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Date: Fri, 7 Jun 2024 11:59:06 -0700
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Charles Wang <charles.goodix@gmail.com>
Cc: jikos@kernel.org, bentiss@kernel.org, hbarnor@chromium.org,
	dianders@chromium.org, linux-input@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] HID: hid-goodix: Add Goodix HID-over-SPI driver
Message-ID: <ZmNYepAl9mdz9hKG@google.com>
References: <20240607133709.3518-1-charles.goodix@gmail.com>
Precedence: bulk
MIME-Version: 1.0
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In-Reply-To: <20240607133709.3518-1-charles.goodix@gmail.com>

Hi Charles,

On Fri, Jun 07, 2024 at 09:36:02PM +0800, Charles Wang wrote:
> This patch introduces a new driver to support the Goodix GT7986U
> touch controller. This device is not compatible with Microsoft's
> HID-over-SPI protocol and therefore needs to implement its own
> flavor. The data reported is packaged according to the HID
> protocol but uses SPI for communication to improve speed. This
> enables the device to transmit not only coordinate data but also
> corresponding raw data that can be accessed by user-space programs
> through the hidraw interface. The raw data can be utilized for
> functions like palm rejection, thereby improving the touch experience.
> 
> Key features:
> - Device connection confirmation and initialization
> - IRQ-based event reporting to the input subsystem
> - Support for HIDRAW operations (GET_REPORT and SET_REPORT)
> 
> Signed-off-by: Charles Wang <charles.goodix@gmail.com>
> ---
> Changes in v3:
> - Renamed the driver file to hid-goodix-spi.c.
> - Mentioned in the commit message that this implementation is not compatible with
>   Microsoft's HID-over-SPI protocol.
> - Modified the driver to fetch the GOODIX_HID_REPORT_ADDR from device properties.
> - Add a lock to prevent concurrent hid feature request operations.
> - Optimized the SPI read/write functions by reducing the number of malloc calls.

Thank you for making the changes. A few more comments below.

