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 Roh��r <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/platform_device.h>
24#include <linux/pm_runtime.h>
25
26#define RNG_RESET			0x01
27#define RNG_GEN_PRNG_HW_INIT		0x02
28#define RNG_GEN_HW			0x08
29
30struct omap_rom_rng {
31	struct clk *clk;
32	struct device *dev;
33	struct hwrng ops;
34	u32 (*rom_rng_call)(u32 ptr, u32 count, u32 flag);
35};
36
37static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w)
38{
39	struct omap_rom_rng *ddata;
40	u32 ptr;
41	int r;
42
43	ddata = (struct omap_rom_rng *)rng->priv;
44
45	r = pm_runtime_get_sync(ddata->dev);
46	if (r < 0) {
47		pm_runtime_put_noidle(ddata->dev);
48
49		return r;
50	}
51
52	ptr = virt_to_phys(data);
53	r = ddata->rom_rng_call(ptr, 4, RNG_GEN_HW);
54	if (r != 0)
55		r = -EINVAL;
56	else
57		r = 4;
58
59	pm_runtime_mark_last_busy(ddata->dev);
60	pm_runtime_put_autosuspend(ddata->dev);
61
62	return r;
63}
64
65static int __maybe_unused omap_rom_rng_runtime_suspend(struct device *dev)
66{
67	struct omap_rom_rng *ddata;
68	int r;
69
70	ddata = dev_get_drvdata(dev);
71
72	r = ddata->rom_rng_call(0, 0, RNG_RESET);
73	if (r != 0)
74		dev_err(dev, "reset failed: %d\n", r);
75
76	clk_disable_unprepare(ddata->clk);
77
78	return 0;
79}
80
81static int __maybe_unused omap_rom_rng_runtime_resume(struct device *dev)
82{
83	struct omap_rom_rng *ddata;
84	int r;
85
86	ddata = dev_get_drvdata(dev);
87
88	r = clk_prepare_enable(ddata->clk);
89	if (r < 0)
90		return r;
91
92	r = ddata->rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
93	if (r != 0) {
94		clk_disable_unprepare(ddata->clk);
95		dev_err(dev, "HW init failed: %d\n", r);
96
97		return -EIO;
98	}
99
100	return 0;
101}
102
103static void omap_rom_rng_finish(void *data)
104{
105	struct omap_rom_rng *ddata = data;
106
107	pm_runtime_dont_use_autosuspend(ddata->dev);
108	pm_runtime_disable(ddata->dev);
109}
110
111static int omap3_rom_rng_probe(struct platform_device *pdev)
112{
113	struct omap_rom_rng *ddata;
114	int ret = 0;
115
116	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
117	if (!ddata)
118		return -ENOMEM;
119
120	ddata->dev = &pdev->dev;
121	ddata->ops.priv = (unsigned long)ddata;
122	ddata->ops.name = "omap3-rom";
123	ddata->ops.read = of_device_get_match_data(&pdev->dev);
124	ddata->ops.quality = 900;
125	if (!ddata->ops.read) {
126		dev_err(&pdev->dev, "missing rom code handler\n");
127
128		return -ENODEV;
129	}
130	dev_set_drvdata(ddata->dev, ddata);
131
132	ddata->rom_rng_call = pdev->dev.platform_data;
133	if (!ddata->rom_rng_call) {
134		dev_err(ddata->dev, "rom_rng_call is NULL\n");
135		return -EINVAL;
136	}
137
138	ddata->clk = devm_clk_get(ddata->dev, "ick");
139	if (IS_ERR(ddata->clk)) {
140		dev_err(ddata->dev, "unable to get RNG clock\n");
141		return PTR_ERR(ddata->clk);
142	}
143
144	pm_runtime_enable(&pdev->dev);
145	pm_runtime_set_autosuspend_delay(&pdev->dev, 500);
146	pm_runtime_use_autosuspend(&pdev->dev);
147
148	ret = devm_add_action_or_reset(ddata->dev, omap_rom_rng_finish,
149				       ddata);
150	if (ret)
151		return ret;
152
153	return devm_hwrng_register(ddata->dev, &ddata->ops);
154}
155
156static const struct of_device_id omap_rom_rng_match[] = {
157	{ .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, },
158	{ /* sentinel */ },
159};
160MODULE_DEVICE_TABLE(of, omap_rom_rng_match);
161
162static const struct dev_pm_ops omap_rom_rng_pm_ops = {
163	SET_SYSTEM_SLEEP_PM_OPS(omap_rom_rng_runtime_suspend,
164				omap_rom_rng_runtime_resume)
165};
166
167static struct platform_driver omap3_rom_rng_driver = {
168	.driver = {
169		.name		= "omap3-rom-rng",
170		.of_match_table = omap_rom_rng_match,
171		.pm = &omap_rom_rng_pm_ops,
172	},
173	.probe		= omap3_rom_rng_probe,
174};
175
176module_platform_driver(omap3_rom_rng_driver);
177
178MODULE_ALIAS("platform:omap3-rom-rng");
179MODULE_AUTHOR("Juha Yrjola");
180MODULE_AUTHOR("Pali Roh��r <pali@kernel.org>");
181MODULE_LICENSE("GPL");
182