projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| a4da0d50 ME |
1 | /* |
| 2 | * Copyright 2013, Michael Ellerman, IBM 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 | |
| 6 | * as published by the Free Software Foundation; either version | |
| 7 | * 2 of the License, or (at your option) any later version. | |
| 8 | */ | |
| 9 | ||
| 10 | #define pr_fmt(fmt) "powernv-rng: " fmt | |
| 11 | ||
| 12 | #include <linux/kernel.h> | |
| 13 | #include <linux/of.h> | |
| 1400b420 | 14 | #include <linux/of_address.h> |
| a4da0d50 ME |
15 | #include <linux/of_platform.h> |
| 16 | #include <linux/slab.h> | |
| 1400b420 | 17 | #include <linux/smp.h> |
| a4da0d50 ME |
18 | #include <asm/archrandom.h> |
| 19 | #include <asm/io.h> | |
| 1400b420 | 20 | #include <asm/prom.h> |
| a4da0d50 | 21 | #include <asm/machdep.h> |
| 3eb906c6 | 22 | #include <asm/smp.h> |
| a4da0d50 ME |
23 | |
| 24 | ||
| 25 | struct powernv_rng { | |
| 26 | void __iomem *regs; | |
| e928e9cb | 27 | void __iomem *regs_real; |
| a4da0d50 ME |
28 | unsigned long mask; |
| 29 | }; | |
| 30 | ||
| 31 | static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng); | |
| 32 | ||
| 33 | ||
| e928e9cb ME |
34 | int powernv_hwrng_present(void) |
| 35 | { | |
| 36 | struct powernv_rng *rng; | |
| 37 | ||
| 38 | rng = get_cpu_var(powernv_rng); | |
| 39 | put_cpu_var(rng); | |
| 40 | return rng != NULL; | |
| 41 | } | |
| 42 | ||
| a4da0d50 ME |
43 | static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val) |
| 44 | { | |
| 45 | unsigned long parity; | |
| 46 | ||
| 47 | /* Calculate the parity of the value */ | |
| 48 | asm ("popcntd %0,%1" : "=r" (parity) : "r" (val)); | |
| 49 | ||
| 50 | /* xor our value with the previous mask */ | |
| 51 | val ^= rng->mask; | |
| 52 | ||
| 53 | /* update the mask based on the parity of this value */ | |
| 54 | rng->mask = (rng->mask << 1) | (parity & 1); | |
| 55 | ||
| 56 | return val; | |
| 57 | } | |
| 58 | ||
| e928e9cb ME |
59 | int powernv_get_random_real_mode(unsigned long *v) |
| 60 | { | |
| 61 | struct powernv_rng *rng; | |
| 62 | ||
| 63 | rng = raw_cpu_read(powernv_rng); | |
| 64 | ||
| 65 | *v = rng_whiten(rng, in_rm64(rng->regs_real)); | |
| 66 | ||
| 67 | return 1; | |
| 68 | } | |
| 69 | ||
| a4da0d50 ME |
70 | int powernv_get_random_long(unsigned long *v) |
| 71 | { | |
| 72 | struct powernv_rng *rng; | |
| 73 | ||
| 74 | rng = get_cpu_var(powernv_rng); | |
| 75 | ||
| 76 | *v = rng_whiten(rng, in_be64(rng->regs)); | |
| 77 | ||
| 78 | put_cpu_var(rng); | |
| 79 | ||
| 80 | return 1; | |
| 81 | } | |
| 82 | EXPORT_SYMBOL_GPL(powernv_get_random_long); | |
| 83 | ||
| 84 | static __init void rng_init_per_cpu(struct powernv_rng *rng, | |
| 85 | struct device_node *dn) | |
| 86 | { | |
| 87 | int chip_id, cpu; | |
| 88 | ||
| 89 | chip_id = of_get_ibm_chip_id(dn); | |
| 90 | if (chip_id == -1) | |
| 91 | pr_warn("No ibm,chip-id found for %s.\n", dn->full_name); | |
| 92 | ||
| 93 | for_each_possible_cpu(cpu) { | |
| 94 | if (per_cpu(powernv_rng, cpu) == NULL || | |
| 95 | cpu_to_chip_id(cpu) == chip_id) { | |
| 96 | per_cpu(powernv_rng, cpu) = rng; | |
| 97 | } | |
| 98 | } | |
| 99 | } | |
| 100 | ||
| 101 | static __init int rng_create(struct device_node *dn) | |
| 102 | { | |
| 103 | struct powernv_rng *rng; | |
| e928e9cb | 104 | struct resource res; |
| a4da0d50 ME |
105 | unsigned long val; |
| 106 | ||
| 107 | rng = kzalloc(sizeof(*rng), GFP_KERNEL); | |
| 108 | if (!rng) | |
| 109 | return -ENOMEM; | |
| 110 | ||
| e928e9cb ME |
111 | if (of_address_to_resource(dn, 0, &res)) { |
| 112 | kfree(rng); | |
| 113 | return -ENXIO; | |
| 114 | } | |
| 115 | ||
| 116 | rng->regs_real = (void __iomem *)res.start; | |
| 117 | ||
| a4da0d50 ME |
118 | rng->regs = of_iomap(dn, 0); |
| 119 | if (!rng->regs) { | |
| 120 | kfree(rng); | |
| 121 | return -ENXIO; | |
| 122 | } | |
| 123 | ||
| 124 | val = in_be64(rng->regs); | |
| 125 | rng->mask = val; | |
| 126 | ||
| 127 | rng_init_per_cpu(rng, dn); | |
| 128 | ||
| 129 | pr_info_once("Registering arch random hook.\n"); | |
| 130 | ||
| 01c9348c | 131 | ppc_md.get_random_seed = powernv_get_random_long; |
| a4da0d50 ME |
132 | |
| 133 | return 0; | |
| 134 | } | |
| 135 | ||
| 136 | static __init int rng_init(void) | |
| 137 | { | |
| 138 | struct device_node *dn; | |
| 139 | int rc; | |
| 140 | ||
| 141 | for_each_compatible_node(dn, NULL, "ibm,power-rng") { | |
| 142 | rc = rng_create(dn); | |
| 143 | if (rc) { | |
| 144 | pr_err("Failed creating rng for %s (%d).\n", | |
| 145 | dn->full_name, rc); | |
| 146 | continue; | |
| 147 | } | |
| 148 | ||
| 149 | /* Create devices for hwrng driver */ | |
| 150 | of_platform_device_create(dn, NULL, NULL); | |
| 151 | } | |
| 152 | ||
| 153 | return 0; | |
| 154 | } | |
| b14726c5 | 155 | machine_subsys_initcall(powernv, rng_init); |