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-rw-r--r--arch/arm/kernel/fiq.c165
1 files changed, 165 insertions, 0 deletions
diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c
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+++ b/arch/arm/kernel/fiq.c
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+// 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,
+ (unsigned long)base + 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;
+}