Date:   Thu, 13 Apr 2023 18:13:05 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Mubashshir <ahmubashshir@...il.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Huseyin BIYIK <huseyinbiyik@...mail.com>,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH v3] staging: HID: Add ShanWan USB WirelessGamepad driver

On Apr 10 2023, Mubashshir wrote:
> This device has a quirky initialization process.
> Depending on how it was initialized, behaves completely differently.
> In default mode, it behaves as expected, but in fallback it disables
> force-feedback, analog stick configurations and L3/R3.
> 
> Signed-off-by: Huseyin BIYIK <huseyinbiyik@...mail.com>
> Signed-off-by: Mubashshir <ahmubashshir@...il.com>
> ---
> v3: Another missed semicolon
> 
>  drivers/hid/Kconfig       |  19 +++
>  drivers/hid/Makefile      |   1 +
>  drivers/hid/hid-ids.h     |   3 +
>  drivers/hid/hid-shanwan.c | 256 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 279 insertions(+)
>  create mode 100644 drivers/hid/hid-shanwan.c
> 
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 82f64fb31fda..a17db9c9694c 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -990,6 +990,25 @@ config HID_SEMITEK
>  	- Woo-dy
>  	- X-Bows Nature/Knight
>  
> +config HID_SHANWAN
> +	tristate "ShanWan USB WirelessGamepad"
> +	depends on USB_HID
> +	help
> +	Support for Shanwan USB WirelessGamepad (and clones).
> +
> +	This device has a quirky initialization process.
> +	Depending on how it was initialized, it behaves completely differently.
> +	In default mode, it behaves as expected, but in fallback it disables
> +	force-feedback, analog stick configurations and L3/R3.
> +
> +config SHANWAN_FF
> +	bool "ShanWan USB WirelessGamepad force feedback support"
> +	depends on HID_SHANWAN
> +	select INPUT_FF_MEMLESS
> +	help
> +	Say Y here if you have a ShanWan USB WirelessGamepad and want to enable
> +	force feedback support for it.
> +
>  config HID_SIGMAMICRO
>  	tristate "SiGma Micro-based keyboards"
>  	depends on USB_HID
> diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> index 5d37cacbde33..52878455fc10 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -116,6 +116,7 @@ obj-$(CONFIG_HID_RMI)		+= hid-rmi.o
>  obj-$(CONFIG_HID_SAITEK)	+= hid-saitek.o
>  obj-$(CONFIG_HID_SAMSUNG)	+= hid-samsung.o
>  obj-$(CONFIG_HID_SEMITEK)	+= hid-semitek.o
> +obj-$(CONFIG_HID_SHANWAN)	+= hid-shanwan.o
>  obj-$(CONFIG_HID_SIGMAMICRO)	+= hid-sigmamicro.o
>  obj-$(CONFIG_HID_SMARTJOYPLUS)	+= hid-sjoy.o
>  obj-$(CONFIG_HID_SONY)		+= hid-sony.o
> diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> index 63545cd307e5..278914e37eb7 100644
> --- a/drivers/hid/hid-ids.h
> +++ b/drivers/hid/hid-ids.h
> @@ -623,6 +623,9 @@
>  #define USB_PRODUCT_ID_HP_PIXART_OEM_USB_OPTICAL_MOUSE_0641	0x0641
>  #define USB_PRODUCT_ID_HP_PIXART_OEM_USB_OPTICAL_MOUSE_1f4a	0x1f4a
>  
> +#define USB_VENDOR_ID_SHANWAN 0x2563
> +#define USB_PRODUCT_ID_SHANWAN_USB_WIRELESSGAMEPAD 0x0575
