[Skiboot] [PATCH v2 (skiboot)] dt: add /cpus/ibm, powerpc-cpu-features device tree bindings
Nicholas Piggin
npiggin at gmail.com
Fri Feb 16 14:40:42 AEDT 2018
This is a new CPU feature advertising interface that is fine-grained,
extensible, aware of privilege levels, and gives control of features
to all levels of the stack (firmware, hypervisor, and OS).
The design and binding specification is described in detail in doc/.
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
Since v1:
- Fold branch-v3 into fixed-point-v3, as pointed out by Segher they
are all fixed point facilities.
- Fixed typo (Segher)
core/Makefile.inc | 2 +-
core/cpufeatures.c | 921 +++++++++++++++++++++
core/device.c | 7 +
core/init.c | 1 +
.../ibm,powerpc-cpu-features/binding.txt | 245 ++++++
.../ibm,powerpc-cpu-features/design.txt | 157 ++++
include/device.h | 1 +
include/skiboot.h | 5 +
8 files changed, 1338 insertions(+), 1 deletion(-)
create mode 100644 core/cpufeatures.c
create mode 100644 doc/device-tree/ibm,powerpc-cpu-features/binding.txt
create mode 100644 doc/device-tree/ibm,powerpc-cpu-features/design.txt
diff --git a/core/Makefile.inc b/core/Makefile.inc
index d6a7269f..5c120564 100644
--- a/core/Makefile.inc
+++ b/core/Makefile.inc
@@ -9,7 +9,7 @@ CORE_OBJS += vpd.o hostservices.o platform.o nvram.o nvram-format.o hmi.o
CORE_OBJS += console-log.o ipmi.o time-utils.o pel.o pool.o errorlog.o
CORE_OBJS += timer.o i2c.o rtc.o flash.o sensor.o ipmi-opal.o
CORE_OBJS += flash-subpartition.o bitmap.o buddy.o pci-quirk.o powercap.o psr.o
-CORE_OBJS += pci-dt-slot.o direct-controls.o
+CORE_OBJS += pci-dt-slot.o direct-controls.o cpufeatures.o
ifeq ($(SKIBOOT_GCOV),1)
CORE_OBJS += gcov-profiling.o
diff --git a/core/cpufeatures.c b/core/cpufeatures.c
new file mode 100644
index 00000000..fa5c4ce5
--- /dev/null
+++ b/core/cpufeatures.c
@@ -0,0 +1,921 @@
+/* Copyright 2017-2018 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * This file deals with setup of /cpus/ibm,powerpc-cpu-features dt
+ */
+
+#include <skiboot.h>
+#include <cpu.h>
+#include <processor.h>
+#include <ccan/str/str.h>
+#include <device.h>
+
+#ifdef DEBUG
+#define DBG(fmt, a...) prlog(PR_DEBUG, "CPUFT: " fmt, ##a)
+#else
+#define DBG(fmt, a...)
+#endif
+
+/* Device-tree visible constants follow */
+#define ISA_V2_07B 2070
+#define ISA_V3_0B 3000
+
+#define USABLE_PR (1U << 0)
+#define USABLE_OS (1U << 1)
+#define USABLE_HV (1U << 2)
+
+#define HV_SUPPORT_HFSCR (1U << 0)
+#define OS_SUPPORT_FSCR (1U << 0)
+
+/* Following are definitions for the match tables, not the DT binding itself */
+#define ISA_BASE 0
+
+#define HV_NONE 0
+#define HV_CUSTOM 1
+#define HV_HFSCR 2
+
+#define OS_NONE 0
+#define OS_CUSTOM 1
+#define OS_FSCR 2
+
+/* CPU bitmasks for match table */
+#define CPU_P8_DD1 (1U << 0)
+#define CPU_P8_DD2 (1U << 1)
+#define CPU_P9_DD1 (1U << 2)
+#define CPU_P9_DD2 (1U << 3)
+
+#define CPU_P8 (CPU_P8_DD1|CPU_P8_DD2)
+#define CPU_P9 (CPU_P9_DD1|CPU_P9_DD2)
+#define CPU_ALL (CPU_P8|CPU_P9)
+
+struct cpu_feature {
+ const char *name;
+ uint32_t cpus_supported;
+ uint32_t isa;
+ uint32_t usable_privilege;
+ uint32_t hv_support;
+ uint32_t os_support;
+ uint32_t hfscr_bit_nr;
+ uint32_t fscr_bit_nr;
+ uint32_t hwcap_bit_nr;
+ const char *dependencies_names; /* space-delimited names */
+};
+
+/*
+ * The base (or NULL) cpu feature set is the CPU features available
+ * when no child nodes of the /cpus/ibm,powerpc-cpu-features node exist. The
+ * base feature set is POWER8 (ISAv2.07B), less features that are listed
+ * explicitly.
