[linux-2.6-block.git] / drivers / char / hw_random / st-rng.c

/*
 * ST Random Number Generator Driver ST's Platforms
 *
 * Author: Pankaj Dev: <pankaj.dev@st.com>
 *         Lee Jones <lee.jones@linaro.org>
 *
 * Copyright (C) 2015 STMicroelectronics (R&D) Limited
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/hw_random.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

/* Registers */
#define ST_RNG_STATUS_REG		0x20
#define ST_RNG_DATA_REG			0x24

/* Registers fields */
#define ST_RNG_STATUS_BAD_SEQUENCE	BIT(0)
#define ST_RNG_STATUS_BAD_ALTERNANCE	BIT(1)
#define ST_RNG_STATUS_FIFO_FULL		BIT(5)

#define ST_RNG_FIFO_SIZE		8
#define ST_RNG_SAMPLE_SIZE		2 /* 2 Byte (16bit) samples */

/* Samples are available every 0.667us, which we round to 1us */
#define ST_RNG_FILL_FIFO_TIMEOUT   (1 * (ST_RNG_FIFO_SIZE / ST_RNG_SAMPLE_SIZE))

struct st_rng_data {
	void __iomem	*base;
	struct clk	*clk;
	struct hwrng	ops;
};

static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
	struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
	u32 status;
	int i;

	if (max < sizeof(u16))
		return -EINVAL;

	/* Wait until FIFO is full - max 4uS*/
	for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
		status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
		if (status & ST_RNG_STATUS_FIFO_FULL)
			break;
		udelay(1);
	}

	if (i == ST_RNG_FILL_FIFO_TIMEOUT)
		return 0;

	for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
		*(u16 *)(data + i) =
			readl_relaxed(ddata->base + ST_RNG_DATA_REG);

	return i;	/* No of bytes read */
}

static int st_rng_probe(struct platform_device *pdev)
{
	struct st_rng_data *ddata;
	struct resource *res;
	struct clk *clk;
	void __iomem *base;
	int ret;

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

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

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

	ret = clk_prepare_enable(clk);
	if (ret)
		return ret;

	ddata->ops.priv	= (unsigned long)ddata;
	ddata->ops.read	= st_rng_read;
	ddata->ops.name	= pdev->name;
	ddata->base	= base;
	ddata->clk	= clk;

	dev_set_drvdata(&pdev->dev, ddata);

	ret = hwrng_register(&ddata->ops);
	if (ret) {
		dev_err(&pdev->dev, "Failed to register HW RNG\n");
		return ret;
	}

	dev_info(&pdev->dev, "Successfully registered HW RNG\n");

	return 0;
}

static int st_rng_remove(struct platform_device *pdev)
{
	struct st_rng_data *ddata = dev_get_drvdata(&pdev->dev);

	hwrng_unregister(&ddata->ops);

	clk_disable_unprepare(ddata->clk);

	return 0;
}

static const struct of_device_id st_rng_match[] = {
	{ .compatible = "st,rng" },
	{},
};
MODULE_DEVICE_TABLE(of, st_rng_match);

static struct platform_driver st_rng_driver = {
	.driver = {
		.name = "st-hwrandom",
		.of_match_table = of_match_ptr(st_rng_match),
	},
	.probe = st_rng_probe,
	.remove = st_rng_remove
};

module_platform_driver(st_rng_driver);

