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Scott Brandenc83d45d2015-03-04 12:42:14 -08001/*
2* Copyright (C) 2015 Broadcom Corporation
3*
4* This program is free software; you can redistribute it and/or
5* modify it under the terms of the GNU General Public License as
6* published by the Free Software Foundation version 2.
7*
8* This program is distributed "as is" WITHOUT ANY WARRANTY of any
9* kind, whether express or implied; without even the implied warranty
10* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11* GNU General Public License for more details.
12*/
13/*
14 * DESCRIPTION: The Broadcom iProc RNG200 Driver
15 */
16
17#include <linux/hw_random.h>
18#include <linux/init.h>
19#include <linux/io.h>
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/of_address.h>
23#include <linux/of_platform.h>
24#include <linux/platform_device.h>
25#include <linux/delay.h>
26
27/* Registers */
28#define RNG_CTRL_OFFSET 0x00
29#define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF
30#define RNG_CTRL_RNG_RBGEN_ENABLE 0x00000001
31#define RNG_CTRL_RNG_RBGEN_DISABLE 0x00000000
32
33#define RNG_SOFT_RESET_OFFSET 0x04
34#define RNG_SOFT_RESET 0x00000001
35
36#define RBG_SOFT_RESET_OFFSET 0x08
37#define RBG_SOFT_RESET 0x00000001
38
39#define RNG_INT_STATUS_OFFSET 0x18
40#define RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK 0x80000000
41#define RNG_INT_STATUS_STARTUP_TRANSITIONS_MET_IRQ_MASK 0x00020000
42#define RNG_INT_STATUS_NIST_FAIL_IRQ_MASK 0x00000020
43#define RNG_INT_STATUS_TOTAL_BITS_COUNT_IRQ_MASK 0x00000001
44
45#define RNG_FIFO_DATA_OFFSET 0x20
46
47#define RNG_FIFO_COUNT_OFFSET 0x24
48#define RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK 0x000000FF
49
50struct iproc_rng200_dev {
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -070051 struct hwrng rng;
52 void __iomem *base;
Scott Brandenc83d45d2015-03-04 12:42:14 -080053};
54
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -070055#define to_rng_priv(rng) container_of(rng, struct iproc_rng200_dev, rng)
56
Scott Brandenc83d45d2015-03-04 12:42:14 -080057static void iproc_rng200_restart(void __iomem *rng_base)
58{
59 uint32_t val;
60
61 /* Disable RBG */
62 val = ioread32(rng_base + RNG_CTRL_OFFSET);
63 val &= ~RNG_CTRL_RNG_RBGEN_MASK;
64 val |= RNG_CTRL_RNG_RBGEN_DISABLE;
65 iowrite32(val, rng_base + RNG_CTRL_OFFSET);
66
67 /* Clear all interrupt status */
68 iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);
69
70 /* Reset RNG and RBG */
71 val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
72 val |= RBG_SOFT_RESET;
73 iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);
74
75 val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
76 val |= RNG_SOFT_RESET;
77 iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);
78
79 val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
80 val &= ~RNG_SOFT_RESET;
81 iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);
82
83 val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
84 val &= ~RBG_SOFT_RESET;
85 iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);
86
87 /* Enable RBG */
88 val = ioread32(rng_base + RNG_CTRL_OFFSET);
89 val &= ~RNG_CTRL_RNG_RBGEN_MASK;
90 val |= RNG_CTRL_RNG_RBGEN_ENABLE;
91 iowrite32(val, rng_base + RNG_CTRL_OFFSET);
92}
93
94static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max,
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -070095 bool wait)
Scott Brandenc83d45d2015-03-04 12:42:14 -080096{
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -070097 struct iproc_rng200_dev *priv = to_rng_priv(rng);
Scott Brandenc83d45d2015-03-04 12:42:14 -080098 uint32_t num_remaining = max;
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -070099 uint32_t status;
Scott Brandenc83d45d2015-03-04 12:42:14 -0800100
101 #define MAX_RESETS_PER_READ 1
102 uint32_t num_resets = 0;
103
104 #define MAX_IDLE_TIME (1 * HZ)
105 unsigned long idle_endtime = jiffies + MAX_IDLE_TIME;
106
107 while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {
108
109 /* Is RNG sane? If not, reset it. */
110 status = ioread32(priv->base + RNG_INT_STATUS_OFFSET);
111 if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK |
112 RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) {
