1/*
  2 * Generic Event Device for ACPI.
  3 *
  4 * Copyright (c) 2016, The Linux Foundation. All rights reserved.
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 and
  8 * only version 2 as published by the Free Software Foundation.
  9 *
 10 * This program is distributed in the hope that it will be useful,
 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13 * GNU General Public License for more details.
 14 *
 15 * Generic Event Device allows platforms to handle interrupts in ACPI
 16 * ASL statements. It follows very similar to  _EVT method approach
 17 * from GPIO events. All interrupts are listed in _CRS and the handler
 18 * is written in _EVT method. Here is an example.
 19 *
 20 * Device (GED0)
 21 * {
 22 *
 23 *     Name (_HID, "ACPI0013")
 24 *     Name (_UID, 0)
 25 *     Method (_CRS, 0x0, Serialized)
 26 *     {
 27 *		Name (RBUF, ResourceTemplate ()
 28 *		{
 29 *		Interrupt(ResourceConsumer, Edge, ActiveHigh, Shared, , , )
 30 *		{123}
 31 *		}
 32 *     })
 33 *
 34 *     Method (_EVT, 1) {
 35 *             if (Lequal(123, Arg0))
 36 *             {
 37 *             }
 38 *     }
 39 * }
 40 *
 41 */
 42
 43#include <linux/err.h>
 44#include <linux/init.h>
 45#include <linux/interrupt.h>
 46#include <linux/list.h>
 47#include <linux/platform_device.h>
 48#include <linux/acpi.h>
 49
 50#define MODULE_NAME	"acpi-ged"
 51
 52struct acpi_ged_event {
 53	struct list_head node;
 54	struct device *dev;
 55	unsigned int gsi;
 56	unsigned int irq;
 57	acpi_handle handle;
 58};
 59
 60static irqreturn_t acpi_ged_irq_handler(int irq, void *data)
 61{
 62	struct acpi_ged_event *event = data;
 63	acpi_status acpi_ret;
 64
 65	acpi_ret = acpi_execute_simple_method(event->handle, NULL, event->gsi);
 66	if (ACPI_FAILURE(acpi_ret))
 67		dev_err_once(event->dev, "IRQ method execution failed\n");
 68
 69	return IRQ_HANDLED;
 70}
 71
 72static acpi_status acpi_ged_request_interrupt(struct acpi_resource *ares,
 73					      void *context)
 74{
 75	struct acpi_ged_event *event;
 76	unsigned int irq;
 77	unsigned int gsi;
 78	unsigned int irqflags = IRQF_ONESHOT;
 79	struct device *dev = context;
 80	acpi_handle handle = ACPI_HANDLE(dev);
 81	acpi_handle evt_handle;
 82	struct resource r;
 83	struct acpi_resource_irq *p = &ares->data.irq;
 84	struct acpi_resource_extended_irq *pext = &ares->data.extended_irq;
 85
 86	if (ares->type == ACPI_RESOURCE_TYPE_END_TAG)
 87		return AE_OK;
 88
 89	if (!acpi_dev_resource_interrupt(ares, 0, &r)) {
 90		dev_err(dev, "unable to parse IRQ resource\n");
 91		return AE_ERROR;
 92	}
 93	if (ares->type == ACPI_RESOURCE_TYPE_IRQ)
 94		gsi = p->interrupts[0];
 95	else
 96		gsi = pext->interrupts[0];
 97
 98	irq = r.start;
 99
100	if (ACPI_FAILURE(acpi_get_handle(handle, "_EVT", &evt_handle))) {
101		dev_err(dev, "cannot locate _EVT method\n");
102		return AE_ERROR;
103	}
104
105	dev_info(dev, "GED listening GSI %u @ IRQ %u\n", gsi, irq);
106
107	event = devm_kzalloc(dev, sizeof(*event), GFP_KERNEL);
108	if (!event)
109		return AE_ERROR;
110
111	event->gsi = gsi;
112	event->dev = dev;
113	event->irq = irq;
114	event->handle = evt_handle;
115
116	if (r.flags & IORESOURCE_IRQ_SHAREABLE)
117		irqflags |= IRQF_SHARED;
118
119	if (devm_request_threaded_irq(dev, irq, NULL, acpi_ged_irq_handler,
120				      irqflags, "ACPI:Ged", event)) {
121		dev_err(dev, "failed to setup event handler for irq %u\n", irq);
122		return AE_ERROR;
123	}
124
125	return AE_OK;
126}
127
128static int ged_probe(struct platform_device *pdev)
129{
130	acpi_status acpi_ret;
131
132	acpi_ret = acpi_walk_resources(ACPI_HANDLE(&pdev->dev), "_CRS",
133				       acpi_ged_request_interrupt, &pdev->dev);
134	if (ACPI_FAILURE(acpi_ret)) {
135		dev_err(&pdev->dev, "unable to parse the _CRS record\n");
136		return -EINVAL;
137	}
138
139	return 0;
140}
141
142static const struct acpi_device_id ged_acpi_ids[] = {
143	{"ACPI0013"},
144	{},
145};
146
147static struct platform_driver ged_driver = {
148	.probe = ged_probe,
149	.driver = {
150		.name = MODULE_NAME,
151		.acpi_match_table = ACPI_PTR(ged_acpi_ids),
152	},
153};
154builtin_platform_driver(ged_driver);