ACPI: implement Generic Event Device

Generic Event Device described in ACPI 6.1 allows platforms to handle
platform interrupts in ACPI ASL statements. It borrows constructs like
_EVT from GPIO events. All interrupts are listed in _CRS and the handler
is written in _EVT method. Here is an example.

Device (GED0)
{

	Name (_HID, "ACPI0013")
	Name (_UID, 0)
	Name(_CRS, ResourceTemplate ()
	{
		Interrupt(ResourceConsumer, Edge, ActiveHigh, Shared, , , )
		 {123}
	})

	Method (_EVT, 1) {
		if (Lequal(123, Arg0))
		{
		}
	}
}

Wake capability has not been implemented yet.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/Makefile

@@ -47,6 +47,7 @@ acpi-$(CONFIG_ARM_AMBA)	+= acpi_amba.o
 acpi-y				+= int340x_thermal.o
 acpi-y				+= power.o
 acpi-y				+= event.o
+acpi-$(CONFIG_ACPI_REDUCED_HARDWARE_ONLY) += evged.o
 acpi-y				+= sysfs.o
 acpi-y				+= property.o
 acpi-$(CONFIG_X86)		+= acpi_cmos_rtc.o

drivers/acpi/evged.c

@@ -0,0 +1,156 @@
+/*
+ * Generic Event Device for ACPI.
+ *
+ * Copyright (c) 2016, The Linux Foundation. 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 version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * 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.  See the
+ * GNU General Public License for more details.
+ *
+ * Generic Event Device allows platforms to handle interrupts in ACPI
+ * ASL statements. It follows very similar to  _EVT method approach
+ * from GPIO events. All interrupts are listed in _CRS and the handler
+ * is written in _EVT method. Here is an example.
+ *
+ * Device (GED0)
+ * {
+ *
+ *     Name (_HID, "ACPI0013")
+ *     Name (_UID, 0)
+ *     Method (_CRS, 0x0, Serialized)
+ *     {
+ *		Name (RBUF, ResourceTemplate ()
+ *		{
+ *		Interrupt(ResourceConsumer, Edge, ActiveHigh, Shared, , , )
+ *		{123}
+ *		}
+ *     })
+ *
+ *     Method (_EVT, 1) {
+ *             if (Lequal(123, Arg0))
+ *             {
+ *             }
+ *     }
+ * }
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/platform_device.h>
+#include <linux/acpi.h>
+
+#define MODULE_NAME	"acpi-ged"
+
+struct acpi_ged_event {
+	struct list_head node;
+	struct device *dev;
+	unsigned int gsi;
+	unsigned int irq;
+	acpi_handle handle;
+};
+
+static irqreturn_t acpi_ged_irq_handler(int irq, void *data)
+{
+	struct acpi_ged_event *event = data;
+	acpi_status acpi_ret;
+
+	acpi_ret = acpi_execute_simple_method(event->handle, NULL, event->gsi);
+	if (ACPI_FAILURE(acpi_ret))
+		dev_err_once(event->dev, "IRQ method execution failed\n");
+
+	return IRQ_HANDLED;
+}
+
+static acpi_status acpi_ged_request_interrupt(struct acpi_resource *ares,
+					      void *context)
+{
+	struct acpi_ged_event *event;
+	unsigned int irq;
+	unsigned int gsi;
+	unsigned int irqflags = IRQF_ONESHOT;
+	struct device *dev = context;
+	acpi_handle handle = ACPI_HANDLE(dev);
+	acpi_handle evt_handle;
+	struct resource r;
+	struct acpi_resource_irq *p = &ares->data.irq;
+	struct acpi_resource_extended_irq *pext = &ares->data.extended_irq;
+
+	if (ares->type == ACPI_RESOURCE_TYPE_END_TAG)
+		return AE_OK;
+
+	if (!acpi_dev_resource_interrupt(ares, 0, &r)) {
+		dev_err(dev, "unable to parse IRQ resource\n");
+		return AE_ERROR;
+	}
+	if (ares->type == ACPI_RESOURCE_TYPE_IRQ)
+		gsi = p->interrupts[0];
+	else
+		gsi = pext->interrupts[0];
+
+	irq = r.start;
+
+	if (ACPI_FAILURE(acpi_get_handle(handle, "_EVT", &evt_handle))) {
+		dev_err(dev, "cannot locate _EVT method\n");
+		return AE_ERROR;
+	}
+
+	dev_info(dev, "GED listening GSI %u @ IRQ %u\n", gsi, irq);
+
+	event = devm_kzalloc(dev, sizeof(*event), GFP_KERNEL);
+	if (!event)
+		return AE_ERROR;
+
+	event->gsi = gsi;
+	event->dev = dev;
+	event->irq = irq;
+	event->handle = evt_handle;
+
+	if (r.flags & IORESOURCE_IRQ_SHAREABLE)
+		irqflags |= IRQF_SHARED;
+
+	if (devm_request_threaded_irq(dev, irq, NULL, acpi_ged_irq_handler,
+				      irqflags, "ACPI:Ged", event)) {
+		dev_err(dev, "failed to setup event handler for irq %u\n", irq);
+		return AE_ERROR;
+	}
+
+	return AE_OK;
+}
+
+static int ged_probe(struct platform_device *pdev)
+{
+	acpi_status acpi_ret;
+
+	acpi_ret = acpi_walk_resources(ACPI_HANDLE(&pdev->dev), "_CRS",
+				       acpi_ged_request_interrupt, &pdev->dev);
+	if (ACPI_FAILURE(acpi_ret)) {
+		dev_err(&pdev->dev, "unable to parse the _CRS record\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct acpi_device_id ged_acpi_ids[] = {
+	{"ACPI0013"},
+	{},
+};
+
+static struct platform_driver ged_driver = {
+	.probe = ged_probe,
+	.driver = {
+		.name = MODULE_NAME,
+		.acpi_match_table = ACPI_PTR(ged_acpi_ids),
+	},
+};
+
+module_platform_driver(ged_driver);
+MODULE_LICENSE("GPL v2");