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/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 
30 struct 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 
omap3_rom_rng_read(struct hwrng * rng,void * data,size_t max,bool w)37 static 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 
omap_rom_rng_runtime_suspend(struct device * dev)65 static 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 
omap_rom_rng_runtime_resume(struct device * dev)81 static 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 
omap_rom_rng_finish(void * data)103 static 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 
omap3_rom_rng_probe(struct platform_device * pdev)111 static 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 
156 static const struct of_device_id omap_rom_rng_match[] = {
157 	{ .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, },
158 	{ /* sentinel */ },
159 };
160 MODULE_DEVICE_TABLE(of, omap_rom_rng_match);
161 
162 static 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 
167 static 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 
176 module_platform_driver(omap3_rom_rng_driver);
177 
178 MODULE_ALIAS("platform:omap3-rom-rng");
179 MODULE_AUTHOR("Juha Yrjola");
180 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
181 MODULE_LICENSE("GPL");
182