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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
31struct 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
38static 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
66static 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
82static 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
104static 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
112static 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
157static const struct of_device_id omap_rom_rng_match[] = {
158 { .compatible = "nokia,n900-rom-rng", .data = omap3_rom_rng_read, },
159 { },
160};
161MODULE_DEVICE_TABLE(of, omap_rom_rng_match);
162
163static 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
168static 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
177module_platform_driver(omap3_rom_rng_driver);
178
179MODULE_ALIAS("platform:omap3-rom-rng");
180MODULE_AUTHOR("Juha Yrjola");
181MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
182MODULE_LICENSE("GPL");
183