+ *
+ * XXX: currently, the feature dependencies are not necessarily captured
+ * exactly or completely. This is somewhat acceptable because all
+ * implementations must be aware of all these features.
+ */
+static const struct cpu_feature cpu_features_table[] = {
+ /*
+ * Big endian as in ISAv2.07B, MSR_LE=0
+ */
+ { "big-endian",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * Little endian as in ISAv2.07B, MSR_LE=1.
+ *
+ * When both big and little endian are defined, there is an LPCR ILE
+ * bit and implementation specific way to switch HILE mode, MSR_SLE,
+ * etc.
+ */
+ { "little-endian",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * MSR_HV=1 mode as in ISAv2.07B (i.e., hypervisor privileged
+ * instructions and registers).
+ */
+ { "hypervisor",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV,
+ HV_CUSTOM, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B interrupt vectors, registers, and control registers
+ * (e.g., AIL, ILE, HV, etc LPCR bits).
+ *
+ * This does not necessarily specify all possible interrupt types.
+ * floating-point, for example requires some ways to handle floating
+ * point exceptions, but the low level details of interrupt handler
+ * is not a dependency there. There will always be *some* interrupt
+ * handler, (and some way to provide memory magagement, etc.).
+ */
+ { "interrupt-facilities",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ { "smt",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, 14,
+ NULL, },
+
+ /*
+ * ISAv2.07B Program Priority Registers (PPR)
+ * PPR and associated control registers (e.g. RPR, PSPB),
+ * priority "or" instructions, etc.
+ */
+ { "program-priority-register",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B Book3S Chapter 5.7.9.1. Virtual Page Class Key Protecion
+ * AMR, IAMR, AMOR, UAMOR, etc registers and MMU key bits.
+ */
+ { "virtual-page-class-key-protection",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B SAO storage control attribute
+ */
+ { "strong-access-ordering",
+ CPU_ALL & ~CPU_P9_DD1,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B no-execute storage control attribute
+ */
+ { "no-execute",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * Cache inhibited attribute supported on large pages.
+ */
+ { "cache-inhibited-large-page",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B Book3S Chapter 8. Debug Facilities
+ * CIEA, CIABR, DEAW, MEte, trace interrupt, etc.
+ * Except CFAR, branch tracing.
+ */
+ { "debug-facilities",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B CFAR
+ */
+ { "come-from-address-register",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ "debug-facilities", },
+
+ /*
+ * ISAv2.07B Branch tracing (optional in ISA)
+ */
+ { "branch-tracing",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ "debug-facilities", },
+
+ /*
+ * ISAv2.07B Floating-point Facility
+ */
+ { "floating-point",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ PPC_BITLSHIFT(63), -1, 27,
+ NULL, },
+
+ /*
+ * ISAv2.07B Vector Facility (VMX)
+ */
+ { "vector",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ PPC_BITLSHIFT(62), -1, 28,
+ "floating-point", },
+
+ /*
+ * ISAv2.07B Vector-scalar Facility (VSX)
+ */
+ { "vector-scalar",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, 7,
+ "vector", },
+
+ { "vector-crypto",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, 57,
+ "vector", },
+
+ /*
+ * ISAv2.07B Quadword Load and Store instructions
+ * including lqarx/stdqcx. instructions.
+ */
+ { "quadword-load-store",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B Binary Coded Decimal (BCD)
+ * BCD fixed point instructions
+ */
+ { "decimal-integer",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B Decimal floating-point Facility (DFP)
+ */
+ { "decimal-floating-point",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, 10,
+ "floating-point", },
+
+ /*
+ * ISAv2.07B
+ * DSCR, default data prefetch LPCR, etc
+ */
+ { "data-stream-control-register",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ PPC_BITLSHIFT(61), PPC_BITLSHIFT(61), 61,
+ NULL, },
+
+ /*
+ * ISAv2.07B Branch History Rolling Buffer (BHRB)
+ */
+ { "branch-history-rolling-buffer",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ PPC_BITLSHIFT(59), -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B Transactional Memory Facility (TM or HTM)
+ */
+ { "transactional-memory",
+ CPU_P8, /* P9 support is not enabled yet */
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ PPC_BITLSHIFT(58), -1, 62,
+ NULL, },
+
+ /*
+ * ISAv3.0B TM additions
+ * TEXASR bit 17, self-induced vs external footprint overflow
+ */
+ { "transactional-memory-v3",
+ 0,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "transactional-memory", },
+
+ /*
+ * ISAv2.07B Event-Based Branch Facility (EBB)
+ */
+ { "event-based-branch",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ PPC_BITLSHIFT(56), PPC_BITLSHIFT(56), 60,
+ NULL, },
+
+ /*
+ * ISAv2.07B Target Address Register (TAR)
+ */
+ { "target-address-register",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_CUSTOM, OS_CUSTOM,
+ PPC_BITLSHIFT(55), PPC_BITLSHIFT(55), 58,
+ NULL, },
+
+ /*
+ * ISAv2.07B Control Register (CTRL)
+ */
+ { "control-register",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B Book3S Chapter 11. Processor Control.
