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, 56 insertions, 0 deletions

diff --git a/arch/powerpc/sysdev/ipic.h b/arch/powerpc/sysdev/ipic.h
new file mode 100644
index 000000000..45ab61406
--- /dev/null
+++ b/arch/powerpc/sysdev/ipic.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * IPIC private definitions and structure.
+ *
+ * Maintainer: Kumar Gala <galak@kernel.crashing.org>
+ *
+ * Copyright 2005 Freescale Semiconductor, Inc
+ */
+#ifndef __IPIC_H__
+#define __IPIC_H__
+
+#include <asm/ipic.h>
+
+#define NR_IPIC_INTS 128
+
+/* External IRQS */
+#define IPIC_IRQ_EXT0 48
+#define IPIC_IRQ_EXT1 17
+#define IPIC_IRQ_EXT7 23
+
+/* Default Priority Registers */
+#define IPIC_PRIORITY_DEFAULT 0x05309770
+
+/* System Global Interrupt Configuration Register */
+#define	SICFR_IPSA	0x00010000
+#define	SICFR_IPSB	0x00020000
+#define	SICFR_IPSC	0x00040000
+#define	SICFR_IPSD	0x00080000
+#define	SICFR_MPSA	0x00200000
+#define	SICFR_MPSB	0x00400000
+
+/* System External Interrupt Mask Register */
+#define	SEMSR_SIRQ0	0x00008000
+
+/* System Error Control Register */
+#define SERCR_MCPR	0x00000001
+
+struct ipic {
+	volatile u32 __iomem	*regs;
+
+	/* The remapper for this IPIC */
+	struct irq_domain		*irqhost;
+};
+
+struct ipic_info {
+	u8	ack;		/* pending register offset from base if the irq
+				   supports ack operation */
+	u8	mask;		/* mask register offset from base */
+	u8	prio;		/* priority register offset from base */
+	u8	force;		/* force register offset from base */
+	u8	bit;		/* register bit position (as per doc)
+				   bit mask = 1 << (31 - bit) */
+	u8	prio_mask;	/* priority mask value */
+};
+
+#endif /* __IPIC_H__ */