--- /dev/null
+/*
+ *  SGI O2 Volume Button interface driver
+ *
+ *  Copyright (C) 2008  Thomas Bogendoerfer <tsbogend@alpha.franken.de>
+ *
+ *  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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <linux/init.h>
+#include <linux/input-polldev.h>
+#include <linux/ioport.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <asm/ip32/mace.h>
+
+#define BUTTONS_POLL_INTERVAL  30      /* msec */
+#define BUTTONS_COUNT_THRESHOLD        3
+
+static const unsigned short sgio2_map[] = {
+       KEY_VOLUMEUP,
+       KEY_VOLUMEDOWN
+};
+
+struct buttons_dev {
+       struct input_polled_dev *poll_dev;
+       unsigned short keymap[ARRAY_SIZE(sgio2_map)];
+       int count[ARRAY_SIZE(sgio2_map)];
+       void __iomem *reg;
+};
+
+static void handle_buttons(struct input_polled_dev *dev)
+{
+       struct buttons_dev *bdev = dev->private;
+       struct input_dev *input = dev->input;
+       u64 status;
+       int i;
+
+       status = (readq(&mace->perif.audio.control) >> 23) & 3;
+
+       for (i = 0; i < ARRAY_SIZE(bdev->keymap); i++) {
+               if (status & (1U << i)) {
+                       writeq(status & ~(1U << i), &mace->perif.audio.control);
+                       if (++bdev->count[i] == BUTTONS_COUNT_THRESHOLD) {
+                               input_event(input, EV_MSC, MSC_SCAN, i);
+                               input_report_key(input, bdev->keymap[i], 1);
+                               input_sync(input);
+                       }
+               } else {
+                       if (bdev->count[i] >= BUTTONS_COUNT_THRESHOLD) {
+                               input_event(input, EV_MSC, MSC_SCAN, i);
+                               input_report_key(input, bdev->keymap[i], 0);
+                               input_sync(input);
+                       }
+                       bdev->count[i] = 0;
+               }
+       }
+}
+
+static int __devinit sgio2_buttons_probe(struct platform_device *pdev)
+{
+       struct buttons_dev *bdev;
+       struct input_polled_dev *poll_dev;
+       struct input_dev *input;
+       int error, i;
+
+       bdev = kzalloc(sizeof(struct buttons_dev), GFP_KERNEL);
+       poll_dev = input_allocate_polled_device();
+       if (!bdev || !poll_dev) {
+               error = -ENOMEM;
+               goto err_free_mem;
+       }
+
+       memcpy(bdev->keymap, sgio2_map, sizeof(bdev->keymap));
+
+       poll_dev->private = bdev;
+       poll_dev->poll = handle_buttons;
+       poll_dev->poll_interval = BUTTONS_POLL_INTERVAL;
+
+       input = poll_dev->input;
+       input->name = "SGI O2 buttons";
+       input->phys = "sgio2/input0";
+       input->id.bustype = BUS_HOST;
+       input->dev.parent = &pdev->dev;
+
+       input->keycode = bdev->keymap;
+       input->keycodemax = ARRAY_SIZE(bdev->keymap);
+       input->keycodesize = sizeof(unsigned short);
+
+       input_set_capability(input, EV_MSC, MSC_SCAN);
+       __set_bit(EV_KEY, input->evbit);
+       for (i = 0; i < ARRAY_SIZE(sgio2_map); i++)
+               __set_bit(bdev->keymap[i], input->keybit);
+       __clear_bit(KEY_RESERVED, input->keybit);
+
+       bdev->poll_dev = poll_dev;
+       dev_set_drvdata(&pdev->dev, bdev);
+
+       error = input_register_polled_device(poll_dev);
+       if (error)
+               goto err_free_mem;
+
+       return 0;
+
+ err_free_mem:
+       input_free_polled_device(poll_dev);
+       kfree(bdev);
+       dev_set_drvdata(&pdev->dev, NULL);
+       return error;
+}
+
+static int __devexit sgio2_buttons_remove(struct platform_device *pdev)
+{
+       struct device *dev = &pdev->dev;
+       struct buttons_dev *bdev = dev_get_drvdata(dev);
+
+       input_unregister_polled_device(bdev->poll_dev);
+       input_free_polled_device(bdev->poll_dev);
+       kfree(bdev);
+       dev_set_drvdata(dev, NULL);
+
+       return 0;
+}
+
+static struct platform_driver sgio2_buttons_driver = {
+       .probe  = sgio2_buttons_probe,
+       .remove = __devexit_p(sgio2_buttons_remove),
+       .driver = {
+               .name   = "sgio2btns",
+               .owner  = THIS_MODULE,
+       },
+};
+
+static int __init sgio2_buttons_init(void)
+{
+       return platform_driver_register(&sgio2_buttons_driver);
+}
+
+static void __exit sgio2_buttons_exit(void)
+{
+       platform_driver_unregister(&sgio2_buttons_driver);
+}
+
+module_init(sgio2_buttons_init);
+module_exit(sgio2_buttons_exit);