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Subject: Re: [PATCHv3 4/5] Input: EXC3000: Add support to query model and
 fw_version
To:     Sebastian Reichel <sebastian.reichel@collabora.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Ahmet Inan <inan@distec.de>,
        Martin Fuzzey <martin.fuzzey@flowbird.group>
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel@collabora.com
References: <20200520153936.46869-1-sebastian.reichel@collabora.com>
 <20200520153936.46869-5-sebastian.reichel@collabora.com>
From:   Enric Balletbo i Serra <enric.balletbo@collabora.com>
Message-ID: <d2cde5c1-c6b1-7e05-5b32-74b3fcc4a1bb@collabora.com>
Date:   Wed, 20 May 2020 18:53:42 +0200
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Hi Sebastian,

On 20/5/20 17:39, Sebastian Reichel wrote:
> Expose model and fw_version via sysfs. Also query the model
> in probe to make sure, that the I2C communication with the
> device works before successfully probing the driver.
> 
> This is a bit complicated, since EETI devices do not have
> a sync interface. Sending the commands and directly reading
> does not work. Sending the command and waiting for some time
> is also not an option, since there might be touch events in
> the mean time.
> 
> Last but not least we do not cache the results, since this
> interface can be used to check the I2C communication is still
> working as expected.
> 
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

I went through the code and understood the reasoning to implement that way, if
it helps:

Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

> ---
>  .../ABI/testing/sysfs-driver-input-exc3000    |  15 ++
>  drivers/input/touchscreen/exc3000.c           | 145 +++++++++++++++++-
>  2 files changed, 159 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-driver-input-exc3000
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-input-exc3000 b/Documentation/ABI/testing/sysfs-driver-input-exc3000
> new file mode 100644
> index 000000000000..d79da4f869af
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-input-exc3000
> @@ -0,0 +1,15 @@
> +What:		/sys/class/input/inputX/fw_version
> +Date:		May 2020
> +Contact:	linux-input@vger.kernel.org
> +Description:	Reports the firmware version provided by the touchscreen, for example "00_T6" on a EXC80H60
> +
> +		Access: Read
> +		Valid values: Represented as string
> +
> +What:		/sys/class/input/inputX/model
> +Date:		May 2020
> +Contact:	linux-input@vger.kernel.org
> +Description:	Reports the model identification provided by the touchscreen, for example "Orion_1320" on a EXC80H60
> +
> +		Access: Read
> +		Valid values: Represented as string
> diff --git a/drivers/input/touchscreen/exc3000.c b/drivers/input/touchscreen/exc3000.c
> index b497bd2ae41d..b5a3bbb63504 100644
> --- a/drivers/input/touchscreen/exc3000.c
> +++ b/drivers/input/touchscreen/exc3000.c
> @@ -25,6 +25,9 @@
>  #define EXC3000_LEN_FRAME		66
>  #define EXC3000_LEN_POINT		10
>  
> +#define EXC3000_LEN_MODEL_NAME		16
> +#define EXC3000_LEN_FW_VERSION		16
> +
>  #define EXC3000_MT1_EVENT		0x06
>  #define EXC3000_MT2_EVENT		0x18
>  
> @@ -65,6 +68,11 @@ struct exc3000_data {
>  	struct touchscreen_properties prop;
>  	struct timer_list timer;
>  	u8 buf[2 * EXC3000_LEN_FRAME];
> +	struct completion wait_event;
> +	struct mutex query_lock;
> +	int query_result;
> +	char model[EXC3000_LEN_MODEL_NAME];
> +	char fw_version[EXC3000_LEN_FW_VERSION];
>  };
>  
>  static void exc3000_report_slots(struct input_dev *input,
> @@ -150,6 +158,28 @@ static int exc3000_read_data(struct exc3000_data *data,
>  	return 0;
>  }
>  
> +static int exc3000_query_interrupt(struct exc3000_data *data)
> +{
> +	u8 *buf = data->buf;
> +	int err;
> +
> +	err = i2c_master_recv(data->client, buf, EXC3000_LEN_FRAME);
> +	if (err < 0)
> +		return err;
> +
> +	if (buf[0] != 0x42)
> +		return -EPROTO;
> +
> +	if (buf[4] == 'E')
> +		strlcpy(data->model, buf+5, sizeof(data->model));
> +	else if (buf[4] == 'D')
> +		strlcpy(data->fw_version, buf+5, sizeof(data->fw_version));
> +	else
> +		return -EPROTO;
> +
> +	return 0;
> +}
> +
>  static irqreturn_t exc3000_interrupt(int irq, void *dev_id)
>  {
>  	struct exc3000_data *data = dev_id;
> @@ -158,6 +188,12 @@ static irqreturn_t exc3000_interrupt(int irq, void *dev_id)
>  	int slots, total_slots;
>  	int error;
>  
> +	if (mutex_is_locked(&data->query_lock)) {
> +		data->query_result = exc3000_query_interrupt(data);
> +		complete(&data->wait_event);
> +		goto out;
> +	}
> +
>  	error = exc3000_read_data(data, buf, &total_slots);
>  	if (error) {
>  		/* Schedule a timer to release "stuck" contacts */
> @@ -185,11 +221,94 @@ static irqreturn_t exc3000_interrupt(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +static ssize_t fw_version_show(struct device *dev,
> +			       struct device_attribute *attr, char *buf)
> +{
> +	struct exc3000_data *data = dev_get_drvdata(dev);
> +	static const u8 request[68] = {
> +		0x67, 0x00, 0x42, 0x00, 0x03, 0x01, 'D', 0x00
> +	};
> +	struct i2c_client *client = data->client;
> +	int err;
> +
> +	mutex_lock(&data->query_lock);
> +
> +	data->query_result = -ETIMEDOUT;
> +	reinit_completion(&data->wait_event);
> +
> +	err = i2c_master_send(client, request, sizeof(request));
> +	if (err < 0) {
> +		mutex_unlock(&data->query_lock);
> +		return err;
> +	}
> +
> +	wait_for_completion_interruptible_timeout(&data->wait_event, 1*HZ);
> +	mutex_unlock(&data->query_lock);
> +
> +	if (data->query_result < 0)
> +		return data->query_result;
> +
> +	return sprintf(buf, "%s\n", data->fw_version);
> +}
> +static DEVICE_ATTR_RO(fw_version);
> +
> +static ssize_t exc3000_get_model(struct exc3000_data *data)
> +{
> +	static const u8 request[68] = {
> +		0x67, 0x00, 0x42, 0x00, 0x03, 0x01, 'E', 0x00
> +	};
> +	struct i2c_client *client = data->client;
> +	int err;
> +
> +	mutex_lock(&data->query_lock);
> +	data->query_result = -ETIMEDOUT;
> +	reinit_completion(&data->wait_event);
> +
> +	err = i2c_master_send(client, request, sizeof(request));
> +	if (err < 0) {
> +		mutex_unlock(&data->query_lock);
> +		return err;
> +	}
> +
> +	wait_for_completion_interruptible_timeout(&data->wait_event, 1 * HZ);
> +	mutex_unlock(&data->query_lock);
> +
> +	return data->query_result;
> +}
> +
> +static ssize_t model_show(struct device *dev,
> +			  struct device_attribute *attr, char *buf)
> +{
> +	struct exc3000_data *data = dev_get_drvdata(dev);
> +	int err = exc3000_get_model(data);
> +
> +	if (err < 0)
> +		return err;
> +
> +	return sprintf(buf, "%s\n", data->model);
> +}
> +static DEVICE_ATTR_RO(model);
> +
> +static struct attribute *sysfs_attrs[] = {
> +	&dev_attr_fw_version.attr,
> +	&dev_attr_model.attr,
> +	NULL
> +};
> +
> +static struct attribute_group exc3000_attribute_group = {
> +	.attrs = sysfs_attrs
> +};
> +
> +static const struct attribute_group *exc3000_attribute_groups[] = {
> +	&exc3000_attribute_group,
> +	NULL
> +};
> +
>  static int exc3000_probe(struct i2c_client *client)
>  {
>  	struct exc3000_data *data;
>  	struct input_dev *input;
> -	int error, max_xy;
> +	int error, max_xy, retry;
>  
>  	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
>  	if (!data)
> @@ -203,15 +322,19 @@ static int exc3000_probe(struct i2c_client *client)
>  		data->info = &exc3000_info[eeti_dev_id];
>  	}
>  	timer_setup(&data->timer, exc3000_timer, 0);
> +	init_completion(&data->wait_event);
> +	mutex_init(&data->query_lock);
>  
>  	input = devm_input_allocate_device(&client->dev);
>  	if (!input)
>  		return -ENOMEM;
>  
>  	data->input = input;
> +	input_set_drvdata(input, data);
>  
>  	input->name = data->info->name;
>  	input->id.bustype = BUS_I2C;
> +	input->dev.groups = exc3000_attribute_groups;
>  
>  	max_xy = data->info->max_xy;
>  	input_set_abs_params(input, ABS_MT_POSITION_X, 0, max_xy, 0, 0);
> @@ -234,6 +357,26 @@ static int exc3000_probe(struct i2c_client *client)
>  	if (error)
>  		return error;
>  
> +	/*
> +	 * I²C does not have built-in recovery, so retry on failure. This ensures,
> +	 * that the device probe will not fail for temporary issues on the bus.
> +	 * This is not needed for the sysfs calls (userspace will receive the error
> +	 * code and can start another query) and cannot be done for touch events
> +	 * (but that only means loosing one or two touch events anyways).
> +	 */
> +	for (retry = 0; retry < 3; ++retry) {
> +		error = exc3000_get_model(data);
> +		if (!error)
> +			break;
> +		dev_warn(&client->dev, "Retry %d get EETI EXC3000 model: %d\n",
> +			 retry + 1, error);
> +	}
> +
> +	if (error)
> +		return error;
> +
> +	dev_dbg(&client->dev, "TS Model: %s", data->model);
> +
>  	return 0;
>  }
>  
>