v4.19.13 snapshot.
diff --git a/arch/arm/mach-w90x900/irq.c b/arch/arm/mach-w90x900/irq.c
new file mode 100644
index 0000000..491b317
--- /dev/null
+++ b/arch/arm/mach-w90x900/irq.c
@@ -0,0 +1,216 @@
+/*
+ * linux/arch/arm/mach-w90x900/irq.c
+ *
+ * based on linux/arch/arm/plat-s3c24xx/irq.c by Ben Dooks
+ *
+ * Copyright (c) 2008 Nuvoton technology corporation
+ * All rights reserved.
+ *
+ * Wan ZongShun <mcuos.com@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation;version 2 of the License.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/ptrace.h>
+#include <linux/device.h>
+#include <linux/io.h>
+
+#include <asm/irq.h>
+#include <asm/mach/irq.h>
+
+#include <mach/hardware.h>
+#include <mach/regs-irq.h>
+
+#include "nuc9xx.h"
+
+struct group_irq {
+	unsigned long		gpen;
+	unsigned int		enabled;
+	void			(*enable)(struct group_irq *, int enable);
+};
+
+static DEFINE_SPINLOCK(groupirq_lock);
+
+#define DEFINE_GROUP(_name, _ctrlbit, _num)				\
+struct group_irq group_##_name = {					\
+		.enable		= nuc900_group_enable,			\
+		.gpen		= ((1 << _num) - 1) << _ctrlbit,	\
+	}
+
+static void nuc900_group_enable(struct group_irq *gpirq, int enable);
+
+static DEFINE_GROUP(nirq0, 0, 4);
+static DEFINE_GROUP(nirq1, 4, 4);
+static DEFINE_GROUP(usbh, 8, 2);
+static DEFINE_GROUP(ottimer, 16, 3);
+static DEFINE_GROUP(gdma, 20, 2);
+static DEFINE_GROUP(sc, 24, 2);
+static DEFINE_GROUP(i2c, 26, 2);
+static DEFINE_GROUP(ps2, 28, 2);
+
+static int group_irq_enable(struct group_irq *group_irq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&groupirq_lock, flags);
+	if (group_irq->enabled++ == 0)
+		(group_irq->enable)(group_irq, 1);
+	spin_unlock_irqrestore(&groupirq_lock, flags);
+
+	return 0;
+}
+
+static void group_irq_disable(struct group_irq *group_irq)
+{
+	unsigned long flags;
+
+	WARN_ON(group_irq->enabled == 0);
+
+	spin_lock_irqsave(&groupirq_lock, flags);
+	if (--group_irq->enabled == 0)
+		(group_irq->enable)(group_irq, 0);
+	spin_unlock_irqrestore(&groupirq_lock, flags);
+}
+
+static void nuc900_group_enable(struct group_irq *gpirq, int enable)
+{
+	unsigned int groupen = gpirq->gpen;
+	unsigned long regval;
+
+	regval = __raw_readl(REG_AIC_GEN);
+
+	if (enable)
+		regval |= groupen;
+	else
+		regval &= ~groupen;
+
+	__raw_writel(regval, REG_AIC_GEN);
+}
+
+static void nuc900_irq_mask(struct irq_data *d)
+{
+	struct group_irq *group_irq;
+
+	group_irq = NULL;
+
+	__raw_writel(1 << d->irq, REG_AIC_MDCR);
+
+	switch (d->irq) {
+	case IRQ_GROUP0:
+		group_irq = &group_nirq0;
+		break;
+
+	case IRQ_GROUP1:
+		group_irq = &group_nirq1;
+		break;
+
+	case IRQ_USBH:
+		group_irq = &group_usbh;
+		break;
+
+	case IRQ_T_INT_GROUP:
+		group_irq = &group_ottimer;
+		break;
+
+	case IRQ_GDMAGROUP:
+		group_irq = &group_gdma;
+		break;
+
+	case IRQ_SCGROUP:
+		group_irq = &group_sc;
+		break;
+
+	case IRQ_I2CGROUP:
+		group_irq = &group_i2c;
+		break;
+
+	case IRQ_P2SGROUP:
+		group_irq = &group_ps2;
+		break;
+	}
+
+	if (group_irq)
+		group_irq_disable(group_irq);
+}
+
+/*
+ * By the w90p910 spec,any irq,only write 1
+ * to REG_AIC_EOSCR for ACK
+ */
+
+static void nuc900_irq_ack(struct irq_data *d)
+{
+	__raw_writel(0x01, REG_AIC_EOSCR);
+}
+
+static void nuc900_irq_unmask(struct irq_data *d)
+{
+	struct group_irq *group_irq;
+
+	group_irq = NULL;
+
+	__raw_writel(1 << d->irq, REG_AIC_MECR);
+
+	switch (d->irq) {
+	case IRQ_GROUP0:
+		group_irq = &group_nirq0;
+		break;
+
+	case IRQ_GROUP1:
+		group_irq = &group_nirq1;
+		break;
+
+	case IRQ_USBH:
+		group_irq = &group_usbh;
+		break;
+
+	case IRQ_T_INT_GROUP:
+		group_irq = &group_ottimer;
+		break;
+
+	case IRQ_GDMAGROUP:
+		group_irq = &group_gdma;
+		break;
+
+	case IRQ_SCGROUP:
+		group_irq = &group_sc;
+		break;
+
+	case IRQ_I2CGROUP:
+		group_irq = &group_i2c;
+		break;
+
+	case IRQ_P2SGROUP:
+		group_irq = &group_ps2;
+		break;
+	}
+
+	if (group_irq)
+		group_irq_enable(group_irq);
+}
+
+static struct irq_chip nuc900_irq_chip = {
+	.irq_ack	= nuc900_irq_ack,
+	.irq_mask	= nuc900_irq_mask,
+	.irq_unmask	= nuc900_irq_unmask,
+};
+
+void __init nuc900_init_irq(void)
+{
+	int irqno;
+
+	__raw_writel(0xFFFFFFFE, REG_AIC_MDCR);
+
+	for (irqno = IRQ_WDT; irqno <= IRQ_ADC; irqno++) {
+		irq_set_chip_and_handler(irqno, &nuc900_irq_chip,
+					 handle_level_irq);
+		irq_clear_status_flags(irqno, IRQ_NOREQUEST);
+	}
+}