1
2
3
4
5
6#define pr_fmt(fmt) "powernv-rng: " fmt
7
8#include <linux/kernel.h>
9#include <linux/of.h>
10#include <linux/of_address.h>
11#include <linux/of_platform.h>
12#include <linux/slab.h>
13#include <linux/smp.h>
14#include <asm/archrandom.h>
15#include <asm/cputable.h>
16#include <asm/io.h>
17#include <asm/prom.h>
18#include <asm/machdep.h>
19#include <asm/smp.h>
20
21#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
22
23struct powernv_rng {
24 void __iomem *regs;
25 void __iomem *regs_real;
26 unsigned long mask;
27};
28
29static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
30
31
32int powernv_hwrng_present(void)
33{
34 struct powernv_rng *rng;
35
36 rng = get_cpu_var(powernv_rng);
37 put_cpu_var(rng);
38 return rng != NULL;
39}
40
41static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
42{
43 unsigned long parity;
44
45
46 asm ("popcntd %0,%1" : "=r" (parity) : "r" (val));
47
48
49 val ^= rng->mask;
50
51
52 rng->mask = (rng->mask << 1) | (parity & 1);
53
54 return val;
55}
56
57int powernv_get_random_real_mode(unsigned long *v)
58{
59 struct powernv_rng *rng;
60
61 rng = raw_cpu_read(powernv_rng);
62
63 *v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
64
65 return 1;
66}
67
68static int powernv_get_random_darn(unsigned long *v)
69{
70 unsigned long val;
71
72
73 asm volatile(PPC_DARN(%0, 1) : "=r"(val));
74
75 if (val == DARN_ERR)
76 return 0;
77
78 *v = val;
79
80 return 1;
81}
82
83static int initialise_darn(void)
84{
85 unsigned long val;
86 int i;
87
88 if (!cpu_has_feature(CPU_FTR_ARCH_300))
89 return -ENODEV;
90
91 for (i = 0; i < 10; i++) {
92 if (powernv_get_random_darn(&val)) {
93 ppc_md.get_random_seed = powernv_get_random_darn;
94 return 0;
95 }
96 }
97
98 pr_warn("Unable to use DARN for get_random_seed()\n");
99
100 return -EIO;
101}
102
103int powernv_get_random_long(unsigned long *v)
104{
105 struct powernv_rng *rng;
106
107 rng = get_cpu_var(powernv_rng);
108
109 *v = rng_whiten(rng, in_be64(rng->regs));
110
111 put_cpu_var(rng);
112
113 return 1;
114}
115EXPORT_SYMBOL_GPL(powernv_get_random_long);
116
117static __init void rng_init_per_cpu(struct powernv_rng *rng,
118 struct device_node *dn)
119{
120 int chip_id, cpu;
121
122 chip_id = of_get_ibm_chip_id(dn);
123 if (chip_id == -1)
124 pr_warn("No ibm,chip-id found for %pOF.\n", dn);
125
126 for_each_possible_cpu(cpu) {
127 if (per_cpu(powernv_rng, cpu) == NULL ||
128 cpu_to_chip_id(cpu) == chip_id) {
129 per_cpu(powernv_rng, cpu) = rng;
130 }
131 }
132}
133
134static __init int rng_create(struct device_node *dn)
135{
136 struct powernv_rng *rng;
137 struct resource res;
138 unsigned long val;
139
140 rng = kzalloc(sizeof(*rng), GFP_KERNEL);
141 if (!rng)
142 return -ENOMEM;
143
144 if (of_address_to_resource(dn, 0, &res)) {
145 kfree(rng);
146 return -ENXIO;
147 }
148
149 rng->regs_real = (void __iomem *)res.start;
150
151 rng->regs = of_iomap(dn, 0);
152 if (!rng->regs) {
153 kfree(rng);
154 return -ENXIO;
155 }
156
157 val = in_be64(rng->regs);
158 rng->mask = val;
159
160 rng_init_per_cpu(rng, dn);
161
162 pr_info_once("Registering arch random hook.\n");
163
164 ppc_md.get_random_seed = powernv_get_random_long;
165
166 return 0;
167}
168
169static __init int rng_init(void)
170{
171 struct device_node *dn;
172 int rc;
173
174 for_each_compatible_node(dn, NULL, "ibm,power-rng") {
175 rc = rng_create(dn);
176 if (rc) {
177 pr_err("Failed creating rng for %pOF (%d).\n",
178 dn, rc);
179 continue;
180 }
181
182
183 of_platform_device_create(dn, NULL, NULL);
184 }
185
186 initialise_darn();
187
188 return 0;
189}
190machine_subsys_initcall(powernv, rng_init);
191