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190 lines
3.5 KiB
190 lines
3.5 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright 2013, Michael Ellerman, IBM Corporation. |
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*/ |
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#define pr_fmt(fmt) "powernv-rng: " fmt |
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#include <linux/kernel.h> |
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#include <linux/of.h> |
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#include <linux/of_address.h> |
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#include <linux/of_platform.h> |
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#include <linux/slab.h> |
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#include <linux/smp.h> |
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#include <asm/archrandom.h> |
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#include <asm/cputable.h> |
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#include <asm/io.h> |
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#include <asm/prom.h> |
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#include <asm/machdep.h> |
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#include <asm/smp.h> |
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#define DARN_ERR 0xFFFFFFFFFFFFFFFFul |
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struct powernv_rng { |
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void __iomem *regs; |
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void __iomem *regs_real; |
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unsigned long mask; |
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}; |
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static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng); |
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int powernv_hwrng_present(void) |
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{ |
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struct powernv_rng *rng; |
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rng = get_cpu_var(powernv_rng); |
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put_cpu_var(rng); |
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return rng != NULL; |
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} |
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static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val) |
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{ |
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unsigned long parity; |
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/* Calculate the parity of the value */ |
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asm ("popcntd %0,%1" : "=r" (parity) : "r" (val)); |
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/* xor our value with the previous mask */ |
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val ^= rng->mask; |
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/* update the mask based on the parity of this value */ |
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rng->mask = (rng->mask << 1) | (parity & 1); |
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return val; |
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} |
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int powernv_get_random_real_mode(unsigned long *v) |
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{ |
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struct powernv_rng *rng; |
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rng = raw_cpu_read(powernv_rng); |
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*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real)); |
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return 1; |
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} |
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static int powernv_get_random_darn(unsigned long *v) |
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{ |
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unsigned long val; |
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/* Using DARN with L=1 - 64-bit conditioned random number */ |
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asm volatile(PPC_DARN(%0, 1) : "=r"(val)); |
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if (val == DARN_ERR) |
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return 0; |
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*v = val; |
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return 1; |
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} |
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static int initialise_darn(void) |
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{ |
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unsigned long val; |
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int i; |
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if (!cpu_has_feature(CPU_FTR_ARCH_300)) |
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return -ENODEV; |
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for (i = 0; i < 10; i++) { |
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if (powernv_get_random_darn(&val)) { |
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ppc_md.get_random_seed = powernv_get_random_darn; |
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return 0; |
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} |
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} |
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pr_warn("Unable to use DARN for get_random_seed()\n"); |
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return -EIO; |
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} |
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int powernv_get_random_long(unsigned long *v) |
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{ |
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struct powernv_rng *rng; |
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rng = get_cpu_var(powernv_rng); |
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*v = rng_whiten(rng, in_be64(rng->regs)); |
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put_cpu_var(rng); |
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return 1; |
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} |
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EXPORT_SYMBOL_GPL(powernv_get_random_long); |
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static __init void rng_init_per_cpu(struct powernv_rng *rng, |
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struct device_node *dn) |
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{ |
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int chip_id, cpu; |
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chip_id = of_get_ibm_chip_id(dn); |
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if (chip_id == -1) |
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pr_warn("No ibm,chip-id found for %pOF.\n", dn); |
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for_each_possible_cpu(cpu) { |
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if (per_cpu(powernv_rng, cpu) == NULL || |
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cpu_to_chip_id(cpu) == chip_id) { |
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per_cpu(powernv_rng, cpu) = rng; |
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} |
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} |
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} |
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static __init int rng_create(struct device_node *dn) |
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{ |
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struct powernv_rng *rng; |
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struct resource res; |
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unsigned long val; |
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rng = kzalloc(sizeof(*rng), GFP_KERNEL); |
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if (!rng) |
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return -ENOMEM; |
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if (of_address_to_resource(dn, 0, &res)) { |
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kfree(rng); |
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return -ENXIO; |
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} |
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rng->regs_real = (void __iomem *)res.start; |
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rng->regs = of_iomap(dn, 0); |
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if (!rng->regs) { |
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kfree(rng); |
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return -ENXIO; |
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} |
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val = in_be64(rng->regs); |
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rng->mask = val; |
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rng_init_per_cpu(rng, dn); |
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pr_info_once("Registering arch random hook.\n"); |
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ppc_md.get_random_seed = powernv_get_random_long; |
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return 0; |
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} |
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static __init int rng_init(void) |
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{ |
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struct device_node *dn; |
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int rc; |
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for_each_compatible_node(dn, NULL, "ibm,power-rng") { |
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rc = rng_create(dn); |
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if (rc) { |
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pr_err("Failed creating rng for %pOF (%d).\n", |
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dn, rc); |
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continue; |
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} |
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/* Create devices for hwrng driver */ |
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of_platform_device_create(dn, NULL, NULL); |
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} |
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initialise_darn(); |
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return 0; |
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} |
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machine_subsys_initcall(powernv, rng_init);
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