Re: [PATCH v4] HID: google: add google hammer HID driver

From: Dmitry Torokhov
Date: Wed Mar 14 2018 - 14:05:50 EST

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On Wed, Mar 14, 2018 at 9:16 AM, Benjamin Tissoires
<benjamin.tissoires@xxxxxxxxxx> wrote:
>
> Hi Nicolas,
>
> On Wed, Mar 14, 2018 at 6:22 AM, Nicolas Boichat <drinkcat@xxxxxxxxxxxx> wrote:
> > From: Wei-Ning Huang <wnhuang@xxxxxxxxxxxx>
> >
> > Add Google hammer HID driver. This driver allow us to control hammer
> > keyboard backlight and support future features.
> >
> > We add a new HID quirk, that allows us to have the keyboard interface
> > to bind to google-hammer driver, while the touchpad interface can
> > bind to the multitouch driver.
> >
> > Signed-off-by: Wei-Ning Huang <wnhuang@xxxxxxxxxx>
> > Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx>
> > ---
> >
> > Changes since v3:
> > - Rebase on latest linux-next/master, which moved the quirk list from
> > hid-core.c to hid-quirks.c. Also, completely rework the logic to make
> > it possible to bind google-hammer driver to keyboard interface, and
> > generic multitouch driver to touchpad interface, as it is much simpler
> > to do now that quirks are read early in hid_add_device.
>
> Ouch, this logic seems too convoluted for me.
>
> Just to be sure:
> - some of your devices export 2 USB interfaces on the same device (so
> same VID/PID)
> - one of this interface should be handled by hid-multitouch
> - the other should be handled by hid-google-hammer
> - the purpose of the new quirk and HID class are to allow
> hid-google-hammer to only bind on the non multitouch interface
>
> Am I correct?
>
> If I am, given that we now don't need to blacklist the drivers for
> hid-generic since e04a0442d33b8cf183bba38646447b891bb02123, I do not
> understand why simply declaring "{ HID_DEVICE(BUS_USB,
> HID_GROUP_GENERIC, USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER)
> }," (same for the 2 others) is not enough to have hid-google-hammer
> binding only on the non-multitouch interface.
>
> Could you please give a shot at it?
>

Ah, cool, if we now forcibly try to rebind devices from generic HID to
specialized driver when it appears, then we indeed to not have to do
this dance with "overrides".