MODULE_AUTHOR("Pankaj Dev <pankaj.dev@st.com>");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
4a4da53c LJ	1	/*
	2	* ST Random Number Generator Driver ST's Platforms
	3	*
	4	* Author: Pankaj Dev: <pankaj.dev@st.com>
	5	* Lee Jones <lee.jones@linaro.org>
	6	*
	7	* Copyright (C) 2015 STMicroelectronics (R&D) Limited
	8	*
	9	* This program is free software; you can redistribute it and/or modify
	10	* it under the terms of the GNU General Public License version 2 as
	11	* published by the Free Software Foundation.
	12	*/
	13
	14	#include <linux/clk.h>
	15	#include <linux/delay.h>
	16	#include <linux/hw_random.h>
	17	#include <linux/io.h>
	18	#include <linux/module.h>
	19	#include <linux/of.h>
	20	#include <linux/platform_device.h>
	21	#include <linux/slab.h>
	22
	23	/* Registers */
	24	#define ST_RNG_STATUS_REG 0x20
	25	#define ST_RNG_DATA_REG 0x24
	26
	27	/* Registers fields */
	28	#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
	29	#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
	30	#define ST_RNG_STATUS_FIFO_FULL BIT(5)
	31
	32	#define ST_RNG_FIFO_SIZE 8
	33	#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */
	34
	35	/* Samples are available every 0.667us, which we round to 1us */
	36	#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE / ST_RNG_SAMPLE_SIZE))
	37
	38	struct st_rng_data {
	39	void __iomem *base;
	40	struct clk *clk;
	41	struct hwrng ops;
	42	};
	43
	44	static int st_rng_read(struct hwrng rng, void data, size_t max, bool wait)
	45	{
	46	struct st_rng_data ddata = (struct st_rng_data )rng->priv;
	47	u32 status;
	48	int i;
	49
	50	if (max < sizeof(u16))
	51	return -EINVAL;
	52
	53	/* Wait until FIFO is full - max 4uS*/
	54	for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
	55	status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
	56	if (status & ST_RNG_STATUS_FIFO_FULL)
	57	break;
	58	udelay(1);
	59	}
	60
	61	if (i == ST_RNG_FILL_FIFO_TIMEOUT)
	62	return 0;
	63
	64	for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
65	(u16 )(data + i) =
66	readl_relaxed(ddata->base + ST_RNG_DATA_REG);
67
68	return i; /* No of bytes read */
69	}
70
71	static int st_rng_probe(struct platform_device *pdev)
72	{
73	struct st_rng_data *ddata;
74	struct resource *res;
75	struct clk *clk;
76	void __iomem *base;
77	int ret;
78
79	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
80	if (!ddata)
81	return -ENOMEM;
82
83	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
84	base = devm_ioremap_resource(&pdev->dev, res);
85	if (IS_ERR(base))
86	return PTR_ERR(base);
87
88	clk = devm_clk_get(&pdev->dev, NULL);
89	if (IS_ERR(clk))
90	return PTR_ERR(clk);
91
92	ret = clk_prepare_enable(clk);
93	if (ret)
94	return ret;
95
96	ddata->ops.priv = (unsigned long)ddata;
97	ddata->ops.read = st_rng_read;
98	ddata->ops.name = pdev->name;
99	ddata->base = base;
100	ddata->clk = clk;
101
102	dev_set_drvdata(&pdev->dev, ddata);
103
104	ret = hwrng_register(&ddata->ops);
105	if (ret) {
106	dev_err(&pdev->dev, "Failed to register HW RNG\n");
107	return ret;
108	}
109
110	dev_info(&pdev->dev, "Successfully registered HW RNG\n");
111
112	return 0;
113	}
114
115	static int st_rng_remove(struct platform_device *pdev)
116	{
117	struct st_rng_data *ddata = dev_get_drvdata(&pdev->dev);
118
119	hwrng_unregister(&ddata->ops);
120
121	clk_disable_unprepare(ddata->clk);
122
123	return 0;
124	}
125
126	static const struct of_device_id st_rng_match[] = {
127	{ .compatible = "st,rng" },
128	{},
129	};
130	MODULE_DEVICE_TABLE(of, st_rng_match);
131
132	static struct platform_driver st_rng_driver = {
133	.driver = {
134	.name = "st-hwrandom",
135	.of_match_table = of_match_ptr(st_rng_match),
136	},
137	.probe = st_rng_probe,
138	.remove = st_rng_remove
139	};
140
141	module_platform_driver(st_rng_driver);
142
143	MODULE_AUTHOR("Pankaj Dev <pankaj.dev@st.com>");
144	MODULE_LICENSE("GPL v2");