113
114 if (num_resets >= MAX_RESETS_PER_READ)
115 return max - num_remaining;
116
117 iproc_rng200_restart(priv->base);
118 num_resets++;
119 }
120
121 /* Are there any random numbers available? */
122 if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) &
123 RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
124
125 if (num_remaining >= sizeof(uint32_t)) {
126 /* Buffer has room to store entire word */
127 *(uint32_t *)buf = ioread32(priv->base +
128 RNG_FIFO_DATA_OFFSET);
129 buf += sizeof(uint32_t);
130 num_remaining -= sizeof(uint32_t);
131 } else {
132 /* Buffer can only store partial word */
133 uint32_t rnd_number = ioread32(priv->base +
134 RNG_FIFO_DATA_OFFSET);
135 memcpy(buf, &rnd_number, num_remaining);
136 buf += num_remaining;
137 num_remaining = 0;
138 }
139
140 /* Reset the IDLE timeout */
141 idle_endtime = jiffies + MAX_IDLE_TIME;
142 } else {
143 if (!wait)
144 /* Cannot wait, return immediately */
145 return max - num_remaining;
146
147 /* Can wait, give others chance to run */
148 usleep_range(min(num_remaining * 10, 500U), 500);
149 }
150 }
151
152 return max - num_remaining;
153}
154
155static int iproc_rng200_init(struct hwrng *rng)
156{
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -0700157 struct iproc_rng200_dev *priv = to_rng_priv(rng);
Scott Brandenc83d45d2015-03-04 12:42:14 -0800158 uint32_t val;
Scott Brandenc83d45d2015-03-04 12:42:14 -0800159
160 /* Setup RNG. */
161 val = ioread32(priv->base + RNG_CTRL_OFFSET);
162 val &= ~RNG_CTRL_RNG_RBGEN_MASK;
163 val |= RNG_CTRL_RNG_RBGEN_ENABLE;
164 iowrite32(val, priv->base + RNG_CTRL_OFFSET);
165
166 return 0;
167}
168
169static void iproc_rng200_cleanup(struct hwrng *rng)
170{
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -0700171 struct iproc_rng200_dev *priv = to_rng_priv(rng);
Scott Brandenc83d45d2015-03-04 12:42:14 -0800172 uint32_t val;
Scott Brandenc83d45d2015-03-04 12:42:14 -0800173
174 /* Disable RNG hardware */
175 val = ioread32(priv->base + RNG_CTRL_OFFSET);
176 val &= ~RNG_CTRL_RNG_RBGEN_MASK;
177 val |= RNG_CTRL_RNG_RBGEN_DISABLE;
178 iowrite32(val, priv->base + RNG_CTRL_OFFSET);
179}
180
Scott Brandenc83d45d2015-03-04 12:42:14 -0800181static int iproc_rng200_probe(struct platform_device *pdev)
182{
183 struct iproc_rng200_dev *priv;
184 struct resource *res;
185 struct device *dev = &pdev->dev;
186 int ret;
187
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -0700188 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
Scott Brandenc83d45d2015-03-04 12:42:14 -0800189 if (!priv)
190 return -ENOMEM;
191
Scott Brandenc83d45d2015-03-04 12:42:14 -0800192 /* Map peripheral */
193 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
194 if (!res) {
195 dev_err(dev, "failed to get rng resources\n");
196 return -EINVAL;
197 }
198
199 priv->base = devm_ioremap_resource(dev, res);
200 if (IS_ERR(priv->base)) {
201 dev_err(dev, "failed to remap rng regs\n");
202 return PTR_ERR(priv->base);
203 }
204
Dmitry Torokhovef0a1b22015-03-12 14:00:06 -0700205 priv->rng.name = "iproc-rng200",
206 priv->rng.read = iproc_rng200_read,
207 priv->rng.init = iproc_rng200_init,
208 priv->rng.cleanup = iproc_rng200_cleanup,
209
Scott Brandenc83d45d2015-03-04 12:42:14 -0800210 /* Register driver */
Dmitry Torokhov73b38622015-03-12 14:00:07 -0700211 ret = devm_hwrng_register(dev, &priv->rng);
Scott Brandenc83d45d2015-03-04 12:42:14 -0800212 if (ret) {
213 dev_err(dev, "hwrng registration failed\n");
214 return ret;
215 }
216
217 dev_info(dev, "hwrng registered\n");
218
219 return 0;
220}
221
Scott Brandenc83d45d2015-03-04 12:42:14 -0800222static const struct of_device_id iproc_rng200_of_match[] = {
223 { .compatible = "brcm,iproc-rng200", },
224 {},
225};
226MODULE_DEVICE_TABLE(of, iproc_rng200_of_match);
227
228static struct platform_driver iproc_rng200_driver = {
229 .driver = {
230 .name = "iproc-rng200",
231 .of_match_table = iproc_rng200_of_match,
232 },
233 .probe = iproc_rng200_probe,
Scott Brandenc83d45d2015-03-04 12:42:14 -0800234};
235module_platform_driver(iproc_rng200_driver);
236
237MODULE_AUTHOR("Broadcom");
238MODULE_DESCRIPTION("iProc RNG200 Random Number Generator driver");
239MODULE_LICENSE("GPL v2");