hwrng: pic32 - Add PIC32 RNG hardware driver

Add support for the hardware true random number generator
peripheral found on PIC32.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Joshua Henderson 2016-02-08 14:17:53 -07:00 committed by Herbert Xu
parent d489d170ea
commit 730d02e276
3 changed files with 169 additions and 0 deletions

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@ -381,6 +381,19 @@ config HW_RANDOM_STM32
If unsure, say N.
config HW_RANDOM_PIC32
tristate "Microchip PIC32 Random Number Generator support"
depends on HW_RANDOM && MACH_PIC32
default y
---help---
This driver provides kernel-side support for the Random Number
Generator hardware found on a PIC32.
To compile this driver as a module, choose M here. the
module will be called pic32-rng.
If unsure, say Y.
endif # HW_RANDOM
config UML_RANDOM

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@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o

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@ -0,0 +1,155 @@
/*
* PIC32 RNG driver
*
* Joshua Henderson <joshua.henderson@microchip.com>
* Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
*
* This program is free software; you can distribute 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 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/clkdev.h>
#include <linux/err.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#define RNGCON 0x04
#define TRNGEN BIT(8)
#define PRNGEN BIT(9)
#define PRNGCONT BIT(10)
#define TRNGMOD BIT(11)
#define SEEDLOAD BIT(12)
#define RNGPOLY1 0x08
#define RNGPOLY2 0x0C
#define RNGNUMGEN1 0x10
#define RNGNUMGEN2 0x14
#define RNGSEED1 0x18
#define RNGSEED2 0x1C
#define RNGRCNT 0x20
#define RCNT_MASK 0x7F
struct pic32_rng {
void __iomem *base;
struct hwrng rng;
struct clk *clk;
};
/*
* The TRNG can generate up to 24Mbps. This is a timeout that should be safe
* enough given the instructions in the loop and that the TRNG may not always
* be at maximum rate.
*/
#define RNG_TIMEOUT 500
static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
bool wait)
{
struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);
u64 *data = buf;
u32 t;
unsigned int timeout = RNG_TIMEOUT;
if (max < 8)
return 0;
do {
t = readl(priv->base + RNGRCNT) & RCNT_MASK;
if (t == 64) {
/* TRNG value comes through the seed registers */
*data = ((u64)readl(priv->base + RNGSEED2) << 32) +
readl(priv->base + RNGSEED1);
return 8;
}
} while (wait && --timeout);
return -EIO;
}
static int pic32_rng_probe(struct platform_device *pdev)
{
struct pic32_rng *priv;
struct resource *res;
u32 v;
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);
priv->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(priv->clk))
return PTR_ERR(priv->clk);
ret = clk_prepare_enable(priv->clk);
if (ret)
return ret;
/* enable TRNG in enhanced mode */
v = TRNGEN | TRNGMOD;
writel(v, priv->base + RNGCON);
priv->rng.name = pdev->name;
priv->rng.read = pic32_rng_read;
ret = hwrng_register(&priv->rng);
if (ret)
goto err_register;
platform_set_drvdata(pdev, priv);
return 0;
err_register:
clk_disable_unprepare(priv->clk);
return ret;
}
static int pic32_rng_remove(struct platform_device *pdev)
{
struct pic32_rng *rng = platform_get_drvdata(pdev);
hwrng_unregister(&rng->rng);
writel(0, rng->base + RNGCON);
clk_disable_unprepare(rng->clk);
return 0;
}
static const struct of_device_id pic32_rng_of_match[] = {
{ .compatible = "microchip,pic32mzda-rng", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
static struct platform_driver pic32_rng_driver = {
.probe = pic32_rng_probe,
.remove = pic32_rng_remove,
.driver = {
.name = "pic32-rng",
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(pic32_rng_of_match),
},
};
module_platform_driver(pic32_rng_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");