1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2010-2012 Broadcom. All rights reserved.
4 * Copyright (c) 2013 Lubomir Rintel
5 */
6
7 #include <linux/hw_random.h>
8 #include <linux/io.h>
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/of_address.h>
12 #include <linux/of_platform.h>
13 #include <linux/platform_device.h>
14 #include <linux/printk.h>
15 #include <linux/clk.h>
16
17 #define RNG_CTRL 0x0
18 #define RNG_STATUS 0x4
19 #define RNG_DATA 0x8
20 #define RNG_INT_MASK 0x10
21
22 /* enable rng */
23 #define RNG_RBGEN 0x1
24
25 /* the initial numbers generated are "less random" so will be discarded */
26 #define RNG_WARMUP_COUNT 0x40000
27
28 #define RNG_INT_OFF 0x1
29
30 struct bcm2835_rng_priv {
31 struct hwrng rng;
32 void __iomem *base;
33 bool mask_interrupts;
34 struct clk *clk;
35 };
36
to_rng_priv(struct hwrng * rng)37 static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng)
38 {
39 return container_of(rng, struct bcm2835_rng_priv, rng);
40 }
41
rng_readl(struct bcm2835_rng_priv * priv,u32 offset)42 static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset)
43 {
44 /* MIPS chips strapped for BE will automagically configure the
45 * peripheral registers for CPU-native byte order.
46 */
47 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
48 return __raw_readl(priv->base + offset);
49 else
50 return readl(priv->base + offset);
51 }
52
rng_writel(struct bcm2835_rng_priv * priv,u32 val,u32 offset)53 static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val,
54 u32 offset)
55 {
56 if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
57 __raw_writel(val, priv->base + offset);
58 else
59 writel(val, priv->base + offset);
60 }
61
bcm2835_rng_read(struct hwrng * rng,void * buf,size_t max,bool wait)62 static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
63 bool wait)
64 {
65 struct bcm2835_rng_priv *priv = to_rng_priv(rng);
66 u32 max_words = max / sizeof(u32);
67 u32 num_words, count;
68
69 while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) {
70 if (!wait)
71 return 0;
72 cpu_relax();
73 }
74
75 num_words = rng_readl(priv, RNG_STATUS) >> 24;
76 if (num_words > max_words)
77 num_words = max_words;
78
79 for (count = 0; count < num_words; count++)
80 ((u32 *)buf)[count] = rng_readl(priv, RNG_DATA);
81
82 return num_words * sizeof(u32);
83 }
84
bcm2835_rng_init(struct hwrng * rng)85 static int bcm2835_rng_init(struct hwrng *rng)
86 {
87 struct bcm2835_rng_priv *priv = to_rng_priv(rng);
88 int ret = 0;
89 u32 val;
90
91 if (!IS_ERR(priv->clk)) {
92 ret = clk_prepare_enable(priv->clk);
93 if (ret)
94 return ret;
95 }
96
97 if (priv->mask_interrupts) {
98 /* mask the interrupt */
99 val = rng_readl(priv, RNG_INT_MASK);
100 val |= RNG_INT_OFF;
101 rng_writel(priv, val, RNG_INT_MASK);
102 }
103
104 /* set warm-up count & enable */
105 rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS);
106 rng_writel(priv, RNG_RBGEN, RNG_CTRL);
107
108 return ret;
109 }
110
bcm2835_rng_cleanup(struct hwrng * rng)111 static void bcm2835_rng_cleanup(struct hwrng *rng)
112 {
113 struct bcm2835_rng_priv *priv = to_rng_priv(rng);
114
115 /* disable rng hardware */
116 rng_writel(priv, 0, RNG_CTRL);
117
118 if (!IS_ERR(priv->clk))
119 clk_disable_unprepare(priv->clk);
120 }
121
122 struct bcm2835_rng_of_data {
123 bool mask_interrupts;
124 };
125
126 static const struct bcm2835_rng_of_data nsp_rng_of_data = {
127 .mask_interrupts = true,
128 };
129
130 static const struct of_device_id bcm2835_rng_of_match[] = {
131 { .compatible = "brcm,bcm2835-rng"},
132 { .compatible = "brcm,bcm-nsp-rng", .data = &nsp_rng_of_data },
133 { .compatible = "brcm,bcm5301x-rng", .data = &nsp_rng_of_data },
134 { .compatible = "brcm,bcm6368-rng"},
135 {},
136 };
137
bcm2835_rng_probe(struct platform_device * pdev)138 static int bcm2835_rng_probe(struct platform_device *pdev)
139 {
140 const struct bcm2835_rng_of_data *of_data;
141 struct device *dev = &pdev->dev;
142 const struct of_device_id *rng_id;
143 struct bcm2835_rng_priv *priv;
144 int err;
145
146 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
147 if (!priv)
148 return -ENOMEM;
149
150 platform_set_drvdata(pdev, priv);
151
152 /* map peripheral */
153 priv->base = devm_platform_ioremap_resource(pdev, 0);
154 if (IS_ERR(priv->base))
155 return PTR_ERR(priv->base);
156
157 /* Clock is optional on most platforms */
158 priv->clk = devm_clk_get(dev, NULL);
159 if (PTR_ERR(priv->clk) == -EPROBE_DEFER)
160 return -EPROBE_DEFER;
161
162 priv->rng.name = pdev->name;
163 priv->rng.init = bcm2835_rng_init;
164 priv->rng.read = bcm2835_rng_read;
165 priv->rng.cleanup = bcm2835_rng_cleanup;
166
167 if (dev_of_node(dev)) {
168 rng_id = of_match_node(bcm2835_rng_of_match, dev->of_node);
169 if (!rng_id)
170 return -EINVAL;
171
172 /* Check for rng init function, execute it */
173 of_data = rng_id->data;
174 if (of_data)
175 priv->mask_interrupts = of_data->mask_interrupts;
176 }
177
178 /* register driver */
179 err = devm_hwrng_register(dev, &priv->rng);
180 if (err)
181 dev_err(dev, "hwrng registration failed\n");
182 else
183 dev_info(dev, "hwrng registered\n");
184
185 return err;
186 }
187
188 MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);
189
190 static const struct platform_device_id bcm2835_rng_devtype[] = {
191 { .name = "bcm2835-rng" },
192 { .name = "bcm63xx-rng" },
193 { /* sentinel */ }
194 };
195 MODULE_DEVICE_TABLE(platform, bcm2835_rng_devtype);
196
197 static struct platform_driver bcm2835_rng_driver = {
198 .driver = {
199 .name = "bcm2835-rng",
200 .of_match_table = bcm2835_rng_of_match,
201 },
202 .probe = bcm2835_rng_probe,
203 .id_table = bcm2835_rng_devtype,
204 };
205 module_platform_driver(bcm2835_rng_driver);
206
207 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
208 MODULE_DESCRIPTION("BCM2835 Random Number Generator (RNG) driver");
209 MODULE_LICENSE("GPL v2");
210