> +
>  #define USB_VENDOR_ID_HUION		0x256c
>  #define USB_DEVICE_ID_HUION_TABLET	0x006e
>  #define USB_DEVICE_ID_HUION_TABLET2	0x006d
> diff --git a/drivers/hid/hid-shanwan.c b/drivers/hid/hid-shanwan.c
> new file mode 100644
> index 000000000000..39c1bb6f40c6
> --- /dev/null
> +++ b/drivers/hid/hid-shanwan.c
> @@ -0,0 +1,256 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Force feedback support for Shanwan USB WirelessGamepad
> + *
> + * Copyright (c) 2022-2023	Huseyin BIYIK	<huseyinbiyik@...mail.com>
> + * Copyright (c) 2023	Ahmad Hasan Mubashshir	<ahmubashshir@...il.com>
> + *
> + * mapping according to Gamepad Protocol
> + *
> + * Button 01: BTN_SOUTH (CROSS)
> + * Button 02: BTN_EAST(CIRCLE)
> + * Button 03: BTN_NORTH (TRIANGLE)
> + * Button 04: BTN_WEST (SQUARE)
> + * Button 05: BTL_TL (L1)
> + * Button 06: BTM_TR (R1)
> + * Button 07: BTN_TL2 (L2)
> + * Button 08: BTN_TR2 (R2)
> + * Button 09: BTN_SELECT
> + * Button 10: BTN_START
> + * Button 11: BTN_MODE
> + * Button 12: BTN_THUMBL (LS1)
> + * Button 13: BTN_THUMBR (LS1)
> + * LS1: X/Y AXIS
> + * LS2: Rx/Ry AXIS
> + * R2/L2 Touch Sensors: R/Rz
> + */
> +
> +#include <linux/input.h>
> +#include <linux/slab.h>
> +#include <linux/hid.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/moduleparam.h>
> +
> +#include "hid-ids.h"
> +
> +#define PID0575_RDESC_ORIG_SIZE 137
> +
> +static bool swap_motors;
> +module_param_named(swap, swap_motors, bool, 0);
> +MODULE_PARM_DESC(swap, "Swap Weak/Strong Feedback motors");
> +
> +static __u8 pid0575_rdesc_fixed[] = {
> +	0x05, 0x01, // Usage Page (Generic Desktop Ctrls)
> +	0x09, 0x05, // Usage (Game Pad)
> +	0xA1, 0x01, // Collection (Application)
> +	0x15, 0x00, // Logical Minimum (0)
> +	0x25, 0x01, // Logical Maximum (1)
> +	0x35, 0x00, // Physical Minimum (0)
> +	0x45, 0x01, // Physical Maximum (1)
> +	0x75, 0x01, // Report Size (1)
> +	0x95, 0x0D, // Report Count (13)
> +	0x05, 0x09, // Usage Page (Button)
> +	0x09, 0x03, // Usage (BTN_NORTH)
> +	0x09, 0x02, // Usage (BTN_EAST)
> +	0x09, 0x01, // Usage (BTN_SOUTH)
> +	0x09, 0x04, // Usage (BTN_WEST)
> +	0x09, 0x05, // Usage (BTN_TL)
> +	0x09, 0x06, // Usage (BTN_TR)
> +	0x09, 0x07, // Usage (BTN_TL2)
> +	0x09, 0x08, // Usage (BTN_TR2)
> +	0x09, 0x09, // Usage (BTN_SELECT)
> +	0x09, 0x10, // Usage (BTN_START)
> +	0x09, 0x12, // Usage (BTN_THUMBL)
> +	0x09, 0x13, // Usage (BTN_THUMBR)
> +	0x09, 0x11, // Usage (BTN_MODE)
> +	0x81, 0x02, // Input (Data,Var,Abs,No Wrap,Linear,PreferredState,NoNullPosition)
> +	0x75, 0x01, // Report Size (1)
> +	0x95, 0x03, // Report Count (3)
> +	0x81, 0x01, // Input (Const,Array,Abs,No Wrap,Linear,PreferredState,NoNullPosition)
> +	0x05, 0x01, // Usage Page (Generic Desktop Ctrls)
> +	0x25, 0x07, // Logical Maximum (7)
> +	0x46, 0x3B, 0x01, // Physical Maximum (315)
> +	0x75, 0x04, // Report Size (4)
> +	0x95, 0x01, // Report Count (1)
> +	0x65, 0x14, // Unit (System: English Rotation, Length: Centimeter)
