm_rng_dev->rng_lock);

	mutex_init(&cached_rng_lock);

	/* register with hwrng framework */

	msm_rng.priv = (unsigned long) msm_rng_dev;

	error = hwrng_register(&msm_rng);

	if (error) {

		dev_err(&pdev->dev, "failed to register hwrng\n");

		error = -EPERM;

		goto rollback_clk;

	}

	ret = register_chrdev(QRNG_IOC_MAGIC, DRIVER_NAME, &msm_rng_fops);

	msm_rng_class = class_create(THIS_MODULE, "msm-rng");

	if (IS_ERR(msm_rng_class)) {

		pr_err("class_create failed\n");

		return PTR_ERR(msm_rng_class);

	}

	dev = device_create(msm_rng_class, NULL, MKDEV(QRNG_IOC_MAGIC, 0),

				NULL, "msm-rng");

	if (IS_ERR(dev)) {

		pr_err("Device create failed\n");

		error = PTR_ERR(dev);

		goto unregister_chrdev;

	}

	cdev_init(&msm_rng_cdev, &msm_rng_fops);

	msm_rng_dev_cached = msm_rng_dev;

	return error;

unregister_chrdev:

	unregister_chrdev(QRNG_IOC_MAGIC, DRIVER_NAME);

rollback_clk:

	clk_put(msm_rng_dev->prng_clk);

err_clk_get:

	iounmap(msm_rng_dev->base);

err_iomap:

	kzfree(msm_rng_dev);

err_exit:

	return error;

}

static int msm_rng_remove(struct platform_device *pdev)

{

	struct msm_rng_device *msm_rng_dev = platform_get_drvdata(pdev);

	unregister_chrdev(QRNG_IOC_MAGIC, DRIVER_NAME);

	hwrng_unregister(&msm_rng);

	clk_put(msm_rng_dev->prng_clk);

	iounmap(msm_rng_dev->base);

	platform_set_drvdata(pdev, NULL);

	if (msm_rng_dev->qrng_perf_client)

		msm_bus_scale_unregister_client(msm_rng_dev->qrng_perf_client);

	kzfree(msm_rng_dev);

	msm_rng_dev_cached = NULL;

	return 0;

}

static int qrng_get_random(struct crypto_rng *tfm, const u8 *src,

				unsigned int slen, u8 *rdata,

				unsigned int dlen)

{

	int sizeread = 0;

	int rv = -EFAULT;

	if (!msm_rng_dev_cached) {

		pr_err("%s: msm_rng_dev is not initialized.\n", __func__);

		rv = -ENODEV;

		goto err_exit;

	}

	if (!rdata) {

		pr_err("%s: data buffer is null!\n", __func__);

		rv = -EINVAL;

		goto err_exit;

	}

	if (signal_pending(current) ||

		mutex_lock_interruptible(&cached_rng_lock)) {

		pr_err("%s: mutex lock interrupted!\n", __func__);

		rv = -ERESTARTSYS;

		goto err_exit;

	}

	sizeread = msm_rng_direct_read(msm_rng_dev_cached, rdata, dlen);

	if (sizeread == dlen)

		rv = 0;

	mutex_unlock(&cached_rng_lock);

err_exit:

	return rv;

}

static int qrng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)

{

	return 0;

}

static struct rng_alg rng_algs[] = { {

	.generate	= qrng_get_random,

	.seed		= qrng_reset,

	.seedsize	= 0,

	.base		= {

		.cra_name		= "qrng",

		.cra_driver_name	= "fips_hw_qrng",

		.cra_priority		= 300,

		.cra_ctxsize		= 0,

		.cra_module		= THIS_MODULE,

	}

} };

static const struct of_device_id qrng_match[] = {

	{	.compatible = "qcom,msm-rng",

	},

	{}

};

static struct platform_driver rng_driver = {

	.probe      = msm_rng_probe,

	.remove     = msm_rng_remove,

	.driver     = {

		.name   = DRIVER_NAME,

		.owner  = THIS_MODULE,

		.of_match_table = qrng_match,

	}

};

static int __init msm_rng_init(void)

{

	int ret;

	msm_rng_dev_cached = NULL;

	ret = platform_driver_register(&rng_driver);

	if (ret) {

		pr_err("%s: platform_driver_register error:%d\n",

			__func__, ret);

		goto err_exit;

	}

	ret = crypto_register_rngs(rng_algs, ARRAY_SIZE(rng_algs));

	if (ret) {

		pr_err("%s: crypto_register_algs error:%d\n",

			__func__, ret);

		goto err_exit;

	}

err_exit:

	return ret;

}

module_init(msm_rng_init);

static void __exit msm_rng_exit(void)

{

	crypto_unregister_rngs(rng_algs, ARRAY_SIZE(rng_algs));

	platform_driver_unregister(&rng_driver);

}

module_exit(msm_rng_exit);

MODULE_DESCRIPTION("QTI MSM Random Number Driver");

MODULE_LICENSE("GPL v2");