ACPI: move arm64 GSI IRQ model to generic GSI IRQ layer

The code deployed to implement GSI linux IRQ numbers mapping on arm64 turns
out to be generic enough so that it can be moved to ACPI core code along
with its respective config option ACPI_GENERIC_GSI selectable on
architectures that can reuse the same code.

Current ACPI IRQ mapping code is not integrated in the kernel IRQ domain
infrastructure, in particular there is no way to look-up the
IRQ domain associated with a particular interrupt controller, so this
first version of GSI generic code carries out the GSI<->IRQ mapping relying
on the IRQ default domain which is supposed to be always set on a
specific architecture in case the domain structure passed to
irq_create/find_mapping() functions is missing.

This patch moves the arm64 acpi functions that implement the gsi mappings:

acpi_gsi_to_irq()
acpi_register_gsi()
acpi_unregister_gsi()

to ACPI core code. Since the generic GSI<->domain mapping is based on IRQ
domains, it can be extended as soon as a way to map an interrupt
controller to an IRQ domain is implemented for ACPI in the IRQ domain
layer.

x86 and ia64 code for GSI mappings cannot rely on the generic GSI
layer at present for legacy reasons, so they do not select the
ACPI_GENERIC_GSI config options and keep relying on their arch
specific GSI mapping layer.

Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Acked-by: Hanjun Guo <hanjun.guo@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 105 insertions, 0 deletions

diff --git a/drivers/acpi/gsi.c b/drivers/acpi/gsi.c
new file mode 100644
index 000000000000..38208f2d0e69
--- /dev/null
+++ b/drivers/acpi/gsi.c
@@ -0,0 +1,105 @@
+/*
+ * ACPI GSI IRQ layer
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.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/acpi.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+
+enum acpi_irq_model_id acpi_irq_model;
+
+static unsigned int acpi_gsi_get_irq_type(int trigger, int polarity)
+{
+	switch (polarity) {
+	case ACPI_ACTIVE_LOW:
+		return trigger == ACPI_EDGE_SENSITIVE ?
+		       IRQ_TYPE_EDGE_FALLING :
+		       IRQ_TYPE_LEVEL_LOW;
+	case ACPI_ACTIVE_HIGH:
+		return trigger == ACPI_EDGE_SENSITIVE ?
+		       IRQ_TYPE_EDGE_RISING :
+		       IRQ_TYPE_LEVEL_HIGH;
+	case ACPI_ACTIVE_BOTH:
+		if (trigger == ACPI_EDGE_SENSITIVE)
+			return IRQ_TYPE_EDGE_BOTH;
+	default:
+		return IRQ_TYPE_NONE;
+	}
+}
+
+/**
+ * acpi_gsi_to_irq() - Retrieve the linux irq number for a given GSI
+ * @gsi: GSI IRQ number to map
+ * @irq: pointer where linux IRQ number is stored
+ *
+ * irq location updated with irq value [>0 on success, 0 on failure]
+ *
+ * Returns: linux IRQ number on success (>0)
+ *          -EINVAL on failure
+ */
+int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
+{
+	/*
+	 * Only default domain is supported at present, always find
+	 * the mapping corresponding to default domain by passing NULL
+	 * as irq_domain parameter
+	 */
+	*irq = irq_find_mapping(NULL, gsi);
+	/*
+	 * *irq == 0 means no mapping, that should
+	 * be reported as a failure
+	 */
+	return (*irq > 0) ? *irq : -EINVAL;
+}
+EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
+
+/**
+ * acpi_register_gsi() - Map a GSI to a linux IRQ number
+ * @dev: device for which IRQ has to be mapped
+ * @gsi: GSI IRQ number
+ * @trigger: trigger type of the GSI number to be mapped
+ * @polarity: polarity of the GSI to be mapped
+ *
+ * Returns: a valid linux IRQ number on success
+ *          -EINVAL on failure
+ */
+int acpi_register_gsi(struct device *dev, u32 gsi, int trigger,
+		      int polarity)
+{
+	unsigned int irq;
+	unsigned int irq_type = acpi_gsi_get_irq_type(trigger, polarity);
+
+	/*
+	 * There is no way at present to look-up the IRQ domain on ACPI,
+	 * hence always create mapping referring to the default domain
+	 * by passing NULL as irq_domain parameter
+	 */
+	irq = irq_create_mapping(NULL, gsi);
+	if (!irq)
+		return -EINVAL;
+
+	/* Set irq type if specified and different than the current one */
+	if (irq_type != IRQ_TYPE_NONE &&
+		irq_type != irq_get_trigger_type(irq))
+		irq_set_irq_type(irq, irq_type);
+	return irq;
+}
+EXPORT_SYMBOL_GPL(acpi_register_gsi);
+
+/**
+ * acpi_unregister_gsi() - Free a GSI<->linux IRQ number mapping
+ * @gsi: GSI IRQ number
+ */
+void acpi_unregister_gsi(u32 gsi)
+{
+	int irq = irq_find_mapping(NULL, gsi);
+
+	irq_dispose_mapping(irq);
+}
+EXPORT_SYMBOL_GPL(acpi_unregister_gsi);