> +	0x09, 0x39, // Usage (Hat switch)
> +	0x81, 0x42, // Input (Data,Var,Abs,No Wrap,Linear,PreferredState,NullState)
> +	0x65, 0x00, // Unit (None)
> +	0x95, 0x01, // Report Count (1)
> +	0x81, 0x01, // Input(Const,Array,Abs,NoWrap,Linear,PreferredState,NoNullPosition)
> +	0x26, 0xFF, 0x00, // Logical Maximum (255)
> +	0x46, 0xFF, 0x00, // Physical Maximum (255)
> +	0x09, 0x30, // Usage (X)
> +	0x09, 0x31, // Usage (Y)
> +	0x09, 0x33, // Usage (Rx)
> +	0x09, 0x34, // Usage (Ry)
> +	0x75, 0x08, // Report Size (8)
> +	0x95, 0x04, // Report Count (4)
> +	0x81, 0x02, // Input (Data,Var,Abs,No Wrap,Linear,PreferredState,NoNullPosition)
> +	0x95, 0x0A, // Report Count (10)
> +	0x81, 0x01, // Input (Const,Array,Abs,No Wrap,Linear,PreferredState,NoNullPosition)
> +	0x05, 0x01, // Usage Page (Generic Desktop Ctrls)
> +	0x26, 0xFF, 0x00, // Logical Maximum (255)
> +	0x46, 0xFF, 0x00, // Physical Maximum (255)
> +	0x09, 0x32, // Usage (Z)
> +	0x09, 0x35, // Usage (Rz)
> +	0x95, 0x02, // Report Count (2)
> +	0x81, 0x02, // Input(Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
> +	0x95, 0x08, // Report Count (8)
> +	0x81, 0x01, // Input(Const,Array,Abs,NoWrap,Linear,PreferredState,NoNullPosition)
> +	0x06, 0x00, 0xFF, // Usage Page (Vendor Defined 0xFF00)
> +	0xB1, 0x02, // Feature(Data,Var,Abs,No Wrap,Linear,PreferredState,NoNullPosition,!volatile)
> +	0x0A, 0x21, 0x26, // Usage (0x2621)
> +	0x95, 0x08, // Report Count (8)
> +	0x91, 0x02, // Output(Data,Var,Abs,No Wrap,Linear,PreferredState,NoNullPosition,!volatile)
> +	0x0A, 0x21, 0x26, // Usage (0x2621)
> +	0x95, 0x08, // Report Count (8)
> +	0x81, 0x02, // Input(Data,Var,Abs,No Wrap,Linear,Preferred State,NoNullPosition)
> +	0xC0,       // End Collection
> +};
> +
> +struct shanwan_device {
> +	struct hid_report *report;
> +};
> +
> +#ifdef CONFIG_SHANWAN_FF
> +static int shanwan_play_effect(struct input_dev *dev, void *data, struct ff_effect *effect)
> +{
> +	struct hid_device *hid = input_get_drvdata(dev);
> +	struct shanwan_device *shanwan = data;
> +	struct hid_report *report = shanwan->report;
> +
> +	if (effect->type != FF_RUMBLE)
> +		return 0;
> +
> +	report->field[0]->value[0] = 0x02; /* 2 = rumble effect message */
> +	report->field[0]->value[1] = 0x08; /* reserved value, always 8 */
> +	if (swap_motors) {
> +		/* weak rumble / strong rumble */
> +		report->field[0]->value[2] = effect->u.rumble.strong_magnitude / 256;
> +		report->field[0]->value[3] = effect->u.rumble.weak_magnitude / 256;
> +	} else {
> +		/* strong rumble / weak rumble */
> +		report->field[0]->value[2] = effect->u.rumble.weak_magnitude / 256;
> +		report->field[0]->value[3] = effect->u.rumble.strong_magnitude / 256;
> +	}
> +	report->field[0]->value[4] = 0xff; /* duration 0-254 (255 = nonstop) */
> +	report->field[0]->value[5] = 0x00; /* padding */
> +	report->field[0]->value[6] = 0x00; /* padding */
> +	report->field[0]->value[7] = 0x00; /* padding */
> +	hid_hw_request(hid, report, HID_REQ_SET_REPORT);

