12874c5fdSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
2a4da0d50SMichael Ellerman /*
3a4da0d50SMichael Ellerman * Copyright 2013, Michael Ellerman, IBM Corporation.
4a4da0d50SMichael Ellerman */
5a4da0d50SMichael Ellerman
6a4da0d50SMichael Ellerman #define pr_fmt(fmt) "powernv-rng: " fmt
7a4da0d50SMichael Ellerman
8a4da0d50SMichael Ellerman #include <linux/kernel.h>
9a4da0d50SMichael Ellerman #include <linux/of.h>
101400b420SStephen Rothwell #include <linux/of_address.h>
11a4da0d50SMichael Ellerman #include <linux/of_platform.h>
12a4da0d50SMichael Ellerman #include <linux/slab.h>
131400b420SStephen Rothwell #include <linux/smp.h>
14a4da0d50SMichael Ellerman #include <asm/archrandom.h>
15e66ca3dbSMatt Brown #include <asm/cputable.h>
16a4da0d50SMichael Ellerman #include <asm/io.h>
171400b420SStephen Rothwell #include <asm/prom.h>
18a4da0d50SMichael Ellerman #include <asm/machdep.h>
193eb906c6SMichael Ellerman #include <asm/smp.h>
20f3eac426SJason A. Donenfeld #include "powernv.h"
21a4da0d50SMichael Ellerman
22e66ca3dbSMatt Brown #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
23a4da0d50SMichael Ellerman
24*978030f0SJason A. Donenfeld struct pnv_rng {
25a4da0d50SMichael Ellerman void __iomem *regs;
26e928e9cbSMichael Ellerman void __iomem *regs_real;
27a4da0d50SMichael Ellerman unsigned long mask;
28a4da0d50SMichael Ellerman };
29a4da0d50SMichael Ellerman
30*978030f0SJason A. Donenfeld static DEFINE_PER_CPU(struct pnv_rng *, pnv_rng);
31a4da0d50SMichael Ellerman
rng_whiten(struct pnv_rng * rng,unsigned long val)32*978030f0SJason A. Donenfeld static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
33a4da0d50SMichael Ellerman {
34a4da0d50SMichael Ellerman unsigned long parity;
35a4da0d50SMichael Ellerman
36a4da0d50SMichael Ellerman /* Calculate the parity of the value */
378667d0d6SAnders Roxell asm (".machine push; \
388667d0d6SAnders Roxell .machine power7; \
398667d0d6SAnders Roxell popcntd %0,%1; \
408667d0d6SAnders Roxell .machine pop;"
418667d0d6SAnders Roxell : "=r" (parity) : "r" (val));
42a4da0d50SMichael Ellerman
43a4da0d50SMichael Ellerman /* xor our value with the previous mask */
44a4da0d50SMichael Ellerman val ^= rng->mask;
45a4da0d50SMichael Ellerman
46a4da0d50SMichael Ellerman /* update the mask based on the parity of this value */
47a4da0d50SMichael Ellerman rng->mask = (rng->mask << 1) | (parity & 1);
48a4da0d50SMichael Ellerman
49a4da0d50SMichael Ellerman return val;
50a4da0d50SMichael Ellerman }
51a4da0d50SMichael Ellerman
pnv_get_random_darn(unsigned long * v)52*978030f0SJason A. Donenfeld static int pnv_get_random_darn(unsigned long *v)
53e66ca3dbSMatt Brown {
54e66ca3dbSMatt Brown unsigned long val;
55e66ca3dbSMatt Brown
56e66ca3dbSMatt Brown /* Using DARN with L=1 - 64-bit conditioned random number */
57e66ca3dbSMatt Brown asm volatile(PPC_DARN(%0, 1) : "=r"(val));
58e66ca3dbSMatt Brown
59e66ca3dbSMatt Brown if (val == DARN_ERR)
60e66ca3dbSMatt Brown return 0;
61e66ca3dbSMatt Brown
62e66ca3dbSMatt Brown *v = val;
63e66ca3dbSMatt Brown
64e66ca3dbSMatt Brown return 1;
65e66ca3dbSMatt Brown }
66e66ca3dbSMatt Brown
initialise_darn(void)67e5913db1SNick Child static int __init initialise_darn(void)
68e66ca3dbSMatt Brown {
69e66ca3dbSMatt Brown unsigned long val;
