[PATCH, RFC] HP WMI hotkey driver

[Matthew Garrett <mjg59@srcf.ucam.org>]

This adds a driver for hotkey events generated through the WMI subsystem 
on some recent HP laptops. Mine only has a single key that works this 
way, so I'd be interested in getting some feedback from anyone else who 
has a recent HP machine which doesn't send hotkey events through the 
keyboard controller. It depends on Carlos's WMI patches, plus a couple 
of bugfixes I've suggested on linux-acpi (limit the memcpy into bus_id 
to 20 bytes and make sure it's null terminated, and invert the sense in 
wmi_register_notify so it's actually possible to register a callback.

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 8f5c7b9..2f96736 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -183,4 +183,13 @@ config HP_SDC_RTC
 	  Say Y here if you want to support the built-in real time clock
 	  of the HP SDC controller.
 
+config INPUT_HP_WMI
+       tristate "HP WMI hotkey interface"
+       depends on ACPI_WMI
+       help
+         Say Y here if you want to support WMI-based hotkeys on HP laptops.
+
+	 To compile this driver as a module, choose M here: the module will
+	 be called hp_wmi.
+
 endif
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index 3585b50..1bc3b15 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_INPUT_POWERMATE)		+= powermate.o
 obj-$(CONFIG_INPUT_YEALINK)		+= yealink.o
 obj-$(CONFIG_HP_SDC_RTC)		+= hp_sdc_rtc.o
 obj-$(CONFIG_INPUT_UINPUT)		+= uinput.o
+obj-$(CONFIG_INPUT_HP_WMI)		+= hp_wmi.o
\ No newline at end of file
diff --git a/drivers/input/misc/hp_wmi.c b/drivers/input/misc/hp_wmi.c
new file mode 100644
index 0000000..17c7d4b
--- /dev/null
+++ b/drivers/input/misc/hp_wmi.c
@@ -0,0 +1,189 @@
+/*
+ * HP WMI hotkeys
+ *
+ * Copyright (C) 2007 Matthew Garrett <mjg59@srcf.ucam.org>
+ *
+ * Portions based on wistron_btns.c:
+ * Copyright (C) 2005 Miloslav Trmac <mitr@volny.cz>
+ * Copyright (C) 2005 Bernhard Rosenkraenzer <bero@arklinux.org>
+ * Copyright (C) 2005 Dmitry Torokhov <dtor@mail.ru>
+ *
+ *  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
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/input.h>
+#include <acpi/acpi_drivers.h>
+
+MODULE_AUTHOR("Matthew Garrett");
+MODULE_DESCRIPTION("HP laptop WMI hotkeys driver");
+MODULE_LICENSE("GPL");
+
+MODULE_ALIAS("wmi:95F24279-4D7B-4334-9387-ACCDC67EF61C");
+
+#define HPWMI_GUID "95F24279-4D7B-4334-9387-ACCDC67EF61C"
+
+struct key_entry {
+        char type;              /* See KE_* below */
+        u8 code;
+        union {
+                u16 keycode;            /* For KE_KEY */
+                struct {                /* For KE_SW */
+                        u8 code;
+                        u8 value;
+                } sw;
+        };
+};
+
+enum {KE_KEY, KE_END };
+
+static struct key_entry hp_wmi_keymap[] = {
+	{ KE_KEY, 0x04, {KEY_HELP} },
+	{ KE_END, 0 }
+};
+
+static struct input_dev *hp_wmi_input_dev;
+
+static struct key_entry *hp_wmi_get_entry_by_scancode (int code)
+{
+	struct key_entry *key;
+
+        for (key = hp_wmi_keymap; key->type != KE_END; key++)
+                if (code == key->code)
+                        return key;
+
+        return NULL;
+}
+
+static struct key_entry *hp_wmi_get_entry_by_keycode(int keycode)
+{
+        struct key_entry *key;
+
+        for (key = hp_wmi_keymap; key->type != KE_END; key++)
+                if (key->type == KE_KEY && keycode == key->keycode)
+                        return key;
+
+        return NULL;
+}
+
+static int hp_wmi_getkeycode(struct input_dev *dev, int scancode, int *keycode)
+{
+	struct key_entry *key = hp_wmi_get_entry_by_scancode(scancode);
+
+        if (key && key->type == KE_KEY) {
+                *keycode = key->keycode;
+                return 0;
+        }
+
+        return -EINVAL;
+}
+
+static int hp_wmi_setkeycode(struct input_dev *dev, int scancode, int keycode)
+{
+	struct key_entry *key;
+
+        int old_keycode;
+
+        if (keycode < 0 || keycode > KEY_MAX)
+                return -EINVAL;
+
+        key = hp_wmi_get_entry_by_scancode(scancode);
+        if (key && key->type == KE_KEY) {
+                old_keycode = key->keycode;
+                key->keycode = keycode;
+                set_bit(keycode, dev->keybit);
+                if (!hp_wmi_get_entry_by_keycode(old_keycode))
+                        clear_bit(old_keycode, dev->keybit);
+                return 0;
+        }
+
+        return -EINVAL;
+}	
+
+void hp_wmi_notify (u32 value, void* context)
+{
+	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
+	static struct key_entry *key;
+	union acpi_object *obj;
+
+	wmi_get_event_data (value, &response);
+	
+	obj = (union acpi_object *) response.pointer;
+
+	if (obj && obj->type == ACPI_TYPE_BUFFER && obj->buffer.length == 8) {
+		key = hp_wmi_get_entry_by_scancode 
+			(*((u8 *) obj->buffer.pointer));
+		if (key) {
+			input_report_key (hp_wmi_input_dev, key->keycode, 1);
+			input_sync (hp_wmi_input_dev);
+			input_report_key (hp_wmi_input_dev, key->keycode, 0);
+			input_sync (hp_wmi_input_dev);
+		} else
+			printk (KERN_INFO "HP WMI: Unknown key pressed\n");
+	} else
+		printk (KERN_INFO "HP WMI: Unknown response received\n");
+
+	return;
+}
+
+static int __init hp_wmi_init(void)
+{
+	int err;
+	const struct key_entry *key;
+
+	if (!wmi_has_guid(HPWMI_GUID)) {
+		printk ("Unable to locate guid\n");
+		return -ENODEV;
+	}
+
+	err = wmi_install_notify_handler (hp_wmi_notify, NULL);
+	if (err)
+		return err;
+	
+	hp_wmi_input_dev = input_allocate_device();
+
+	hp_wmi_input_dev->name = "HP WMI hotkeys";
+	hp_wmi_input_dev->phys = "wmi/input0";
+	hp_wmi_input_dev->id.bustype = BUS_HOST;
+	hp_wmi_input_dev->getkeycode = hp_wmi_getkeycode;
+	hp_wmi_input_dev->setkeycode = hp_wmi_setkeycode;
+	
+	for (key = hp_wmi_keymap; key->type != KE_END; key++) {
+		set_bit(EV_KEY, hp_wmi_input_dev->evbit);
+		set_bit(key->keycode, hp_wmi_input_dev->keybit);
+	}
+	
+	err = input_register_device (hp_wmi_input_dev);
+
+	if (err) {
+		input_free_device (hp_wmi_input_dev);
+		return err;
+	}
+
+	return 0;
+}
+
+static void __exit hp_wmi_exit(void)
+{
+	wmi_remove_notify_handler();
+	input_unregister_device (hp_wmi_input_dev);
+	input_free_device (hp_wmi_input_dev);
+}
+
+module_init(hp_wmi_init);
+module_exit(hp_wmi_exit);

-- 
Matthew Garrett | mjg59@srcf.ucam.org