x86/acpi: Handle SCI interrupts above legacy space gracefully

Platforms which support only IOAPIC mode, pass the SCI information above
the legacy space (0-15) via the FADT mechanism and not via MADT.

In such cases mp_override_legacy_irq() which is invoked from
acpi_sci_ioapic_setup() to register SCI interrupts fails for interrupts
greater equal 16, since it is meant to handle only the legacy space and
emits error "Invalid bus_irq %u for legacy override".

Add a new function to handle SCI interrupts >= 16 and invoke it
conditionally in acpi_sci_ioapic_setup().

The code duplication due to this new function will be cleaned up in a
separate patch.
Co-developed-by: Sunil V L <sunil.vl@hpe.com>
Signed-off-by: Vikas C Sajjan <vikas.cha.sajjan@hpe.com>
Signed-off-by: Sunil V L <sunil.vl@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Abdul Lateef Attar <abdul-lateef.attar@hpe.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: linux-pm@vger.kernel.org
Cc: kkamagui@gmail.com
Cc: linux-acpi@vger.kernel.org
Link: https://lkml.kernel.org/r/1510848825-21965-2-git-send-email-vikas.cha.sajjan@hpe.com

arch/x86/kernel/acpi/boot.c

@@ -429,6 +429,34 @@ static int mp_config_acpi_gsi(struct device *dev, u32 gsi, int trigger,
 	return 0;
 }
 
+static int __init mp_register_ioapic_irq(u8 bus_irq, u8 polarity,
+						u8 trigger, u32 gsi)
+{
+	struct mpc_intsrc mp_irq;
+	int ioapic, pin;
+
+	/* Convert 'gsi' to 'ioapic.pin'(INTIN#) */
+	ioapic = mp_find_ioapic(gsi);
+	if (ioapic < 0) {
+		pr_warn("Failed to find ioapic for gsi : %u\n", gsi);
+		return ioapic;
+	}
+
+	pin = mp_find_ioapic_pin(ioapic, gsi);
+
+	mp_irq.type = MP_INTSRC;
+	mp_irq.irqtype = mp_INT;
+	mp_irq.irqflag = (trigger << 2) | polarity;
+	mp_irq.srcbus = MP_ISA_BUS;
+	mp_irq.srcbusirq = bus_irq;
+	mp_irq.dstapic = mpc_ioapic_id(ioapic);
+	mp_irq.dstirq = pin;
+
+	mp_save_irq(&mp_irq);
+
+	return 0;
+}
+
 static int __init
 acpi_parse_ioapic(struct acpi_subtable_header * header, const unsigned long end)
 {
@@ -473,7 +501,11 @@ static void __init acpi_sci_ioapic_setup(u8 bus_irq, u16 polarity, u16 trigger,
 	if (acpi_sci_flags & ACPI_MADT_POLARITY_MASK)
 		polarity = acpi_sci_flags & ACPI_MADT_POLARITY_MASK;
 
+	if (bus_irq < NR_IRQS_LEGACY)
 		mp_override_legacy_irq(bus_irq, polarity, trigger, gsi);
+	else
+		mp_register_ioapic_irq(bus_irq, polarity, trigger, gsi);
+
 	acpi_penalize_sci_irq(bus_irq, trigger, polarity);
 
 	/*