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-rw-r--r--include/linux/cpufeature.h60
1 files changed, 60 insertions, 0 deletions
diff --git a/include/linux/cpufeature.h b/include/linux/cpufeature.h
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+++ b/include/linux/cpufeature.h
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+/*
+ * 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 __LINUX_CPUFEATURE_H
+#define __LINUX_CPUFEATURE_H
+
+#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
+
+#include <linux/mod_devicetable.h>
+#include <asm/cpufeature.h>
+
+/*
+ * Macros imported from <asm/cpufeature.h>:
+ * - cpu_feature(x) ordinal value of feature called 'x'
+ * - cpu_have_feature(u32 n) whether feature #n is available
+ * - MAX_CPU_FEATURES upper bound for feature ordinal values
+ * Optional:
+ * - CPU_FEATURE_TYPEFMT format string fragment for printing the cpu type
+ * - CPU_FEATURE_TYPEVAL set of values matching the format string above
+ */
+
+#ifndef CPU_FEATURE_TYPEFMT
+#define CPU_FEATURE_TYPEFMT "%s"
+#endif
+
+#ifndef CPU_FEATURE_TYPEVAL
+#define CPU_FEATURE_TYPEVAL ELF_PLATFORM
+#endif
+
+/*
+ * Use module_cpu_feature_match(feature, module_init_function) to
+ * declare that
+ * a) the module shall be probed upon discovery of CPU feature 'feature'
+ * (typically at boot time using udev)
+ * b) the module must not be loaded if CPU feature 'feature' is not present
+ * (not even by manual insmod).
+ *
+ * For a list of legal values for 'feature', please consult the file
+ * 'asm/cpufeature.h' of your favorite architecture.
+ */
+#define module_cpu_feature_match(x, __init) \
+static struct cpu_feature const cpu_feature_match_ ## x[] = \
+ { { .feature = cpu_feature(x) }, { } }; \
+MODULE_DEVICE_TABLE(cpu, cpu_feature_match_ ## x); \
+ \
+static int cpu_feature_match_ ## x ## _init(void) \
+{ \
+ if (!cpu_have_feature(cpu_feature(x))) \
+ return -ENODEV; \
+ return __init(); \
+} \
+module_init(cpu_feature_match_ ## x ## _init)
+
+#endif
+#endif