1/*
2 * omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family
3 *
4 * Copyright (C) 2009 Nokia Corporation
5 * Author: Juha Yrjola <juha.yrjola@solidboot.com>
6 *
7 * Copyright (C) 2013 Pali Rohár <pali@kernel.org>
8 *
9 * This file is licensed under  the terms of the GNU General Public
10 * License version 2. This program is licensed "as is" without any
11 * warranty of any kind, whether express or implied.
12 */
13
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/random.h>
17#include <linux/hw_random.h>
18#include <linux/workqueue.h>
19#include <linux/clk.h>
20#include <linux/err.h>
21#include <linux/io.h>
22#include <linux/of.h>
23#include <linux/of_device.h>
24#include <linux/platform_device.h>
25#include <linux/pm_runtime.h>
26
27#define RNG_RESET			0x01
28#define RNG_GEN_PRNG_HW_INIT		0x02
29#define RNG_GEN_HW			0x08
30
31struct omap_rom_rng {
32	struct clk *clk;
33	struct device *dev;
34	struct hwrng ops;
35	u32 (*rom_rng_call)(u32 ptr, u32 count, u32 flag);
36};
37
38static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w)
39{
40	struct omap_rom_rng *ddata;
41	u32 ptr;
42	int r;
43
44	ddata = (struct omap_rom_rng *)rng->priv;
45
46	r = pm_runtime_get_sync(ddata->dev);
47	if (r < 0) {
48		pm_runtime_put_noidle(ddata->dev);
49
50		return r;
51	}
52
53	ptr = virt_to_phys(data);
54	r = ddata->rom_rng_call(ptr, 4, RNG_GEN_HW);
55	if (r != 0)
56		r = -EINVAL;
57	else
58		r = 4;
59
60	pm_runtime_mark_last_busy(ddata->dev);
61	pm_runtime_put_autosuspend(ddata->dev);
62
63	return r;
64}
65
66static int __maybe_unused omap_rom_rng_runtime_suspend(struct device *dev)
67{
68	struct omap_rom_rng *ddata;
69	int r;
70
71	ddata = dev_get_drvdata(dev);
72
73	r = ddata->rom_rng_call(0, 0, RNG_RESET);
74	if (r != 0)
75		dev_err(dev, "reset failed: %d\n", r);
76
77	clk_disable_unprepare(ddata->clk);
78
79	return 0;
80}
81
82static int __maybe_unused omap_rom_rng_runtime_resume(struct device *dev)
83{
84	struct omap_rom_rng *ddata;
85	int r;
86
87	ddata = dev_get_drvdata(dev);
88
89	r = clk_prepare_enable(ddata->clk);
90	if (r < 0)
91		return r;
92
93	r = ddata->rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
94	if (r != 0) {
95		clk_disable_unprepare(ddata->clk);
96		dev_err(dev, "HW init failed: %d\n", r);
97
98		return -EIO;
99	}
100
101	return 0;
102}
103
104static void omap_rom_rng_finish(void *data)
105{
106	struct omap_rom_rng *ddata = data;
107
108	pm_runtime_dont_use_autosuspend(ddata->dev);
109	pm_runtime_disable(ddata->dev);
110}
111
112static int omap3_rom_rng_probe(struct platform_device *pdev)
113{
114	struct omap_rom_rng *ddata;
115	int ret = 0;
116
117	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
118	if (!ddata)
119		return -ENOMEM;
120
121	ddata->dev = &pdev->dev;
122	ddata->ops.priv = (unsigned long)ddata;
123	ddata->ops.name = "omap3-rom";
124	ddata->ops.read = of_device_get_match_data(&pdev->dev);
125	ddata->ops.quality = 900;
126	if (!ddata->ops.read) {
127		dev_err(&pdev->dev, "missing rom code handler\n");
128
129		return -ENODEV;
130	}
131	dev_set_drvdata(ddata->dev, ddata);
132
133	ddata->rom_rng_call = pdev->dev.platform_data;
134	if (!ddata->rom_rng_call) {
135		dev_err(ddata->dev, "rom_rng_call is NULL\n");
136		return -EINVAL;
137	}
138
139	ddata->clk = devm_clk_get(ddata->dev, "ick");
140	if (IS_ERR(ddata->clk)) {
141		dev_err(ddata->dev, "unable to get RNG clock\n");
142		return PTR_ERR(ddata->clk);
143	}
144
145	pm_runtime_enable(&pdev->dev);
146	pm_runtime_set_autosuspend_delay(&pdev->dev, 500);
147	pm_runtime_use_autosuspend(&pdev->dev);
148
149	ret = devm_add_action_or_reset(ddata->dev, omap_rom_rng_finish,
150				       ddata);
151	if (ret)
152		return ret;
153
154	return devm_hwrng_register(ddata->dev, &ddata->ops);
155}
156
157static const struct of_device_id omap_rom_rng_match[] = {
158	{ .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, },
159	{ /* sentinel */ },
160};
161MODULE_DEVICE_TABLE(of, omap_rom_rng_match);
162
163static const struct dev_pm_ops omap_rom_rng_pm_ops = {
164	SET_SYSTEM_SLEEP_PM_OPS(omap_rom_rng_runtime_suspend,
165				omap_rom_rng_runtime_resume)
166};
167
168static struct platform_driver omap3_rom_rng_driver = {
169	.driver = {
170		.name		= "omap3-rom-rng",
171		.of_match_table = omap_rom_rng_match,
172		.pm = &omap_rom_rng_pm_ops,
173	},
174	.probe		= omap3_rom_rng_probe,
175};
176
177module_platform_driver(omap3_rom_rng_driver);
178
179MODULE_ALIAS("platform:omap3-rom-rng");
180MODULE_AUTHOR("Juha Yrjola");
181MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
182MODULE_LICENSE("GPL");
183