Commit c9842929 authored by Tomer Maimon's avatar Tomer Maimon Committed by Herbert Xu
Browse files

hwrng: npcm - add NPCM RNG driver 



Add Nuvoton NPCM BMC Random Number Generator(RNG) driver.

Signed-off-by: default avatarTomer Maimon <tmaimon77@gmail.com>
Reviewed-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 911aa194

drivers/char/hw_random/Kconfig

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@@ -440,6 +440,19 @@ config HW_RANDOM_OPTEE 


	  If unsure, say Y.



config HW_RANDOM_NPCM

	tristate "NPCM Random Number Generator support"

	depends on ARCH_NPCM || COMPILE_TEST

	default HW_RANDOM

	help

 	  This driver provides support for the Random Number

	  Generator hardware available in Nuvoton NPCM SoCs.



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

	  module will be called npcm-rng.



 	  If unsure, say Y.



endif # HW_RANDOM



config UML_RANDOM

drivers/char/hw_random/Makefile

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@@ -39,3 +39,4 @@ obj-$(CONFIG_HW_RANDOM_MTK) += mtk-rng.o 
obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o

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

obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o

obj-$(CONFIG_HW_RANDOM_NPCM) += npcm-rng.o

drivers/char/hw_random/npcm-rng.c

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+186 −0
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// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2019 Nuvoton Technology corporation.



#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/io.h>

#include <linux/iopoll.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/of_irq.h>

#include <linux/pm_runtime.h>



#define NPCM_RNGCS_REG		0x00	/* Control and status register */

#define NPCM_RNGD_REG		0x04	/* Data register */

#define NPCM_RNGMODE_REG	0x08	/* Mode register */



#define NPCM_RNG_CLK_SET_25MHZ	GENMASK(4, 3) /* 20-25 MHz */

#define NPCM_RNG_DATA_VALID	BIT(1)

#define NPCM_RNG_ENABLE		BIT(0)

#define NPCM_RNG_M1ROSEL	BIT(1)



#define NPCM_RNG_TIMEOUT_USEC	20000

#define NPCM_RNG_POLL_USEC	1000



#define to_npcm_rng(p)	container_of(p, struct npcm_rng, rng)



struct npcm_rng {

	void __iomem *base;

	struct hwrng rng;

};



static int npcm_rng_init(struct hwrng *rng)

{

	struct npcm_rng *priv = to_npcm_rng(rng);



	writel(NPCM_RNG_CLK_SET_25MHZ | NPCM_RNG_ENABLE,

	       priv->base + NPCM_RNGCS_REG);



	return 0;

}



static void npcm_rng_cleanup(struct hwrng *rng)

{

	struct npcm_rng *priv = to_npcm_rng(rng);



	writel(NPCM_RNG_CLK_SET_25MHZ, priv->base + NPCM_RNGCS_REG);

}



static int npcm_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)

{

	struct npcm_rng *priv = to_npcm_rng(rng);

	int retval = 0;

	int ready;



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



	while (max >= sizeof(u32)) {

		if (wait) {

			if (readl_poll_timeout(priv->base + NPCM_RNGCS_REG,

					       ready,

					       ready & NPCM_RNG_DATA_VALID,

					       NPCM_RNG_POLL_USEC,

					       NPCM_RNG_TIMEOUT_USEC))

				break;

		} else {

			if ((readl(priv->base + NPCM_RNGCS_REG) &

			    NPCM_RNG_DATA_VALID) == 0)

				break;

		}



		*(u32 *)buf = readl(priv->base + NPCM_RNGD_REG);

		retval += sizeof(u32);

		buf += sizeof(u32);

		max -= sizeof(u32);

	}



	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 npcm_rng_probe(struct platform_device *pdev)

{

	struct npcm_rng *priv;

	struct resource *res;

	int ret;



	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);

	if (!priv)

		return -ENOMEM;



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	priv->base = devm_ioremap_resource(&pdev->dev, res);

	if (IS_ERR(priv->base))

		return PTR_ERR(priv->base);



	dev_set_drvdata(&pdev->dev, priv);

	pm_runtime_set_autosuspend_delay(&pdev->dev, 100);

	pm_runtime_use_autosuspend(&pdev->dev);

	pm_runtime_enable(&pdev->dev);



#ifndef CONFIG_PM

	priv->rng.init = npcm_rng_init;

	priv->rng.cleanup = npcm_rng_cleanup;

#endif

	priv->rng.name = pdev->name;

	priv->rng.read = npcm_rng_read;

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

	priv->rng.quality = 1000;



	writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG);



	ret = devm_hwrng_register(&pdev->dev, &priv->rng);

	if (ret) {

		dev_err(&pdev->dev, "Failed to register rng device: %d\n",

			ret);

		pm_runtime_disable(&pdev->dev);

		pm_runtime_set_suspended(&pdev->dev);

		return ret;

	}



	return 0;

}



static int npcm_rng_remove(struct platform_device *pdev)

{

	struct npcm_rng *priv = platform_get_drvdata(pdev);



	devm_hwrng_unregister(&pdev->dev, &priv->rng);

	pm_runtime_disable(&pdev->dev);

	pm_runtime_set_suspended(&pdev->dev);



	return 0;

}



#ifdef CONFIG_PM

static int npcm_rng_runtime_suspend(struct device *dev)

{

	struct npcm_rng *priv = dev_get_drvdata(dev);



	npcm_rng_cleanup(&priv->rng);



	return 0;

}



static int npcm_rng_runtime_resume(struct device *dev)

{

	struct npcm_rng *priv = dev_get_drvdata(dev);



	return npcm_rng_init(&priv->rng);

}

#endif



static const struct dev_pm_ops npcm_rng_pm_ops = {

	SET_RUNTIME_PM_OPS(npcm_rng_runtime_suspend,

			   npcm_rng_runtime_resume, NULL)

	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,

				pm_runtime_force_resume)

};



static const struct of_device_id rng_dt_id[] = {

	{ .compatible = "nuvoton,npcm750-rng",  },

	{},

};

MODULE_DEVICE_TABLE(of, rng_dt_id);



static struct platform_driver npcm_rng_driver = {

	.driver = {

		.name		= "npcm-rng",

		.pm		= &npcm_rng_pm_ops,

		.of_match_table = of_match_ptr(rng_dt_id),

	},

	.probe		= npcm_rng_probe,

	.remove		= npcm_rng_remove,

};



module_platform_driver(npcm_rng_driver);



MODULE_DESCRIPTION("Nuvoton NPCM Random Number Generator Driver");

MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");

MODULE_LICENSE("GPL v2");