xtensa: add IRQ domains support

IRQ domains provide a mechanism for conversion of linux IRQ numbers to
hardware IRQ numbers and vice versus. It is used by OpenFirmware for
linking device tree objects to their respective interrupt controllers.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/Kconfig

@@ -17,6 +17,7 @@ config XTENSA
 	select GENERIC_KERNEL_EXECVE
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select CLONE_BACKWARDS
+	select IRQ_DOMAIN
 	help
 	  Xtensa processors are 32-bit RISC machines designed by Tensilica
 	  primarily for embedded systems.  These processors are both

arch/xtensa/kernel/irq.c

@@ -18,6 +18,7 @@
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/kernel_stat.h>
+#include <linux/irqdomain.h>
 
 #include <asm/uaccess.h>
 #include <asm/platform.h>
@@ -26,19 +27,22 @@ static unsigned int cached_irq_mask;
 
 atomic_t irq_err_count;
 
+static struct irq_domain *root_domain;
+
 /*
  * do_IRQ handles all normal device IRQ's (the special
  * SMP cross-CPU interrupts have their own specific
  * handlers).
  */
 
-asmlinkage void do_IRQ(int irq, struct pt_regs *regs)
+asmlinkage void do_IRQ(int hwirq, struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
+	int irq = irq_find_mapping(root_domain, hwirq);
 
-	if (irq >= NR_IRQS) {
+	if (hwirq >= NR_IRQS) {
 		printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
-				__func__, irq);
+				__func__, hwirq);
 	}
 
 	irq_enter();
@@ -71,40 +75,39 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 
 static void xtensa_irq_mask(struct irq_data *d)
 {
-	cached_irq_mask &= ~(1 << d->irq);
+	cached_irq_mask &= ~(1 << d->hwirq);
 	set_sr (cached_irq_mask, intenable);
 }
 
 static void xtensa_irq_unmask(struct irq_data *d)
 {
-	cached_irq_mask |= 1 << d->irq;
+	cached_irq_mask |= 1 << d->hwirq;
 	set_sr (cached_irq_mask, intenable);
 }
 
 static void xtensa_irq_enable(struct irq_data *d)
 {
-	variant_irq_enable(d->irq);
+	variant_irq_enable(d->hwirq);
 	xtensa_irq_unmask(d);
 }
 
 static void xtensa_irq_disable(struct irq_data *d)
 {
 	xtensa_irq_mask(d);
-	variant_irq_disable(d->irq);
+	variant_irq_disable(d->hwirq);
 }
 
 static void xtensa_irq_ack(struct irq_data *d)
 {
-	set_sr(1 << d->irq, intclear);
+	set_sr(1 << d->hwirq, intclear);
 }
 
 static int xtensa_irq_retrigger(struct irq_data *d)
 {
-	set_sr (1 << d->irq, INTSET);
+	set_sr(1 << d->hwirq, intset);
 	return 1;
 }
 
-
 static struct irq_chip xtensa_irq_chip = {
 	.name		= "xtensa",
 	.irq_enable	= xtensa_irq_enable,
@@ -115,37 +118,90 @@ static struct irq_chip xtensa_irq_chip = {
 	.irq_retrigger	= xtensa_irq_retrigger,
 };
 
-void __init init_IRQ(void)
+static int xtensa_irq_map(struct irq_domain *d, unsigned int irq,
+		irq_hw_number_t hw)
 {
-	int index;
-
-	for (index = 0; index < XTENSA_NR_IRQS; index++) {
-		int mask = 1 << index;
+	u32 mask = 1 << hw;
+
+	if (mask & XCHAL_INTTYPE_MASK_SOFTWARE) {
+		irq_set_chip_and_handler_name(irq, &xtensa_irq_chip,
+				handle_simple_irq, "level");
+		irq_set_status_flags(irq, IRQ_LEVEL);
+	} else if (mask & XCHAL_INTTYPE_MASK_EXTERN_EDGE) {
+		irq_set_chip_and_handler_name(irq, &xtensa_irq_chip,
+				handle_edge_irq, "edge");
+		irq_clear_status_flags(irq, IRQ_LEVEL);
+	} else if (mask & XCHAL_INTTYPE_MASK_EXTERN_LEVEL) {
+		irq_set_chip_and_handler_name(irq, &xtensa_irq_chip,
+				handle_level_irq, "level");
+		irq_set_status_flags(irq, IRQ_LEVEL);
+	} else if (mask & XCHAL_INTTYPE_MASK_TIMER) {
+		irq_set_chip_and_handler_name(irq, &xtensa_irq_chip,
+				handle_edge_irq, "edge");
+		irq_clear_status_flags(irq, IRQ_LEVEL);
+	} else {/* XCHAL_INTTYPE_MASK_WRITE_ERROR */
+		/* XCHAL_INTTYPE_MASK_NMI */
 
