Re: [PATCH v4 1/4] HID: add driver for Valve Steam Controller

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Wed, Feb 28, 2018 at 8:43 PM, Rodrigo Rivas Costa
<rodrigorivascosta@gmail.com> wrote:
> There are two ways to connect the Steam Controller: directly to the USB
> or with the USB wireless adapter.  Both methods are similar, but the
> wireless adapter can connect up to 4 devices at the same time.
>
> The wired device will appear as 3 interfaces: a virtual mouse, a virtual
> keyboard and a custom HID device.
>
> The wireless device will appear as 5 interfaces: a virtual keyboard and
> 4 custom HID devices, that will remain silent until a device is actually
> connected.
>
> The custom HID device has a report descriptor with all vendor specific
> usages, so the hid-generic is not very useful. In a PC/SteamBox Valve
> Steam Client provices a software translation by using direct USB access
> and a creates a uinput virtual gamepad.
>
> This driver was reverse engineered to provide direct kernel support in
> case you cannot, or do not want to, use Valve Steam Client. It disables
> the virtual keyboard and mouse, as they are not so useful when you have
> a working gamepad.


> +// SPDX-License-Identifier: GPL-2.0

> +MODULE_LICENSE("GPL");

Not the same.

> +static void steam_unregister(struct steam_device *steam)
> +{
> +       struct input_dev *input;
> +
> +       rcu_read_lock();
> +       input = rcu_dereference(steam->input);
> +       rcu_read_unlock();
> +

> +       if (input) {

if (!input)
 return;

?

> +               RCU_INIT_POINTER(steam->input, NULL);
> +               synchronize_rcu();
> +               hid_info(steam->hdev, "Steam Controller disconnected");
> +               input_unregister_device(input);
> +       }
> +}

> +static bool steam_is_valve_interface(struct hid_device *hdev)
> +{
> +       struct hid_report_enum *rep_enum;
> +       struct hid_report *hreport;
> +
> +       /*
> +        * The wired device creates 3 interfaces:
> +        *  0: emulated mouse.
> +        *  1: emulated keyboard.
> +        *  2: the real game pad.
> +        * The wireless device creates 5 interfaces:
> +        *  0: emulated keyboard.
> +        *  1-4: slots where up to 4 real game pads will be connected to.
> +        * We know which one is the real gamepad interface because they are the
> +        * only ones with a feature report.
> +        */
> +       rep_enum = &hdev->report_enum[HID_FEATURE_REPORT];

> +       list_for_each_entry(hreport, &rep_enum->report_list, list) {
> +               /* should we check hreport->id == 0? */
> +               return true;
> +       }
> +       return false;

So, for now it's just an equivalent of

return !list_empty();

?

> +}

> +       /*
> +        * From this point on, if anything fails return 0 and ignores
> +        * the error, so that the default HID devices are still bound.
> +        */
> +       steam = devm_kzalloc(&hdev->dev,
> +                       sizeof(struct steam_device), GFP_KERNEL);

sizeof(*steam) saves a line.

> +       if (!steam) {
> +               ret = -ENOMEM;
> +               goto mem_fail;
> +       }

> +static void steam_remove(struct hid_device *hdev)
> +{
> +       struct steam_device *steam = hid_get_drvdata(hdev);
> +
> +       if (steam && (steam->quirks & STEAM_QUIRK_WIRELESS)) {
> +               hid_info(hdev, "Steam wireless receiver disconnected");
> +               hid_hw_close(hdev);
> +       }
> +
> +       hid_hw_stop(hdev);
> +
> +       if (steam) {
> +               cancel_work_sync(&steam->work_connect);
> +               steam_unregister(steam);

> +               hid_set_drvdata(hdev, NULL);

Hmm.. Doesn't HID do this?

> +       }

if (steam) {
...
       hid_hw_stop(hdev);
...
} else {
       hid_hw_stop(hdev);
}

?

> +}

> +static void steam_do_input_event(struct steam_device *steam,
> +               struct input_dev *input, u8 *data)
> +{
> +       /* 24 bits of buttons */
> +       u8 b8, b9, b10;
> +       bool lpad_touched, lpad_and_joy;
> +
> +       b8 = data[8];
> +       b9 = data[9];
> +       b10 = data[10];
> +
> +       input_report_abs(input, ABS_Z, data[11]);
> +       input_report_abs(input, ABS_RZ, data[12]);
> +
> +       /*
> +        * These two bits tells how to interpret the values X and Y.
> +        * lpad_and_joy tells that the joystick and the lpad are used at the
> +        * same time.
> +        * lpad_touched tells whether X/Y are to be read as lpad coord or
> +        * joystick values.
> +        * (lpad_touched || lpad_and_joy) tells if the lpad is really touched.
> +        */

> +       lpad_touched = b10 & 0x08;

BIT(3) ?

> +       lpad_and_joy = b10 & 0x80;

BIT(7) ?

> +       input_event(input, EV_KEY, BTN_TR2, !!(b8 & 0x01));
> +       input_event(input, EV_KEY, BTN_TL2, !!(b8 & 0x02));
> +       input_event(input, EV_KEY, BTN_TR, !!(b8 & 0x04));
> +       input_event(input, EV_KEY, BTN_TL, !!(b8 & 0x08));
> +       input_event(input, EV_KEY, BTN_Y, !!(b8 & 0x10));
> +       input_event(input, EV_KEY, BTN_B, !!(b8 & 0x20));
> +       input_event(input, EV_KEY, BTN_X, !!(b8 & 0x40));
> +       input_event(input, EV_KEY, BTN_A, !!(b8 & 0x80));
> +       input_event(input, EV_KEY, BTN_SELECT, !!(b9 & 0x10));
> +       input_event(input, EV_KEY, BTN_MODE, !!(b9 & 0x20));
> +       input_event(input, EV_KEY, BTN_START, !!(b9 & 0x40));
> +       input_event(input, EV_KEY, BTN_GEAR_DOWN, !!(b9 & 0x80));
> +       input_event(input, EV_KEY, BTN_GEAR_UP, !!(b10 & 0x01));
> +       input_event(input, EV_KEY, BTN_THUMBR, !!(b10 & 0x04));
> +       input_event(input, EV_KEY, BTN_THUMBL, !!(b10 & 0x40));
> +       input_event(input, EV_KEY, BTN_THUMB, lpad_touched || lpad_and_joy);
> +       input_event(input, EV_KEY, BTN_THUMB2, !!(b10 & 0x10));

BIT(x) ?

> +
> +       input_report_abs(input, ABS_HAT0X,
> +                       !!(b9 & 0x02) - !!(b9 & 0x04));
> +       input_report_abs(input, ABS_HAT0Y,
> +                       !!(b9 & 0x08) - !!(b9 & 0x01));

BIT(x) ?

> +}

> +static int steam_raw_event(struct hid_device *hdev,
> +                       struct hid_report *report, u8 *data,
> +                       int size)
> +{
> +       struct steam_device *steam = hid_get_drvdata(hdev);
> +       struct input_dev *input;
> +

> +       if (!steam)
> +               return 0;

When it's possible?

> +       return 0;
> +}

-- 
With Best Regards,
Andy Shevchenko