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-rw-r--r--arch/powerpc/platforms/powernv/rng.c220
1 files changed, 220 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
new file mode 100644
index 000000000..a99033c3d
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2013, Michael Ellerman, IBM Corporation.
+ */
+
+#define pr_fmt(fmt) "powernv-rng: " fmt
+
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <asm/archrandom.h>
+#include <asm/cputable.h>
+#include <asm/io.h>
+#include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/smp.h>
+#include "powernv.h"
+
+#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
+
+struct powernv_rng {
+ void __iomem *regs;
+ void __iomem *regs_real;
+ unsigned long mask;
+};
+
+static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
+
+int powernv_hwrng_present(void)
+{
+ struct powernv_rng *rng;
+
+ rng = get_cpu_var(powernv_rng);
+ put_cpu_var(rng);
+ return rng != NULL;
+}
+
+static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
+{
+ unsigned long parity;
+
+ /* Calculate the parity of the value */
+ asm (".machine push; \
+ .machine power7; \
+ popcntd %0,%1; \
+ .machine pop;"
+ : "=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_real_mode(unsigned long *v)
+{
+ struct powernv_rng *rng;
+
+ rng = raw_cpu_read(powernv_rng);
+ if (!rng)
+ return 0;
+
+ *v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
+
+ return 1;
+}
+
+static int powernv_get_random_darn(unsigned long *v)
+{
+ unsigned long val;
+
+ /* Using DARN with L=1 - 64-bit conditioned random number */
+ asm volatile(PPC_DARN(%0, 1) : "=r"(val));
+
+ if (val == DARN_ERR)
+ return 0;
+
+ *v = val;
+
+ return 1;
+}
+
+static int initialise_darn(void)
+{
+ unsigned long val;
+ int i;
+
+ if (!cpu_has_feature(CPU_FTR_ARCH_300))
+ return -ENODEV;
+
+ for (i = 0; i < 10; i++) {
+ if (powernv_get_random_darn(&val)) {
+ ppc_md.get_random_seed = powernv_get_random_darn;
+ return 0;
+ }
+ }
+ return -EIO;
+}
+
+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 %pOF.\n", dn);
+
+ 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;
+ struct resource res;
+ unsigned long val;
+
+ rng = kzalloc(sizeof(*rng), GFP_KERNEL);
+ if (!rng)
+ return -ENOMEM;
+
+ if (of_address_to_resource(dn, 0, &res)) {
+ kfree(rng);
+ return -ENXIO;
+ }
+
+ rng->regs_real = (void __iomem *)res.start;
+
+ 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);
+
+ ppc_md.get_random_seed = powernv_get_random_long;
+
+ return 0;
+}
+
+static int __init pnv_get_random_long_early(unsigned long *v)
+{
+ struct device_node *dn;
+
+ if (!slab_is_available())
+ return 0;
+
+ if (cmpxchg(&ppc_md.get_random_seed, pnv_get_random_long_early,
+ NULL) != pnv_get_random_long_early)
+ return 0;
+
+ for_each_compatible_node(dn, NULL, "ibm,power-rng")
+ rng_create(dn);
+
+ if (!ppc_md.get_random_seed)
+ return 0;
+ return ppc_md.get_random_seed(v);
+}
+
+void __init pnv_rng_init(void)
+{
+ struct device_node *dn;
+
+ /* Prefer darn over the rest. */
+ if (!initialise_darn())
+ return;
+
+ dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
+ if (dn)
+ ppc_md.get_random_seed = pnv_get_random_long_early;
+
+ of_node_put(dn);
+}
+
+static int __init pnv_rng_late_init(void)
+{
+ struct device_node *dn;
+ unsigned long v;
+
+ /* In case it wasn't called during init for some other reason. */
+ if (ppc_md.get_random_seed == pnv_get_random_long_early)
+ pnv_get_random_long_early(&v);
+
+ if (ppc_md.get_random_seed == powernv_get_random_long) {
+ for_each_compatible_node(dn, NULL, "ibm,power-rng")
+ of_platform_device_create(dn, NULL, NULL);
+ }
+
+ return 0;
+}
+machine_subsys_initcall(powernv, pnv_rng_late_init);