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

/*
 * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
 *
 * This file is licensed under  the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/hw_random.h>
#include <linux/platform_device.h>

#define TRNG_CR		0x00
#define TRNG_ISR	0x1c
#define TRNG_ODATA	0x50

#define TRNG_KEY	0x524e4700 /* RNG */

struct atmel_trng {
	struct clk *clk;
	void __iomem *base;
	struct hwrng rng;
};

static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
			   bool wait)
{
	struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
	u32 *data = buf;

	/* data ready? */
	if (readl(trng->base + TRNG_ISR) & 1) {
		*data = readl(trng->base + TRNG_ODATA);
		/*
		  ensure data ready is only set again AFTER the next data
		  word is ready in case it got set between checking ISR
		  and reading ODATA, so we don't risk re-reading the
		  same word
		*/
		readl(trng->base + TRNG_ISR);
		return 4;
	} else
		return 0;
}

static int atmel_trng_probe(struct platform_device *pdev)
{
	struct atmel_trng *trng;
	struct resource *res;
	int ret;

	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
	if (!trng)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	trng->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(trng->base))
		return PTR_ERR(trng->base);

	trng->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(trng->clk))
		return PTR_ERR(trng->clk);

	ret = clk_enable(trng->clk);
	if (ret)
		return ret;

	writel(TRNG_KEY | 1, trng->base + TRNG_CR);
	trng->rng.name = pdev->name;
	trng->rng.read = atmel_trng_read;

	ret = hwrng_register(&trng->rng);
	if (ret)
		goto err_register;

	platform_set_drvdata(pdev, trng);

	return 0;

err_register:
	clk_disable(trng->clk);
	return ret;
}

static int atmel_trng_remove(struct platform_device *pdev)
{
	struct atmel_trng *trng = platform_get_drvdata(pdev);

	hwrng_unregister(&trng->rng);

	writel(TRNG_KEY, trng->base + TRNG_CR);
	clk_disable(trng->clk);

	return 0;
}

#ifdef CONFIG_PM
static int atmel_trng_suspend(struct device *dev)
{
	struct atmel_trng *trng = dev_get_drvdata(dev);

	clk_disable(trng->clk);

	return 0;
}

static int atmel_trng_resume(struct device *dev)
{
	struct atmel_trng *trng = dev_get_drvdata(dev);

	return clk_enable(trng->clk);
}

static const struct dev_pm_ops atmel_trng_pm_ops = {
	.suspend	= atmel_trng_suspend,
	.resume		= atmel_trng_resume,
};
#endif /* CONFIG_PM */

static struct platform_driver atmel_trng_driver = {
	.probe		= atmel_trng_probe,
	.remove		= atmel_trng_remove,
	.driver		= {
		.name	= "atmel-trng",
		.owner	= THIS_MODULE,
#ifdef CONFIG_PM
		.pm	= &atmel_trng_pm_ops,
#endif /* CONFIG_PM */
	},
};

