Re: [PATCH 01/13] HID: playstation: initial DualSense USB support.

["Barnabás Pőcze" <pobrn@protonmail.com>]

Hi


2020. december 19., szombat 7:23 keltezéssel, Roderick Colenbrander írta:

> [...]
> diff --git a/drivers/hid/hid-playstation.c b/drivers/hid/hid-playstation.c
> new file mode 100644
> index 000000000000..8dbd0ae7e082
> --- /dev/null
> +++ b/drivers/hid/hid-playstation.c
> @@ -0,0 +1,317 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + *  HID driver for Sony DualSense(TM) controller.
> + *
> + *  Copyright (c) 2020 Sony Interactive Entertainment
> + */
> +
> +#include <linux/device.h>
> +#include <linux/hid.h>
> +#include <linux/input/mt.h>
> +#include <linux/module.h>
> +#include <linux/crc32.h>
> +#include <asm/unaligned.h>
> +

I believe it would be preferable to keep the list of includes lexicographically
sorted.


> +#include "hid-ids.h"
> +
> +/* Base class for playstation devices. */
> +struct ps_device {
> +	struct hid_device *hdev;
> +
> +	int (*parse_report)(struct ps_device *dev, struct hid_report *report, u8 *data, int size);
> +};
> +
> +#define DS_INPUT_REPORT_USB			0x01
> +
> +/* Button masks for DualSense input report. */
> +#define DS_BUTTONS0_HAT_SWITCH	GENMASK(3, 0)
> +#define DS_BUTTONS0_SQUARE	BIT(4)
> +#define DS_BUTTONS0_CROSS	BIT(5)
> +#define DS_BUTTONS0_CIRCLE	BIT(6)
> +#define DS_BUTTONS0_TRIANGLE	BIT(7)
> +#define DS_BUTTONS1_L1		BIT(0)
> +#define DS_BUTTONS1_R1		BIT(1)
> +#define DS_BUTTONS1_L2		BIT(2)
> +#define DS_BUTTONS1_R2		BIT(3)
> +#define DS_BUTTONS1_CREATE	BIT(4)
> +#define DS_BUTTONS1_OPTIONS	BIT(5)
> +#define DS_BUTTONS1_L3		BIT(6)
> +#define DS_BUTTONS1_R3		BIT(7)
> +#define DS_BUTTONS2_PS_HOME	BIT(0)
> +#define DS_BUTTONS2_TOUCHPAD	BIT(1)

I believe it would be preferable to explicitly include everything you need
and not to count on other headers indirectly including it for you. In this
case `linux/bits.h` is not included.


> [...]
> +/* Common gamepad buttons across DualShock 3 / 4 and DualSense.
> + * Note: for device with a touchpad, touchpad button is not included
> + *        as it will be part of the touchpad device.
> + */
> +static int ps_gamepad_buttons[] = {

Any reason why it's not `const`?


> +	BTN_WEST, /* Square */
> +	BTN_NORTH, /* Triangle */
> +	BTN_EAST, /* Circle */
> +	BTN_SOUTH, /* Cross */
> +	BTN_TL, /* L1 */
> +	BTN_TR, /* R1 */
> +	BTN_TL2, /* L2 */
> +	BTN_TR2, /* R2 */
> +	BTN_SELECT, /* Create (PS5) / Share (PS4) */
> +	BTN_START, /* Option */
> +	BTN_THUMBL, /* L3 */
> +	BTN_THUMBR, /* R3 */
> +	BTN_MODE, /* PS Home */
> +};
> [...]
> +static struct input_dev *ps_allocate_input_dev(struct hid_device *hdev, const char *name_suffix)
> +{
> +	struct input_dev *input_dev;
> +
> +	input_dev = devm_input_allocate_device(&hdev->dev);
> +	if (!input_dev)
> +		return ERR_PTR(-ENOMEM);
> +
> +	input_dev->id.bustype = hdev->bus;
> +	input_dev->id.vendor = hdev->vendor;
> +	input_dev->id.product = hdev->product;
> +	input_dev->id.version = hdev->version;
> +	input_dev->uniq = hdev->uniq;
> +
> +	if (name_suffix) {
> +		input_dev->name = devm_kasprintf(&hdev->dev, GFP_KERNEL, "%s %s", hdev->name,
> +				name_suffix);
> +		if (!input_dev->name)
> +			return ERR_PTR(-ENOMEM);
> +	} else
> +		input_dev->name = hdev->name;
> +

As per [1], please use braces around the body of the `else`.


