1 files changed, 165 insertions, 0 deletions
diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c
new file mode 100644
index 000000000..cd1234c10
--- /dev/null
+++ b/arch/arm/kernel/fiq.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/arch/arm/kernel/fiq.c
+ *
+ *  Copyright (C) 1998 Russell King
+ *  Copyright (C) 1998, 1999 Phil Blundell
+ *
+ *  FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
+ *
+ *  FIQ support re-written by Russell King to be more generic
+ *
+ * We now properly support a method by which the FIQ handlers can
+ * be stacked onto the vector.  We still do not support sharing
+ * the FIQ vector itself.
+ *
+ * Operation is as follows:
+ *  1. Owner A claims FIQ:
+ *     - default_fiq relinquishes control.
+ *  2. Owner A:
+ *     - inserts code.
+ *     - sets any registers,
+ *     - enables FIQ.
+ *  3. Owner B claims FIQ:
+ *     - if owner A has a relinquish function.
+ *       - disable FIQs.
+ *       - saves any registers.
+ *       - returns zero.
+ *  4. Owner B:
+ *     - inserts code.
+ *     - sets any registers,
+ *     - enables FIQ.
+ *  5. Owner B releases FIQ:
+ *     - Owner A is asked to reacquire FIQ:
+ *	 - inserts code.
+ *	 - restores saved registers.
+ *	 - enables FIQ.
+ *  6. Goto 3
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/seq_file.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cp15.h>
+#include <asm/fiq.h>
+#include <asm/irq.h>
+#include <asm/traps.h>
+
+#define FIQ_OFFSET ({					\
+		extern void *vector_fiq_offset;		\
+		(unsigned)&vector_fiq_offset;		\
+	})
+
+static unsigned long dfl_fiq_insn;
+static struct pt_regs dfl_fiq_regs;
+
+/* Default reacquire function
+ * - we always relinquish FIQ control
+ * - we always reacquire FIQ control
+ */
+static int fiq_def_op(void *ref, int relinquish)
+{
+	if (!relinquish) {
+		/* Restore default handler and registers */
+		local_fiq_disable();
+		set_fiq_regs(&dfl_fiq_regs);
+		set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn));
+		local_fiq_enable();
+
+		/* FIXME: notify irq controller to standard enable FIQs */
+	}
+
+	return 0;
+}
+
+static struct fiq_handler default_owner = {
+	.name	= "default",
+	.fiq_op = fiq_def_op,
+};
+
+static struct fiq_handler *current_fiq = &default_owner;
+
+int show_fiq_list(struct seq_file *p, int prec)
+{
+	if (current_fiq != &default_owner)
+		seq_printf(p, "%*s:              %s\n", prec, "FIQ",
+			current_fiq->name);
+
+	return 0;
+}
+
+void set_fiq_handler(void *start, unsigned int length)
+{
+	void *base = vectors_page;
+	unsigned offset = FIQ_OFFSET;
+
+	memcpy(base + offset, start, length);
+	if (!cache_is_vipt_nonaliasing())
+		flush_icache_range((unsigned long)base + offset, offset +
+				   length);
+	flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
+}
+
+int claim_fiq(struct fiq_handler *f)
+{
+	int ret = 0;
+
+	if (current_fiq) {
+		ret = -EBUSY;
+
+		if (current_fiq->fiq_op != NULL)
+			ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
+	}
+
+	if (!ret) {
+		f->next = current_fiq;
+		current_fiq = f;
+	}
+
+	return ret;
+}
+
+void release_fiq(struct fiq_handler *f)
+{
+	if (current_fiq != f) {
+		pr_err("%s FIQ trying to release %s FIQ\n",
+		       f->name, current_fiq->name);
+		dump_stack();
+		return;
+	}
+
+	do
+		current_fiq = current_fiq->next;
+	while (current_fiq->fiq_op(current_fiq->dev_id, 0));
+}
+
+static int fiq_start;
+
+void enable_fiq(int fiq)
+{
+	enable_irq(fiq + fiq_start);
+}
+
+void disable_fiq(int fiq)
+{
+	disable_irq(fiq + fiq_start);
+}
+
+EXPORT_SYMBOL(set_fiq_handler);
+EXPORT_SYMBOL(__set_fiq_regs);	/* defined in fiqasm.S */
+EXPORT_SYMBOL(__get_fiq_regs);	/* defined in fiqasm.S */
+EXPORT_SYMBOL(claim_fiq);
+EXPORT_SYMBOL(release_fiq);
+EXPORT_SYMBOL(enable_fiq);
+EXPORT_SYMBOL(disable_fiq);
+
+void __init init_FIQ(int start)
+{
+	unsigned offset = FIQ_OFFSET;
+	dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
+	get_fiq_regs(&dfl_fiq_regs);
+	fiq_start = start;
+}