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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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