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    SubjectRe: [PATCH 2/2] Add a device driver for the Apple Magic Mouse.
    Hi Michael,

    On Tue, Feb 09, 2010 at 08:13:08AM -0500, Michael Poole wrote:
    > +
    > +static bool emulate_3button = 1;

    If it is a bool then values should be true/false.

    > +module_param(emulate_3button, bool, 0644);
    > +MODULE_PARM_DESC(emulate_3button, "Emulate a middle button");
    > +
    > +static int middle_button_start = -350;
    > +static int middle_button_stop = +350;
    > +
    > +static bool emulate_scroll_wheel = 1;
    > +module_param(emulate_scroll_wheel, bool, 0644);
    > +MODULE_PARM_DESC(emulate_scroll_wheel, "Emulate a scroll wheel");
    > +
    > +static bool report_touches = 1;
    > +module_param(report_touches, bool, 0644);
    > +MODULE_PARM_DESC(report_touches, "Emit touch records (otherwise, only use them for emulation)");
    > +
    > +static bool report_undeciphered = 0;

    No need to initialize statics to 0/false.

    > +module_param(report_undeciphered, bool, 0644);
    > +MODULE_PARM_DESC(report_undeciphered, "Report undeciphered multi-touch state field using a MSC_RAW event");
    > +
    > +#define TOUCH_REPORT_ID 0x29
    > +/* These definitions are not precise, but they're close enough. (Bits
    > + * 0x03 seem to indicate the aspect ratio of the touch, bits 0x70 seem
    > + * to be some kind of bit mask -- 0x20 may be a near-field reading,
    > + * and 0x40 is actual contact, and 0x10 may be a start/stop or change
    > + * indication.)
    > + */
    > +#define TOUCH_STATE_MASK 0xf0
    > +#define TOUCH_STATE_NONE 0x00
    > +#define TOUCH_STATE_START 0x30
    > +#define TOUCH_STATE_DRAG 0x40
    > +
    > +/**
    > + * struct magicmouse_sc - Tracks Magic Mouse-specific data.
    > + * @input: Input device through which we report events.
    > + * @quirks: Currently unused.
    > + * @last_timestamp: Timestamp from most recent (18-bit) touch report
    > + * (units of milliseconds over short windows, but seems to
    > + * increase faster when there are no touches).
    > + * @delta_time: 18-bit difference between the two most recent touch
    > + * reports from the mouse.
    > + * @ntouches: Number of touches in most recent touch report.
    > + * @scroll_accel: Number of consecutive scroll motions.
    > + * @scroll_jiffies: Time of last scroll motion.
    > + * @touches: Most recent data for a touch, indexed by tracking ID.
    > + * @tracking_ids: Mapping of current touch input data to @touches.
    > + */
    > +struct magicmouse_sc {
    > + struct input_dev *input;
    > + unsigned long quirks;
    > +
    > + int last_timestamp;
    > + int delta_time;
    > + int ntouches;
    > + int scroll_accel;
    > + unsigned long scroll_jiffies;
    > +
    > + struct {
    > + short x;
    > + short y;
    > + short scroll_y;
    > + u8 size;
    > + } touches[16];
    > + int tracking_ids[16];
    > +};
    > +
    > +static int magicmouse_firm_touch(struct magicmouse_sc *msc)
    > +{
    > + int touch = -1;
    > + int ii;
    > +
    > + /* If there is only one "firm" touch, set touch to its
    > + * tracking ID.
    > + */
    > + for (ii = 0; ii < msc->ntouches; ii++) {
    > + int idx = msc->tracking_ids[ii];
    > + if (msc->touches[idx].size < 8) {
    > + /* Ignore this touch. */
    > + } else if (touch >= 0) {
    > + touch = -1;
    > + break;
    > + } else {
    > + touch = idx;
    > + }
    > + }
    > +
    > + return touch;
    > +}
    > +
    > +static void magicmouse_emit_buttons(struct magicmouse_sc *msc, int state)
    > +{
    > + int last_state = test_bit(BTN_LEFT, msc->input->key) << 0 |
    > + test_bit(BTN_RIGHT, msc->input->key) << 1 |
    > + test_bit(BTN_MIDDLE, msc->input->key) << 2;

    Indented with spaces, we prefer tabs.

