[PATCH 1/3] powerpc: Implement arch_get_random_long/int() for powernv

Michael Ellerman
2013-09-26T06:31:31Z

Add the plumbing to implement arch_get_random_long/int(). It didn't seem
worth adding an extra ppc_md hook for int, so we reuse the one for long.

Add an implementation for powernv based on the hwrng found in power7+
systems. We whiten the output of the hwrng, and the result passes all
the dieharder tests.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---
arch/powerpc/Kconfig | 3 +
arch/powerpc/include/asm/archrandom.h | 32 +++++++++
arch/powerpc/include/asm/machdep.h | 4 ++
arch/powerpc/platforms/powernv/Kconfig | 1 +
arch/powerpc/platforms/powernv/Makefile | 2 +-
arch/powerpc/platforms/powernv/rng.c | 122 ++++++++++++++++++++++++++++++++
6 files changed, 163 insertions(+), 1 deletion(-)
create mode 100644 arch/powerpc/include/asm/archrandom.h
create mode 100644 arch/powerpc/platforms/powernv/rng.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 38f3b7e..45f16f7 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -1009,6 +1009,9 @@ config PHYSICAL_START
default "0x00000000"
endif

+config ARCH_RANDOM
+ def_bool n
+
source "net/Kconfig"

source "drivers/Kconfig"
diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
new file mode 100644
index 0000000..d853d16
--- /dev/null
+++ b/arch/powerpc/include/asm/archrandom.h
@@ -0,0 +1,32 @@
+#ifndef _ASM_POWERPC_ARCHRANDOM_H
+#define _ASM_POWERPC_ARCHRANDOM_H
+
+#ifdef CONFIG_ARCH_RANDOM
+
+#include <asm/machdep.h>
+
+static inline int arch_get_random_long(unsigned long *v)
+{
+ if (ppc_md.get_random_long)
+ return ppc_md.get_random_long(v);
+
+ return 0;
+}
+
+static inline int arch_get_random_int(unsigned int *v)
+{
+ unsigned long val;
+ int rc;
+
+ rc = arch_get_random_long(&val);
+ if (rc)
+ *v = val;
+
+ return rc;
+}
+
+int powernv_get_random_long(unsigned long *v);
+
+#endif /* CONFIG_ARCH_RANDOM */
+
+#endif /* _ASM_POWERPC_ARCHRANDOM_H */
diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 8b48090..ce6cc2a 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -263,6 +263,10 @@ struct machdep_calls {
ssize_t (*cpu_probe)(const char *, size_t);
ssize_t (*cpu_release)(const char *, size_t);
#endif
+
+#ifdef CONFIG_ARCH_RANDOM
+ int (*get_random_long)(unsigned long *v);
+#endif
};

extern void e500_idle(void);
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index 6fae5eb..2108464 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -9,6 +9,7 @@ config PPC_POWERNV
select EPAPR_BOOT
select PPC_INDIRECT_PIO
select PPC_UDBG_16550
+ select ARCH_RANDOM
default y

config POWERNV_MSI
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index 300c437..6760a86 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -1,5 +1,5 @@
obj-y += setup.o opal-takeover.o opal-wrappers.o opal.o
-obj-y += opal-rtc.o opal-nvram.o opal-lpc.o
+obj-y += opal-rtc.o opal-nvram.o opal-lpc.o rng.o

obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
new file mode 100644
index 0000000..51d2e6a
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -0,0 +1,122 @@
+/*
+ * Copyright 2013, Michael Ellerman, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "powernv-rng: " fmt
+
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <asm/archrandom.h>
+#include <asm/io.h>
+#include <asm/machdep.h>
+
+
+struct powernv_rng {
+ void __iomem *regs;
+ unsigned long mask;
+};
+
+static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
+
+
+static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
+{
+ unsigned long parity;
+
+ /* Calculate the parity of the value */
+ asm ("popcntd %0,%1" : "=r" (parity) : "r" (val));
+
+ /* xor our value with the previous mask */
+ val ^= rng->mask;
+
+ /* update the mask based on the parity of this value */
+ rng->mask = (rng->mask << 1) | (parity & 1);
+
+ return val;
+}
+
+int powernv_get_random_long(unsigned long *v)
+{
+ struct powernv_rng *rng;
+
+ rng = get_cpu_var(powernv_rng);
+
+ *v = rng_whiten(rng, in_be64(rng->regs));
+
+ put_cpu_var(rng);
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(powernv_get_random_long);
+
+static __init void rng_init_per_cpu(struct powernv_rng *rng,
+ struct device_node *dn)
+{
+ int chip_id, cpu;
+
+ chip_id = of_get_ibm_chip_id(dn);
+ if (chip_id == -1)
+ pr_warn("no ibm,chip-id found for %s\n", dn->full_name);
+
+ for_each_possible_cpu(cpu) {
+ if (per_cpu(powernv_rng, cpu) == NULL ||
+ cpu_to_chip_id(cpu) == chip_id) {
+ per_cpu(powernv_rng, cpu) = rng;
+ }
+ }
+}
+
+static __init int rng_create(struct device_node *dn)
+{
+ struct powernv_rng *rng;
+ unsigned long val;
+
+ rng = kzalloc(sizeof(*rng), GFP_KERNEL);
+ if (!rng)
+ return -ENOMEM;
+
+ rng->regs = of_iomap(dn, 0);
+ if (!rng->regs) {
+ kfree(rng);
+ return -ENXIO;
+ }
+
+ val = in_be64(rng->regs);
+ rng->mask = val;
+
+ rng_init_per_cpu(rng, dn);
+
+ pr_info_once("registering arch random hook\n");
+
+ ppc_md.get_random_long = powernv_get_random_long;
+
+ return 0;
+}
+
+static __init int rng_init(void)
+{
+ struct device_node *dn;
+ int rc;
+
+ for_each_compatible_node(dn, NULL, "ibm,power-rng") {
+ rc = rng_create(dn);
+ if (rc) {
+ pr_err("failed creating rng for %s (%d)\n",
+ dn->full_name, rc);
+ continue;
+ }
+
+ /* Create devices for hwrng driver */
+ of_platform_device_create(dn, NULL, NULL);
+ }
+
+ return 0;
+}
+subsys_initcall(rng_init);
--
1.8.1.2