+ * msgsnd, msgsndp, doorbell, etc.
+ *
+ * ISAv3.0B is not compatible (different addressing, HFSCR required
+ * for msgsndp).
+ */
+ { "processor-control-facility",
+ CPU_P8_DD2, /* P8 DD1 has no dbell */
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B PURR, SPURR registers
+ */
+ { "processor-utilization-of-resources-register",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * POWER8 initiate coprocessor store word indexed (icswx) instruction
+ */
+ { "coprocessor-icswx",
+ CPU_P8,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B hash based MMU and all instructions, registers,
+ * data structures, exceptions, etc.
+ */
+ { "mmu-hash",
+ CPU_P8,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * POWER8 MCE / machine check exception.
+ */
+ { "machine-check-power8",
+ CPU_P8,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * POWER8 PMU / performance monitor unit.
+ */
+ { "performance-monitor-power8",
+ CPU_P8,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B alignment interrupts set DSISR register
+ *
+ * POWER CPUs do not used this, and it's removed from ISAv3.0B.
+ */
+ { "alignment-interrupt-dsisr",
+ 0,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B / POWER8 doze, nap, sleep, winkle instructions
+ * XXX: is Linux we using some BookIV specific implementation details
+ * in nap handling? We have no POWER8 specific key here.
+ */
+ { "idle-nap",
+ CPU_P8,
+ ISA_BASE, USABLE_HV,
+ HV_CUSTOM, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B wait instruction
+ */
+ { "wait",
+ CPU_P8,
+ ISA_BASE, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ { "subcore",
+ CPU_P8,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ "smt", },
+
+ /*
+ * ISAv3.0B radix based MMU
+ */
+ { "mmu-radix",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B hash based MMU, new hash pte format, PCTR, etc
+ */
+ { "mmu-hash-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B wait instruction
+ */
+ { "wait-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B stop idle instructions and registers
+ * XXX: Same question as for idle-nap
+ */
+ { "idle-stop",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B Hypervisor Virtualization Interrupt
+ * Also associated system registers, LPCR EE, HEIC, HVICE,
+ * system reset SRR1 reason, etc.
+ */
+ { "hypervisor-virtualization-interrupt",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV,
+ HV_CUSTOM, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * POWER9 MCE / machine check exception.
+ */
+ { "machine-check-power9",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * POWER9 PMU / performance monitor unit.
+ */
+ { "performance-monitor-power9",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_CUSTOM,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B scv/rfscv system call instructions and exceptions, fscr bit
+ * etc.
+ */
+ { "system-call-vectored",
+ CPU_P9,
+ ISA_V3_0B, USABLE_OS|USABLE_PR,
+ HV_NONE, OS_CUSTOM,
+ -1, PPC_BITLSHIFT(51), -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B Book3S Chapter 10. Processor Control.
+ * global msgsnd, msgsndp, msgsync, doorbell, etc.
+ */
+ { "processor-control-facility-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_CUSTOM, OS_NONE,
+ PPC_BITLSHIFT(53), -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B addpcis instruction
+ */
+ { "pc-relative-addressing",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv2.07B Book3S Chapter 7. Timer Facilities
+ * TB, VTB, DEC, HDEC, IC, etc registers and exceptions.
+ * Not including PURR or SPURR registers.
+ */
+ { "timer-facilities",
+ CPU_ALL,
+ ISA_BASE, USABLE_HV|USABLE_OS,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B Book3S Chapter 7. Timer Facilities
+ * Large decrementer and hypervisor decrementer
+ */
+ { "timer-facilities-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "timer-facilities", },
+
+ /*
+ * ISAv3.0B deliver a random number instruction (darn)
+ */