    > +
    > + if (emulate_3button) {
    > + int id;
    > +
    > + /* If some button was pressed before, keep it held
    > + * down. Otherwise, if there's exactly one firm
    > + * touch, use that to override the mouse's guess.
    > + */
    > + if (state == 0) {
    > + /* The button was released. */
    > + } else if (last_state != 0) {
    > + state = last_state;
    > + } else if ((id = magicmouse_firm_touch(msc)) >= 0) {
    > + int x = msc->touches[id].x;
    > + if (x < middle_button_start)
    > + state = 1;
    > + else if (x > middle_button_stop)
    > + state = 2;
    > + else
    > + state = 4;
    > + } /* else: we keep the mouse's guess */
    > +
    > + input_report_key(msc->input, BTN_MIDDLE, state & 4);
    > + }
    > +
    > + input_report_key(msc->input, BTN_LEFT, state & 1);
    > + input_report_key(msc->input, BTN_RIGHT, state & 2);
    > +
    > + if (state != last_state)
    > + msc->scroll_accel = 0;
    > +}
    > +
    > +static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tdata)
    > +{
    > + struct input_dev *input = msc->input;
    > + __s32 x_y = tdata[0] << 8 | tdata[1] << 16 | tdata[2] << 24;
    > + int misc = tdata[5] | tdata[6] << 8;
    > + int id = (misc >> 6) & 15;
    > + int x = x_y << 12 >> 20;
    > + int y = -(x_y >> 20);
    > +
    > + /* Store tracking ID and other fields. */
    > + msc->tracking_ids[raw_id] = id;
    > + msc->touches[id].x = x;
    > + msc->touches[id].y = y;
    > + msc->touches[id].size = misc & 63;
    > +
    > + /* If requested, emulate a scroll wheel by detecting small
    > + * vertical touch motions along the middle of the mouse.
    > + */
    > + if (emulate_scroll_wheel &&
    > + middle_button_start < x && x < middle_button_stop) {
    > + static const int accel_profile[] = {
    > + 256, 228, 192, 160, 128, 96, 64, 32,
    > + };
    > + unsigned long now = jiffies;
    > + int step = msc->touches[id].scroll_y - y;
    > +
    > + /* Reset acceleration after half a second. */
    > + if (time_after(now, msc->scroll_jiffies + HZ / 2))
    > + msc->scroll_accel = 0;
    > +
    > + /* Calculate and apply the scroll motion. */
    > + switch (tdata[7] & TOUCH_STATE_MASK) {
    > + case TOUCH_STATE_START:
    > + msc->touches[id].scroll_y = y;
    > + msc->scroll_accel = min_t(int, msc->scroll_accel + 1,
    > + ARRAY_SIZE(accel_profile) - 1);
    > + break;
    > + case TOUCH_STATE_DRAG:
    > + step = step / accel_profile[msc->scroll_accel];
    > + if (step != 0) {
    > + msc->touches[id].scroll_y = y;
    > + msc->scroll_jiffies = now;
    > + input_report_rel(input, REL_WHEEL, step);
    > + }
    > + break;
    > + }
    > + }
    > +
    > + /* Generate the input events for this touch. */
    > + if (report_touches) {
    > + int orientation = (misc >> 10) - 32;
    > +
    > + input_report_abs(input, ABS_MT_TRACKING_ID, id);
    > + input_report_abs(input, ABS_MT_TOUCH_MAJOR, tdata[3]);
    > + input_report_abs(input, ABS_MT_TOUCH_MINOR, tdata[4]);
    > + input_report_abs(input, ABS_MT_ORIENTATION, orientation);
    > + input_report_abs(input, ABS_MT_POSITION_X, x);
    > + input_report_abs(input, ABS_MT_POSITION_Y, y);
    > +
    > + if (report_undeciphered) {
    > + input_event(input, EV_MSC, MSC_RAW, tdata[7]);
    > + }

    No need for braces for single statement.