-		if (mask & XCHAL_INTTYPE_MASK_SOFTWARE)
-			irq_set_chip_and_handler(index, &xtensa_irq_chip,
-						 handle_simple_irq);
+		irq_set_chip_and_handler_name(irq, &xtensa_irq_chip,
+				handle_level_irq, "level");
+		irq_set_status_flags(irq, IRQ_LEVEL);
+	}
+	return 0;
+}
 
-		else if (mask & XCHAL_INTTYPE_MASK_EXTERN_EDGE)
-			irq_set_chip_and_handler(index, &xtensa_irq_chip,
-						 handle_edge_irq);
+static unsigned map_ext_irq(unsigned ext_irq)
+{
+	unsigned mask = XCHAL_INTTYPE_MASK_EXTERN_EDGE |
+		XCHAL_INTTYPE_MASK_EXTERN_LEVEL;
+	unsigned i;
 
-		else if (mask & XCHAL_INTTYPE_MASK_EXTERN_LEVEL)
-			irq_set_chip_and_handler(index, &xtensa_irq_chip,
-						 handle_level_irq);
+	for (i = 0; mask; ++i, mask >>= 1) {
+		if ((mask & 1) && ext_irq-- == 0)
+			return i;
+	}
+	return XCHAL_NUM_INTERRUPTS;
+}
 
-		else if (mask & XCHAL_INTTYPE_MASK_TIMER)
-			irq_set_chip_and_handler(index, &xtensa_irq_chip,
-						 handle_edge_irq);
+/*
+ * Device Tree IRQ specifier translation function which works with one or
+ * two cell bindings. First cell value maps directly to the hwirq number.
+ * Second cell if present specifies whether hwirq number is external (1) or
+ * internal (0).
+ */
+int xtensa_irq_domain_xlate(struct irq_domain *d, struct device_node *ctrlr,
+		const u32 *intspec, unsigned int intsize,
+		unsigned long *out_hwirq, unsigned int *out_type)
+{
+	if (WARN_ON(intsize < 1 || intsize > 2))
+		return -EINVAL;
+	if (intsize == 2 && intspec[1] == 1) {
+		unsigned int_irq = map_ext_irq(intspec[0]);
+		if (int_irq < XCHAL_NUM_INTERRUPTS)
+			*out_hwirq = int_irq;
+		else
+			return -EINVAL;
+	} else {
+		*out_hwirq = intspec[0];
+	}
+	*out_type = IRQ_TYPE_NONE;
+	return 0;
+}
 
-		else	/* XCHAL_INTTYPE_MASK_WRITE_ERROR */
-			/* XCHAL_INTTYPE_MASK_NMI */
+static const struct irq_domain_ops xtensa_irq_domain_ops = {
+	.xlate = xtensa_irq_domain_xlate,
+	.map = xtensa_irq_map,
+};
 
-			irq_set_chip_and_handler(index, &xtensa_irq_chip,
-						 handle_level_irq);
-	}
+void __init init_IRQ(void)
+{
+	struct device_node *intc = NULL;
 
 	cached_irq_mask = 0;
+	set_sr(~0, intclear);
+
+	root_domain = irq_domain_add_legacy(intc, NR_IRQS, 0, 0,
+			&xtensa_irq_domain_ops, NULL);
+	irq_set_default_host(root_domain);
 
 	variant_init_irq();
 }

arch/xtensa/kernel/time.c

@@ -22,6 +22,7 @@
 #include <linux/irq.h>
 #include <linux/profile.h>
 #include <linux/delay.h>
+#include <linux/irqdomain.h>
 
 #include <asm/timex.h>
 #include <asm/platform.h>
@@ -52,6 +53,7 @@ static struct irqaction timer_irqaction = {
 
 void __init time_init(void)
 {
+	unsigned int irq;
 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
 	printk("Calibrating CPU frequency ");
 	platform_calibrate_ccount();
@@ -62,7 +64,8 @@ void __init time_init(void)
 
 	/* Initialize the linux timer interrupt. */
 
-	setup_irq(LINUX_TIMER_INT, &timer_irqaction);
+	irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
+	setup_irq(irq, &timer_irqaction);
 	set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
 }