> 
> Changes in v2:
> - Fixed build warnings reported by kernel test robot
> ---
>  drivers/hid/Kconfig          |   6 +
>  drivers/hid/Makefile         |   1 +
>  drivers/hid/hid-goodix-spi.c | 687 +++++++++++++++++++++++++++++++++++
>  3 files changed, 694 insertions(+)
>  create mode 100644 drivers/hid/hid-goodix-spi.c
> 
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 4c682c650..03e750e04 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -404,6 +404,12 @@ config HID_VIVALDI_COMMON
>  	  option so that drivers can use common code to parse the HID
>  	  descriptors for vivaldi function row keymap.
>  
> +config HID_GOODIX_SPI
> +	tristate "Goodix GT7986U SPI HID touchscreen"
> +	depends on SPI_MASTER
> +	help
> +	  Support for Goodix GT7986U SPI HID touchscreen device.
> +
>  config HID_GOOGLE_HAMMER
>  	tristate "Google Hammer Keyboard"
>  	select HID_VIVALDI_COMMON
> diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> index 082a728ea..56e3ed4c1 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_HID_GEMBIRD)	+= hid-gembird.o
>  obj-$(CONFIG_HID_GFRM)		+= hid-gfrm.o
>  obj-$(CONFIG_HID_GLORIOUS)  += hid-glorious.o
>  obj-$(CONFIG_HID_VIVALDI_COMMON) += hid-vivaldi-common.o
> +obj-$(CONFIG_HID_GOODIX_SPI)	+= hid-goodix-spi.o
>  obj-$(CONFIG_HID_GOOGLE_HAMMER)	+= hid-google-hammer.o
>  obj-$(CONFIG_HID_GOOGLE_STADIA_FF)	+= hid-google-stadiaff.o
>  obj-$(CONFIG_HID_VIVALDI)	+= hid-vivaldi.o
> diff --git a/drivers/hid/hid-goodix-spi.c b/drivers/hid/hid-goodix-spi.c
> new file mode 100644
> index 000000000..7ba7016e1
> --- /dev/null
> +++ b/drivers/hid/hid-goodix-spi.c
> @@ -0,0 +1,687 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Goodix GT7986U SPI Driver Code for HID.
> + *
> + * Copyright (C) 2024 Godix, Inc.
> + */
> +#include <asm/unaligned.h>
> +#include <linux/delay.h>
> +#include <linux/hid.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/sizes.h>
> +#include <linux/spi/spi.h>
> +
> +#define GOODIX_DEV_CONFIRM_ADDR		0x10000
> +#define GOODIX_HID_DESC_ADDR		0x1058C
> +#define GOODIX_HID_REPORT_DESC_ADDR	0x105AA
> +#define GOODIX_HID_SIGN_ADDR		0x10D32
> +
> +#define GOODIX_HID_GET_REPORT_CMD	0x02
> +#define GOODIX_HID_SET_REPORT_CMD	0x03
> +
> +#define GOODIX_HID_MAX_INBUF_SIZE	128
> +#define GOODIX_HID_ACK_READY_FLAG	0x01
> +#define GOODIX_HID_REPORT_READY_FLAG	0x80
> +
> +#define GOODIX_DEV_CONFIRM_VAL		0xAA
> +
> +#define GOODIX_SPI_WRITE_FLAG		0xF0
> +#define GOODIX_SPI_READ_FLAG		0xF1
> +#define GOODIX_SPI_TRANS_PREFIX_LEN	1
> +#define GOODIX_REGISTER_WIDTH		4
> +#define GOODIX_SPI_READ_DUMMY_LEN	3
> +#define GOODIX_SPI_READ_PREFIX_LEN	(GOODIX_SPI_TRANS_PREFIX_LEN + \
> +					 GOODIX_REGISTER_WIDTH + \
> +					 GOODIX_SPI_READ_DUMMY_LEN)
> +#define GOODIX_SPI_WRITE_PREFIX_LEN	(GOODIX_SPI_TRANS_PREFIX_LEN + \
> +					 GOODIX_REGISTER_WIDTH)
> +
> +#define GOODIX_CHECKSUM_SIZE		sizeof(u16)
> +#define GOODIX_NORMAL_RESET_DELAY_MS	150
> +
> +struct goodix_hid_report_header {
> +	u8 flag;
> +	__le16 size;
> +} __packed;
> +#define GOODIX_HID_ACK_HEADER_SIZE	sizeof(struct goodix_hid_report_header)
> +
> +struct goodix_hid_report_package {
> +	__le16 size;
> +	u8 data[];
> +};
> +
> +#define GOODIX_HID_PKG_LEN_SIZE		sizeof(u16)
> +#define GOODIX_HID_COOR_DATA_LEN	82
> +#define GOODIX_HID_COOR_PKG_LEN		(GOODIX_HID_PKG_LEN_SIZE + \
> +					 GOODIX_HID_COOR_DATA_LEN)
> +
> +#define GOODIX_HID_MAX_PKG_SIZE		(GOODIX_HID_COOR_PKG_LEN + SZ_4K)
> +
> +struct goodix_hid_report_event {
> +	struct goodix_hid_report_header hdr;
> +	u8 data[GOODIX_HID_COOR_PKG_LEN];
> +} __packed;
> +
> +struct goodix_hid_desc {
> +	__le16 desc_length;
> +	__le16 bcd_version;
> +	__le16 report_desc_lenght;
> +	__le16 report_desc_register;
> +	__le16 input_register;
> +	__le16 max_input_length;
> +	__le16 output_register;
> +	__le16 max_output_length;
> +	__le16 cmd_register;
> +	__le16 data_register;
> +	__le16 vendor_id;
> +	__le16 product_id;
> +	__le16 version_id;
> +	__le32 reserved;
> +} __packed;
> +
> +struct goodix_ts_data {
> +	struct device *dev;
> +	struct spi_device *spi;
> +	struct hid_device *hid;
> +	struct goodix_hid_desc hid_desc;
> +
> +	struct gpio_desc *reset_gpio;
> +	u32 hid_report_addr;
> +
> +	/* lock for hid raw request operation */
> +	struct mutex hid_request_lock;
> +	/* lock for reg read write operations */
> +	struct mutex reg_rw_lock;
> +	u32 spi_xfer_max_sz;
> +	/* buffer used to store hid report event */
> +	u8 event_buf[SZ_4K] ____cacheline_aligned;

Why does this have to be cacheline aligned? I do not think it is
directly involved in the transfers.

Also, 4K is quite a bit of data. How often does the device send more
than 1 report? Maybe you should do what i2c-hid does and scan reports
for the maximum report size and use it to allocate sufficiently sized
buffer(s)? See drivers/hid/i2c-hid/i2c-hid-core.c::i2c_hid_start(). 