>
> > - Add dynamic backlight detection support (only such devices have an
> > output HID descriptor).
> > - Add support for wand (one more USB product ID).
> > - Add SPDX-License-Identifier, fix one minor formatting issue.
> >
> > drivers/hid/Kconfig | 6 ++
> > drivers/hid/Makefile | 1 +
> > drivers/hid/hid-core.c | 4 ++
> > drivers/hid/hid-google-hammer.c | 116 ++++++++++++++++++++++++++++++++
> > drivers/hid/hid-ids.h | 3 +
> > drivers/hid/hid-quirks.c | 5 ++
> > include/linux/hid.h | 2 +
> > 7 files changed, 137 insertions(+)
> > create mode 100644 drivers/hid/hid-google-hammer.c
> >
> > diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> > index 1fce4c94e5ac..60252fd796f6 100644
> > --- a/drivers/hid/Kconfig
> > +++ b/drivers/hid/Kconfig
> > @@ -339,6 +339,12 @@ config HOLTEK_FF
> > Say Y here if you have a Holtek On Line Grip based game controller
> > and want to have force feedback support for it.
> >
> > +config HID_GOOGLE_HAMMER
> > + tristate "Google Hammer Keyboard"
> > + depends on USB_HID && LEDS_CLASS
> > + ---help---
> > + Say Y here if you have a Google Hammer device.
> > +
> > config HID_GT683R
> > tristate "MSI GT68xR LED support"
> > depends on LEDS_CLASS && USB_HID
> > diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> > index 713601c7bfa6..17a8bd97da9d 100644
> > --- a/drivers/hid/Makefile
> > +++ b/drivers/hid/Makefile
> > @@ -45,6 +45,7 @@ obj-$(CONFIG_HID_ELO) += hid-elo.o
> > obj-$(CONFIG_HID_EZKEY) += hid-ezkey.o
> > obj-$(CONFIG_HID_GEMBIRD) += hid-gembird.o
> > obj-$(CONFIG_HID_GFRM) += hid-gfrm.o
> > +obj-$(CONFIG_HID_GOOGLE_HAMMER) += hid-google-hammer.o
> > obj-$(CONFIG_HID_GT683R) += hid-gt683r.o
> > obj-$(CONFIG_HID_GYRATION) += hid-gyration.o
> > obj-$(CONFIG_HID_HOLTEK) += hid-holtek-kbd.o
> > diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> > index 36af26c2565b..61c7d135d680 100644
> > --- a/drivers/hid/hid-core.c
> > +++ b/drivers/hid/hid-core.c
> > @@ -2116,6 +2116,10 @@ int hid_add_device(struct hid_device *hdev)
> > ret = hid_scan_report(hdev);
> > if (ret)
> > hid_warn(hdev, "bad device descriptor (%d)\n", ret);
> > +
> > + if (hdev->quirks & HID_QUIRK_NO_GENERIC &&
> > + hdev->group == HID_GROUP_GENERIC)
> > + hdev->group = HID_GROUP_GENERIC_OVERRIDE;
> > }
> >
> > /* XXX hack, any other cleaner solution after the driver core
> > diff --git a/drivers/hid/hid-google-hammer.c b/drivers/hid/hid-google-hammer.c
> > new file mode 100644
> > index 000000000000..e7ad042a8464
> > --- /dev/null
> > +++ b/drivers/hid/hid-google-hammer.c
> > @@ -0,0 +1,116 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * HID driver for Google Hammer device.
> > + *
> > + * Copyright (c) 2017 Google Inc.
> > + * Author: Wei-Ning Huang <wnhuang@xxxxxxxxxx>
> > + */
> > +
> > +/*
> > + * 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.
> > + */
> > +
> > +#include <linux/hid.h>
> > +#include <linux/leds.h>
> > +#include <linux/module.h>
> > +#include <linux/usb.h>
>
> Generally that's a no from me to include usb.h. I'd rather have you
> decide on which interface to create the LEDs based on the report
> descriptors, so we can replay the device with uhid without crashing
> the kernel.
>
> > +
> > +#include "hid-ids.h"
> > +
> > +#define MAX_BRIGHTNESS 100
> > +
> > +struct hammer_kbd_leds {
> > + struct led_classdev cdev;
> > + struct hid_device *hdev;
> > + u8 buf[2] ____cacheline_aligned;
> > +};
> > +
> > +static int hammer_kbd_brightness_set_blocking(struct led_classdev *cdev,
> > + enum led_brightness br)
> > +{
> > + struct hammer_kbd_leds *led = container_of(cdev,
> > + struct hammer_kbd_leds,
> > + cdev);
> > + int ret;
> > +
> > + led->buf[0] = 0;
> > + led->buf[1] = br;
> > +
> > + ret = hid_hw_output_report(led->hdev, led->buf, sizeof(led->buf));
> > + if (ret == -ENOSYS)
> > + ret = hid_hw_raw_request(led->hdev, 0, led->buf,
> > + sizeof(led->buf),
> > + HID_OUTPUT_REPORT,
> > + HID_REQ_SET_REPORT);
> > + if (ret < 0)
> > + hid_err(led->hdev, "failed to set keyboard backlight: %d\n",
> > + ret);
> > + return ret;
> > +}
> > +
> > +static int hammer_register_leds(struct hid_device *hdev)
> > +{
> > + struct hammer_kbd_leds *kbd_backlight;
> > +
> > + kbd_backlight = devm_kzalloc(&hdev->dev,
> > + sizeof(*kbd_backlight),
> > + GFP_KERNEL);
> > + if (!kbd_backlight)
> > + return -ENOMEM;
> > +
> > + kbd_backlight->hdev = hdev;
> > + kbd_backlight->cdev.name = "hammer::kbd_backlight";
> > + kbd_backlight->cdev.max_brightness = MAX_BRIGHTNESS;
> > + kbd_backlight->cdev.brightness_set_blocking =
> > + hammer_kbd_brightness_set_blocking;
> > + kbd_backlight->cdev.flags = LED_HW_PLUGGABLE;
