1 files changed, 225 insertions, 0 deletions
diff --git a/arch/arc/kernel/intc-compact.c b/arch/arc/kernel/intc-compact.c
new file mode 100644
index 000000000..039fac30b
--- /dev/null
+++ b/arch/arc/kernel/intc-compact.c
@@ -0,0 +1,225 @@
+/*
+ * Copyright (C) 2011-12 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/irqdomain.h>
+#include <linux/irqchip.h>
+#include <asm/irq.h>
+
+/*
+ * Early Hardware specific Interrupt setup
+ * -Platform independent, needed for each CPU (not foldable into init_IRQ)
+ * -Called very early (start_kernel -> setup_arch -> setup_processor)
+ *
+ * what it does ?
+ * -Optionally, setup the High priority Interrupts as Level 2 IRQs
+ */
+void arc_init_IRQ(void)
+{
+	int level_mask = 0;
+
+       /* setup any high priority Interrupts (Level2 in ARCompact jargon) */
+	level_mask |= IS_ENABLED(CONFIG_ARC_IRQ3_LV2) << 3;
+	level_mask |= IS_ENABLED(CONFIG_ARC_IRQ5_LV2) << 5;
+	level_mask |= IS_ENABLED(CONFIG_ARC_IRQ6_LV2) << 6;
+
+	/*
+	 * Write to register, even if no LV2 IRQs configured to reset it
+	 * in case bootloader had mucked with it
+	 */
+	write_aux_reg(AUX_IRQ_LEV, level_mask);
+
+	if (level_mask)
+		pr_info("Level-2 interrupts bitset %x\n", level_mask);
+}
+
+/*
+ * ARC700 core includes a simple on-chip intc supporting
+ * -per IRQ enable/disable
+ * -2 levels of interrupts (high/low)
+ * -all interrupts being level triggered
+ *
+ * To reduce platform code, we assume all IRQs directly hooked-up into intc.
+ * Platforms with external intc, hence cascaded IRQs, are free to over-ride
+ * below, per IRQ.
+ */
+
+static void arc_irq_mask(struct irq_data *data)
+{
+	unsigned int ienb;
+
+	ienb = read_aux_reg(AUX_IENABLE);
+	ienb &= ~(1 << data->irq);
+	write_aux_reg(AUX_IENABLE, ienb);
+}
+
+static void arc_irq_unmask(struct irq_data *data)
+{
+	unsigned int ienb;
+
+	ienb = read_aux_reg(AUX_IENABLE);
+	ienb |= (1 << data->irq);
+	write_aux_reg(AUX_IENABLE, ienb);
+}
+
+static struct irq_chip onchip_intc = {
+	.name           = "ARC In-core Intc",
+	.irq_mask	= arc_irq_mask,
+	.irq_unmask	= arc_irq_unmask,
+};
+
+static int arc_intc_domain_map(struct irq_domain *d, unsigned int irq,
+			       irq_hw_number_t hw)
+{
+	/*
+	 * XXX: the IPI IRQ needs to be handled like TIMER too. However ARC core
+	 *      code doesn't own it (like TIMER0). ISS IDU / ezchip define it
+	 *      in platform header which can't be included here as it goes
+	 *      against multi-platform image philisophy
+	 */
+	if (irq == TIMER0_IRQ)
+		irq_set_chip_and_handler(irq, &onchip_intc, handle_percpu_irq);
+	else
+		irq_set_chip_and_handler(irq, &onchip_intc, handle_level_irq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops arc_intc_domain_ops = {
+	.xlate = irq_domain_xlate_onecell,
+	.map = arc_intc_domain_map,
+};
+
+static struct irq_domain *root_domain;
+
+static int __init
+init_onchip_IRQ(struct device_node *intc, struct device_node *parent)
+{
+	if (parent)
+		panic("DeviceTree incore intc not a root irq controller\n");
+
+	root_domain = irq_domain_add_legacy(intc, NR_CPU_IRQS, 0, 0,
+					    &arc_intc_domain_ops, NULL);
+
+	if (!root_domain)
+		panic("root irq domain not avail\n");
+
+	/* with this we don't need to export root_domain */
+	irq_set_default_host(root_domain);
+
+	return 0;
+}
+
+IRQCHIP_DECLARE(arc_intc, "snps,arc700-intc", init_onchip_IRQ);
+
+/*
+ * arch_local_irq_enable - Enable interrupts.
