1 files changed, 227 insertions, 0 deletions
diff --git a/arch/tile/kernel/irq.c b/arch/tile/kernel/irq.c
new file mode 100644
index 00000000000..24cc6b2abc2
--- /dev/null
+++ b/arch/tile/kernel/irq.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   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.
+ *
+ *   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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel_stat.h>
+#include <linux/uaccess.h>
+#include <hv/drv_pcie_rc_intf.h>
+
+/*
+ * The set of interrupts we enable for raw_local_irq_enable().
+ * This is initialized to have just a single interrupt that the kernel
+ * doesn't actually use as a sentinel.  During kernel init,
+ * interrupts are added as the kernel gets prepared to support them.
+ * NOTE: we could probably initialize them all statically up front.
+ */
+DEFINE_PER_CPU(unsigned long long, interrupts_enabled_mask) =
+  INITIAL_INTERRUPTS_ENABLED;
+EXPORT_PER_CPU_SYMBOL(interrupts_enabled_mask);
+
+/* Define per-tile device interrupt state */
+DEFINE_PER_CPU(HV_IntrState, dev_intr_state);
+
+DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
+EXPORT_PER_CPU_SYMBOL(irq_stat);
+
+
+
+/*
+ * Interrupt dispatcher, invoked upon a hypervisor device interrupt downcall
+ */
+void tile_dev_intr(struct pt_regs *regs, int intnum)
+{
+	int irq;
+
+	/*
+	 * Get the device interrupt pending mask from where the hypervisor
+	 * has tucked it away for us.
+	 */
+	unsigned long pending_dev_intr_mask = __insn_mfspr(SPR_SYSTEM_SAVE_1_3);
+
+
+	/* Track time spent here in an interrupt context. */
+	struct pt_regs *old_regs = set_irq_regs(regs);
+	irq_enter();
+
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
+	/* Debugging check for stack overflow: less than 1/8th stack free? */
+	{
+		long sp = stack_pointer - (long) current_thread_info();
+		if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
+			printk(KERN_EMERG "tile_dev_intr: "
+			       "stack overflow: %ld\n",
+			       sp - sizeof(struct thread_info));
+			dump_stack();
+		}
+	}
+#endif
+
+	for (irq = 0; pending_dev_intr_mask; ++irq) {
+		if (pending_dev_intr_mask & 0x1) {
+			generic_handle_irq(irq);
+
+			/* Count device irqs; IPIs are counted elsewhere. */
+			if (irq > HV_MAX_IPI_INTERRUPT)
+				__get_cpu_var(irq_stat).irq_dev_intr_count++;
+		}
+		pending_dev_intr_mask >>= 1;
+	}
+
+	/*
+	 * Track time spent against the current process again and
+	 * process any softirqs if they are waiting.
+	 */
+	irq_exit();
+	set_irq_regs(old_regs);
+}
+
+
+/* Mask an interrupt. */
+static void hv_dev_irq_mask(unsigned int irq)
+{
+	HV_IntrState *p_intr_state = &__get_cpu_var(dev_intr_state);
+	hv_disable_intr(p_intr_state, 1 << irq);
+}
+
+/* Unmask an interrupt. */
+static void hv_dev_irq_unmask(unsigned int irq)
+{
+	/* Re-enable the hypervisor to generate interrupts. */
+	HV_IntrState *p_intr_state = &__get_cpu_var(dev_intr_state);
+	hv_enable_intr(p_intr_state, 1 << irq);
+}
+
+/*
+ * The HV doesn't latch incoming interrupts while an interrupt is
+ * disabled, so we need to reenable interrupts before running the
+ * handler.
+ *
+ * ISSUE: Enabling the interrupt this early avoids any race conditions
+ * but introduces the possibility of nested interrupt stack overflow.
+ * An imminent change to the HV IRQ model will fix this.
+ */
+static void hv_dev_irq_ack(unsigned int irq)
+{
+	hv_dev_irq_unmask(irq);
+}
+
+/*
+ * Since ack() reenables interrupts, there's nothing to do at eoi().
+ */
+static void hv_dev_irq_eoi(unsigned int irq)
+{
+}
+
+static struct irq_chip hv_dev_irq_chip = {
+	.typename = "hv_dev_irq_chip",
+	.ack = hv_dev_irq_ack,
+	.mask = hv_dev_irq_mask,
+	.unmask = hv_dev_irq_unmask,
+	.eoi = hv_dev_irq_eoi,
+};
+
+static struct irqaction resched_action = {
+	.handler = handle_reschedule_ipi,
+	.name = "resched",
+	.dev_id = handle_reschedule_ipi /* unique token */,
+};
+
+void __init init_IRQ(void)
+{
+	/* Bind IPI irqs. Does this belong somewhere else in init? */
+	tile_irq_activate(IRQ_RESCHEDULE);
+	BUG_ON(setup_irq(IRQ_RESCHEDULE, &resched_action));
+}
+
+void __cpuinit init_per_tile_IRQs(void)
+{
+	int rc;
+
+	/* Set the pointer to the per-tile device interrupt state. */
+	HV_IntrState *sv_ptr = &__get_cpu_var(dev_intr_state);
+	rc = hv_dev_register_intr_state(sv_ptr);
+	if (rc != HV_OK)
+		panic("hv_dev_register_intr_state: error %d", rc);
+
+}
+
+void tile_irq_activate(unsigned int irq)
+{
+	/*
+	 * Paravirtualized drivers can call up to the HV to find out
+	 * which irq they're associated with.  The HV interface
+	 * doesn't provide a generic call for discovering all valid
+	 * IRQs, so drivers must call this method to initialize newly
+	 * discovered IRQs.
+	 *
+	 * We could also just initialize all 32 IRQs at startup, but
+	 * doing so would lead to a kernel fault if an unexpected
+	 * interrupt fires and jumps to a NULL action.  By defering
+	 * the set_irq_chip_and_handler() call, unexpected IRQs are
+	 * handled properly by handle_bad_irq().
+	 */
+	hv_dev_irq_mask(irq);
+	set_irq_chip_and_handler(irq, &hv_dev_irq_chip, handle_percpu_irq);
+}
+
+void ack_bad_irq(unsigned int irq)
+{
+	printk(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);
+}
+
+/*
+ * Generic, controller-independent functions:
+ */
+
+int show_interrupts(struct seq_file *p, void *v)
+{
+	int i = *(loff_t *) v, j;
+	struct irqaction *action;
+	unsigned long flags;
+
+	if (i == 0) {
+		seq_printf(p, "           ");
+		for (j = 0; j < NR_CPUS; j++)
+			if (cpu_online(j))
+				seq_printf(p, "CPU%-8d", j);
+		seq_putc(p, '\n');
+	}
+
+	if (i < NR_IRQS) {
+		raw_spin_lock_irqsave(&irq_desc[i].lock, flags);
+		action = irq_desc[i].action;
+		if (!action)
+			goto skip;
+		seq_printf(p, "%3d: ", i);
+#ifndef CONFIG_SMP
+		seq_printf(p, "%10u ", kstat_irqs(i));
+#else
+		for_each_online_cpu(j)
+			seq_printf(p, "%10u ", kstat_irqs_cpu(i, j));
+#endif
+		seq_printf(p, " %14s", irq_desc[i].chip->typename);
+		seq_printf(p, "  %s", action->name);
+
+		for (action = action->next; action; action = action->next)
+			seq_printf(p, ", %s", action->name);
+
+		seq_putc(p, '\n');
+skip:
+		raw_spin_unlock_irqrestore(&irq_desc[i].lock, flags);
+	}
+	return 0;
+}