xtensa: don't use linux IRQ #0

Linux IRQ #0 is reserved for error reporting and may not be used.
Increase NR_IRQS for one additional slot and increase
irq_domain_add_legacy parameter first_irq value to 1, so that linux
IRQ #0 is not associated with hardware IRQ #0 in legacy IRQ domains.
Introduce macro XTENSA_PIC_LINUX_IRQ for static translation of xtensa
PIC hardware IRQ # to linux IRQ #. Use this macro in XTFPGA platform
data definitions.

This fixes inability to use hardware IRQ #0 in configurations that don't
use device tree and allows for non-identity mapping between linux IRQ #
and hardware IRQ #.

Cc: [e-mail]
Signed-off-by: Max Filippov <[e-mail]>

arch/xtensa/include/asm/irq.h

···
 # define PLATFORM_NR_IRQS 0
 #endif
 #define XTENSA_NR_IRQS XCHAL_NUM_INTERRUPTS
-#define NR_IRQS (XTENSA_NR_IRQS + VARIANT_NR_IRQS + PLATFORM_NR_IRQS)
+#define NR_IRQS (XTENSA_NR_IRQS + VARIANT_NR_IRQS + PLATFORM_NR_IRQS + 1)
+#define XTENSA_PIC_LINUX_IRQ(hwirq) ((hwirq) + 1)
 
 #if VARIANT_NR_IRQS == 0
 static inline void variant_init_irq(void) { }

arch/xtensa/kernel/irq.c

···
 {
 	int irq = irq_find_mapping(NULL, hwirq);
 
-	if (hwirq >= NR_IRQS) {
-		printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
-				__func__, hwirq);
-	}
-
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
 	/* Debugging check for stack overflow: is there less than 1KB free? */
 	{

arch/xtensa/platforms/xtfpga/include/platform/hardware.h

···
 
 /* Interrupt configuration. */
 
-#define PLATFORM_NR_IRQS	10
+#define PLATFORM_NR_IRQS	0
 
 /* Default assignment of LX60 devices to external interrupts. */
 
 #ifdef CONFIG_XTENSA_MX
 #define DUART16552_INTNUM	XCHAL_EXTINT3_NUM
 #define OETH_IRQ		XCHAL_EXTINT4_NUM
+#define C67X00_IRQ		XCHAL_EXTINT8_NUM
 #else
 #define DUART16552_INTNUM	XCHAL_EXTINT0_NUM
 #define OETH_IRQ		XCHAL_EXTINT1_NUM
+#define C67X00_IRQ		XCHAL_EXTINT5_NUM
 #endif
 
 /*
···
 
 #define C67X00_PADDR		(XCHAL_KIO_PADDR + 0x0D0D0000)
 #define C67X00_SIZE		0x10
-#define C67X00_IRQ		5
+
 #endif /* __XTENSA_XTAVNET_HARDWARE_H */

arch/xtensa/platforms/xtfpga/setup.c

···
 		.flags = IORESOURCE_MEM,
 	},
 	[2] = { /* IRQ number */
-		.start = OETH_IRQ,
-		.end   = OETH_IRQ,
+		.start = XTENSA_PIC_LINUX_IRQ(OETH_IRQ),
+		.end   = XTENSA_PIC_LINUX_IRQ(OETH_IRQ),
 		.flags = IORESOURCE_IRQ,
 	},
 };
···
 		.flags = IORESOURCE_MEM,
 	},
 	[1] = { /* IRQ number */
-		.start = C67X00_IRQ,
-		.end   = C67X00_IRQ,
+		.start = XTENSA_PIC_LINUX_IRQ(C67X00_IRQ),
+		.end   = XTENSA_PIC_LINUX_IRQ(C67X00_IRQ),
 		.flags = IORESOURCE_IRQ,
 	},
 };
···
 static struct plat_serial8250_port serial_platform_data[] = {
 	[0] = {
 		.mapbase	= DUART16552_PADDR,
-		.irq		= DUART16552_INTNUM,
+		.irq		= XTENSA_PIC_LINUX_IRQ(DUART16552_INTNUM),
 		.flags		= UPF_BOOT_AUTOCONF | UPF_SKIP_TEST |
 				  UPF_IOREMAP,
 		.iotype		= XCHAL_HAVE_BE ? UPIO_MEM32BE : UPIO_MEM32,

drivers/irqchip/irq-xtensa-mx.c

···
 int __init xtensa_mx_init_legacy(struct device_node *interrupt_parent)
 {
 	struct irq_domain *root_domain =
-		irq_domain_add_legacy(NULL, NR_IRQS, 0, 0,
+		irq_domain_add_legacy(NULL, NR_IRQS - 1, 1, 0,
 				&xtensa_mx_irq_domain_ops,
 				&xtensa_mx_irq_chip);
 	irq_set_default_host(root_domain);

drivers/irqchip/irq-xtensa-pic.c

···
 int __init xtensa_pic_init_legacy(struct device_node *interrupt_parent)
 {
 	struct irq_domain *root_domain =
-		irq_domain_add_legacy(NULL, NR_IRQS, 0, 0,
+		irq_domain_add_legacy(NULL, NR_IRQS - 1, 1, 0,
 				&xtensa_irq_domain_ops, &xtensa_irq_chip);
 	irq_set_default_host(root_domain);
 	return 0;