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_device {
 53	struct device *dev;
 54	struct list_head event_list;
 55};
 56
 57struct acpi_ged_event {
 58	struct list_head node;
 59	struct device *dev;
 60	unsigned int gsi;
 61	unsigned int irq;
 62	acpi_handle handle;
 63};
 64
 65static irqreturn_t acpi_ged_irq_handler(int irq, void *data)
 66{
 67	struct acpi_ged_event *event = data;
 68	acpi_status acpi_ret;
 69
 70	acpi_ret = acpi_execute_simple_method(event->handle, NULL, event->gsi);
 71	if (ACPI_FAILURE(acpi_ret))
 72		dev_err_once(event->dev, "IRQ method execution failed\n");
 73
 74	return IRQ_HANDLED;
 75}
 76
 77static acpi_status acpi_ged_request_interrupt(struct acpi_resource *ares,
 78					      void *context)
 79{
 80	struct acpi_ged_event *event;
 81	unsigned int irq;
 82	unsigned int gsi;
 83	unsigned int irqflags = IRQF_ONESHOT;
 84	struct acpi_ged_device *geddev = context;
 85	struct device *dev = geddev->dev;
 86	acpi_handle handle = ACPI_HANDLE(dev);
 87	acpi_handle evt_handle;
 88	struct resource r;
 89	struct acpi_resource_irq *p = &ares->data.irq;
 90	struct acpi_resource_extended_irq *pext = &ares->data.extended_irq;
 91
 92	if (ares->type == ACPI_RESOURCE_TYPE_END_TAG)
 93		return AE_OK;
 94
 95	if (!acpi_dev_resource_interrupt(ares, 0, &r)) {
 96		dev_err(dev, "unable to parse IRQ resource\n");
 97		return AE_ERROR;
 98	}
 99	if (ares->type == ACPI_RESOURCE_TYPE_IRQ)
100		gsi = p->interrupts[0];
101	else
102		gsi = pext->interrupts[0];
103
104	irq = r.start;
105
106	if (ACPI_FAILURE(acpi_get_handle(handle, "_EVT", &evt_handle))) {
107		dev_err(dev, "cannot locate _EVT method\n");
108		return AE_ERROR;
109	}
110
111	event = devm_kzalloc(dev, sizeof(*event), GFP_KERNEL);
112	if (!event)
113		return AE_ERROR;
114
115	event->gsi = gsi;
116	event->dev = dev;
117	event->irq = irq;
118	event->handle = evt_handle;
119
120	if (r.flags & IORESOURCE_IRQ_SHAREABLE)
121		irqflags |= IRQF_SHARED;
122
123	if (request_threaded_irq(irq, NULL, acpi_ged_irq_handler,
124				 irqflags, "ACPI:Ged", event)) {
125		dev_err(dev, "failed to setup event handler for irq %u\n", irq);
126		return AE_ERROR;
127	}
128
129	dev_dbg(dev, "GED listening GSI %u @ IRQ %u\n", gsi, irq);
130	list_add_tail(&event->node, &geddev->event_list);
131	return AE_OK;
132}
133
134static int ged_probe(struct platform_device *pdev)
135{
136	struct acpi_ged_device *geddev;
137	acpi_status acpi_ret;
138
139	geddev = devm_kzalloc(&pdev->dev, sizeof(*geddev), GFP_KERNEL);
140	if (!geddev)
141		return -ENOMEM;
142
143	geddev->dev = &pdev->dev;
144	INIT_LIST_HEAD(&geddev->event_list);
145	acpi_ret = acpi_walk_resources(ACPI_HANDLE(&pdev->dev), "_CRS",
146				       acpi_ged_request_interrupt, geddev);
147	if (ACPI_FAILURE(acpi_ret)) {
148		dev_err(&pdev->dev, "unable to parse the _CRS record\n");
149		return -EINVAL;
150	}
151	platform_set_drvdata(pdev, geddev);
152
153	return 0;
154}
155
156static void ged_shutdown(struct platform_device *pdev)
157{
158	struct acpi_ged_device *geddev = platform_get_drvdata(pdev);
159	struct acpi_ged_event *event, *next;
160
161	list_for_each_entry_safe(event, next, &geddev->event_list, node) {
162		free_irq(event->irq, event);
163		list_del(&event->node);
164		dev_dbg(geddev->dev, "GED releasing GSI %u @ IRQ %u\n",
165			 event->gsi, event->irq);
166	}
167}
168
169static int ged_remove(struct platform_device *pdev)
170{
171	ged_shutdown(pdev);
172	return 0;
173}
174
175static const struct acpi_device_id ged_acpi_ids[] = {
176	{"ACPI0013"},
177	{},
178};
179
180static struct platform_driver ged_driver = {
181	.probe = ged_probe,
182	.remove = ged_remove,
183	.shutdown = ged_shutdown,
184	.driver = {
185		.name = MODULE_NAME,
186		.acpi_match_table = ACPI_PTR(ged_acpi_ids),
187	},
188};
189builtin_platform_driver(ged_driver);