1 /*
2 * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
3 *
4 * This file is licensed under the terms of the GNU General Public
5 * License version 2. This program is licensed "as is" without any
6 * warranty of any kind, whether express or implied.
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/mod_devicetable.h>
12 #include <linux/slab.h>
13 #include <linux/err.h>
14 #include <linux/clk.h>
15 #include <linux/io.h>
16 #include <linux/iopoll.h>
17 #include <linux/hw_random.h>
18 #include <linux/of.h>
19 #include <linux/platform_device.h>
20 #include <linux/pm_runtime.h>
21
22 #define TRNG_CR 0x00
23 #define TRNG_MR 0x04
24 #define TRNG_ISR 0x1c
25 #define TRNG_ISR_DATRDY BIT(0)
26 #define TRNG_ODATA 0x50
27
28 #define TRNG_KEY 0x524e4700 /* RNG */
29
30 #define TRNG_HALFR BIT(0) /* generate RN every 168 cycles */
31
32 struct atmel_trng_data {
33 bool has_half_rate;
34 };
35
36 struct atmel_trng {
37 struct clk *clk;
38 void __iomem *base;
39 struct hwrng rng;
40 bool has_half_rate;
41 };
42
atmel_trng_wait_ready(struct atmel_trng * trng,bool wait)43 static bool atmel_trng_wait_ready(struct atmel_trng *trng, bool wait)
44 {
45 int ready;
46
47 ready = readl(trng->base + TRNG_ISR) & TRNG_ISR_DATRDY;
48 if (!ready && wait)
49 readl_poll_timeout(trng->base + TRNG_ISR, ready,
50 ready & TRNG_ISR_DATRDY, 1000, 20000);
51
52 return !!ready;
53 }
54
atmel_trng_read(struct hwrng * rng,void * buf,size_t max,bool wait)55 static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
56 bool wait)
57 {
58 struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
59 u32 *data = buf;
60 int ret;
61
62 ret = pm_runtime_get_sync((struct device *)trng->rng.priv);
63 if (ret < 0) {
64 pm_runtime_put_sync((struct device *)trng->rng.priv);
65 return ret;
66 }
67
68 ret = atmel_trng_wait_ready(trng, wait);
69 if (!ret)
70 goto out;
71
72 *data = readl(trng->base + TRNG_ODATA);
73 /*
74 * ensure data ready is only set again AFTER the next data word is ready
75 * in case it got set between checking ISR and reading ODATA, so we
76 * don't risk re-reading the same word
77 */
78 readl(trng->base + TRNG_ISR);
79 ret = 4;
80
81 out:
82 pm_runtime_mark_last_busy((struct device *)trng->rng.priv);
83 pm_runtime_put_sync_autosuspend((struct device *)trng->rng.priv);
84 return ret;
85 }
86
atmel_trng_init(struct atmel_trng * trng)87 static int atmel_trng_init(struct atmel_trng *trng)
88 {
89 unsigned long rate;
90 int ret;
91
92 ret = clk_prepare_enable(trng->clk);
93 if (ret)
94 return ret;
95
96 if (trng->has_half_rate) {
97 rate = clk_get_rate(trng->clk);
98
99 /* if peripheral clk is above 100MHz, set HALFR */
100 if (rate > 100000000)
101 writel(TRNG_HALFR, trng->base + TRNG_MR);
102 }
103
104 writel(TRNG_KEY | 1, trng->base + TRNG_CR);
105
106 return 0;
107 }
108
atmel_trng_cleanup(struct atmel_trng * trng)109 static void atmel_trng_cleanup(struct atmel_trng *trng)
110 {
111 writel(TRNG_KEY, trng->base + TRNG_CR);
112 clk_disable_unprepare(trng->clk);
113 }
114
atmel_trng_probe(struct platform_device * pdev)115 static int atmel_trng_probe(struct platform_device *pdev)
116 {
117 struct atmel_trng *trng;
118 const struct atmel_trng_data *data;
