lkml.org 
[lkml]   [2014]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4/5] arm64: enable generic CPU feature modalias matching for this arch
Date
This enables support for the generic CPU feature modalias implementation that
wires up optional CPU features to udev based module autoprobing.

A file <asm/cpufeatures.h> is provided that maps CPU feature numbers to
elf_hwcap bits, which is the standard way on arm64 to advertise optional CPU
features both internally and to user space.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/cpufeature.h | 30 ++++++++++++++++++++++++++++++
2 files changed, 31 insertions(+)
create mode 100644 arch/arm64/include/asm/cpufeature.h

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index dd4327f09ba4..e339099b6fbd 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -16,6 +16,7 @@ config ARM64
select DCACHE_WORD_ACCESS
select GENERIC_CLOCKEVENTS
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
+ select GENERIC_CPU_AUTOPROBE
select GENERIC_IOMAP
select GENERIC_IRQ_PROBE
select GENERIC_IRQ_SHOW
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
new file mode 100644
index 000000000000..1d902efa201d
--- /dev/null
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ASM_CPUFEATURE_H
+#define __ASM_CPUFEATURE_H
+
+#include <asm/elf.h>
+#include <asm/hwcap.h>
+
+/*
+ * In the arm64 world (as in the ARM world), elf_hwcap is used both internally
+ * in the kernel and for user space to keep track of which optional features
+ * are supported by the current system. So let's map feature 'x' to HWCAP_x.
+ * Note that HWCAP_x constants are bit fields so we need to take the log.
+ */
+
+#define MAX_CPU_FEATURES sizeof(elf_hwcap)
+#define cpu_feature(x) ((unsigned int)ilog2(HWCAP_ ## x))
+
+static inline bool cpu_have_feature(unsigned int num)
+{
+ return !!(elf_hwcap & (1 << num));
+}
+
+#endif
--
1.8.3.2


\
 
 \ /
  Last update: 2014-01-29 18:01    [W:0.065 / U:0.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site