[systemd-devel] [WIP PATCH 3/4] ACPI: button: Let input filter out the LID events

[Zheng, Lv]

Hi, Benjamin

> From: Benjamin Tissoires [mailto:benjamin.tissoires at redhat.com]
> Subject: [WIP PATCH 3/4] ACPI: button: Let input filter out the LID events
> 
> The input stack already filters out the LID events. So instead of
> filtering them out at the source, we can hook up after the input
> processing and propagate the lid switch events when the input stack
> tells us to.
> 
> An other benefit is that if userspace (think libinput) "fixes" the lid
> switch state by some heuristics, this new state is forwarded to the
> listeners in the kernel.

See my comments to PATCH 4.
IMO, it sounds better that
1. ACPI lid works as a driver of SW_LID, and
2. i915 registers notification (the only user) via input layer.
So it looks i915 rather than button driver should call input_register_handler().
And input layer may help to provide a simplified interface for drivers to register key notifications.

Thanks and best regards
Lv

> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires at redhat.com>
> ---
>  drivers/acpi/button.c | 156 ++++++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 139 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> index 9ad7604..03e5981 100644
> --- a/drivers/acpi/button.c
> +++ b/drivers/acpi/button.c
> @@ -109,8 +109,6 @@ struct acpi_button {
>  	struct input_dev *input;
>  	char phys[32];			/* for input device */
>  	unsigned long pushed;
> -	int last_state;
> -	ktime_t last_time;
>  	bool suspended;
>  };
> 
> @@ -184,7 +182,6 @@ static int acpi_lid_evaluate_state(struct acpi_device *device)
>  static int acpi_lid_notify_state(struct acpi_device *device, int state)
>  {
>  	struct acpi_button *button = acpi_driver_data(device);
> -	int ret;
> 
>  	/* button_input_lock must be held */
> 
> @@ -205,20 +202,129 @@ static int acpi_lid_notify_state(struct acpi_device *device, int state)
>  	if (state)
>  		pm_wakeup_hard_event(&device->dev);
> 
> -	ret = blocking_notifier_call_chain(&acpi_lid_notifier, state, device);
> -	if (ret == NOTIFY_DONE)
> -		ret = blocking_notifier_call_chain(&acpi_lid_notifier, state,
> -						   device);
> -	if (ret == NOTIFY_DONE || ret == NOTIFY_OK) {
> -		/*
> -		 * It is also regarded as success if the notifier_chain
> -		 * returns NOTIFY_OK or NOTIFY_DONE.
> -		 */
> -		ret = 0;
> +	return 0;
> +}
> +
> +/*
> + * Pass incoming event to all connected clients.
> + */
> +static void acpi_button_lid_events(struct input_handle *handle,
> +				   const struct input_value *vals,
> +				   unsigned int count)
> +{
> +	const struct input_value *v;
> +	int state = -1;
> +	int ret;
> +
> +	for (v = vals; v != vals + count; v++) {
> +		switch (v->type) {
> +		case EV_SYN:
> +			if (v->code == SYN_REPORT && state >= 0) {
> +				ret = blocking_notifier_call_chain(&acpi_lid_notifier,
> +								state,
> +								lid_device);
> +				if (ret == NOTIFY_DONE)
> +					ret = blocking_notifier_call_chain(&acpi_lid_notifier,
> +								state,
> +								lid_device);
> +				if (ret == NOTIFY_DONE || ret == NOTIFY_OK) {
> +					/*
> +					 * It is also regarded as success if
> +					 * the notifier_chain returns NOTIFY_OK
> +					 * or NOTIFY_DONE.
> +					 */
> +					ret = 0;
> +				}
> +			}
> +			break;
> +		case EV_SW:
> +			if (v->code == SW_LID)
> +				state = !v->value;
> +			break;
> +		}
>  	}
> -	return ret;
>  }
> 
> +static int acpi_button_lid_connect(struct input_handler *handler,
> +				   struct input_dev *dev,
> +				   const struct input_device_id *id)
> +{
> +	struct input_handle *handle;
> +	int error;
> +
> +	handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
> +	if (!handle)
> +		return -ENOMEM;
> +
> +	handle->dev = dev;
> +	handle->handler = handler;
> +	handle->name = "acpi-button-lid";
> +
> +	error = input_register_handle(handle);
> +	if (error) {
> +		dev_err(&lid_device->dev, "Error installing input handle\n");
> +		goto err_free;
> +	}
> +
> +	error = input_open_device(handle);
> +	if (error) {
> +		dev_err(&lid_device->dev, "Failed to open input device\n");
> +		goto err_unregister;
> +	}
> +
> +	return 0;
> +
> + err_unregister:
> +	input_unregister_handle(handle);
> + err_free:
> +	kfree(handle);
> +	return error;
> +}
> +
> +static void acpi_button_lid_disconnect(struct input_handle *handle)
> +{
> +	input_close_device(handle);
> +	input_unregister_handle(handle);
> +	kfree(handle);
> +}
> +
> +bool acpi_button_lid_match(struct input_handler *handler,
> +			   struct input_dev *dev)
> +{
> +	struct acpi_button *button;
> +
> +	if (!lid_device)
> +		return false;
> +
> +	button = acpi_driver_data(lid_device);
> +
> +	if (dev != button->input)
> +		return false;
> +
> +	return true;
> +}
> +
> +static const struct input_device_id acpi_button_lid_ids[] = {
> +	{
> +		.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
> +		.evbit = { BIT_MASK(EV_SW) },
> +		.swbit = { BIT_MASK(SW_LID) },
> +	},
> +	{ },
> +};
> +
> +MODULE_DEVICE_TABLE(input, acpi_button_lid_ids);
> +
> +static struct input_handler acpi_button_lid_handler = {
> +	.match		= acpi_button_lid_match,
> +	.connect	= acpi_button_lid_connect,
> +	.disconnect	= acpi_button_lid_disconnect,
> +	.events		= acpi_button_lid_events,
> +	.name		= "acpi-lid-callchain",
> +	.id_table	= acpi_button_lid_ids,
> +};
> +
> +
>  static int acpi_button_state_seq_show(struct seq_file *seq, void *offset)
>  {
>  	struct acpi_device *device = seq->private;
> @@ -581,8 +687,6 @@ static int acpi_button_add(struct acpi_device *device)
>  		strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
>  		sprintf(class, "%s/%s",
>  			ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
> -		button->last_state = !!acpi_lid_evaluate_state(device);
> -		button->last_time = ktime_get();
>  	} else {
>  		printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
>  		error = -ENODEV;
> @@ -674,4 +778,22 @@ module_param_call(lid_init_state,
>  		  NULL, 0644);
>  MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
> 
> -module_acpi_driver(acpi_button_driver);
> +static int __init acpi_button_init(void)
> +{
> +	int error;
> +
> +	error = input_register_handler(&acpi_button_lid_handler);
> +	if (error)
> +		return error;
> +
> +	return acpi_bus_register_driver(&acpi_button_driver);
> +}
> +
> +static void __exit acpi_button_exit(void)
> +{
> +	acpi_bus_unregister_driver(&acpi_button_driver);
> +	input_unregister_handler(&acpi_button_lid_handler);
> +}
> +
> +module_init(acpi_button_init);
> +module_exit(acpi_button_exit);
> --
> 2.9.4