+ *
+ * 1. Explicitly called to re-enable interrupts
+ * 2. Implicitly called from spin_unlock_irq, write_unlock_irq etc
+ *    which maybe in hard ISR itself
+ *
+ * Semantics of this function change depending on where it is called from:
+ *
+ * -If called from hard-ISR, it must not invert interrupt priorities
+ *  e.g. suppose TIMER is high priority (Level 2) IRQ
+ *    Time hard-ISR, timer_interrupt( ) calls spin_unlock_irq several times.
+ *    Here local_irq_enable( ) shd not re-enable lower priority interrupts
+ * -If called from soft-ISR, it must re-enable all interrupts
+ *    soft ISR are low prioity jobs which can be very slow, thus all IRQs
+ *    must be enabled while they run.
+ *    Now hardware context wise we may still be in L2 ISR (not done rtie)
+ *    still we must re-enable both L1 and L2 IRQs
+ *  Another twist is prev scenario with flow being
+ *     L1 ISR ==> interrupted by L2 ISR  ==> L2 soft ISR
+ *     here we must not re-enable Ll as prev Ll Interrupt's h/w context will get
+ *     over-written (this is deficiency in ARC700 Interrupt mechanism)
+ */
+
+#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS	/* Complex version for 2 IRQ levels */
+
+void arch_local_irq_enable(void)
+{
+
+	unsigned long flags = arch_local_save_flags();
+
+	/* Allow both L1 and L2 at the onset */
+	flags |= (STATUS_E1_MASK | STATUS_E2_MASK);
+
+	/* Called from hard ISR (between irq_enter and irq_exit) */
+	if (in_irq()) {
+
+		/* If in L2 ISR, don't re-enable any further IRQs as this can
+		 * cause IRQ priorities to get upside down. e.g. it could allow
+		 * L1 be taken while in L2 hard ISR which is wrong not only in
+		 * theory, it can also cause the dreaded L1-L2-L1 scenario
+		 */
+		if (flags & STATUS_A2_MASK)
+			flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK);
+
+		/* Even if in L1 ISR, allowe Higher prio L2 IRQs */
+		else if (flags & STATUS_A1_MASK)
+			flags &= ~(STATUS_E1_MASK);
+	}
+
+	/* called from soft IRQ, ideally we want to re-enable all levels */
+
+	else if (in_softirq()) {
+
+		/* However if this is case of L1 interrupted by L2,
+		 * re-enabling both may cause whaco L1-L2-L1 scenario
+		 * because ARC700 allows level 1 to interrupt an active L2 ISR
+		 * Thus we disable both
+		 * However some code, executing in soft ISR wants some IRQs
+		 * to be enabled so we re-enable L2 only
+		 *
+		 * How do we determine L1 intr by L2
+		 *  -A2 is set (means in L2 ISR)
+		 *  -E1 is set in this ISR's pt_regs->status32 which is
+		 *      saved copy of status32_l2 when l2 ISR happened
+		 */
+		struct pt_regs *pt = get_irq_regs();
+
+		if ((flags & STATUS_A2_MASK) && pt &&
+		    (pt->status32 & STATUS_A1_MASK)) {
+			/*flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK); */
+			flags &= ~(STATUS_E1_MASK);
+		}
+	}
+
+	arch_local_irq_restore(flags);
+}
+
+#else /* ! CONFIG_ARC_COMPACT_IRQ_LEVELS */
+
+/*
+ * Simpler version for only 1 level of interrupt
+ * Here we only Worry about Level 1 Bits
+ */
+void arch_local_irq_enable(void)
+{
+	unsigned long flags;
+
+	/*
+	 * ARC IDE Drivers tries to re-enable interrupts from hard-isr
+	 * context which is simply wrong
+	 */
+	if (in_irq()) {
+		WARN_ONCE(1, "IRQ enabled from hard-isr");
+		return;
+	}
+
+	flags = arch_local_save_flags();
+	flags |= (STATUS_E1_MASK | STATUS_E2_MASK);
+	arch_local_irq_restore(flags);
+}
+#endif
+EXPORT_SYMBOL(arch_local_irq_enable);