> +	/* buffer used to do spi data transfer */
> +	u8 xfer_buf[GOODIX_HID_MAX_PKG_SIZE] ____cacheline_aligned;
> +};
> +
> +static int goodix_spi_read(struct goodix_ts_data *ts, u32 addr,
> +			   u8 *data, unsigned int len)

Maybe make data void * so callers do not need to cast? Also maybe size_t
for len?

> +{
> +	struct spi_device *spi = to_spi_device(&ts->spi->dev);
> +	struct spi_transfer xfers;
> +	struct spi_message spi_msg;
> +	int error;
> +
> +	if (GOODIX_SPI_READ_PREFIX_LEN + len > ts->spi_xfer_max_sz) {
> +		dev_err(ts->dev, "read data len exceed limit %d",
> +			ts->spi_xfer_max_sz - GOODIX_SPI_READ_PREFIX_LEN);
> +		return -EINVAL;
> +	}
> +
> +	mutex_lock(&ts->reg_rw_lock);

This can be written as

	guard(mutex)(&ts->reg_rw_lock);

and you do not need to explicitly unlock the mutex at the end of the
function. You can also safely return early and the mutex will be
unlocked.

> +	/* buffer format: 0xF1 + addr(4bytes) + dummy(3bytes) + data */
> +	ts->xfer_buf[0] = GOODIX_SPI_READ_FLAG;
> +	put_unaligned_be32(addr, ts->xfer_buf + GOODIX_SPI_TRANS_PREFIX_LEN);
> +
> +	spi_message_init(&spi_msg);
> +	memset(&xfers, 0, sizeof(xfers));
> +	xfers.tx_buf = ts->xfer_buf;
> +	xfers.rx_buf = ts->xfer_buf;
> +	xfers.len = GOODIX_SPI_READ_PREFIX_LEN + len;
> +	spi_message_add_tail(&xfers, &spi_msg);
> +
> +	error = spi_sync(spi, &spi_msg);
> +	if (error)
> +		dev_err(ts->dev, "spi transfer error:%d", error);

"error: %d"

> +	else
> +		memcpy(data, ts->xfer_buf + GOODIX_SPI_READ_PREFIX_LEN, len);
> +
> +	mutex_unlock(&ts->reg_rw_lock);
> +	return error;
> +}
> +
> +static int goodix_spi_write(struct goodix_ts_data *ts, u32 addr,
> +			    u8 *data, unsigned int len)

const void *data

> +{
> +	struct spi_device *spi = to_spi_device(&ts->spi->dev);
> +	struct spi_transfer xfers;
> +	struct spi_message spi_msg;
> +	int error;
> +
> +	if (GOODIX_SPI_WRITE_PREFIX_LEN + len > ts->spi_xfer_max_sz) {
> +		dev_err(ts->dev, "write data len exceed limit %d",
> +			ts->spi_xfer_max_sz - GOODIX_SPI_WRITE_PREFIX_LEN);
> +		return -EINVAL;
> +	}
> +
> +	mutex_lock(&ts->reg_rw_lock);

	guard(mutex)(&ts->reg_rw_lock);