> > +
> > + /* Set backlight to 0% initially. */
> > + hammer_kbd_brightness_set_blocking(&kbd_backlight->cdev, 0);
> > +
> > + return devm_led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
> > +}
> > +
> > +static int hammer_input_configured(struct hid_device *hdev,
> > + struct hid_input *hi)
> > +{
> > + struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
> > +
> > + struct list_head *report_list =
> > + &hdev->report_enum[HID_OUTPUT_REPORT].report_list;
> > +
> > + if (intf->cur_altsetting->desc.bInterfaceProtocol ==
> > + USB_INTERFACE_PROTOCOL_KEYBOARD && !list_empty(report_list)) {
>
> See above. I am pretty sure you can find something in the report
> descriptor to discriminate the LED capable device from the others.
>
> Cheers,
> Benjamin
>
> > + int err = hammer_register_leds(hdev);
> > +
> > + if (err)
> > + hid_warn(hdev,
> > + "Failed to register keyboard backlight: %d\n",
> > + err);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static const struct hid_device_id hammer_devices[] = {
> > + { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC_OVERRIDE,
> > + USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER) },
> > + { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC_OVERRIDE,
> > + USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_STAFF) },
> > + { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC_OVERRIDE,
> > + USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_WAND) },
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(hid, hammer_devices);
> > +
> > +static struct hid_driver hammer_driver = {
> > + .name = "hammer",
> > + .id_table = hammer_devices,
> > + .input_configured = hammer_input_configured,
> > +};
> > +module_hid_driver(hammer_driver);
> > +
> > +MODULE_LICENSE("GPL");
> > diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> > index 41f227a841fb..5a3a7ead3012 100644
> > --- a/drivers/hid/hid-ids.h
> > +++ b/drivers/hid/hid-ids.h
> > @@ -448,7 +448,10 @@
> > #define USB_DEVICE_ID_GOODTOUCH_000f 0x000f
> >
> > #define USB_VENDOR_ID_GOOGLE 0x18d1
> > +#define USB_DEVICE_ID_GOOGLE_HAMMER 0x5022
> > #define USB_DEVICE_ID_GOOGLE_TOUCH_ROSE 0x5028
> > +#define USB_DEVICE_ID_GOOGLE_STAFF 0x502b
> > +#define USB_DEVICE_ID_GOOGLE_WAND 0x502d
> >
> > #define USB_VENDOR_ID_GOTOP 0x08f2
> > #define USB_DEVICE_ID_SUPER_Q2 0x007f
> > diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
> > index 587e2681a53f..d112a14da200 100644
> > --- a/drivers/hid/hid-quirks.c
> > +++ b/drivers/hid/hid-quirks.c
> > @@ -84,6 +84,11 @@ static const struct hid_device_id hid_quirks[] = {
> > { HID_USB_DEVICE(USB_VENDOR_ID_FREESCALE, USB_DEVICE_ID_FREESCALE_MX28), HID_QUIRK_NOGET },
> > { HID_USB_DEVICE(USB_VENDOR_ID_FUTABA, USB_DEVICE_ID_LED_DISPLAY), HID_QUIRK_NO_INIT_REPORTS },
> > { HID_USB_DEVICE(USB_VENDOR_ID_GREENASIA, USB_DEVICE_ID_GREENASIA_DUAL_USB_JOYPAD), HID_QUIRK_MULTI_INPUT },
> > +#if IS_ENABLED(CONFIG_HID_GOOGLE_HAMMER)
> > + { HID_USB_DEVICE(USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER), HID_QUIRK_NO_GENERIC },
> > + { HID_USB_DEVICE(USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_STAFF), HID_QUIRK_NO_GENERIC },
> > + { HID_USB_DEVICE(USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_WAND), HID_QUIRK_NO_GENERIC },
> > +#endif
> > { HID_USB_DEVICE(USB_VENDOR_ID_HAPP, USB_DEVICE_ID_UGCI_DRIVING), HID_QUIRK_BADPAD | HID_QUIRK_MULTI_INPUT },
> > { HID_USB_DEVICE(USB_VENDOR_ID_HAPP, USB_DEVICE_ID_UGCI_FIGHTING), HID_QUIRK_BADPAD | HID_QUIRK_MULTI_INPUT },
> > { HID_USB_DEVICE(USB_VENDOR_ID_HAPP, USB_DEVICE_ID_UGCI_FLYING), HID_QUIRK_BADPAD | HID_QUIRK_MULTI_INPUT },
> > diff --git a/include/linux/hid.h b/include/linux/hid.h
> > index dfea5a656a1a..f2655265f8b5 100644
> > --- a/include/linux/hid.h
> > +++ b/include/linux/hid.h
> > @@ -340,6 +340,7 @@ struct hid_item {
> > #define HID_QUIRK_NO_EMPTY_INPUT 0x00000100
> > /* 0x00000200 reserved for backward compatibility, was NO_INIT_INPUT_REPORTS */
> > #define HID_QUIRK_ALWAYS_POLL 0x00000400
> > +#define HID_QUIRK_NO_GENERIC 0x00000800
> > #define HID_QUIRK_SKIP_OUTPUT_REPORTS 0x00010000
> > #define HID_QUIRK_SKIP_OUTPUT_REPORT_ID 0x00020000
> > #define HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP 0x00040000
> > @@ -359,6 +360,7 @@ struct hid_item {
> > #define HID_GROUP_MULTITOUCH 0x0002
> > #define HID_GROUP_SENSOR_HUB 0x0003
> > #define HID_GROUP_MULTITOUCH_WIN_8 0x0004
> > +#define HID_GROUP_GENERIC_OVERRIDE 0x0005
> >
> > /*
> > * Vendor specific HID device groups
> > --
> > 2.16.2.804.g6dcf76e118-goog
> >

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