    > +
    > + input_mt_sync(input);
    > + }
    > +}
    > +
    > +static int magicmouse_raw_event(struct hid_device *hdev,
    > + struct hid_report *report, u8 *data, int size)
    > +{
    > + struct magicmouse_sc *msc = hid_get_drvdata(hdev);
    > + struct input_dev *input = msc->input;
    > + int x, y, ts, ii, clicks;
    > +
    > + switch (data[0]) {
    > + case 0x10:
    > + if (size != 6)
    > + return 0;
    > + x = (__s16)(data[2] | data[3] << 8);
    > + y = (__s16)(data[4] | data[5] << 8);
    > + clicks = data[1];
    > + break;
    > + case TOUCH_REPORT_ID:
    > + /* Expect six bytes of prefix, and N*8 bytes of touch data. */
    > + if (size < 6 || ((size - 6) % 8) != 0)
    > + return 0;
    > + ts = data[3] >> 6 | data[4] << 2 | data[5] << 10;
    > + msc->delta_time = (ts - msc->last_timestamp) & 0x3ffff;
    > + msc->last_timestamp = ts;
    > + msc->ntouches = (size - 6) / 8;
    > + for (ii = 0; ii < msc->ntouches; ii++)
    > + magicmouse_emit_touch(msc, ii, data + ii * 8 + 6);
    > + /* When emulating three-button mode, it is important
    > + * to have the current touch information before
    > + * generating a click event.
    > + */
    > + x = (signed char)data[1];
    > + y = (signed char)data[2];
    > + clicks = data[3];
    > + break;
    > + case 0x20: /* Theoretically battery status (0-100), but I have
    > + * never seen it -- maybe it is only upon request.
    > + */
    > + case 0x60: /* Unknown, maybe laser on/off. */
    > + case 0x61: /* Laser reflection status change.
    > + * data[1]: 0 = spotted, 1 = lost
    > + */
    > + default:
    > + return 0;
    > + }
    > +
    > + magicmouse_emit_buttons(msc, clicks & 3);
    > + input_report_rel(input, REL_X, x);
    > + input_report_rel(input, REL_Y, y);
    > + input_sync(input);
    > + return 1;
    > +}
    > +
    > +static int magicmouse_input_open(struct input_dev *dev)
    > +{
    > + struct hid_device *hid = input_get_drvdata(dev);
    > +
    > + return hid->ll_driver->open(hid);
    > +}
    > +
    > +static void magicmouse_input_close(struct input_dev *dev)
    > +{
    > + struct hid_device *hid = input_get_drvdata(dev);
    > +
    > + hid->ll_driver->close(hid);
    > +}
    > +
    > +static void magicmouse_setup_input(struct input_dev *input, struct hid_device *hdev)
    > +{
    > + input_set_drvdata(input, hdev);
    > + input->event = hdev->ll_driver->hidinput_input_event;
    > + input->open = magicmouse_input_open;
    > + input->close = magicmouse_input_close;
    > +
    > + input->name = hdev->name;
    > + input->phys = hdev->phys;
    > + input->uniq = hdev->uniq;
    > + input->id.bustype = hdev->bus;
    > + input->id.vendor = hdev->vendor;
    > + input->id.product = hdev->product;
    > + input->id.version = hdev->version;
    > + input->dev.parent = hdev->dev.parent;
    > +
    > + set_bit(EV_KEY, input->evbit);
    > + set_bit(BTN_LEFT, input->keybit);
    > + set_bit(BTN_RIGHT, input->keybit);
    > + if (emulate_3button)
    > + set_bit(BTN_MIDDLE, input->keybit);
    > + set_bit(BTN_TOOL_FINGER, input->keybit);
    > +
    > + set_bit(EV_REL, input->evbit);
    > + set_bit(REL_X, input->relbit);
    > + set_bit(REL_Y, input->relbit);
    > + if (emulate_scroll_wheel)
    > + set_bit(REL_WHEEL, input->relbit);

    I'd use __set_bit() instead, no need to lock the bus.

    > +
    > + if (report_touches) {
    > + set_bit(EV_ABS, input->evbit);
    > +
    > + set_bit(ABS_MT_TRACKING_ID, input->absbit);
    > + input->absmin[ABS_MT_TRACKING_ID] = 0;
    > + input->absmax[ABS_MT_TRACKING_ID] = 15;
    > + input->absfuzz[ABS_MT_TRACKING_ID] = 0;

    input_set_abs_params() is a bit more compact.