module_platform_driver(atmel_trng_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
MODULE_DESCRIPTION("Atmel true random number generator driver");
Commit	Line	Data
677d3e2f PK	1	/*
	2	* Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
	3	*
	4	* This file is licensed under the terms of the GNU General Public
	5	* License version 2. This program is licensed "as is" without any
	6	* warranty of any kind, whether express or implied.
	7	*/
	8
	9	#include <linux/kernel.h>
	10	#include <linux/module.h>
	11	#include <linux/slab.h>
	12	#include <linux/err.h>
	13	#include <linux/clk.h>
	14	#include <linux/io.h>
	15	#include <linux/hw_random.h>
	16	#include <linux/platform_device.h>
	17
	18	#define TRNG_CR 0x00
	19	#define TRNG_ISR 0x1c
	20	#define TRNG_ODATA 0x50
	21
	22	#define TRNG_KEY 0x524e4700 /* RNG */
	23
	24	struct atmel_trng {
	25	struct clk *clk;
	26	void __iomem *base;
	27	struct hwrng rng;
	28	};
	29
	30	static int atmel_trng_read(struct hwrng rng, void buf, size_t max,
	31	bool wait)
	32	{
	33	struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
	34	u32 *data = buf;
	35
	36	/* data ready? */
c475c06f	37	if (readl(trng->base + TRNG_ISR) & 1) {
677d3e2f	38	*data = readl(trng->base + TRNG_ODATA);
121daad8 PK	39	/*
	40	ensure data ready is only set again AFTER the next data
	41	word is ready in case it got set between checking ISR
	42	and reading ODATA, so we don't risk re-reading the
	43	same word
	44	*/
	45	readl(trng->base + TRNG_ISR);
677d3e2f PK	46	return 4;
	47	} else
	48	return 0;
	49	}
	50
	51	static int atmel_trng_probe(struct platform_device *pdev)
	52	{
	53	struct atmel_trng *trng;
	54	struct resource *res;
	55	int ret;
	56
677d3e2f PK	57	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
	58	if (!trng)
	59	return -ENOMEM;
	60
bfaff75b JH	61	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	62	trng->base = devm_ioremap_resource(&pdev->dev, res);
	63	if (IS_ERR(trng->base))
	64	return PTR_ERR(trng->base);
677d3e2f	65
0c0becd0	66	trng->clk = devm_clk_get(&pdev->dev, NULL);
677d3e2f PK	67	if (IS_ERR(trng->clk))
	68	return PTR_ERR(trng->clk);
	69
	70	ret = clk_enable(trng->clk);
	71	if (ret)
0c0becd0	72	return ret;
677d3e2f PK	73
	74	writel(TRNG_KEY \| 1, trng->base + TRNG_CR);
	75	trng->rng.name = pdev->name;
	76	trng->rng.read = atmel_trng_read;
	77
	78	ret = hwrng_register(&trng->rng);
	79	if (ret)
	80	goto err_register;
	81
	82	platform_set_drvdata(pdev, trng);
	83
	84	return 0;
	85
	86	err_register:
	87	clk_disable(trng->clk);
677d3e2f PK	88	return ret;
	89	}
	90
39af33fc	91	static int atmel_trng_remove(struct platform_device *pdev)
677d3e2f PK	92	{
	93	struct atmel_trng *trng = platform_get_drvdata(pdev);
	94
	95	hwrng_unregister(&trng->rng);
	96
	97	writel(TRNG_KEY, trng->base + TRNG_CR);
	98	clk_disable(trng->clk);
677d3e2f	99
677d3e2f PK	100	return 0;
	101	}
	102
	103	#ifdef CONFIG_PM
	104	static int atmel_trng_suspend(struct device *dev)
	105	{
	106	struct atmel_trng *trng = dev_get_drvdata(dev);
	107
	108	clk_disable(trng->clk);
	109
	110	return 0;
	111	}
	112
	113	static int atmel_trng_resume(struct device *dev)
	114	{
	115	struct atmel_trng *trng = dev_get_drvdata(dev);
	116
	117	return clk_enable(trng->clk);
	118	}
	119
	120	static const struct dev_pm_ops atmel_trng_pm_ops = {
	121	.suspend = atmel_trng_suspend,
	122	.resume = atmel_trng_resume,
	123	};
	124	#endif /* CONFIG_PM */
	125
	126	static struct platform_driver atmel_trng_driver = {
	127	.probe = atmel_trng_probe,
bcd2982a	128	.remove = atmel_trng_remove,
677d3e2f PK	129	.driver = {
	130	.name = "atmel-trng",
	131	.owner = THIS_MODULE,
	132	#ifdef CONFIG_PM
	133	.pm = &atmel_trng_pm_ops,
	134	#endif /* CONFIG_PM */
	135	},
	136	};
	137
b21cb324	138	module_platform_driver(atmel_trng_driver);
677d3e2f PK	139
	140	MODULE_LICENSE("GPL");
	141	MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
	142	MODULE_DESCRIPTION("Atmel true random number generator driver");