nios2: Interrupt handling

This patch adds the support for IRQ handling.

Signed-off-by: Ley Foon Tan <[e-mail]>
Reviewed-by: Thomas Gleixner <[e-mail]>

arch/nios2/include/asm/irq.h

···
+/*
+ * Copyright (C) 2013 Altera Corporation
+ * Copyright (C) 2011 Tobias Klauser <[e-mail]>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef _ASM_NIOS2_IRQ_H
+#define _ASM_NIOS2_IRQ_H
+
+#define NIOS2_CPU_NR_IRQS	32
+
+#include <asm-generic/irq.h>
+#include <linux/irqdomain.h>
+
+#endif

arch/nios2/include/asm/irqflags.h

···
+/*
+ * Copyright (C) 2010 Thomas Chou <[e-mail]>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+#include <asm/registers.h>
+
+static inline unsigned long arch_local_save_flags(void)
+{
+	return RDCTL(CTL_STATUS);
+}
+
+/*
+ * This will restore ALL status register flags, not only the interrupt
+ * mask flag.
+ */
+static inline void arch_local_irq_restore(unsigned long flags)
+{
+	WRCTL(CTL_STATUS, flags);
+}
+
+static inline void arch_local_irq_disable(void)
+{
+	unsigned long flags;
+
+	flags = arch_local_save_flags();
+	arch_local_irq_restore(flags & ~STATUS_PIE);
+}
+
+static inline void arch_local_irq_enable(void)
+{
+	unsigned long flags;
+
+	flags = arch_local_save_flags();
+	arch_local_irq_restore(flags | STATUS_PIE);
+}
+
+static inline int arch_irqs_disabled_flags(unsigned long flags)
+{
+	return (flags & STATUS_PIE) == 0;
+}
+
+static inline int arch_irqs_disabled(void)
+{
+	return arch_irqs_disabled_flags(arch_local_save_flags());
+}
+
+static inline unsigned long arch_local_irq_save(void)
+{
+	unsigned long flags;
+
+	flags = arch_local_save_flags();
+	arch_local_irq_restore(flags & ~STATUS_PIE);
+	return flags;
+}
+
+#endif /* _ASM_IRQFLAGS_H */

arch/nios2/kernel/irq.c

···
+/*
+ * Copyright (C) 2013 Altera Corporation
+ * Copyright (C) 2011 Tobias Klauser <[e-mail]>
+ * Copyright (C) 2008 Thomas Chou <[e-mail]>
+ *
+ * based on irq.c from m68k which is:
+ *
+ * Copyright (C) 2007 Greg Ungerer <[e-mail]>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+
+static u32 ienable;
+
+asmlinkage void do_IRQ(int hwirq, struct pt_regs *regs)
+{
+	struct pt_regs *oldregs = set_irq_regs(regs);
+	int irq;
+
+	irq_enter();
+	irq = irq_find_mapping(NULL, hwirq);
+	generic_handle_irq(irq);
+	irq_exit();
+
+	set_irq_regs(oldregs);
+}
+
+static void chip_unmask(struct irq_data *d)
+{
+	ienable |= (1 << d->hwirq);
+	WRCTL(CTL_IENABLE, ienable);
+}
+
+static void chip_mask(struct irq_data *d)
+{
+	ienable &= ~(1 << d->hwirq);
+	WRCTL(CTL_IENABLE, ienable);
+}
+
+static struct irq_chip m_irq_chip = {
+	.name		= "NIOS2-INTC",
+	.irq_unmask	= chip_unmask,
+	.irq_mask	= chip_mask,
+};
+
+static int irq_map(struct irq_domain *h, unsigned int virq,
+				irq_hw_number_t hw_irq_num)
+{
+	irq_set_chip_and_handler(virq, &m_irq_chip, handle_level_irq);
+
+	return 0;
+}
+
+static struct irq_domain_ops irq_ops = {
+	.map	= irq_map,
+	.xlate	= irq_domain_xlate_onecell,
+};
+
+void __init init_IRQ(void)
+{
+	struct irq_domain *domain;
+	struct device_node *node;
+
+	node = of_find_compatible_node(NULL, NULL, "altr,nios2-1.0");
+	if (!node)
+		node = of_find_compatible_node(NULL, NULL, "altr,nios2-1.1");
+
+	BUG_ON(!node);
+
+	domain = irq_domain_add_linear(node, NIOS2_CPU_NR_IRQS, &irq_ops, NULL);
+	BUG_ON(!domain);
+
+	irq_set_default_host(domain);
+	of_node_put(node);
+	/* Load the initial ienable value */
+	ienable = RDCTL(CTL_IENABLE);
+}