[deliverable/linux.git] / drivers / char / hw_random / pic32-rng.c

/*
 * 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",
		.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");
Commit	Line	Data
730d02e2 JH	1	/*
	2	* PIC32 RNG driver
	3	*
	4	* Joshua Henderson <joshua.henderson@microchip.com>
	5	* Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
	6	*
	7	* This program is free software; you can distribute it and/or modify it
	8	* under the terms of the GNU General Public License (Version 2) as
	9	* published by the Free Software Foundation.
	10	*
	11	* This program is distributed in the hope it will be useful, but WITHOUT
	12	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	13	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	14	* for more details.
	15	*/
	16
	17	#include <linux/clk.h>
	18	#include <linux/clkdev.h>
	19	#include <linux/err.h>
	20	#include <linux/hw_random.h>
	21	#include <linux/io.h>
	22	#include <linux/kernel.h>
	23	#include <linux/module.h>
	24	#include <linux/of.h>
	25	#include <linux/of_device.h>
	26	#include <linux/platform_device.h>
	27	#include <linux/slab.h>
	28
	29	#define RNGCON 0x04
	30	#define TRNGEN BIT(8)
	31	#define PRNGEN BIT(9)
	32	#define PRNGCONT BIT(10)
	33	#define TRNGMOD BIT(11)
	34	#define SEEDLOAD BIT(12)
	35	#define RNGPOLY1 0x08
	36	#define RNGPOLY2 0x0C
	37	#define RNGNUMGEN1 0x10
	38	#define RNGNUMGEN2 0x14
	39	#define RNGSEED1 0x18
	40	#define RNGSEED2 0x1C
	41	#define RNGRCNT 0x20
	42	#define RCNT_MASK 0x7F
	43
	44	struct pic32_rng {
	45	void __iomem *base;
	46	struct hwrng rng;
	47	struct clk *clk;
	48	};
	49
	50	/*
	51	* The TRNG can generate up to 24Mbps. This is a timeout that should be safe
	52	* enough given the instructions in the loop and that the TRNG may not always
	53	* be at maximum rate.
	54	*/
	55	#define RNG_TIMEOUT 500
	56
	57	static int pic32_rng_read(struct hwrng rng, void buf, size_t max,
	58	bool wait)
	59	{
	60	struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);
	61	u64 *data = buf;
	62	u32 t;
	63	unsigned int timeout = RNG_TIMEOUT;
	64
65	if (max < 8)
66	return 0;
67
68	do {
69	t = readl(priv->base + RNGRCNT) & RCNT_MASK;
70	if (t == 64) {
71	/* TRNG value comes through the seed registers */
72	*data = ((u64)readl(priv->base + RNGSEED2) << 32) +
73	readl(priv->base + RNGSEED1);
74	return 8;
75	}
76	} while (wait && --timeout);
77
78	return -EIO;
79	}
80
81	static int pic32_rng_probe(struct platform_device *pdev)
82	{
83	struct pic32_rng *priv;
84	struct resource *res;
85	u32 v;
86	int ret;
87
88	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
89	if (!priv)
90	return -ENOMEM;
91
92	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
93	priv->base = devm_ioremap_resource(&pdev->dev, res);
94	if (IS_ERR(priv->base))
95	return PTR_ERR(priv->base);
96
97	priv->clk = devm_clk_get(&pdev->dev, NULL);
98	if (IS_ERR(priv->clk))
99	return PTR_ERR(priv->clk);
100
101	ret = clk_prepare_enable(priv->clk);
102	if (ret)
103	return ret;
104
105	/* enable TRNG in enhanced mode */
106	v = TRNGEN \| TRNGMOD;
107	writel(v, priv->base + RNGCON);
108
109	priv->rng.name = pdev->name;
110	priv->rng.read = pic32_rng_read;
111
112	ret = hwrng_register(&priv->rng);
113	if (ret)
114	goto err_register;
115
116	platform_set_drvdata(pdev, priv);
117
118	return 0;
119
120	err_register:
121	clk_disable_unprepare(priv->clk);
122	return ret;
123	}
124
125	static int pic32_rng_remove(struct platform_device *pdev)
126	{
127	struct pic32_rng *rng = platform_get_drvdata(pdev);
128
129	hwrng_unregister(&rng->rng);
130	writel(0, rng->base + RNGCON);
131	clk_disable_unprepare(rng->clk);
132	return 0;
133	}
134
135	static const struct of_device_id pic32_rng_of_match[] = {
136	{ .compatible = "microchip,pic32mzda-rng", },
137	{ /* sentinel */ }
138	};
139	MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
140
141	static struct platform_driver pic32_rng_driver = {
142	.probe = pic32_rng_probe,
143	.remove = pic32_rng_remove,
144	.driver = {
145	.name = "pic32-rng",
730d02e2 JH	146	.of_match_table = of_match_ptr(pic32_rng_of_match),
	147	},
	148	};
	149
	150	module_platform_driver(pic32_rng_driver);
	151
	152	MODULE_LICENSE("GPL");
	153	MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
	154	MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");