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