> +	/* buffer format: 0xF0 + addr(4bytes) + data */
> +	ts->xfer_buf[0] = GOODIX_SPI_WRITE_FLAG;
> +	put_unaligned_be32(addr, ts->xfer_buf + GOODIX_SPI_TRANS_PREFIX_LEN);
> +	memcpy(ts->xfer_buf + GOODIX_SPI_WRITE_PREFIX_LEN, data, len);
> +
> +	spi_message_init(&spi_msg);
> +	memset(&xfers, 0, sizeof(xfers));
> +	xfers.tx_buf = ts->xfer_buf;
> +	xfers.len = GOODIX_SPI_WRITE_PREFIX_LEN + len;
> +	spi_message_add_tail(&xfers, &spi_msg);
> +
> +	error = spi_sync(spi, &spi_msg);
> +	if (error)
> +		dev_err(ts->dev, "spi transfer error:%d", error);
> +
> +	mutex_unlock(&ts->reg_rw_lock);
> +	return error;
> +}
> +
> +static int goodix_dev_confirm(struct goodix_ts_data *ts)
> +{
> +	u8 tx_buf[8], rx_buf[8];
> +	int retry = 3;
> +	int error;
> +
> +	gpiod_set_value_cansleep(ts->reset_gpio, 0);
> +	usleep_range(4000, 4100);
> +
> +	memset(tx_buf, GOODIX_DEV_CONFIRM_VAL, sizeof(tx_buf));
> +	while (retry--) {
> +		error = goodix_spi_write(ts, GOODIX_DEV_CONFIRM_ADDR,
> +					 tx_buf, sizeof(tx_buf));
> +		if (error)
> +			return error;
> +
> +		error = goodix_spi_read(ts, GOODIX_DEV_CONFIRM_ADDR,
> +					rx_buf, sizeof(rx_buf));
> +		if (error)
> +			return error;
> +
> +		if (!memcmp(tx_buf, rx_buf, sizeof(tx_buf)))
> +			return 0;
> +
> +		usleep_range(5000, 5100);
> +	}
> +
> +	dev_err(ts->dev, "device confirm failed, rx_buf:%*ph", 8, rx_buf);
> +	return -EINVAL;
> +}
> +
> +/**
> + * goodix_hid_parse() - hid-core .parse() callback
> + * @hid: hid device instance
> + *
> + * This function gets called during call to hid_add_device
> + *
> + * Return: 0 on success and non zero on error
> + */
> +static int goodix_hid_parse(struct hid_device *hid)
> +{
> +	struct goodix_ts_data *ts = hid->driver_data;
> +	u8 *rdesc __free(kfree);

This is not proper use of this. rdesc will contain garbage (not NULL),
so if rsize check below failed we'll get a nasty surprise.

> +	u16 rsize;
> +	int error;
> +
> +	rsize = le16_to_cpu(ts->hid_desc.report_desc_lenght);
> +	if (!rsize || rsize > HID_MAX_DESCRIPTOR_SIZE) {
> +		dev_err(ts->dev, "invalid report desc size %d", rsize);
> +		return -EINVAL;
> +	}
> +
> +	rdesc = kzalloc(rsize, GFP_KERNEL);
> +	if (!rdesc)
> +		return -ENOMEM;

Linus said that for pointers annotated with __free() he prefers
combining declaration with allocation, like this:

	u8 *rdesc __free(kfree) = kzalloc(rsize, GFP_KERNEL);
	if (!rdesc)
		return -ENOMEM;

> +
> +	error = goodix_spi_read(ts, GOODIX_HID_REPORT_DESC_ADDR, rdesc, rsize);
> +	if (error) {
> +		dev_err(ts->dev, "failed get report desc, %d", error);
> +		return error;
> +	}
> +
> +	error = hid_parse_report(hid, rdesc, rsize);
> +	if (error)
> +		dev_err(ts->dev, "failed parse report, %d", error);
> +
> +	return error;

I am not sure what Benjamin and Jiri prefer, but my preference is to
explicitly return error or 0 instead of returning "error" in both
success and failure cases, especially when there are multiple failure
points in a function. So:

	error = hid_parse_report(hid, rdesc, rsize);
	if (error) {
		dev_err(ts->dev, "failed parse report, %d", error);
		return error;
	}

	return 0;

> +}
> +
> +/* Empty callbacks with success return code */
> +static int goodix_hid_start(struct hid_device *hid)
> +{
> +	return 0;
> +}
> +
> +static void goodix_hid_stop(struct hid_device *hid)
> +{
> +}
> +
> +static int goodix_hid_open(struct hid_device *hid)
> +{
> +	return 0;
> +}
> +
> +static void goodix_hid_close(struct hid_device *hid)
> +{
> +}
> +
> +/* Return date length of response data */
> +static int goodix_hid_check_ack_status(struct goodix_ts_data *ts)
> +{
> +	struct goodix_hid_report_header hdr;
> +	int retry = 20;
> +	int error;
> +
> +	while (retry--) {
> +		/*
> +		 * 3 bytes of hid request response data
> +		 * - byte 0:    Ack flag, value of 1 for data ready
> +		 * - bytes 1-2: Response data length
> +		 */
> +		error = goodix_spi_read(ts, ts->hid_report_addr,
> +					(u8 *)&hdr, sizeof(hdr));
> +		if (!error && (hdr.flag & GOODIX_HID_ACK_READY_FLAG))
> +			return le16_to_cpu(hdr.size);
> +
> +		/* Wait 10ms for another try */
> +		usleep_range(10000, 11000);
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +/**
> + * goodix_hid_get_raw_report() - Process hidraw GET REPORT operation
> + * @hid: hid device instance
> + * @reportnum: Report ID
> + * @buf: Buffer for store the reprot date
> + * @len: Length fo reprot data
> + * @report_type: Report type
> + *
> + * The function for hid_ll_driver.get_raw_report to handle the HIDRAW ioctl
> + * get report request. The transmitted data follows the standard i2c-hid
> + * protocol with a specified header.
> + *
> + * Return: The length of the data in the buf on success, negative error code
> + */
> +static int goodix_hid_get_raw_report(struct hid_device *hid,
> +				     unsigned char reportnum,
> +				     __u8 *buf, size_t len,
> +				     unsigned char report_type)

