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SubjectRe: [PATCH v4] HID: google: add google hammer HID driver
Hi Nicolas,

On Wed, Mar 14, 2018 at 6:22 AM, Nicolas Boichat <drinkcat@chromium.org> wrote:
> From: Wei-Ning Huang <wnhuang@chromium.org>
>
> 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@google.com>
> Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> ---
>
> 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?

> - 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@google.com>
> + */
> +
> +/*
> + * 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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