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_put_autosuspend(ddata->dev);
60
61 return r;
62 }
63
omap_rom_rng_runtime_suspend(struct device * dev)64 static int __maybe_unused omap_rom_rng_runtime_suspend(struct device *dev)
65 {
66 struct omap_rom_rng *ddata;
67 int r;
68
69 ddata = dev_get_drvdata(dev);
70
71 r = ddata->rom_rng_call(0, 0, RNG_RESET);
72 if (r != 0)
73 dev_err(dev, "reset failed: %d\n", r);
74
75 clk_disable_unprepare(ddata->clk);
76
77 return 0;
78 }
79
omap_rom_rng_runtime_resume(struct device * dev)80 static int __maybe_unused omap_rom_rng_runtime_resume(struct device *dev)
81 {
82 struct omap_rom_rng *ddata;
83 int r;
84
85 ddata = dev_get_drvdata(dev);
86
87 r = clk_prepare_enable(ddata->clk);
88 if (r < 0)
89 return r;
90
91 r = ddata->rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
92 if (r != 0) {
93 clk_disable_unprepare(ddata->clk);
94 dev_err(dev, "HW init failed: %d\n", r);
95
96 return -EIO;
97 }
98
99 return 0;
100 }
101
omap_rom_rng_finish(void * data)102 static void omap_rom_rng_finish(void *data)
103 {
104 struct omap_rom_rng *ddata = data;
105
106 pm_runtime_dont_use_autosuspend(ddata->dev);
107 pm_runtime_disable(ddata->dev);
108 }
109
omap3_rom_rng_probe(struct platform_device * pdev)110 static int omap3_rom_rng_probe(struct platform_device *pdev)
111 {
112 struct omap_rom_rng *ddata;
113 int ret = 0;
114
115 ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
116 if (!ddata)
117 return -ENOMEM;
118
119 ddata->dev = &pdev->dev;
120 ddata->ops.priv = (unsigned long)ddata;
121 ddata->ops.name = "omap3-rom";
122 ddata->ops.read = of_device_get_match_data(&pdev->dev);
123 ddata->ops.quality = 900;
124 if (!ddata->ops.read) {
125 dev_err(&pdev->dev, "missing rom code handler\n");
126
127 return -ENODEV;
128 }
129 dev_set_drvdata(ddata->dev, ddata);
130
131 ddata->rom_rng_call = pdev->dev.platform_data;
132 if (!ddata->rom_rng_call) {
133 dev_err(ddata->dev, "rom_rng_call is NULL\n");
134 return -EINVAL;
135 }
136
137 ddata->clk = devm_clk_get(ddata->dev, "ick");
138 if (IS_ERR(ddata->clk)) {
139 dev_err(ddata->dev, "unable to get RNG clock\n");
140 return PTR_ERR(ddata->clk);
141 }
142
143 pm_runtime_enable(&pdev->dev);
144 pm_runtime_set_autosuspend_delay(&pdev->dev, 500);
145 pm_runtime_use_autosuspend(&pdev->dev);
146
147 ret = devm_add_action_or_reset(ddata->dev, omap_rom_rng_finish,
148 ddata);
149 if (ret)
150 return ret;
151
152 return devm_hwrng_register(ddata->dev, &ddata->ops);
153 }
154
155 static const struct of_device_id omap_rom_rng_match[] = {
156 { .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, },
157 { /* sentinel */ },
158 };
159 MODULE_DEVICE_TABLE(of, omap_rom_rng_match);
160
161 static const struct dev_pm_ops omap_rom_rng_pm_ops = {
162 SET_SYSTEM_SLEEP_PM_OPS(omap_rom_rng_runtime_suspend,
163 omap_rom_rng_runtime_resume)
164 };
165
166 static struct platform_driver omap3_rom_rng_driver = {
167 .driver = {
168 .name = "omap3-rom-rng",
169 .of_match_table = omap_rom_rng_match,
170 .pm = &omap_rom_rng_pm_ops,
171 },
172 .probe = omap3_rom_rng_probe,
173 };
174
175 module_platform_driver(omap3_rom_rng_driver);
176
177 MODULE_ALIAS("platform:omap3-rom-rng");
178 MODULE_AUTHOR("Juha Yrjola");
179 MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
180 MODULE_DESCRIPTION("RNG driver for TI OMAP3 CPU family");
181 MODULE_LICENSE("GPL");
182