I think u8 for report type is better. It is not a character but a
number.

> +{
> +	struct goodix_ts_data *ts = hid->driver_data;
> +	u16 data_register = le16_to_cpu(ts->hid_desc.data_register);
> +	u16 cmd_register = le16_to_cpu(ts->hid_desc.cmd_register);
> +	u8 tmp_buf[GOODIX_HID_MAX_INBUF_SIZE];
> +	int tx_len = 0, args_len = 0;
> +	int response_data_len;
> +	u8 args[3];
> +	int error;
> +
> +	if (report_type == HID_OUTPUT_REPORT)
> +		return -EINVAL;
> +
> +	if (reportnum == 3) {
> +		/* Get win8 signature data */
> +		error = goodix_spi_read(ts, GOODIX_HID_SIGN_ADDR, buf, len);
> +		if (error) {
> +			dev_err(ts->dev, "failed get win8 sign:%d", error);
> +			return -EINVAL;
> +		}
> +		return len;
> +	}
> +
> +	if (reportnum >= 0x0F)
> +		args[args_len++] = reportnum;
> +
> +	put_unaligned_le16(data_register, args + args_len);
> +	args_len += sizeof(data_register);
> +
> +	/* Clean 3 bytes of hid ack header data */
> +	memset(tmp_buf, 0, GOODIX_HID_ACK_HEADER_SIZE);
> +	tx_len += GOODIX_HID_ACK_HEADER_SIZE;
> +
> +	put_unaligned_le16(cmd_register, tmp_buf + tx_len);
> +	tx_len += sizeof(cmd_register);
> +
> +	tmp_buf[tx_len] = (report_type == HID_FEATURE_REPORT ? 0x03 : 0x01) << 4;
> +	tmp_buf[tx_len] |=  reportnum >= 0x0F ? 0x0F : reportnum;
> +	tx_len++;
> +
> +	tmp_buf[tx_len++] = GOODIX_HID_GET_REPORT_CMD;
> +
> +	memcpy(tmp_buf + tx_len, args, args_len);
> +	tx_len += args_len;
> +
> +	/* Step1: write report request info */
> +	error = goodix_spi_write(ts, ts->hid_report_addr, tmp_buf, tx_len);
> +	if (error) {
> +		dev_err(ts->dev, "failed send read feature cmd, %d", error);
> +		return error;
> +	}
> +
> +	/* No need read response data */
> +	if (!len)
> +		return 0;
> +
> +	/* Step2: check response data status */
> +	response_data_len = goodix_hid_check_ack_status(ts);
> +	if (response_data_len <= GOODIX_HID_PKG_LEN_SIZE)
> +		return -EINVAL;
> +
> +	len = min(len, response_data_len - GOODIX_HID_PKG_LEN_SIZE);
> +	/* Step3: read response data(skip 2bytes of hid pkg length) */
> +	error = goodix_spi_read(ts, ts->hid_report_addr +
> +				GOODIX_HID_ACK_HEADER_SIZE +
> +				GOODIX_HID_PKG_LEN_SIZE, buf, len);
> +	if (error) {
> +		dev_err(ts->dev, "failed read hid response data, %d", error);
> +		return error;
> +	}
> +
> +	if (buf[0] != reportnum) {
> +		dev_err(ts->dev, "incorrect reprot (%d vs %d expected)",