    > +
    > + set_bit(ABS_MT_TOUCH_MAJOR, input->absbit);
    > + input->absmin[ABS_MT_TOUCH_MAJOR] = 0;
    > + input->absmax[ABS_MT_TOUCH_MAJOR] = 255;
    > + input->absfuzz[ABS_MT_TOUCH_MAJOR] = 4;
    > +
    > + set_bit(ABS_MT_TOUCH_MINOR, input->absbit);
    > + input->absmin[ABS_MT_TOUCH_MINOR] = 0;
    > + input->absmax[ABS_MT_TOUCH_MINOR] = 255;
    > + input->absfuzz[ABS_MT_TOUCH_MINOR] = 4;
    > +
    > + set_bit(ABS_MT_ORIENTATION, input->absbit);
    > + input->absmin[ABS_MT_ORIENTATION] = -32;
    > + input->absmax[ABS_MT_ORIENTATION] = 31;
    > + input->absfuzz[ABS_MT_ORIENTATION] = 1;
    > +
    > + set_bit(ABS_MT_POSITION_X, input->absbit);
    > + input->absmin[ABS_MT_POSITION_X] = -1100;
    > + input->absmax[ABS_MT_POSITION_X] = 1358;
    > + input->absfuzz[ABS_MT_POSITION_X] = 4;
    > +
    > + /* Note: Touch Y position from the device is inverted relative
    > + * to how pointer motion is reported (and relative to how USB
    > + * HID recommends the coordinates work). This driver keeps
    > + * the origin at the same position, and just uses the additive
    > + * inverse of the reported Y.
    > + */
    > + set_bit(ABS_MT_POSITION_Y, input->absbit);
    > + input->absmin[ABS_MT_POSITION_Y] = -1589;
    > + input->absmax[ABS_MT_POSITION_Y] = 2047;
    > + input->absfuzz[ABS_MT_POSITION_Y] = 4;
    > + }
    > +
    > + if (report_undeciphered) {
    > + set_bit(EV_MSC, input->evbit);
    > + set_bit(MSC_RAW, input->mscbit);
    > + }
    > +}
    > +
    > +static int magicmouse_probe(struct hid_device *hdev,
    > + const struct hid_device_id *id)
    > +{
    > + __u8 feature_1[] = { 0xd7, 0x01 };
    > + __u8 feature_2[] = { 0xf8, 0x01, 0x32 };
    > + struct input_dev *input;
    > + struct magicmouse_sc *msc;
    > + struct hid_report *report;
    > + int ret;
    > +
    > + msc = kzalloc(sizeof(*msc), GFP_KERNEL);
    > + if (msc == NULL) {
    > + dev_err(&hdev->dev, "can't alloc magicmouse descriptor\n");
    > + return -ENOMEM;
    > + }
    > +
    > + msc->quirks = id->driver_data;
    > + hid_set_drvdata(hdev, msc);
    > +
    > + ret = hid_parse(hdev);
    > + if (ret) {
    > + dev_err(&hdev->dev, "magicmouse hid parse failed\n");
    > + goto err_free;
    > + }
    > +
    > + ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
    > + if (ret) {
    > + dev_err(&hdev->dev, "magicmouse hw start failed\n");
    > + goto err_free;
    > + }
    > +
    > + report = hid_register_report(hdev, HID_INPUT_REPORT, TOUCH_REPORT_ID);
    > + if (!report) {
    > + dev_err(&hdev->dev, "unable to register touch report\n");
    > + ret = -ENOMEM;
    > + goto err_free;
    > + }
    > + report->size = 6;
    > +
    > + ret = hdev->hid_output_raw_report(hdev, feature_1, sizeof(feature_1),
    > + HID_FEATURE_REPORT);

    This will cause transmission of on-stack data through USB which it does
    not like.

    > + if (ret != sizeof(feature_1)) {
    > + dev_err(&hdev->dev, "unable to request touch data (1:%d)\n",
    > + ret);
    > + goto err_free;
    > + }
    > + ret = hdev->hid_output_raw_report(hdev, feature_2,
    > + sizeof(feature_2), HID_FEATURE_REPORT);

    Same here.

    > + if (ret != sizeof(feature_2)) {
    > + dev_err(&hdev->dev, "unable to request touch data (2:%d)\n",
    > + ret);
    > + goto err_free;
    > + }
    > +
    > + input = input_allocate_device();
    > + if (!input) {
    > + dev_err(&hdev->dev, "can't alloc input device\n");
    > + ret = -ENOMEM;
    > + goto err_free;
    > + }
    > + magicmouse_setup_input(input, hdev);
    > +
    > + ret = input_register_device(input);
    > + if (ret) {
    > + dev_err(&hdev->dev, "input device registration failed\n");
    > + goto err_both;
    > + }
    > + msc->input = input;
    > +
    > + return 0;
    > + err_both:
    > + input_free_device(input);
    > + err_free:
    > + kfree(msc);
    > + return ret;

    hid_hw_stop() is missing in error path. Also see question about freeing
    report below.

    > +}
    > +
    > +static void magicmouse_remove(struct hid_device *hdev)
    > +{

    Do we need to unregister report (I am not that familiar with HID, who is
    responsible for cleaning report lists?)?

    > + hid_hw_stop(hdev);
    > + kfree(hid_get_drvdata(hdev));
    > +}
    > +
    > +static const struct hid_device_id magic_mice[] = {
    > + { HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_MAGICMOUSE),
    > + .driver_data = 0 },
    > + { }
    > +};
    > +MODULE_DEVICE_TABLE(hid, magic_mice);
    > +
    > +static struct hid_driver magicmouse_driver = {
    > + .name = "magicmouse",
    > + .id_table = magic_mice,
    > + .probe = magicmouse_probe,
    > + .remove = magicmouse_remove,
    > + .raw_event = magicmouse_raw_event,
    > +};
    > +
    > +static int __init magicmouse_init(void)
    > +{
    > + int ret;
    > +
    > + ret = hid_register_driver(&magicmouse_driver);
    > + if (ret)
    > + printk(KERN_ERR "can't register magicmouse driver\n");
    > +
    > + return ret;
    > +}
    > +
    > +static void __exit magicmouse_exit(void)
    > +{
    > + hid_unregister_driver(&magicmouse_driver);
    > +}
    > +
    > +module_init(magicmouse_init);
    > +module_exit(magicmouse_exit);
    > +MODULE_LICENSE("GPL");
    > --
    > 1.6.5.6
    >
    > --
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    --
    Dmitry


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