152 lines
3.6 KiB
C
Executable file
152 lines
3.6 KiB
C
Executable file
/*
|
|
* 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;
|
|
|
|
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",
|
|
.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");
|