1
2
3
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/io.h>
7#include <linux/iopoll.h>
8#include <linux/init.h>
9#include <linux/random.h>
10#include <linux/err.h>
11#include <linux/platform_device.h>
12#include <linux/hw_random.h>
13#include <linux/delay.h>
14#include <linux/of_irq.h>
15#include <linux/pm_runtime.h>
16
17#define NPCM_RNGCS_REG 0x00
18#define NPCM_RNGD_REG 0x04
19#define NPCM_RNGMODE_REG 0x08
20
21#define NPCM_RNG_CLK_SET_25MHZ GENMASK(4, 3)
22#define NPCM_RNG_DATA_VALID BIT(1)
23#define NPCM_RNG_ENABLE BIT(0)
24#define NPCM_RNG_M1ROSEL BIT(1)
25
26#define NPCM_RNG_TIMEOUT_USEC 20000
27#define NPCM_RNG_POLL_USEC 1000
28
29#define to_npcm_rng(p) container_of(p, struct npcm_rng, rng)
30
31struct npcm_rng {
32 void __iomem *base;
33 struct hwrng rng;
34};
35
36static int npcm_rng_init(struct hwrng *rng)
37{
38 struct npcm_rng *priv = to_npcm_rng(rng);
39
40 writel(NPCM_RNG_CLK_SET_25MHZ | NPCM_RNG_ENABLE,
41 priv->base + NPCM_RNGCS_REG);
42
43 return 0;
44}
45
46static void npcm_rng_cleanup(struct hwrng *rng)
47{
48 struct npcm_rng *priv = to_npcm_rng(rng);
49
50 writel(NPCM_RNG_CLK_SET_25MHZ, priv->base + NPCM_RNGCS_REG);
51}
52
53static int npcm_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
54{
55 struct npcm_rng *priv = to_npcm_rng(rng);
56 int retval = 0;
57 int ready;
58
59 pm_runtime_get_sync((struct device *)priv->rng.priv);
60
61 while (max) {
62 if (wait) {
63 if (readb_poll_timeout(priv->base + NPCM_RNGCS_REG,
64 ready,
65 ready & NPCM_RNG_DATA_VALID,
66 NPCM_RNG_POLL_USEC,
67 NPCM_RNG_TIMEOUT_USEC))
68 break;
69 } else {
70 if ((readb(priv->base + NPCM_RNGCS_REG) &
71 NPCM_RNG_DATA_VALID) == 0)
72 break;
73 }
74
75 *(u8 *)buf = readb(priv->base + NPCM_RNGD_REG);
76 retval++;
77 buf++;
78 max--;
79 }
80
81 pm_runtime_mark_last_busy((struct device *)priv->rng.priv);
82 pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv);
83
84 return retval || !wait ? retval : -EIO;
85}
86
87static int npcm_rng_probe(struct platform_device *pdev)
88{
89 struct npcm_rng *priv;
90 int ret;
91
92 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
93 if (!priv)
94 return -ENOMEM;
95
96 priv->base = devm_platform_ioremap_resource(pdev, 0);
97 if (IS_ERR(priv->base))
98 return PTR_ERR(priv->base);
99
100 dev_set_drvdata(&pdev->dev, priv);
101 pm_runtime_set_autosuspend_delay(&pdev->dev, 100);
102 pm_runtime_use_autosuspend(&pdev->dev);
103 pm_runtime_enable(&pdev->dev);
104
105#ifndef CONFIG_PM
106 priv->rng.init = npcm_rng_init;
107 priv->rng.cleanup = npcm_rng_cleanup;
108#endif
109 priv->rng.name = pdev->name;
110 priv->rng.read = npcm_rng_read;
111 priv->rng.priv = (unsigned long)&pdev->dev;
112 priv->rng.quality = 1000;
113
114 writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG);
115
116 ret = devm_hwrng_register(&pdev->dev, &priv->rng);
117 if (ret) {
118 dev_err(&pdev->dev, "Failed to register rng device: %d\n",
119 ret);
120 pm_runtime_disable(&pdev->dev);
121 pm_runtime_set_suspended(&pdev->dev);
122 return ret;
123 }
124
125 return 0;
126}
127
128static int npcm_rng_remove(struct platform_device *pdev)
129{
130 struct npcm_rng *priv = platform_get_drvdata(pdev);
131
132 devm_hwrng_unregister(&pdev->dev, &priv->rng);
133 pm_runtime_disable(&pdev->dev);
134 pm_runtime_set_suspended(&pdev->dev);
135
136 return 0;
137}
138
139#ifdef CONFIG_PM
140static int npcm_rng_runtime_suspend(struct device *dev)
141{
142 struct npcm_rng *priv = dev_get_drvdata(dev);
143
144 npcm_rng_cleanup(&priv->rng);
145
146 return 0;
147}
148
149static int npcm_rng_runtime_resume(struct device *dev)
150{
151 struct npcm_rng *priv = dev_get_drvdata(dev);
152
153 return npcm_rng_init(&priv->rng);
154}
155#endif
156
157static const struct dev_pm_ops npcm_rng_pm_ops = {
158 SET_RUNTIME_PM_OPS(npcm_rng_runtime_suspend,
159 npcm_rng_runtime_resume, NULL)
160 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
161 pm_runtime_force_resume)
162};
163
164static const struct of_device_id rng_dt_id[] __maybe_unused = {
165 { .compatible = "nuvoton,npcm750-rng", },
166 {},
167};
168MODULE_DEVICE_TABLE(of, rng_dt_id);
169
170static struct platform_driver npcm_rng_driver = {
171 .driver = {
172 .name = "npcm-rng",
173 .pm = &npcm_rng_pm_ops,
174 .of_match_table = of_match_ptr(rng_dt_id),
175 },
176 .probe = npcm_rng_probe,
177 .remove = npcm_rng_remove,
178};
179
180module_platform_driver(npcm_rng_driver);
181
182MODULE_DESCRIPTION("Nuvoton NPCM Random Number Generator Driver");
183MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
184MODULE_LICENSE("GPL v2");
185