+ { "random-number-generator",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B fixed point instructions and registers
+ * multiply-add, modulo, count trailing zeroes, cmprb, cmpeqb,
+ * extswsli, mfvsrld, mtvsrdd, mtvsrws, addex, CA32, OV32,
+ * mcrxrx, setb
+ */
+ { "fixed-point-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ { "decimal-integer-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "fixed-point-v3 decimal-integer", },
+
+ /*
+ * ISAv3.0B lightweight mffs
+ */
+ { "floating-point-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "floating-point", },
+
+ { "decimal-floating-point-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "floating-point-v3 decimal-floating-point", },
+
+ { "vector-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "vector", },
+
+ { "vector-scalar-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "vector-v3 vector-scalar" },
+
+ { "vector-binary128",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, 54,
+ "vector-scalar-v3", },
+
+ { "vector-binary16",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "vector-v3", },
+
+ /*
+ * ISAv3.0B external exception for EBB
+ */
+ { "event-based-branch-v3",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ "event-based-branch", },
+
+ /*
+ * ISAv3.0B Atomic Memory Operations (AMO)
+ */
+ { "atomic-memory-operations",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B Copy-Paste Facility
+ */
+ { "copy-paste",
+ CPU_P9,
+ ISA_V3_0B, USABLE_HV|USABLE_OS|USABLE_PR,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+
+ /*
+ * ISAv3.0B GSR SPR register
+ * POWER9 does not implement it
+ */
+ { "group-start-register",
+ 0,
+ ISA_V3_0B, USABLE_HV|USABLE_OS,
+ HV_NONE, OS_NONE,
+ -1, -1, -1,
+ NULL, },
+};
+
+static void add_cpu_feature_nodeps(struct dt_node *features,
+ const struct cpu_feature *f)
+{
+ struct dt_node *feature;
+
+ feature = dt_new(features, f->name);
+ assert(feature);
+
+ dt_add_property_cells(feature, "isa", f->isa);
+ dt_add_property_cells(feature, "usable-privilege", f->usable_privilege);
+
+ if (f->usable_privilege & USABLE_HV) {
+ if (f->hv_support != HV_NONE) {
+ uint32_t s = 0;
+ if (f->hv_support == HV_HFSCR)
+ s |= HV_SUPPORT_HFSCR;
+
+ dt_add_property_cells(feature, "hv-support", s);
+ if (f->hfscr_bit_nr != -1)
+ dt_add_property_cells(feature, "hfscr-bit-nr", f->hfscr_bit_nr);
+ } else {
+ assert(f->hfscr_bit_nr == -1);
+ }
+ }
+
+ if (f->usable_privilege & USABLE_OS) {
+ if (f->os_support != OS_NONE) {
+ uint32_t s = 0;
+ if (f->os_support == OS_FSCR)
+ s |= OS_SUPPORT_FSCR;
+ dt_add_property_cells(feature, "os-support", s);
+ if (f->fscr_bit_nr != -1)
+ dt_add_property_cells(feature, "fscr-bit-nr", f->fscr_bit_nr);
+ } else {
+ assert(f->fscr_bit_nr == -1);
+ }
+ }
+
+ if (f->usable_privilege & USABLE_PR) {
+ if (f->hwcap_bit_nr != -1)
+ dt_add_property_cells(feature, "hwcap-bit-nr", f->hwcap_bit_nr);
+ }
+
+ if (f->dependencies_names)
+ dt_add_property(feature, "dependencies", NULL, 0);
+}
+
+static void add_cpufeatures_dependencies(struct dt_node *features)
+{
+ struct dt_node *feature;
+
+ dt_for_each_node(features, feature) {
+ const struct cpu_feature *f;
+ const char *deps_names;
+ struct dt_property *deps;
+ int nr_deps;
+ int i;
+
+ /* Find features with dependencies */
+
+ deps = __dt_find_property(feature, "dependencies");
+ if (!deps)
+ continue;
+
+ /* Find the matching cpu table */
+ for (i = 0; i < ARRAY_SIZE(cpu_features_table); i++) {
+ f = &cpu_features_table[i];
+ if (!strcmp(f->name, feature->name))
+ break;
+ }
+ assert(f->dependencies_names);
+
+ /*
+ * Count number of depended features and allocate space
+ * for phandles in the property.
+ */
+ deps_names = f->dependencies_names;
+ nr_deps = strcount(deps_names, " ") + 1;
+ dt_resize_property(&deps, nr_deps * sizeof(u32));
+ deps->len = nr_deps * sizeof(u32);
+
+ DBG("feature %s has %d dependencies (%s)\n", f->name, nr_deps, deps_names);
+ /*
+ * For each one, find the depended feature then advance to
+ * next name.
