OpenRISC: IRQ

This patch adds support for the OpenRISC PIC.

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Cc: tglx@linutronix.de
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 172 insertions, 0 deletions

diff --git a/arch/openrisc/kernel/irq.c b/arch/openrisc/kernel/irq.c
new file mode 100644
index 0000000..59b3023
--- /dev/null
+++ b/arch/openrisc/kernel/irq.c
@@ -0,0 +1,172 @@
+/*
+ * OpenRISC irq.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ *      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.
+ */
+
+#include <linux/ptrace.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/ftrace.h>
+#include <linux/irq.h>
+#include <linux/seq_file.h>
+#include <linux/kernel_stat.h>
+
+#include <linux/irqflags.h>
+
+/* read interrupt enabled status */
+unsigned long arch_local_save_flags(void)
+{
+	return mfspr(SPR_SR) & (SPR_SR_IEE|SPR_SR_TEE);
+}
+EXPORT_SYMBOL(arch_local_save_flags);
+
+/* set interrupt enabled status */
+void arch_local_irq_restore(unsigned long flags)
+{
+	mtspr(SPR_SR, ((mfspr(SPR_SR) & ~(SPR_SR_IEE|SPR_SR_TEE)) | flags));
+}
+EXPORT_SYMBOL(arch_local_irq_restore);
+
+
+/* OR1K PIC implementation */
+
+/* We're a couple of cycles faster than the generic implementations with
+ * these 'fast' versions.
+ */
+
+static void or1k_pic_mask(struct irq_data *data)
+{
+	mtspr(SPR_PICMR, mfspr(SPR_PICMR) & ~(1UL << data->irq));
+}
+
+static void or1k_pic_unmask(struct irq_data *data)
+{
+	mtspr(SPR_PICMR, mfspr(SPR_PICMR) | (1UL << data->irq));
+}
+
+static void or1k_pic_ack(struct irq_data *data)
+{
+	/* EDGE-triggered interrupts need to be ack'ed in order to clear
+	 * the latch.
+	 * LEVER-triggered interrupts do not need to be ack'ed; however,
+	 * ack'ing the interrupt has no ill-effect and is quicker than
+	 * trying to figure out what type it is...
+	 */
+
+	/* The OpenRISC 1000 spec says to write a 1 to the bit to ack the
+	 * interrupt, but the OR1200 does this backwards and requires a 0
+	 * to be written...
+	 */
+
+#ifdef CONFIG_OR1K_1200
+	/* There are two oddities with the OR1200 PIC implementation:
+	 * i)  LEVEL-triggered interrupts are latched and need to be cleared
+	 * ii) the interrupt latch is cleared by writing a 0 to the bit,
+	 *     as opposed to a 1 as mandated by the spec
+	 */
+
+	mtspr(SPR_PICSR, mfspr(SPR_PICSR) & ~(1UL << data->irq));
+#else
+	WARN(1, "Interrupt handling possibily broken\n");
+	mtspr(SPR_PICSR, (1UL << irq));
+#endif
+}
+
+static void or1k_pic_mask_ack(struct irq_data *data)
+{
+	/* Comments for pic_ack apply here, too */
+
+#ifdef CONFIG_OR1K_1200
+	mtspr(SPR_PICSR, mfspr(SPR_PICSR) & ~(1UL << data->irq));
+#else
+	WARN(1, "Interrupt handling possibily broken\n");
+	mtspr(SPR_PICSR, (1UL << irq));
+#endif
+}
+
+static int or1k_pic_set_type(struct irq_data *data, unsigned int flow_type)
+{
+	/* There's nothing to do in the PIC configuration when changing
+	 * flow type.  Level and edge-triggered interrupts are both
+	 * supported, but it's PIC-implementation specific which type
+	 * is handled. */
+
+	return irq_setup_alt_chip(data, flow_type);
+}
+
+static inline int pic_get_irq(int first)
+{
+	int irq;
+
+	irq = ffs(mfspr(SPR_PICSR) >> first);
+
+	return irq ? irq + first - 1 : NO_IRQ;
+}
+
+static void __init or1k_irq_init(void)
+{
+	struct irq_chip_generic *gc;
+	struct irq_chip_type *ct;
+
+	/* Disable all interrupts until explicitly requested */
+	mtspr(SPR_PICMR, (0UL));
+
+	gc = irq_alloc_generic_chip("or1k-PIC", 1, 0, 0, handle_level_irq);
+	ct = gc->chip_types;
+
+	ct->chip.irq_unmask = or1k_pic_unmask;
+	ct->chip.irq_mask = or1k_pic_mask;
+	ct->chip.irq_ack = or1k_pic_ack;
+	ct->chip.irq_mask_ack = or1k_pic_mask_ack;
+	ct->chip.irq_set_type = or1k_pic_set_type;
+
+	/* The OR1K PIC can handle both level and edge trigged
+	 * interrupts in roughly the same manner
+	 */
+#if 0
+	/* FIXME: chip.type??? */
+	ct->chip.type = IRQ_TYPE_EDGE_BOTH | IRQ_TYPE_LEVEL_MASK;
+#endif
+
+	irq_setup_generic_chip(gc, IRQ_MSK(NR_IRQS), 0,
+			       IRQ_NOREQUEST, IRQ_LEVEL | IRQ_NOPROBE);
+}
+
+void __init init_IRQ(void)
+{
+	or1k_irq_init();
+}
+
+void __irq_entry do_IRQ(struct pt_regs *regs)
+{
+	int irq = -1;
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	irq_enter();
+
+	while ((irq = pic_get_irq(irq + 1)) != NO_IRQ)
+		generic_handle_irq(irq);
+
+	irq_exit();
+	set_irq_regs(old_regs);
+}
+
+unsigned int irq_create_of_mapping(struct device_node *controller,
+				   const u32 *intspec, unsigned int intsize)
+{
+	return intspec[0];
+}
+EXPORT_SYMBOL_GPL(irq_create_of_mapping);