119 int ret;
120
121 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
122 if (!trng)
123 return -ENOMEM;
124
125 trng->base = devm_platform_ioremap_resource(pdev, 0);
126 if (IS_ERR(trng->base))
127 return PTR_ERR(trng->base);
128
129 trng->clk = devm_clk_get(&pdev->dev, NULL);
130 if (IS_ERR(trng->clk))
131 return PTR_ERR(trng->clk);
132 data = of_device_get_match_data(&pdev->dev);
133 if (!data)
134 return -ENODEV;
135
136 trng->has_half_rate = data->has_half_rate;
137 trng->rng.name = pdev->name;
138 trng->rng.read = atmel_trng_read;
139 trng->rng.priv = (unsigned long)&pdev->dev;
140 platform_set_drvdata(pdev, trng);
141
142 #ifndef CONFIG_PM
143 ret = atmel_trng_init(trng);
144 if (ret)
145 return ret;
146 #endif
147
148 pm_runtime_set_autosuspend_delay(&pdev->dev, 100);
149 pm_runtime_use_autosuspend(&pdev->dev);
150 pm_runtime_enable(&pdev->dev);
151
152 ret = devm_hwrng_register(&pdev->dev, &trng->rng);
153 if (ret) {
154 pm_runtime_disable(&pdev->dev);
155 pm_runtime_set_suspended(&pdev->dev);
156 #ifndef CONFIG_PM
157 atmel_trng_cleanup(trng);
158 #endif
159 }
160
161 return ret;
162 }
163
atmel_trng_remove(struct platform_device * pdev)164 static int atmel_trng_remove(struct platform_device *pdev)
165 {
166 struct atmel_trng *trng = platform_get_drvdata(pdev);
167
168 atmel_trng_cleanup(trng);
169 pm_runtime_disable(&pdev->dev);
170 pm_runtime_set_suspended(&pdev->dev);
171
172 return 0;
173 }
174
atmel_trng_runtime_suspend(struct device * dev)175 static int __maybe_unused atmel_trng_runtime_suspend(struct device *dev)
176 {
177 struct atmel_trng *trng = dev_get_drvdata(dev);
178
179 atmel_trng_cleanup(trng);
180
181 return 0;
182 }
183
atmel_trng_runtime_resume(struct device * dev)184 static int __maybe_unused atmel_trng_runtime_resume(struct device *dev)
185 {
186 struct atmel_trng *trng = dev_get_drvdata(dev);
187
188 return atmel_trng_init(trng);
189 }
190
191 static const struct dev_pm_ops __maybe_unused atmel_trng_pm_ops = {
192 SET_RUNTIME_PM_OPS(atmel_trng_runtime_suspend,
193 atmel_trng_runtime_resume, NULL)
194 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
195 pm_runtime_force_resume)
196 };
197
198 static const struct atmel_trng_data at91sam9g45_config = {
199 .has_half_rate = false,
200 };
201
202 static const struct atmel_trng_data sam9x60_config = {
203 .has_half_rate = true,
204 };
205
206 static const struct of_device_id atmel_trng_dt_ids[] = {
207 {
208 .compatible = "atmel,at91sam9g45-trng",
209 .data = &at91sam9g45_config,
210 }, {
211 .compatible = "microchip,sam9x60-trng",
212 .data = &sam9x60_config,
213 }, {
214 /* sentinel */
215 }
216 };
217 MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids);
218
219 static struct platform_driver atmel_trng_driver = {
220 .probe = atmel_trng_probe,
221 .remove = atmel_trng_remove,
222 .driver = {
223 .name = "atmel-trng",
224 .pm = pm_ptr(&atmel_trng_pm_ops),
225 .of_match_table = atmel_trng_dt_ids,
226 },
227 };
228
229 module_platform_driver(atmel_trng_driver);
230
231 MODULE_LICENSE("GPL");
232 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
233 MODULE_DESCRIPTION("Atmel true random number generator driver");
234