+ */
+ for (i = 0; i < nr_deps; i++) {
+ struct dt_node *dep;
+ int len;
+
+ if (nr_deps - i == 1)
+ len = strlen(deps_names);
+ else
+ len = strchr(deps_names, ' ') - deps_names;
+
+ dt_for_each_node(features, dep) {
+ if (!strncmp(deps_names, dep->name, len))
+ goto found_dep;
+ }
+
+ prlog(PR_ERR, "CPUFT: feature %s dependencies not found\n", f->name);
+ break;
+found_dep:
+ DBG(" %s found dep (%s)\n", f->name, dep->name);
+ dt_property_set_cell(deps, i, dep->phandle);
+
+ /* Advance over the name + delimiter */
+ deps_names += len + 1;
+ }
+ }
+}
+
+static void add_cpufeatures(struct dt_node *cpus,
+ uint32_t cpu_feature_isa, uint32_t cpu_feature_cpu,
+ const char *cpu_name)
+{
+ struct dt_node *features;
+ int i;
+
+ DBG("creating cpufeatures for cpu:%d isa:%d\n", cpu_feature_cpu, cpu_feature_isa);
+
+ features = dt_new(cpus, "ibm,powerpc-cpu-features");
+ assert(features);
+
+ dt_add_property_cells(features, "isa", cpu_feature_isa);
+
+ dt_add_property_string(features, "device_type", "cpu-features");
+ dt_add_property_string(features, "compatible", "ibm,powerpc-cpu-features");
+ dt_add_property_string(features, "display-name", cpu_name);
+
+ /* add without dependencies */
+ for (i = 0; i < ARRAY_SIZE(cpu_features_table); i++) {
+ const struct cpu_feature *f = &cpu_features_table[i];
+
+ if (f->cpus_supported & cpu_feature_cpu) {
+ DBG(" '%s'\n", f->name);
+ add_cpu_feature_nodeps(features, f);
+ }
+ }
+
+ /* dependency construction pass */
+ add_cpufeatures_dependencies(features);
+}
+
+void dt_add_cpufeatures(struct dt_node *root)
+{
+ int version;
+ uint32_t cpu_feature_isa = 0;
+ uint32_t cpu_feature_cpu = 0;
+ struct dt_node *cpus;
+ const char *cpu_name = NULL;
+
+ version = mfspr(SPR_PVR);
+ switch(PVR_TYPE(version)) {
+ case PVR_TYPE_P8:
+ if (!cpu_name)
+ cpu_name = "POWER8";
+ /* fallthrough */
+ case PVR_TYPE_P8E:
+ if (!cpu_name)
+ cpu_name = "POWER8E";
+ /* fallthrough */
+ case PVR_TYPE_P8NVL:
+ if (!cpu_name)
+ cpu_name = "POWER8NVL";
+
+ cpu_feature_isa = ISA_V2_07B;
+ if (PVR_VERS_MAJ(version) == 1)
+ cpu_feature_cpu = CPU_P8_DD1;
+ else
+ cpu_feature_cpu = CPU_P8_DD2;
+ break;
+ case PVR_TYPE_P9:
+ if (!cpu_name)
+ cpu_name = "POWER9";
+
+ cpu_feature_isa = ISA_V3_0B;
+ if (is_power9n(version) && (PVR_VERS_MAJ(version) == 1)) {
+ /* P9N DD1 */
+ cpu_feature_cpu = CPU_P9_DD1;
+ } else if (is_power9n(version) &&
+ (PVR_VERS_MAJ(version) == 2)) {
+ /* P9N DD2.x */
+ cpu_feature_cpu = CPU_P9_DD2;
+ } else {
+ assert(0);
+ }
+
+ break;
+ default:
+ return;
+ }
+
+ cpus = dt_new_check(root, "cpus");
+
+ add_cpufeatures(cpus, cpu_feature_isa, cpu_feature_cpu, cpu_name);
+}
diff --git a/core/device.c b/core/device.c
index 50fbb186..38dbdfc0 100644
--- a/core/device.c
+++ b/core/device.c
@@ -598,6 +598,13 @@ u32 dt_property_get_cell(const struct dt_property *prop, u32 index)
return fdt32_to_cpu(((const u32 *)prop->prop)[index]);
}
+void dt_property_set_cell(struct dt_property *prop, u32 index, u32 val)
+{
+ assert(prop->len >= (index+1)*sizeof(u32));
+ /* Always aligned, so this works. */
+ ((u32 *)prop->prop)[index] = cpu_to_fdt32(val);
+}
+
/* First child of this node. */
struct dt_node *dt_first(const struct dt_node *root)
{
diff --git a/core/init.c b/core/init.c
index 5736d330..e8c84a95 100644
--- a/core/init.c
+++ b/core/init.c
@@ -876,6 +876,7 @@ void __noreturn __nomcount main_cpu_entry(const void *fdt)
} else {
dt_expand(fdt);
}
+ dt_add_cpufeatures(dt_root);
/* Now that we have a full devicetree, verify that we aren't on fire. */
per_thread_sanity_checks();
diff --git a/doc/device-tree/ibm,powerpc-cpu-features/binding.txt b/doc/device-tree/ibm,powerpc-cpu-features/binding.txt
new file mode 100644
index 00000000..4dd327ff
--- /dev/null
+++ b/doc/device-tree/ibm,powerpc-cpu-features/binding.txt
@@ -0,0 +1,245 @@
+ibm,powerpc-cpu-features binding
+================================
+
+This device tree binding describes CPU features available to software, with
+enablement, privilege, and compatibility metadata.
+
+More general description of design and implementation of this binding is
+found in design.txt, which also points to documentation of specific features.
+
+
+/cpus/ibm,powerpc-cpu-features node binding
+-------------------------------------------
+
+Node: ibm,powerpc-cpu-features
+
+Description: Container of CPU feature nodes.
+
+The node name must be "ibm,powerpc-cpu-features".
+
+It is implemented as a child of the node "/cpus", but this must not be
+assumed by parsers.
+
+The node is optional but should be provided by new OPAL firmware.