I see some other drivers using a workqueue here because ->play() can be
called in atomic context. Are you sure you can sleep here?

> +
> +	return 0;
> +}
> +
> +static int shanwan_init_ff(struct hid_device *hid)
> +{
> +	struct shanwan_device *shanwan;
> +	struct hid_report *report;
> +	struct hid_input *hidinput;
> +	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
> +	struct input_dev *dev;
> +
> +	if (list_empty(&hid->inputs)) {
> +		hid_err(hid, "no inputs found\n");
> +		return -ENODEV;
> +	}
> +	hidinput = list_first_entry(&hid->inputs, struct hid_input, list);
> +	dev = hidinput->input;
> +
> +	if (list_empty(report_list)) {
> +		hid_err(hid, "no output reports found\n");
> +		return -ENODEV;
> +	}
> +
> +	report = list_first_entry(report_list, struct hid_report, list);
> +
> +	shanwan = kzalloc(sizeof(*shanwan), GFP_KERNEL);
> +	if (!shanwan)
> +		return -ENOMEM;
> +
> +	set_bit(FF_RUMBLE, dev->ffbit);
> +
> +	if (input_ff_create_memless(dev, shanwan, shanwan_play_effect)) {
> +		kfree(shanwan);
> +		return -ENODEV;
> +	}
> +
> +	shanwan->report = report;
> +
> +	return 0;
> +}
> +#else
> +static int shanwan_init_ff(struct hid_device *hid)
> +{
> +	return 0;
> +}
> +#endif
> +
> +static int shanwan_probe(struct hid_device *hdev, const struct hid_device_id *id)
> +{
> +	int error;
> +
> +	error = hid_parse(hdev);
> +	if (error) {
> +		hid_err(hdev, "parse failed\n");
> +		return error;
> +	}
> +
> +	error = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
> +	if (error) {
> +		hid_err(hdev, "hw start failed\n");
> +		return error;
> +	}
> +
> +	error = shanwan_init_ff(hdev);
> +	if (error)
> +		hid_warn(hdev, "Failed to enable force feedback support, error: %d\n", error);
> +
> +	error = hid_hw_open(hdev);

What's the point of keeping it opened for the lifetime of the device? Do
you really need this?

> +	if (error) {
> +		dev_err(&hdev->dev, "hw open failed\n");
> +		hid_hw_stop(hdev);
> +		return error;
> +	}
> +
> +	return 0;
> +}
> +
> +static void shanwan_remove(struct hid_device *hdev)
> +{
> +	hid_hw_close(hdev);

If you can drop the last hid_hw_open/close, then you can entirely skip
the ->remove().

Cheers,
Benjamin

> +	hid_hw_stop(hdev);
> +}
> +
> +static __u8 *shanwan_report_fixup(struct hid_device *hid, __u8 *rdesc, unsigned int *rsize)
> +{
> +	if (*rsize == PID0575_RDESC_ORIG_SIZE) {
> +		rdesc = pid0575_rdesc_fixed;
> +		*rsize = sizeof(pid0575_rdesc_fixed);
> +	} else {
> +		hid_warn(hid, "unexpected rdesc, please submit for review\n");
> +	}
> +	return rdesc;
> +}
> +
> +static const struct hid_device_id shanwan_devices[] = {
> +	{ HID_USB_DEVICE(USB_VENDOR_ID_SHANWAN, USB_PRODUCT_ID_SHANWAN_USB_WIRELESSGAMEPAD) },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(hid, shanwan_devices);
> +
> +static struct hid_driver shanwan_driver = {
> +	.name			= "shanwan",
> +	.id_table		= shanwan_devices,
> +	.probe			= shanwan_probe,
> +	.report_fixup		= shanwan_report_fixup,
> +	.remove			= shanwan_remove,
> +};
> +module_hid_driver(shanwan_driver);
> +
> +MODULE_AUTHOR("Huseyin BIYIK <huseyinbiyik@...mail.com>");
> +MODULE_AUTHOR("Ahmad Hasan Mubashshir <ahmubashshir@...il.com>");
> +MODULE_DESCRIPTION("Force feedback support for Shanwan USB WirelessGamepad");
> +MODULE_LICENSE("GPL");
> -- 
> 2.40.0
> 

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