powerpc/pseries: Implement arch_get_random_long() based on H_RANDOM

Add support for the arch_get_random_long() hook based on the H_RANDOM
hypervisor call. We trust the hypervisor to provide us with random data,
ie. we don't whiten it in anyway.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 6c61ec5..fbccac9 100644 (file)
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -3,7 +3,7 @@ ccflags-$(CONFIG_PPC_PSERIES_DEBUG)     += -DDEBUG
 
 obj-y                  := lpar.o hvCall.o nvram.o reconfig.o \
                           setup.o iommu.o event_sources.o ras.o \
-                          firmware.o power.o dlpar.o mobility.o
+                          firmware.o power.o dlpar.o mobility.o rng.o
 obj-$(CONFIG_SMP)      += smp.o
 obj-$(CONFIG_SCANLOG)  += scanlog.o
 obj-$(CONFIG_EEH)      += eeh_pseries.o

diff --git a/arch/powerpc/platforms/pseries/rng.c b/arch/powerpc/platforms/pseries/rng.c
new file mode 100644 (file)
index 0000000..a702f1c
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/rng.c
@@ -0,0 +1,44 @@
+/*
+ * 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)    "pseries-rng: " fmt
+
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <asm/archrandom.h>
+#include <asm/machdep.h>
+
+
+static int pseries_get_random_long(unsigned long *v)
+{
+       unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+
+       if (plpar_hcall(H_RANDOM, retbuf) == H_SUCCESS) {
+               *v = retbuf[0];
+               return 1;
+       }
+
+       return 0;
+}
+
+static __init int rng_init(void)
+{
+       struct device_node *dn;
+
+       dn = of_find_compatible_node(NULL, NULL, "ibm,random");
+       if (!dn)
+               return -ENODEV;
+
+       pr_info("Registering arch random hook.\n");
+
+       ppc_md.get_random_long = pseries_get_random_long;
+
+       return 0;
+}
+subsys_initcall(rng_init);