Enable Dell All-In-One volume up/down keys

Enable volume up and down hotkeys on WMI events
GUID 284A0E6B-380E-472A-921F-E52786257FB4 and
GUID 02314822-307C-4F66-bf0E-48AEAEB26CC8.

Also works around a firmware bug where the _WED method
should return an integer containing the key code and in fact
the method returns the key code in element zero of a buffer.

BugLink: http://bugs.launchpad.net/bugs/701530
BugLink: http://bugs.launchpad.net/bugs/676997

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/Kconfig

@@ -101,6 +101,19 @@ config DELL_WMI
 	  To compile this driver as a module, choose M here: the module will
 	  be called dell-wmi.
 
+config DELL_WMI_AIO
+	tristate "WMI Hotkeys for Dell All-In-One series"
+	depends on ACPI_WMI
+	depends on INPUT
+	select INPUT_SPARSEKMAP
+	---help---
+	  Say Y here if you want to support WMI-based hotkeys on Dell
+	  All-In-One machines.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called dell-wmi.
+
+
 config FUJITSU_LAPTOP
 	tristate "Fujitsu Laptop Extras"
 	depends on ACPI

drivers/platform/x86/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_ACPI_CMPC)		+= classmate-laptop.o
 obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
 obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o
 obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o
+obj-$(CONFIG_DELL_WMI_AIO)	+= dell-wmi-aio.o
 obj-$(CONFIG_ACER_WMI)		+= acer-wmi.o
 obj-$(CONFIG_ACERHDF)		+= acerhdf.o
 obj-$(CONFIG_HP_ACCEL)		+= hp_accel.o

drivers/platform/x86/dell-wmi-aio.c

@@ -0,0 +1,171 @@
+/*
+ *  WMI hotkeys support for Dell All-In-One series
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  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.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/input.h>
+#include <linux/input/sparse-keymap.h>
+#include <acpi/acpi_drivers.h>
+#include <linux/acpi.h>
+#include <linux/string.h>
+
+MODULE_DESCRIPTION("WMI hotkeys driver for Dell All-In-One series");
+MODULE_LICENSE("GPL");
+
+#define EVENT_GUID1 "284A0E6B-380E-472A-921F-E52786257FB4"
+#define EVENT_GUID2 "02314822-307C-4F66-BF0E-48AEAEB26CC8"
+
+static const char *dell_wmi_aio_guids[] = {
+	EVENT_GUID1,
+	EVENT_GUID2,
+	NULL
+};
+
+MODULE_ALIAS("wmi:"EVENT_GUID1);
+MODULE_ALIAS("wmi:"EVENT_GUID2);
+
+static const struct key_entry dell_wmi_aio_keymap[] = {
+	{ KE_KEY, 0xc0, { KEY_VOLUMEUP } },
+	{ KE_KEY, 0xc1, { KEY_VOLUMEDOWN } },
+	{ KE_END, 0 }
+};
+
+static struct input_dev *dell_wmi_aio_input_dev;
+
+static void dell_wmi_aio_notify(u32 value, void *context)
+{
+	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+
+	status = wmi_get_event_data(value, &response);
+	if (status != AE_OK) {
+		pr_info("bad event status 0x%x\n", status);
+		return;
+	}
+
+	obj = (union acpi_object *)response.pointer;
+	if (obj) {
+		unsigned int scancode;
+
+		switch (obj->type) {
+		case ACPI_TYPE_INTEGER:
+			/* Most All-In-One correctly return integer scancode */
+			scancode = obj->integer.value;
+			sparse_keymap_report_event(dell_wmi_aio_input_dev,
+				scancode, 1, true);
+			break;
+		case ACPI_TYPE_BUFFER:
+			/* Broken machines return the scancode in a buffer */
+			if (obj->buffer.pointer && obj->buffer.length > 0) {
+				scancode = obj->buffer.pointer[0];
+				sparse_keymap_report_event(
+					dell_wmi_aio_input_dev,
+					scancode, 1, true);
+			}
+			break;
+		}
+	}
+	kfree(obj);
+}
+
+static int __init dell_wmi_aio_input_setup(void)
+{
+	int err;
+
+	dell_wmi_aio_input_dev = input_allocate_device();
+
+	if (!dell_wmi_aio_input_dev)
+		return -ENOMEM;
+
+	dell_wmi_aio_input_dev->name = "Dell AIO WMI hotkeys";
+	dell_wmi_aio_input_dev->phys = "wmi/input0";
+	dell_wmi_aio_input_dev->id.bustype = BUS_HOST;
+
+	err = sparse_keymap_setup(dell_wmi_aio_input_dev,
+			dell_wmi_aio_keymap, NULL);
+	if (err) {
+		pr_err("Unable to setup input device keymap\n");
+		goto err_free_dev;
+	}
+	err = input_register_device(dell_wmi_aio_input_dev);
+	if (err) {
+		pr_info("Unable to register input device\n");
+		goto err_free_keymap;
+	}
+	return 0;
+
+err_free_keymap:
+	sparse_keymap_free(dell_wmi_aio_input_dev);
+err_free_dev:
+	input_free_device(dell_wmi_aio_input_dev);
+	return err;
+}
+
+static const char *dell_wmi_aio_find(void)
+{
+	int i;
+
+	for (i = 0; dell_wmi_aio_guids[i] != NULL; i++)
+		if (wmi_has_guid(dell_wmi_aio_guids[i]))
+			return dell_wmi_aio_guids[i];
+
+	return NULL;
+}
+
+static int __init dell_wmi_aio_init(void)
+{
+	int err;
+	const char *guid;
+
+	guid = dell_wmi_aio_find();
+	if (!guid) {
+		pr_warning("No known WMI GUID found\n");
+		return -ENXIO;
+	}
+
+	err = dell_wmi_aio_input_setup();
+	if (err)
+		return err;
+
+	err = wmi_install_notify_handler(guid, dell_wmi_aio_notify, NULL);
+	if (err) {
+		pr_err("Unable to register notify handler - %d\n", err);
+		sparse_keymap_free(dell_wmi_aio_input_dev);
+		input_unregister_device(dell_wmi_aio_input_dev);
+		return err;
+	}
+
+	return 0;
+}
+
+static void __exit dell_wmi_aio_exit(void)
+{
+	const char *guid;
+
+	guid = dell_wmi_aio_find();
+	wmi_remove_notify_handler(guid);
+	sparse_keymap_free(dell_wmi_aio_input_dev);
+	input_unregister_device(dell_wmi_aio_input_dev);
+}
+
+module_init(dell_wmi_aio_init);
+module_exit(dell_wmi_aio_exit);