MN10300: ASB2364: Handle the IRQ multiplexer in the FPGA

Handle the IRQ multiplexer in the FPGA by implementing a cascade interrupt
driver for it.

Signed-off-by: David Howells <dhowells@redhat.com>

arch/mn10300/include/asm/irq.h

@@ -21,11 +21,15 @@
 /* this number is used when no interrupt has been assigned */
 #define NO_IRQ		INT_MAX
 
-/* hardware irq numbers */
-#ifdef CONFIG_SMP
-#define NR_IRQS		GxICR_NUM_EXT_IRQS
+/*
+ * hardware irq numbers
+ * - the ASB2364 has an FPGA with an IRQ multiplexer on it
+ */
+#ifdef CONFIG_MN10300_UNIT_ASB2364
+#include <unit/irq.h>
 #else
-#define NR_IRQS		GxICR_NUM_IRQS
+#define NR_CPU_IRQS	GxICR_NUM_IRQS
+#define NR_IRQS		NR_CPU_IRQS
 #endif
 
 /* external hardware irq numbers */

arch/mn10300/kernel/irq.c

@@ -381,9 +381,16 @@ int show_interrupts(struct seq_file *p, void *v)
 			seq_printf(p, "%3d: ", i);
 			for_each_present_cpu(cpu)
 				seq_printf(p, "%10u ", kstat_irqs_cpu(i, cpu));
-			seq_printf(p, " %14s.%u", irq_desc[i].chip->name,
-				   (GxICR(i) & GxICR_LEVEL) >>
-				   GxICR_LEVEL_SHIFT);
+
+			if (i < NR_CPU_IRQS)
+				seq_printf(p, " %14s.%u",
+					   irq_desc[i].chip->name,
+					   (GxICR(i) & GxICR_LEVEL) >>
+					   GxICR_LEVEL_SHIFT);
+			else
+				seq_printf(p, " %14s",
+					   irq_desc[i].chip->name);
+
 			seq_printf(p, "  %s", action->name);
 
 			for (action = action->next;

arch/mn10300/unit-asb2364/Makefile

@@ -7,4 +7,4 @@
 #
 # Note 2! The CFLAGS definitions are now in the main makefile...
 
-obj-y   := unit-init.o leds.o
+obj-y   := unit-init.o leds.o irq-fpga.o

arch/mn10300/unit-asb2364/include/unit/fpga-regs.h

@@ -14,17 +14,19 @@
 #define ASB2364_FPGA_REG_RESET_USB	__SYSREG(0xa900130c, u16)
 #define ASB2364_FPGA_REG_RESET_AV	__SYSREG(0xa9001310, u16)
 
-#define ASB2364_FPGA_REG_IRQ_LAN	__SYSREG(0xa9001510, u16)
-#define ASB2364_FPGA_REG_IRQ_UART	__SYSREG(0xa9001514, u16)
-#define ASB2364_FPGA_REG_IRQ_I2C	__SYSREG(0xa9001518, u16)
-#define ASB2364_FPGA_REG_IRQ_USB	__SYSREG(0xa900151c, u16)
-#define ASB2364_FPGA_REG_IRQ_FPGA	__SYSREG(0xa9001524, u16)
-
-#define ASB2364_FPGA_REG_MASK_LAN	__SYSREG(0xa9001590, u16)
-#define ASB2364_FPGA_REG_MASK_UART	__SYSREG(0xa9001594, u16)
-#define ASB2364_FPGA_REG_MASK_I2C	__SYSREG(0xa9001598, u16)
-#define ASB2364_FPGA_REG_MASK_USB	__SYSREG(0xa900159c, u16)
-#define ASB2364_FPGA_REG_MASK_FPGA	__SYSREG(0xa90015a4, u16)
+#define ASB2364_FPGA_REG_IRQ(X)		__SYSREG(0xa9001590+((X)*4), u16)
+#define ASB2364_FPGA_REG_IRQ_LAN	ASB2364_FPGA_REG_IRQ(0)
+#define ASB2364_FPGA_REG_IRQ_UART	ASB2364_FPGA_REG_IRQ(1)
+#define ASB2364_FPGA_REG_IRQ_I2C	ASB2364_FPGA_REG_IRQ(2)
+#define ASB2364_FPGA_REG_IRQ_USB	ASB2364_FPGA_REG_IRQ(3)
+#define ASB2364_FPGA_REG_IRQ_FPGA	ASB2364_FPGA_REG_IRQ(5)
+
+#define ASB2364_FPGA_REG_MASK(X)	__SYSREG(0xa9001590+((X)*4), u16)
+#define ASB2364_FPGA_REG_MASK_LAN	ASB2364_FPGA_REG_MASK(0)
+#define ASB2364_FPGA_REG_MASK_UART	ASB2364_FPGA_REG_MASK(1)
+#define ASB2364_FPGA_REG_MASK_I2C	ASB2364_FPGA_REG_MASK(2)
+#define ASB2364_FPGA_REG_MASK_USB	ASB2364_FPGA_REG_MASK(3)
+#define ASB2364_FPGA_REG_MASK_FPGA	ASB2364_FPGA_REG_MASK(5)
 