+
+Properties:
+
+- device_type
+ Usage: required
+ Value type: string
+ Definition: "cpu-features"
+
+- compatible
+ Usage: required
+ Value type: string
+ Definition: "ibm,powerpc-cpu-features"
+
+ This compatibility refers to backwards compatibility of the overall
+ design with parsers that behave according to these guidelines. This can
+ be extended in a backward compatible manner which would not warrant a
+ revision of the compatible property.
+
+- isa
+ Usage: required
+ Value type: <u32>
+ Definition:
+
+ isa that the CPU is currently running in. This provides instruction set
+ compatibility, less the individual feature nodes. For example, an ISA v3.0
+ implementation that lacks the "transactional-memory" cpufeature node
+ should not use transactional memory facilities.
+
+ Value corresponds to the "Power ISA Version" multiplied by 1000.
+ For example, <3000> corresponds to Version 3.0, <2070> to Version 2.07.
+ The minor digit is available for revisions.
+
+/cpus/ibm,powerpc-cpu-features/example-feature node bindings
+----------------------------------------------------------------
+
+Each child node of cpu-features represents a CPU feature / capability.
+
+Node: A string describing an architected CPU feature, e.g., "floating-point".
+
+Description: A feature or capability supported by the CPUs.
+
+The name of the node is a human readable string that forms the interface
+used to describe features to software. Features are currently documented
+in the code where they are implemented in skiboot/core/cpufeatures.c
+
+Presence of the node indicates the feature is available.
+
+Properties:
+
+- isa
+ Usage: required
+ Value type: <u32>
+ Definition:
+
+ First level of the Power ISA that the feature appears in.
+ Software should filter out features when constraining the
+ environment to a particular ISA version.
+
+ Value is defined similarly to /cpus/features/isa
+
+- usable-privilege
+ Usage: required
+ Value type: <u32> bit mask
+ Definition:
+ Bit numbers are LSB0
+ bit 0 - PR (problem state / user mode)
+ bit 1 - OS (privileged state)
+ bit 2 - HV (hypervisor state)
+ All other bits reserved and should be zero.
+
+ This property describes the privilege levels and/or software components
+ that can use the feature.
+
+ If bit 0 is set, then the hwcap-bit-nr property will exist.
+
+
+- hv-support
+ Usage: optional
+ Value type: <u32> bit mask
+ Definition:
+ Bit numbers are LSB0
+ bit 0 - HFSCR
+ All other bits reserved and should be zero.
+
+ This property describes the HV privilege support required to enable the
+ feature to lesser privilege levels. If the property does not exist then no
+ support is required.
+
+ If no bits are set, the hypervisor must have explicit/custom support for
+ this feature.
+
+ If the HFSCR bit is set, then the hfscr-bit-nr property will exist and
+ the feature may be enabled by setting this bit in the HFSCR register.
+
+
+- os-support
+ Usage: optional
+ Value type: <u32> bit mask
+ Definition:
+ Bit numbers are LSB0
+ bit 0 - FSCR
+ All other bits reserved and should be zero.
+
+ This property describes the OS privilege support required to enable the
+ feature to lesser privilege levels. If the property does not exist then no
+ support is required.
+
+ If no bits are set, the operating system must have explicit/custom support
+ for this feature.
+
+ If the FSCR bit is set, then the fscr-bit-nr property will exist and
+ the feature may be enabled by setting this bit in the FSCR register.
+
+
+- hfscr-bit-nr
+ Usage: optional
+ Value type: <u32>
+ Definition: HFSCR bit position (LSB0)
+
+ This property exists when the hv-support property HFSCR bit is set. This
+ property describes the bit number in the HFSCR register that the
+ hypervisor must set in order to enable this feature.
+
+ This property also exists if an HFSCR bit corresponds with this feature.
+ This makes CPU feature parsing slightly simpler.
+
+
+- fscr-bit-nr
+ Usage: optional
+ Value type: <u32>
+ Definition: FSCR bit position (LSB0)
+
+ This property exists when the os-support property FSCR bit is set. This
+ property describes the bit number in the FSCR register that the
+ operating system must set in order to enable this feature.
+
+ This property also exists if an FSCR bit corresponds with this feature.
+ This makes CPU feature parsing slightly simpler.
+
+
+- hwcap-bit-nr
+ Usage: optional
+ Value type: <u32>
+ Definition: Linux ELF AUX vector bit position (LSB0)
+
+ This property may exist when the usable-privilege property value has PR bit set.
+ This property describes the bit number that should be set in the ELF AUX
+ hardware capability vectors in order to advertise this feature to userspace.
+ Bits 0-31 correspond to bits 0-31 in AT_HWCAP vector. Bits 32-63 correspond
+ to 0-31 in AT_HWCAP2 vector, and so on. Missing AT_HWCAPx vectors implies
+ that the feature is not enabled or can not be advertised. Operating systems
+ may provide a number of unassigned hardware capability bits to allow for new
+ features to be advertised.