s/reprot/report/

> +			buf[0], reportnum);
> +		return -EINVAL;
> +	}
> +	return len;
> +}
> +
> +/**
> + * goodix_hid_set_raw_report() - process hidraw SET REPORT operation
> + * @hid: HID device
> + * @reportnum: Report ID
> + * @buf: Buffer for communication
> + * @len: Length of data in the buffer
> + * @report_type: Report type
> + *
> + * The function for hid_ll_driver.get_raw_report to handle the HIDRAW ioctl
> + * set report request. The transmitted data follows the standard i2c-hid
> + * protocol with a specified header.
> + *
> + * Return: The length of the data sent, negative error code on failure
> + */
> +static int goodix_hid_set_raw_report(struct hid_device *hid,
> +				     unsigned char reportnum,
> +				     __u8 *buf, size_t len,
> +				     unsigned char report_type)
> +{
> +	struct goodix_ts_data *ts = hid->driver_data;
> +	u16 data_register = le16_to_cpu(ts->hid_desc.data_register);
> +	u16 cmd_register = le16_to_cpu(ts->hid_desc.cmd_register);
> +	int tx_len = 0, args_len = 0;
> +	u8 tmp_buf[GOODIX_HID_MAX_INBUF_SIZE];
> +	u8 args[5];
> +	int error;
> +
> +	if (reportnum >= 0x0F) {
> +		args[args_len++] = reportnum;
> +		reportnum = 0x0F;
> +	}
> +
> +	put_unaligned_le16(data_register, args + args_len);
> +	args_len += sizeof(data_register);
> +
> +	put_unaligned_le16(GOODIX_HID_PKG_LEN_SIZE + len, args + args_len);
> +	args_len += GOODIX_HID_PKG_LEN_SIZE;
> +
> +	/* Clean 3 bytes of hid ack header data */
> +	memset(tmp_buf, 0, GOODIX_HID_ACK_HEADER_SIZE);
> +	tx_len += GOODIX_HID_ACK_HEADER_SIZE;
> +
> +	put_unaligned_le16(cmd_register, tmp_buf + tx_len);
> +	tx_len += sizeof(cmd_register);
> +
> +	tmp_buf[tx_len++] = ((report_type == HID_FEATURE_REPORT ? 0x03 : 0x02) << 4) | reportnum;
> +	tmp_buf[tx_len++] = GOODIX_HID_SET_REPORT_CMD;
> +
> +	memcpy(tmp_buf + tx_len, args, args_len);
> +	tx_len += args_len;
> +
> +	memcpy(tmp_buf + tx_len, buf, len);
> +	tx_len += len;
> +
> +	error = goodix_spi_write(ts, ts->hid_report_addr, tmp_buf, tx_len);
> +	if (error) {
> +		dev_err(ts->dev, "failed send report %*ph", tx_len, tmp_buf);
> +		return error;
> +	}
> +	return len;
> +}
> +
> +static int goodix_hid_raw_request(struct hid_device *hid,
> +				  unsigned char reportnum,
> +				  __u8 *buf, size_t len,
> +				  unsigned char rtype, int reqtype)
> +{
> +	struct goodix_ts_data *ts = hid->driver_data;
> +	int error = -EINVAL;
> +
> +	mutex_lock(&ts->hid_request_lock);

	guard(mutex)(&ts->hid_request_lock);

> +	switch (reqtype) {
> +	case HID_REQ_GET_REPORT:
> +		error = goodix_hid_get_raw_report(hid, reportnum, buf,
> +						  len, rtype);
> +		break;
> +	case HID_REQ_SET_REPORT:
> +		if (buf[0] == reportnum)
> +			error = goodix_hid_set_raw_report(hid, reportnum,
> +							  buf, len, rtype);
> +		break;
> +	default:
> +		break;
> +	}
> +	mutex_unlock(&ts->hid_request_lock);
> +
> +	return error;
> +}
> +
> +static struct hid_ll_driver goodix_hid_ll_driver = {
> +	.parse = goodix_hid_parse,
> +	.start = goodix_hid_start,
> +	.stop = goodix_hid_stop,
> +	.open = goodix_hid_open,
> +	.close = goodix_hid_close,
> +	.raw_request = goodix_hid_raw_request
> +};
> +
> +static irqreturn_t goodix_hid_irq(int irq, void *data)
> +{
> +	struct goodix_ts_data *ts = data;
> +	struct goodix_hid_report_event event;
> +	struct goodix_hid_report_package *pkg;
> +	u16 report_size;
> +	int error;
> +
> +	/*
> +	 * First, read buffer with space for header and coordinate package:
> +	 * - event header = 3 bytes
> +	 * - coordinate event = GOODIX_HID_COOR_PKG_LEN bytes
> +	 *
> +	 * If the data size info in the event header exceeds
> +	 * GOODIX_HID_COOR_PKG_LEN, it means that there are other packages
> +	 * besides the coordinate package.
> +	 */
> +	error = goodix_spi_read(ts, ts->hid_report_addr, (u8 *)&event,

Drop cast.

