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12#define KMSG_COMPONENT "trng"
13#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
14
15#include <linux/hw_random.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/cpufeature.h>
19#include <linux/miscdevice.h>
20#include <linux/debugfs.h>
21#include <linux/atomic.h>
22#include <linux/random.h>
23#include <linux/sched/signal.h>
24#include <asm/debug.h>
25#include <asm/cpacf.h>
26
27MODULE_LICENSE("GPL v2");
28MODULE_AUTHOR("IBM Corporation");
29MODULE_DESCRIPTION("s390 CPACF TRNG device driver");
30
31
32
33
34static debug_info_t *debug_info;
35
36#define DEBUG_DBG(...) debug_sprintf_event(debug_info, 6, ##__VA_ARGS__)
37#define DEBUG_INFO(...) debug_sprintf_event(debug_info, 5, ##__VA_ARGS__)
38#define DEBUG_WARN(...) debug_sprintf_event(debug_info, 4, ##__VA_ARGS__)
39#define DEBUG_ERR(...) debug_sprintf_event(debug_info, 3, ##__VA_ARGS__)
40
41
42
43
44static atomic64_t trng_dev_counter = ATOMIC64_INIT(0);
45static atomic64_t trng_hwrng_counter = ATOMIC64_INIT(0);
46
47
48
49
50static int trng_open(struct inode *inode, struct file *file)
51{
52 return nonseekable_open(inode, file);
53}
54
55static ssize_t trng_read(struct file *file, char __user *ubuf,
56 size_t nbytes, loff_t *ppos)
57{
58 u8 buf[32];
59 u8 *p = buf;
60 unsigned int n;
61 ssize_t ret = 0;
62
63
64
65
66
67
68
69 if (nbytes > sizeof(buf)) {
70 p = (u8 *) __get_free_page(GFP_KERNEL);
71 if (!p)
72 return -ENOMEM;
73 }
74
75 while (nbytes) {
76 if (need_resched()) {
77 if (signal_pending(current)) {
78 if (ret == 0)
79 ret = -ERESTARTSYS;
80 break;
81 }
82 schedule();
83 }
84 n = nbytes > PAGE_SIZE ? PAGE_SIZE : nbytes;
85 cpacf_trng(NULL, 0, p, n);
86 atomic64_add(n, &trng_dev_counter);
87 if (copy_to_user(ubuf, p, n)) {
88 ret = -EFAULT;
89 break;
90 }
91 nbytes -= n;
92 ubuf += n;
93 ret += n;
94 }
95
96 if (p != buf)
97 free_page((unsigned long) p);
98
99 DEBUG_DBG("trng_read()=%zd\n", ret);
100 return ret;
101}
102
103
104
105
106static ssize_t trng_counter_show(struct device *dev,
107 struct device_attribute *attr, char *buf)
108{
109 u64 dev_counter = atomic64_read(&trng_dev_counter);
110 u64 hwrng_counter = atomic64_read(&trng_hwrng_counter);
111#if IS_ENABLED(CONFIG_ARCH_RANDOM)
112 u64 arch_counter = atomic64_read(&s390_arch_random_counter);
113
114 return sysfs_emit(buf,
115 "trng: %llu\n"
116 "hwrng: %llu\n"
117 "arch: %llu\n"
118 "total: %llu\n",
119 dev_counter, hwrng_counter, arch_counter,
120 dev_counter + hwrng_counter + arch_counter);
121#else
122 return sysfs_emit(buf,
123 "trng: %llu\n"
124 "hwrng: %llu\n"
125 "total: %llu\n",
126 dev_counter, hwrng_counter,
127 dev_counter + hwrng_counter);
128#endif
129}
130static DEVICE_ATTR(byte_counter, 0444, trng_counter_show, NULL);
131
132static struct attribute *trng_dev_attrs[] = {
133 &dev_attr_byte_counter.attr,
134 NULL
135};
136
137static const struct attribute_group trng_dev_attr_group = {
138 .attrs = trng_dev_attrs
139};
140
141static const struct attribute_group *trng_dev_attr_groups[] = {
142 &trng_dev_attr_group,
143 NULL
144};
145
146static const struct file_operations trng_fops = {
147 .owner = THIS_MODULE,
148 .open = &trng_open,
149 .release = NULL,
150 .read = &trng_read,
151 .llseek = noop_llseek,
152};
153
154static struct miscdevice trng_dev = {
155 .name = "trng",
156 .minor = MISC_DYNAMIC_MINOR,
157 .mode = 0444,
158 .fops = &trng_fops,
159 .groups = trng_dev_attr_groups,
160};
161
162
163
164
165static inline void _trng_hwrng_read(u8 *buf, size_t len)
166{
167 cpacf_trng(NULL, 0, buf, len);
168 atomic64_add(len, &trng_hwrng_counter);
169}
170
171static int trng_hwrng_data_read(struct hwrng *rng, u32 *data)
172{
173 size_t len = sizeof(*data);
174
175 _trng_hwrng_read((u8 *) data, len);
176
177 DEBUG_DBG("trng_hwrng_data_read()=%zu\n", len);
178
179 return len;
180}
181
182static int trng_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
183{
184 size_t len = max <= PAGE_SIZE ? max : PAGE_SIZE;
185
186 _trng_hwrng_read((u8 *) data, len);
187
188 DEBUG_DBG("trng_hwrng_read()=%zu\n", len);
189
190 return len;
191}
192
193
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195
196
197
198
199static struct hwrng trng_hwrng_dev = {
200 .name = "s390-trng",
201 .data_read = trng_hwrng_data_read,
202 .read = trng_hwrng_read,
203 .quality = 1024,
204};
205
206
207
208
209static void __init trng_debug_init(void)
210{
211 debug_info = debug_register("trng", 1, 1, 4 * sizeof(long));
212 debug_register_view(debug_info, &debug_sprintf_view);
213 debug_set_level(debug_info, 3);
214}
215
216static void trng_debug_exit(void)
217{
218 debug_unregister(debug_info);
219}
220
221static int __init trng_init(void)
222{
223 int ret;
224
225 trng_debug_init();
226
227
228 if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG)) {
229 DEBUG_INFO("trng_init CPACF_PRNO_TRNG not available\n");
230 ret = -ENODEV;
231 goto out_dbg;
232 }
233
234 ret = misc_register(&trng_dev);
235 if (ret) {
236 DEBUG_WARN("trng_init misc_register() failed rc=%d\n", ret);
237 goto out_dbg;
238 }
239
240 ret = hwrng_register(&trng_hwrng_dev);
241 if (ret) {
242 DEBUG_WARN("trng_init hwrng_register() failed rc=%d\n", ret);
243 goto out_misc;
244 }
245
246 DEBUG_DBG("trng_init successful\n");
247
248 return 0;
249
250out_misc:
251 misc_deregister(&trng_dev);
252out_dbg:
253 trng_debug_exit();
254 return ret;
255}
256
257static void __exit trng_exit(void)
258{
259 hwrng_unregister(&trng_hwrng_dev);
260 misc_deregister(&trng_dev);
261 trng_debug_exit();
262}
263
264module_cpu_feature_match(MSA, trng_init);
265module_exit(trng_exit);
266