+
+ Some properties representing features created before this binding are
+ advertised to userspace without a one-to-one hwcap bit number may not specify
+ this bit. Operating system will handle those bits specifically. All new
+ features usable by userspace will have a hwcap-bit-nr property.
+
+
+- dependencies
+ Usage: optional
+ Value type: <prop-encoded-array>
+ Definition:
+
+ If this property exists then it is a list of phandles to cpu feature
+ nodes that must be enabled for this feature to be enabled.
+
+
+- Custom properties of the feature
+ Usage: optional
+ Definition:
+
+ Particular features may define their own properties.
+
+
+Example
+-------
+
+ /cpus/ibm,powerpc-cpu-features {
+ device_type = "ibm,powerpc-cpu-features";
+
+ isa = <3020>;
+
+ darn {
+ isa = <3000>;
+ usable-privilege = <1 | 2 | 4>;
+ hwcap-bit-nr = <xx>;
+ };
+
+ scv {
+ isa = <3000>;
+ usable-privilege = <1 | 2>;
+ os-support = <0>;
+ hwcap-bit-nr = <xx>;
+ };
+
+ stop {
+ isa = <3000>;
+ usable-privilege = <2 | 4>;
+ hv-support = <0>;
+ os-support = <0>;
+ };
+
+ vsx2 (hypothetical) {
+ isa = <3010>;
+ usable-privilege = <1 | 2 | 4>;
+ hv-support = <0>;
+ os-support = <0>;
+ hwcap-bit-nr = <xx>;
+ };
+
+ vsx2-newinsns {
+ isa = <3020>;
+ usable-privilege = <1 | 2 | 4>;
+ os-support = <1>;
+ fscr-bit-nr = <xx>;
+ hwcap-bit-nr = <xx>;
+ dependencies = <&vsx2>;
+ };
+
+ };
diff --git a/doc/device-tree/ibm,powerpc-cpu-features/design.txt b/doc/device-tree/ibm,powerpc-cpu-features/design.txt
new file mode 100644
index 00000000..2f9f870c
--- /dev/null
+++ b/doc/device-tree/ibm,powerpc-cpu-features/design.txt
@@ -0,0 +1,157 @@
+ibm,powerpc-cpu-features binding
+================================
+
+The OPAL / skiboot code is the canonical location for this specification. All
+definitions of features, constant, bit positions, etc. must be documented here
+before being deployed in Linux. This is not presently part of LoPAPR.
+
+
+Interfaces
+----------
+This specification describes the ibm,powerpc-cpu-features binding (the formal
+definition of binding can be found in binding.txt in this directory).
+
+This specification also involves the Linux ELF AUXV AT_HWCAP and AT_HWCAP2
+interfaces for PPC_FEATURE* bits. Allocation of new AT_HWCAP bits should be
+done in coordination with OPAL / skiboot, Linux, and glibc projects.
+
+The binding is passed to the hypervisor by firmware. The hypervisor may
+build a subset with unsupported/disabled features and hypervisor specifics
+removed, and pass that to a guest OS. The OS may advertise features to
+userspace.
+
+
+Background
+----------
+The cpu-features binding (subsequently "cpu-features") aims to provide an
+extensible metadata and protocol between different levels of system software
+(firmware, hypervisor, OS/guest, userspace) to advertise the CPU features
+available on the system. With each level able to shape the features available
+to the next.
+
+The binding specifies features common to all CPUs in the system. Heterogeneous
+CPU features are not supported at present (such could be added by providing
+additional cpu-features nodes and linking those to particular CPUs with
+additional features).
+
+There is no strict definition for what a CPU feature must be, but an
+architectural behaviour or performance characteristic (or group of related
+behaviours). They must be documented in skiboot/core/cpufeatures.c sufficiently
+precisely. More guidelines for feature definitions below.
+
+cpu-features is intended to provide fine grained control of CPU features at
+all levels of the stack (firmware, hypervisor, OS, userspace), with the
+ability for new CPU features to be used by some components without all
+components being upgraded (e.g., a new floating point instruction could be
+used by userspace math library without upgrading kernel and hypervisor).
+
+
+Overview
+--------
+
+The cpu-features node is created by firmware and passed to the hypervisor.
+The hypervisor may create cpu-features node to be passed to guest, based on
+the features that have been enabled, and policy decisions. Hypervisor specific
+features, and hypervisor bits and properties should not be advertised to
+guests. Guest OS may advertise features to userspace using another method
+(e.g., using AUXV vectors, userspace typically does not parse DT).
+
+When the cpu-features node is present, ibm,pa-features and individual feature
+properties (e.g., "ibm,vsx"), and cpu-version under the "cpu" compatible nodes
+can be ignored by the consumer. For compatibility, the provider must continue
+to provide those older properties and the consumer must not assume cpu-features
+exists.