70e66ca3dbSMatt Brown int i;
71e66ca3dbSMatt Brown
72e66ca3dbSMatt Brown if (!cpu_has_feature(CPU_FTR_ARCH_300))
73e66ca3dbSMatt Brown return -ENODEV;
74e66ca3dbSMatt Brown
75e66ca3dbSMatt Brown for (i = 0; i < 10; i++) {
76*978030f0SJason A. Donenfeld if (pnv_get_random_darn(&val)) {
77*978030f0SJason A. Donenfeld ppc_md.get_random_seed = pnv_get_random_darn;
78e66ca3dbSMatt Brown return 0;
79e66ca3dbSMatt Brown }
80e66ca3dbSMatt Brown }
81e66ca3dbSMatt Brown return -EIO;
82e66ca3dbSMatt Brown }
83e66ca3dbSMatt Brown
pnv_get_random_long(unsigned long * v)84*978030f0SJason A. Donenfeld int pnv_get_random_long(unsigned long *v)
85a4da0d50SMichael Ellerman {
86*978030f0SJason A. Donenfeld struct pnv_rng *rng;
87a4da0d50SMichael Ellerman
887ef3d06fSJason A. Donenfeld if (mfmsr() & MSR_DR) {
89*978030f0SJason A. Donenfeld rng = get_cpu_var(pnv_rng);
90a4da0d50SMichael Ellerman *v = rng_whiten(rng, in_be64(rng->regs));
91a4da0d50SMichael Ellerman put_cpu_var(rng);
927ef3d06fSJason A. Donenfeld } else {
93*978030f0SJason A. Donenfeld rng = raw_cpu_read(pnv_rng);
947ef3d06fSJason A. Donenfeld *v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
957ef3d06fSJason A. Donenfeld }
96a4da0d50SMichael Ellerman return 1;
97a4da0d50SMichael Ellerman }
98*978030f0SJason A. Donenfeld EXPORT_SYMBOL_GPL(pnv_get_random_long);
99a4da0d50SMichael Ellerman
rng_init_per_cpu(struct pnv_rng * rng,struct device_node * dn)100*978030f0SJason A. Donenfeld static __init void rng_init_per_cpu(struct pnv_rng *rng,
101a4da0d50SMichael Ellerman struct device_node *dn)
102a4da0d50SMichael Ellerman {
103a4da0d50SMichael Ellerman int chip_id, cpu;
104a4da0d50SMichael Ellerman
105a4da0d50SMichael Ellerman chip_id = of_get_ibm_chip_id(dn);
106a4da0d50SMichael Ellerman if (chip_id == -1)
107b7c670d6SRob Herring pr_warn("No ibm,chip-id found for %pOF.\n", dn);
108a4da0d50SMichael Ellerman
109a4da0d50SMichael Ellerman for_each_possible_cpu(cpu) {
110*978030f0SJason A. Donenfeld if (per_cpu(pnv_rng, cpu) == NULL ||
111a4da0d50SMichael Ellerman cpu_to_chip_id(cpu) == chip_id) {
112*978030f0SJason A. Donenfeld per_cpu(pnv_rng, cpu) = rng;
113a4da0d50SMichael Ellerman }
114a4da0d50SMichael Ellerman }
115a4da0d50SMichael Ellerman }
116a4da0d50SMichael Ellerman
rng_create(struct device_node * dn)117a4da0d50SMichael Ellerman static __init int rng_create(struct device_node *dn)
118a4da0d50SMichael Ellerman {
119*978030f0SJason A. Donenfeld struct pnv_rng *rng;
120e928e9cbSMichael Ellerman struct resource res;
121a4da0d50SMichael Ellerman unsigned long val;
122a4da0d50SMichael Ellerman
123a4da0d50SMichael Ellerman rng = kzalloc(sizeof(*rng), GFP_KERNEL);
124a4da0d50SMichael Ellerman if (!rng)
125a4da0d50SMichael Ellerman return -ENOMEM;
126a4da0d50SMichael Ellerman
127e928e9cbSMichael Ellerman if (of_address_to_resource(dn, 0, &res)) {
128e928e9cbSMichael Ellerman kfree(rng);
129e928e9cbSMichael Ellerman return -ENXIO;
130e928e9cbSMichael Ellerman }
131e928e9cbSMichael Ellerman
132e928e9cbSMichael Ellerman rng->regs_real = (void __iomem *)res.start;
133e928e9cbSMichael Ellerman
134a4da0d50SMichael Ellerman rng->regs = of_iomap(dn, 0);
135a4da0d50SMichael Ellerman if (!rng->regs) {
136a4da0d50SMichael Ellerman kfree(rng);
