introduce-fiq-basis.patch

Adds a C-based FIQ ISR which is very convenient (and unusual --
normally you have to do FIQ ISR in assembler only).
Based on my article:

http://warmcat.com/_wp/2007/09/17/at91rm9200-fiq-faq-and-simple-example-code-patch/

Implemented as a platform device and driver.

Suspend / resume is tested and works.

Signed-off-by: Andy Green <andy@warmcat.com>

1 files changed, 64 insertions, 0 deletions

diff --git a/arch/arm/mach-s3c2440/fiq_c_isr.h b/arch/arm/mach-s3c2440/fiq_c_isr.h
new file mode 100644
index 00000000000..f08740ee8d3
--- /dev/null
+++ b/arch/arm/mach-s3c2440/fiq_c_isr.h
@@ -0,0 +1,64 @@
+#ifndef _LINUX_FIQ_C_ISR_H
+#define _LINUX_FIQ_C_ISR_H
+
+#include <asm/arch-s3c2410/regs-irq.h>
+
+extern unsigned long _fiq_count_fiqs;
+extern u32 _fiq_ack_mask;
+
+/* This CANNOT be implemented in a module -- it has to be used in code
+ * included in the monolithic kernel
+ */
+
+#define FIQ_HANDLER_START() \
+void __attribute__ ((naked)) s3c2440_fiq_isr(void) \
+{\
+	/*\
+	 * you can declare local vars here, take care to set the frame size\
+	 *  below accordingly if there are more than a few dozen bytes of them\
+	 */\
+
+/* stick your locals here :-)
+ * Do NOT initialize them here!  define them and initialize them after
+ * FIQ_HANDLER_ENTRY() is done.
+ */
+
+#define FIQ_HANDLER_ENTRY(LOCALS, FRAME) \
+	const int _FIQ_FRAME_SIZE = FRAME; \
+	/* entry takes care to store registers we will be treading on here */\
+	asm __volatile__ (\
+		"mov     ip, sp ;"\
+		/* stash FIQ and r0-r8 normal regs */\
+		"stmdb	sp!, {r0-r12, lr};"\
+		/* allow SP to get some space */\
+		"sub     sp, sp, %1 ;"\
+		/* !! THIS SETS THE FRAME, adjust to > sizeof locals */\
+		"sub     fp, sp, %0 ;"\
+		:\
+		: "rI" (LOCALS), "rI" (FRAME)\
+		:"r9"\
+	);
+
+/* stick your ISR code here and then end with... */
+
+#define FIQ_HANDLER_END() \
+	_fiq_count_fiqs++;\
+	__raw_writel(_fiq_ack_mask, S3C2410_SRCPND);\
+\
+	/* exit back to normal mode restoring everything */\
+	asm __volatile__ (\
+		/* pop our allocation */\
+		"add     sp, sp, %0 ;"\
+		/* return FIQ regs back to pristine state\
+		 * and get normal regs back\
+		 */\
+		"ldmia	sp!, {r0-r12, lr};"\
+\
+		/* return */\
+		"subs	pc, lr, #4;"\
+		: \
+		: "rI" (_FIQ_FRAME_SIZE) \
+	);\
+}
+
+#endif /* _LINUX_FIQ_C_ISR_H */