> +				sizeof(event));
> +	if (error) {
> +		dev_err(ts->dev, "failed get coordinate data, %d", error);
> +		return IRQ_HANDLED;
> +	}
 > +
> +	/* Check coordinate data valid falg */
> +	if (event.hdr.flag != GOODIX_HID_REPORT_READY_FLAG) {
> +		dev_err(ts->dev, "invalid event flag 0x%x", event.hdr.flag);
> +		return IRQ_HANDLED;
> +	}
> +
> +	pkg = (struct goodix_hid_report_package *)event.data;
> +	hid_input_report(ts->hid, HID_INPUT_REPORT, pkg->data,
> +			 le16_to_cpu(pkg->size) - GOODIX_HID_PKG_LEN_SIZE, 1);
> +
> +	report_size = le16_to_cpu(event.hdr.size);
> +	/* Check if there are other packages */
> +	if (report_size <= GOODIX_HID_COOR_PKG_LEN)
> +		return IRQ_HANDLED;
> +
> +	if (report_size - GOODIX_HID_COOR_PKG_LEN > sizeof(ts->event_buf)) {
> +		dev_err(ts->dev, "invalid package size, %d", report_size);
> +		return IRQ_HANDLED;
> +	}
> +
> +	/* Read the package behind the coordinate data */
> +	error = goodix_spi_read(ts, ts->hid_report_addr + sizeof(event),
> +				ts->event_buf,
> +				report_size - GOODIX_HID_COOR_PKG_LEN);
> +	if (error) {
> +		dev_err(ts->dev, "failed read data, %d", error);
> +		return IRQ_HANDLED;
> +	}
> +
> +	pkg = (struct goodix_hid_report_package *)ts->event_buf;
> +	hid_input_report(ts->hid, HID_INPUT_REPORT, pkg->data,
> +			 le16_to_cpu(pkg->size) - GOODIX_HID_PKG_LEN_SIZE, 1);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int goodix_hid_init(struct goodix_ts_data *ts)
> +{
> +	struct hid_device *hid;
> +	int error;
> +
> +	/* Get hid descriptor */
> +	error = goodix_spi_read(ts, GOODIX_HID_DESC_ADDR, (u8 *)&ts->hid_desc,

Drop cast.

> +				sizeof(ts->hid_desc));
> +	if (error) {
> +		dev_err(ts->dev, "failed get hid desc, %d", error);
> +		return error;
> +	}
> +
> +	hid = hid_allocate_device();
> +	if (IS_ERR(hid))
> +		return PTR_ERR(hid);
> +
> +	hid->driver_data = ts;
> +	hid->ll_driver = &goodix_hid_ll_driver;
> +	hid->bus = BUS_SPI;
> +	hid->dev.parent = &ts->spi->dev;
> +
> +	hid->version = le16_to_cpu(ts->hid_desc.bcd_version);
> +	hid->vendor = le16_to_cpu(ts->hid_desc.vendor_id);
> +	hid->product = le16_to_cpu(ts->hid_desc.product_id);
> +	snprintf(hid->name, sizeof(hid->name), "%s %04X:%04X", "hid-gdix",
> +		 hid->vendor, hid->product);
> +
> +	error = hid_add_device(hid);
> +	if (error) {
> +		dev_err(ts->dev, "failed add hid device, %d", error);
> +		hid_destroy_device(hid);
> +		return error;
> +	}
> +
> +	ts->hid = hid;
> +	return 0;
> +}
> +
> +static int goodix_spi_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct goodix_ts_data *ts;
> +	int error;
> +
> +	/* init spi_device */
> +	spi->mode            = SPI_MODE_0;
> +	spi->bits_per_word   = 8;
> +	error = spi_setup(spi);
> +	if (error)
> +		return error;
> +
> +	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +
> +	mutex_init(&ts->hid_request_lock);
> +	mutex_init(&ts->reg_rw_lock);
> +	spi_set_drvdata(spi, ts);
> +	if (spi->controller->max_transfer_size)
> +		ts->spi_xfer_max_sz = spi->controller->max_transfer_size(spi);
> +	else
> +		ts->spi_xfer_max_sz = GOODIX_HID_MAX_PKG_SIZE;
> +
> +	ts->spi_xfer_max_sz = min(GOODIX_HID_MAX_PKG_SIZE, ts->spi_xfer_max_sz);
> +	ts->spi = spi;
> +	ts->dev = dev;
> +	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(ts->reset_gpio))
> +		return dev_err_probe(dev, PTR_ERR(ts->reset_gpio),
> +				     "failed to request reset gpio\n");
> +
> +	error = device_property_read_u32(dev, "hid-report-addr",
> +					 &ts->hid_report_addr);

