ARM: 9480/1: entry: expand comment in __switch_tografted

As per discussion between the developers in the mail thread
linked, expand the comment in __switch_to so that readers
of the code understand what is going on.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/s390/char/ctrlchar.h b/drivers/s390/char/ctrlchar.h
new file mode 100644
index 000000000..e52afa3b8
--- /dev/null
+++ b/drivers/s390/char/ctrlchar.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  Unified handling of special chars.
+ *
+ *    Copyright IBM Corp. 2001
+ *    Author(s): Fritz Elfert <felfert@millenux.com> <elfert@de.ibm.com>
+ *
+ */
+
+#include <linux/tty.h>
+#include <linux/sysrq.h>
+#include <linux/workqueue.h>
+
+extern unsigned int
+ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty);
+
+
+#define CTRLCHAR_NONE  (1 << 8)
+#define CTRLCHAR_CTRL  (2 << 8)
+#define CTRLCHAR_SYSRQ (3 << 8)
+
+#define CTRLCHAR_MASK (~0xffu)
+
+
+#ifdef CONFIG_MAGIC_SYSRQ
+struct sysrq_work {
+	int key;
+	struct work_struct work;
+};
+
+void schedule_sysrq_work(struct sysrq_work *sw);
+#endif