> +	input_set_drvdata(input_dev, hdev);
> +
> +	return input_dev;
> +}
> [...]
> +static int dualsense_parse_report(struct ps_device *ps_dev, struct hid_report *report,
> +		u8 *data, int size)
> +{
> +	struct hid_device *hdev = ps_dev->hdev;
> +	struct dualsense *ds = (struct dualsense *)ps_dev;

I believe `container_of(ps_dev, struct dualsense, base)` would be preferable here
(and everywhere this pattern emerges).


> +	struct dualsense_input_report *ds_report;
> +	uint8_t value;
> +
> +	/* DualSense in USB uses the full HID report for reportID 1, but
> +	 * Bluetooth uses a minimal HID report for reportID 1 and reports
> +	 * the full report using reportID 49.
> +	 */
> +	if (report->id == DS_INPUT_REPORT_USB && hdev->bus == BUS_USB) {
> +		ds_report = (struct dualsense_input_report *)&data[1];
> +	} else {
> +		hid_err(hdev, "Unhandled reportID=%d\n", report->id);
> +		return -1;
> +	}
> +
> +	input_report_abs(ds->gamepad, ABS_X, ds_report->x);
> +	input_report_abs(ds->gamepad, ABS_Y, ds_report->y);
> +	input_report_abs(ds->gamepad, ABS_RX, ds_report->rx);
> +	input_report_abs(ds->gamepad, ABS_RY, ds_report->ry);
> +	input_report_abs(ds->gamepad, ABS_Z, ds_report->z);
> +	input_report_abs(ds->gamepad, ABS_RZ, ds_report->rz);
> +
> +	value = ds_report->buttons[0] & DS_BUTTONS0_HAT_SWITCH;
> +	if (value > 7)
> +		value = 8; /* center */
> +	input_report_abs(ds->gamepad, ABS_HAT0X, ps_gamepad_hat_mapping[value].x);
> +	input_report_abs(ds->gamepad, ABS_HAT0Y, ps_gamepad_hat_mapping[value].y);
> +
> +	input_report_key(ds->gamepad, BTN_WEST, ds_report->buttons[0] & DS_BUTTONS0_SQUARE);
> +	input_report_key(ds->gamepad, BTN_SOUTH, ds_report->buttons[0] & DS_BUTTONS0_CROSS);
> +	input_report_key(ds->gamepad, BTN_EAST, ds_report->buttons[0] & DS_BUTTONS0_CIRCLE);
> +	input_report_key(ds->gamepad, BTN_NORTH, ds_report->buttons[0] & DS_BUTTONS0_TRIANGLE);
> +	input_report_key(ds->gamepad, BTN_TL, ds_report->buttons[1] & DS_BUTTONS1_L1);
> +	input_report_key(ds->gamepad, BTN_TR, ds_report->buttons[1] & DS_BUTTONS1_R1);
> +	input_report_key(ds->gamepad, BTN_TL2, ds_report->buttons[1] & DS_BUTTONS1_L2);
> +	input_report_key(ds->gamepad, BTN_TR2, ds_report->buttons[1] & DS_BUTTONS1_R2);
> +	input_report_key(ds->gamepad, BTN_SELECT, ds_report->buttons[1] & DS_BUTTONS1_CREATE);
> +	input_report_key(ds->gamepad, BTN_START, ds_report->buttons[1] & DS_BUTTONS1_OPTIONS);
> +	input_report_key(ds->gamepad, BTN_THUMBL, ds_report->buttons[1] & DS_BUTTONS1_L3);
> +	input_report_key(ds->gamepad, BTN_THUMBR, ds_report->buttons[1] & DS_BUTTONS1_R3);
> +	input_report_key(ds->gamepad, BTN_MODE, ds_report->buttons[2] & DS_BUTTONS2_PS_HOME);

Possibly this could be replaced with a loop? I have something like this in mind:

```
struct ps_gamepad_button {
  unsigned int code;
  uint8_t button_idx;
  uint8_t mask;
} ps_gamepad_buttons[] = {...};

for (...) {
  struct ps_gamepad_button *b = ...;
  input_report_key(...);
}
```

Or is there any reason why the unrolled version is preffered that I'm missing?


