summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/thumbee.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/kernel/thumbee.c')
-rw-r--r--arch/arm/kernel/thumbee.c70
1 files changed, 70 insertions, 0 deletions
diff --git a/arch/arm/kernel/thumbee.c b/arch/arm/kernel/thumbee.c
new file mode 100644
index 0000000000..d832eb9e62
--- /dev/null
+++ b/arch/arm/kernel/thumbee.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/arm/kernel/thumbee.c
+ *
+ * Copyright (C) 2008 ARM Limited
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+
+#include <asm/cputype.h>
+#include <asm/system_info.h>
+#include <asm/thread_notify.h>
+
+/*
+ * Access to the ThumbEE Handler Base register
+ */
+static inline unsigned long teehbr_read(void)
+{
+ unsigned long v;
+ asm("mrc p14, 6, %0, c1, c0, 0\n" : "=r" (v));
+ return v;
+}
+
+static inline void teehbr_write(unsigned long v)
+{
+ asm("mcr p14, 6, %0, c1, c0, 0\n" : : "r" (v));
+}
+
+static int thumbee_notifier(struct notifier_block *self, unsigned long cmd, void *t)
+{
+ struct thread_info *thread = t;
+
+ switch (cmd) {
+ case THREAD_NOTIFY_FLUSH:
+ teehbr_write(0);
+ break;
+ case THREAD_NOTIFY_SWITCH:
+ current_thread_info()->thumbee_state = teehbr_read();
+ teehbr_write(thread->thumbee_state);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block thumbee_notifier_block = {
+ .notifier_call = thumbee_notifier,
+};
+
+static int __init thumbee_init(void)
+{
+ unsigned long pfr0;
+ unsigned int cpu_arch = cpu_architecture();
+
+ if (cpu_arch < CPU_ARCH_ARMv7)
+ return 0;
+
+ pfr0 = read_cpuid_ext(CPUID_EXT_PFR0);
+ if ((pfr0 & 0x0000f000) != 0x00001000)
+ return 0;
+
+ pr_info("ThumbEE CPU extension supported.\n");
+ elf_hwcap |= HWCAP_THUMBEE;
+ thread_register_notifier(&thumbee_notifier_block);
+
+ return 0;
+}
+
+late_initcall(thumbee_init);