137a4da0d50SMichael Ellerman return -ENXIO;
138a4da0d50SMichael Ellerman }
139a4da0d50SMichael Ellerman
140a4da0d50SMichael Ellerman val = in_be64(rng->regs);
141a4da0d50SMichael Ellerman rng->mask = val;
142a4da0d50SMichael Ellerman
143a4da0d50SMichael Ellerman rng_init_per_cpu(rng, dn);
144a4da0d50SMichael Ellerman
145*978030f0SJason A. Donenfeld ppc_md.get_random_seed = pnv_get_random_long;
146a4da0d50SMichael Ellerman
147a4da0d50SMichael Ellerman return 0;
148a4da0d50SMichael Ellerman }
149a4da0d50SMichael Ellerman
pnv_get_random_long_early(unsigned long * v)150f3eac426SJason A. Donenfeld static int __init pnv_get_random_long_early(unsigned long *v)
151a4da0d50SMichael Ellerman {
152a4da0d50SMichael Ellerman struct device_node *dn;
153f3eac426SJason A. Donenfeld
154f3eac426SJason A. Donenfeld if (!slab_is_available())
155f3eac426SJason A. Donenfeld return 0;
156f3eac426SJason A. Donenfeld
157f3eac426SJason A. Donenfeld if (cmpxchg(&ppc_md.get_random_seed, pnv_get_random_long_early,
158f3eac426SJason A. Donenfeld NULL) != pnv_get_random_long_early)
159f3eac426SJason A. Donenfeld return 0;
160a4da0d50SMichael Ellerman
16188750282SJason A. Donenfeld for_each_compatible_node(dn, NULL, "ibm,power-rng")
16288750282SJason A. Donenfeld rng_create(dn);
163a4da0d50SMichael Ellerman
164f3eac426SJason A. Donenfeld if (!ppc_md.get_random_seed)
165f3eac426SJason A. Donenfeld return 0;
166f3eac426SJason A. Donenfeld return ppc_md.get_random_seed(v);
167f3eac426SJason A. Donenfeld }
168e66ca3dbSMatt Brown
pnv_rng_init(void)169f3eac426SJason A. Donenfeld void __init pnv_rng_init(void)
170f3eac426SJason A. Donenfeld {
171f3eac426SJason A. Donenfeld struct device_node *dn;
172f3eac426SJason A. Donenfeld
173f3eac426SJason A. Donenfeld /* Prefer darn over the rest. */
174f3eac426SJason A. Donenfeld if (!initialise_darn())
175f3eac426SJason A. Donenfeld return;
176f3eac426SJason A. Donenfeld
177f3eac426SJason A. Donenfeld dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
178f3eac426SJason A. Donenfeld if (dn)
179f3eac426SJason A. Donenfeld ppc_md.get_random_seed = pnv_get_random_long_early;
180f3eac426SJason A. Donenfeld
181f3eac426SJason A. Donenfeld of_node_put(dn);
182f3eac426SJason A. Donenfeld }
183f3eac426SJason A. Donenfeld
pnv_rng_late_init(void)184f3eac426SJason A. Donenfeld static int __init pnv_rng_late_init(void)
185f3eac426SJason A. Donenfeld {
18688750282SJason A. Donenfeld struct device_node *dn;
187f3eac426SJason A. Donenfeld unsigned long v;
18888750282SJason A. Donenfeld
189f3eac426SJason A. Donenfeld /* In case it wasn't called during init for some other reason. */
190f3eac426SJason A. Donenfeld if (ppc_md.get_random_seed == pnv_get_random_long_early)
191f3eac426SJason A. Donenfeld pnv_get_random_long_early(&v);
19288750282SJason A. Donenfeld
193*978030f0SJason A. Donenfeld if (ppc_md.get_random_seed == pnv_get_random_long) {
19488750282SJason A. Donenfeld for_each_compatible_node(dn, NULL, "ibm,power-rng")
19588750282SJason A. Donenfeld of_platform_device_create(dn, NULL, NULL);
19688750282SJason A. Donenfeld }
19788750282SJason A. Donenfeld
198a4da0d50SMichael Ellerman return 0;
199a4da0d50SMichael Ellerman }
200f3eac426SJason A. Donenfeld machine_subsys_initcall(powernv, pnv_rng_late_init);
201