+
+When this node exists, software may assume a base feature set which is ISA
+v2.07B (BookS) minus the explicit features listed in core/cpufeatures.c
+entries in this source tree.
+
+Each feature is advertised as a node underneath the cpu-features node, named
+with a human-readable string name that uniquely identifies specification of
+that capability.
+
+A feature node has a number of metadata properties describing privilege levels
+a feature may be used (HV, OS, PR/user), and information about how it is to
+be enabled and advertised to lesser privilege levels. Enabling means to make
+it available at a lesser privilege level, (how to enable a given feature
+for this privilege level is implicit: if the software know how to use a
+feature, it also knows how to enable it).
+
+Feature node properties:
+
+- "isa", the Power ISA version where this feature first became available.
+ In case of an implementation specific feature
+
+- "usable-privilege", a bitmask (HV, OS, PR/user) specifying which privilege
+ levels this feature may be used in.
+
+- "hv-support", a bitmask. If this exists, the hypervisor must do some work
+ to enable support for lesser privilege levels. Bits can be set in this mask
+ to specify prescription/recipes to enable the feature without custom code.
+ If no bits are set, no recipe exists and custom code must be used. HFSCR
+ register enable bit is the only such recipe currently.
+
+- "os-support", similar to hv-support. FSCR recipe.
+
+- Features may have additional properties associated, must be documented with
+ the feature.
+
+- Recipes may have additional properties associated. HFSCR recipe has
+ hfscr-bit-nr, and FSCR recipe has fscr-bit-nr.
+
+- "dependencies" array of phandles. If this exists, it links to the
+ features that must be enabled in order for this feature to be enabled.
+
+- "hwcap-bit-nr" if it exists provides a Linux ELF AUXV HWCAP bit number that
+ can be used to advertise this feature to userspace.
+
+Together, these compatibility, support, and dependencies properties allow
+unknown features to be enabled and advertised to lesser privilege levels
+(when possible).
+
+All bits not defined in usable, support masks must be 0, and should be ignored
+by consumers. This allows extensibility to add new privilege levels and new
+recipes. Unknown properties should also be ignored. This allows extensibility
+for additional methods and metadata for enablement and advertisement.
+
+The policy for selecting and configuring which features to advertise and use
+is left for implementations.
+
+
+Guidelines for defining features
+--------------------------------
+
+As a rough guide, features should be based on functional groups of changes
+to the ISA, or related performance characteristics.
+
+Grouping should be made by one or a combination of those that:
+- Share common enablement requirements (e.g., share particular registers or
+ firmware setup requirements).
+- Share common usage patterns (e..g, likely to be used together).
+- Are implemented with a particular new hardware unit.
+- Are optional in the ISA.
+
+Granularity can be debated, but fine grained and encompassing is generally
+preferable. For example, memory management unit may be considered fundamental,
+but the MMU in POWER9 is very different and in many ways incompatible from
+that in POWER8 even in hash mode.
+
+For example, "POWER9" would be too general, but a new feature for every
+instruction would be too specific. The "summary of changes" preface in Power
+ISA specification is a good starting point to give a guideline for granularity
+of the architected features.
+
+New features that offer additional or incompatible functionality beyond
+an existing feature may contain an ISA version postfix.
+
+Implementation specific behaviour should contain a CPU type postfix. E.g.,
+"machine-check-power9" gives exact MCE properties. If a future CPU has the same
+MCE architecture, it should define the same property. If it has a
+backward-compatible superset, it could additionally define
+"machine-check-newcpu".
+
+Features should be "positive" as much as possible. That is, the presence of
+a feature should indicate the presence of an additional CPU feature (e.g., a
+new instruction or register). This requires some anticipation and foresight
+for defining CPU features. "Negative" features may be unavoidable in some
+cases.
diff --git a/include/device.h b/include/device.h
index 1e5875dc..fd66df11 100644
--- a/include/device.h
+++ b/include/device.h
@@ -141,6 +141,7 @@ void dt_check_del_prop(struct dt_node *node, const char *name);
/* Warning: moves *prop! */
void dt_resize_property(struct dt_property **prop, size_t len);
+void dt_property_set_cell(struct dt_property *prop, u32 index, u32 val);
u32 dt_property_get_cell(const struct dt_property *prop, u32 index);
/* First child of this node. */
diff --git a/include/skiboot.h b/include/skiboot.h
index d1de10a4..2f81a058 100644
--- a/include/skiboot.h
+++ b/include/skiboot.h
@@ -195,6 +195,11 @@ extern void start_kernel_secondary(uint64_t entry) __noreturn;
/* Get description of machine from HDAT and create device-tree */
extern int parse_hdat(bool is_opal);
+struct dt_node;
+
+/* Add /cpus/features node for boot environment that passes an fdt */
+extern void dt_add_cpufeatures(struct dt_node *root);
+
/* Root of device tree. */
extern struct dt_node *dt_root;
--
2.16.1
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