 #define ASB2364_FPGA_REG_CPLD5_SET1	__SYSREG(0xa9002500, u16)
 #define ASB2364_FPGA_REG_CPLD5_SET2	__SYSREG(0xa9002504, u16)

arch/mn10300/unit-asb2364/include/unit/irq.h

@@ -0,0 +1,35 @@
+/* ASB2364 FPGA irq numbers
+ *
+ * Copyright (C) 2010 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#ifndef _UNIT_IRQ_H
+#define _UNIT_IRQ_H
+
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_SMP
+#define NR_CPU_IRQS	GxICR_NUM_EXT_IRQS
+#else
+#define NR_CPU_IRQS	GxICR_NUM_IRQS
+#endif
+
+enum {
+	FPGA_LAN_IRQ	= NR_CPU_IRQS,
+	FPGA_UART_IRQ,
+	FPGA_I2C_IRQ,
+	FPGA_USB_IRQ,
+	FPGA_RESERVED_IRQ,
+	FPGA_FPGA_IRQ,
+	NR_IRQS
+};
+
+extern void __init irq_fpga_init(void);
+
+#endif /* !__ASSEMBLY__ */
+#endif /* _UNIT_IRQ_H */

arch/mn10300/unit-asb2364/irq-fpga.c

@@ -0,0 +1,96 @@
+/* ASB2364 FPGA interrupt multiplexing
+ *
+ * Copyright (C) 2010 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <unit/fpga-regs.h>
+
+/*
+ * FPGA PIC operations
+ */
+static void asb2364_fpga_mask(unsigned int irq)
+{
+	ASB2364_FPGA_REG_MASK(irq - NR_CPU_IRQS) = 0x0001;
+	SyncExBus();
+}
+
+static void asb2364_fpga_ack(unsigned int irq)
+{
+	ASB2364_FPGA_REG_IRQ(irq - NR_CPU_IRQS) = 0x0001;
+	SyncExBus();
+}
+
+static void asb2364_fpga_mask_ack(unsigned int irq)
+{
+	ASB2364_FPGA_REG_MASK(irq - NR_CPU_IRQS) = 0x0001;
+	SyncExBus();
+	ASB2364_FPGA_REG_IRQ(irq - NR_CPU_IRQS) = 0x0001;
+	SyncExBus();
+}
+
+static void asb2364_fpga_unmask(unsigned int irq)
+{
+	ASB2364_FPGA_REG_MASK(irq - NR_CPU_IRQS) = 0x0000;
+	SyncExBus();
+}
+
+static struct irq_chip asb2364_fpga_pic = {
+	.name		= "fpga",
+	.ack		= asb2364_fpga_ack,
+	.mask		= asb2364_fpga_mask,
+	.mask_ack	= asb2364_fpga_mask_ack,
+	.unmask		= asb2364_fpga_unmask,
+};
+
+/*
+ * FPGA PIC interrupt handler
+ */
+static irqreturn_t fpga_interrupt(int irq, void *_mask)
+{
+	if ((ASB2364_FPGA_REG_IRQ_LAN  & 0x0001) != 0x0001)
+		generic_handle_irq(FPGA_LAN_IRQ);
+	if ((ASB2364_FPGA_REG_IRQ_UART & 0x0001) != 0x0001)
+		generic_handle_irq(FPGA_UART_IRQ);
+	if ((ASB2364_FPGA_REG_IRQ_I2C  & 0x0001) != 0x0001)
+		generic_handle_irq(FPGA_I2C_IRQ);
+	if ((ASB2364_FPGA_REG_IRQ_USB  & 0x0001) != 0x0001)
+		generic_handle_irq(FPGA_USB_IRQ);
+	if ((ASB2364_FPGA_REG_IRQ_FPGA & 0x0001) != 0x0001)
+		generic_handle_irq(FPGA_FPGA_IRQ);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Define an interrupt action for each FPGA PIC output
+ */
+static struct irqaction fpga_irq[]  = {
+	[0] = {
+		.handler	= fpga_interrupt,
+		.flags		= IRQF_DISABLED | IRQF_SHARED,
+		.name		= "fpga",
+	},
+};
+
+/*
+ * Initialise the FPGA's PIC
+ */
+void __init irq_fpga_init(void)
+{
+	int irq;
+
+	for (irq = NR_CPU_IRQS; irq < NR_IRQS; irq++)
+		set_irq_chip_and_handler(irq, &asb2364_fpga_pic, handle_level_irq);
+
+	/* the FPGA drives the XIRQ1 input on the CPU PIC */
+	setup_irq(XIRQ1, &fpga_irq[0]);
+}

arch/mn10300/unit-asb2364/unit-init.c

@@ -20,6 +20,7 @@
 #include <asm/processor.h>
 #include <asm/irq.h>
 #include <asm/intctl-regs.h>
+#include <unit/fpga-regs.h>
 
 /*
  * initialise some of the unit hardware before gdbstub is set up
@@ -82,4 +83,6 @@ void __init unit_init_IRQ(void)
 
 #define IRQCTL	__SYSREG(0xd5000090, u32)
 	IRQCTL |= 0x02;
+
+	irq_fpga_init();
 }