This will require device binding document. Well, we needed it anyway to
describe the reset GPIO. You should add regulator handling as well.

> +	if (error)
> +		return dev_err_probe(dev, error,
> +				     "failed get hid report addr\n");
> +
> +	error = goodix_dev_confirm(ts);
> +	if (error)
> +		return error;
> +
> +	/* Waits 150ms for firmware to fully boot */
> +	msleep(GOODIX_NORMAL_RESET_DELAY_MS);
> +
> +	error = goodix_hid_init(ts);
> +	if (error) {
> +		dev_err(dev, "failed init hid device");
> +		return error;
> +	}
> +
> +	error = devm_request_threaded_irq(&ts->spi->dev, ts->spi->irq,
> +					  NULL, goodix_hid_irq, IRQF_ONESHOT,
> +					  "goodix_spi_hid", ts);

I think we still have an issue. The hid device is "added" to hid bus in
goodix_hid_init(). Immediately HID bus will attempt to match the HID
device and HID driver, start the low level transport (i.e. us), and try
to interrogate and initiate the device. That means that interrupts need
to be working already. However we only request IRQ after returning from
goodix_hid_init(), which is too late.

Please take a look at how i2c-hid driver allocates HID device, requests
IRQ, and then calls to hid_add_device(). Also see how it checks for
I2C_HID_STARTED flags in the interrupt routine to see of the data needs
to be reported to the HID subsystem.

> +	if (error < 0) {

	if (error)

> +		dev_err(ts->dev, "could not register interrupt, irq = %d, %d",
> +			ts->spi->irq, error);
> +		goto err_destroy_hid;
> +	}
> +
> +	return 0;
> +
> +err_destroy_hid:
> +	hid_destroy_device(ts->hid);
> +	return error;
> +}
> +
> +static void goodix_spi_remove(struct spi_device *spi)
> +{
> +	struct goodix_ts_data *ts = spi_get_drvdata(spi);
> +
> +	disable_irq(spi->irq);
> +	hid_destroy_device(ts->hid);

Here we again need to make sure interrupts are working while the device
is being used but the HID subsystem, but make sure we are not trying to
service interrupts once device is fully gone.

> +}
> +
> +static void goodix_spi_shutdown(struct spi_device *spi)
> +{
> +	struct goodix_ts_data *ts = spi_get_drvdata(spi);
> +
> +	disable_irq(spi->irq);
> +	hid_destroy_device(ts->hid);

Same as above.

> +}
> +
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id goodix_spi_acpi_match[] = {
> +	{ "GXTS7986" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(acpi, goodix_spi_acpi_match);
> +#endif
> +
> +static struct spi_driver goodix_spi_driver = {
> +	.driver = {
> +		.name = "goodix-spi-hid",
> +		.acpi_match_table = ACPI_PTR(goodix_spi_acpi_match),
> +	},
> +	.probe =	goodix_spi_probe,
> +	.remove =	goodix_spi_remove,
> +	.shutdown =	goodix_spi_shutdown,
> +};
> +module_spi_driver(goodix_spi_driver);
> +
> +MODULE_DESCRIPTION("Goodix SPI driver for HID touchscreen");
> +MODULE_AUTHOR("Goodix, Inc.");
> +MODULE_LICENSE("GPL");
> -- 
> 2.43.0
> 

Thanks.

-- 
Dmitry