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 
31 struct 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 
38 static 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 
66 static 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 
82 static 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(ddata->clk);
96 		dev_err(dev, "HW init failed: %d\n", r);
97 
98 		return -EIO;
99 	}
100 
101 	return 0;
102 }
103 
104 static 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 
112 static 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 
157 static const struct of_device_id omap_rom_rng_match[] = {
158 	{ .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, },
159 	{ /* sentinel */ },
160 };
161 MODULE_DEVICE_TABLE(of, omap_rom_rng_match);
162 
163 static 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 
168 static 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 
177 module_platform_driver(omap3_rom_rng_driver);
178 
179 MODULE_ALIAS("platform:omap3-rom-rng");
180 MODULE_AUTHOR("Juha Yrjola");
181 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
182 MODULE_LICENSE("GPL");
183