> +	input_sync(ds->gamepad);
> +
> +	return 0;
> +}
> +
> +static struct ps_device *dualsense_create(struct hid_device *hdev)
> +{
> +	struct dualsense *ds;
> +	int ret;
> +
> +	ds = devm_kzalloc(&hdev->dev, sizeof(*ds), GFP_KERNEL);
> +	if (!ds)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Patch version to allow userspace to distinguish between
> +	 * hid-generic vs hid-playstation axis and button mapping.
> +	 */
> +	hdev->version |= 0x8000;

Maybe that '0x8000' could be given a name?


> +
> +	ds->base.hdev = hdev;
> +	ds->base.parse_report = dualsense_parse_report;
> +	hid_set_drvdata(hdev, ds);
> +
> +	ds->gamepad = ps_gamepad_create(hdev);
> +	if (IS_ERR(ds->gamepad)) {
> +		ret = PTR_ERR(ds->gamepad);
> +		goto err;
> +	}
> +
> +	return (struct ps_device *)ds;

I believe using `&ds->base` instead of `(struct ps_device *)ds` would be somewhat
better as it does not subvert the type system as much.


> +
> +err:
> +	return ERR_PTR(ret);
> +}
> +
> +static int ps_raw_event(struct hid_device *hdev, struct hid_report *report,
> +		u8 *data, int size)
> +{
> +	struct ps_device *dev = hid_get_drvdata(hdev);
> +
> +	if (dev && dev->parse_report)
> +		return dev->parse_report(dev, report, data, size);
> +
> +	return 0;
> +}
> +
> +static int ps_probe(struct hid_device *hdev, const struct hid_device_id *id)
> +{
> +	struct ps_device *dev;
> +	int ret;
> +
> +	ret = hid_parse(hdev);
> +	if (ret) {
> +		hid_err(hdev, "parse failed\n");
> +		return ret;
> +	}
> +
> +	ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
> +	if (ret) {
> +		hid_err(hdev, "hw start failed\n");
> +		return ret;
> +	}
> +
> +	ret = hid_hw_open(hdev);
> +	if (ret) {
> +		hid_err(hdev, "hw open failed\n");
> +		goto err_stop;
> +	}
> +
> +	if (hdev->product == USB_DEVICE_ID_SONY_PS5_CONTROLLER) {
> +		dev = dualsense_create(hdev);
> +		if (IS_ERR(dev)) {
> +			hid_err(hdev, "Failed to create dualsense.\n");
> +			ret = PTR_ERR(dev);
> +			goto err_close;
> +		}
> +	} else {

When would this be possible?


> +		hid_err(hdev, "Unhandled device\n");
> +		ret = -EINVAL;

Assuming it's possible, I believe `-ENODEV` is a better error code here.


> +		goto err_close;
> +	}
> +
> +	return ret;
> +
> +err_close:
> +	hid_hw_close(hdev);
> +err_stop:
> +	hid_hw_stop(hdev);
> +	return ret;
> +}
> [...]
> +static const struct hid_device_id ps_devices[] = {
> +	{ HID_USB_DEVICE(USB_VENDOR_ID_SONY, USB_DEVICE_ID_SONY_PS5_CONTROLLER),
> +		.driver_data = 0 },
> [...]

`.driver_data` would be initialized to zero anyways, why is it necessary to do
so explicitly?


[1]: https://www.kernel.org/doc/html/latest/process/coding-style.html


Regards,
Barnabás Pőcze