Re: [Intel-gfx] [PATCH 1/4] ACPI button: provide lid status functions

[ykzhao <yakui.zhao@intel.com>]

On Thu, 2009-07-16 at 06:11 +0800, Jesse Barnes wrote:
> Some drivers need to know when a lid event occurs and get the current
> status.  This can be useful for when a platform firmware clobbers some
> hardware state at lid time, and a driver needs to restore things when
> the lid is opened again.
> 
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/acpi/button.c |   45 +++++++++++++++++++++++++++++++++++++++++++--
>  include/acpi/button.h |   10 ++++++++++
>  2 files changed, 53 insertions(+), 2 deletions(-)
>  create mode 100644 include/acpi/button.h
> 
> diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> index 9195deb..ebb593e 100644
> --- a/drivers/acpi/button.c
> +++ b/drivers/acpi/button.c
> @@ -113,6 +113,9 @@ static const struct file_operations acpi_button_state_fops = {
>  	.release = single_release,
>  };
>  
> +static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
> +static struct acpi_device *lid_device;
If the box is booted with ACPI disabled, the variable of lid_device
won't be initialized correctly. In such case when we call the function
of acpi_lid_open, we will access the uninitialized variable. This is
incorrect.
At the same time we should assume that the LID status is open.
> +
>  /* --------------------------------------------------------------------------
>                                FS Interface (/proc)
>     -------------------------------------------------------------------------- */
> @@ -229,11 +232,38 @@ static int acpi_button_remove_fs(struct acpi_device *device)
>  /* --------------------------------------------------------------------------
>                                  Driver Interface
>     -------------------------------------------------------------------------- */
> +int acpi_lid_notifier_register(struct notifier_block *nb)
> +{
> +	return blocking_notifier_chain_register(&acpi_lid_notifier, nb);
> +}
> +EXPORT_SYMBOL(acpi_lid_notifier_register);
> +
> +int acpi_lid_notifier_unregister(struct notifier_block *nb)
> +{
> +	return blocking_notifier_chain_unregister(&acpi_lid_notifier, nb);
> +}
> +EXPORT_SYMBOL(acpi_lid_notifier_unregister);
> +
> +int acpi_lid_open(void)
> +{
> +	acpi_status status;
> +	unsigned long long state;
> +
> +	status = acpi_evaluate_integer(lid_device->handle, "_LID", NULL,
> +				       &state);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	return !!state;
> +}
> +EXPORT_SYMBOL(acpi_lid_open);
> +
>  static int acpi_lid_send_state(struct acpi_device *device)
>  {
>  	struct acpi_button *button = acpi_driver_data(device);
>  	unsigned long long state;
>  	acpi_status status;
> +	int ret;
>  
>  	status = acpi_evaluate_integer(device->handle, "_LID", NULL, &state);
>  	if (ACPI_FAILURE(status))
> @@ -242,7 +272,12 @@ static int acpi_lid_send_state(struct acpi_device *device)
>  	/* input layer checks if event is redundant */
>  	input_report_switch(button->input, SW_LID, !state);
>  	input_sync(button->input);
> -	return 0;
> +
> +	ret = blocking_notifier_call_chain(&acpi_lid_notifier, state, device);
> +	if (ret == NOTIFY_DONE)
> +		ret = blocking_notifier_call_chain(&acpi_lid_notifier, state,
> +						   device);
> +	return ret;
>  }
>  
>  static void acpi_button_notify(struct acpi_device *device, u32 event)
> @@ -364,8 +399,14 @@ static int acpi_button_add(struct acpi_device *device)
>  	error = input_register_device(input);
>  	if (error)
>  		goto err_remove_fs;
> -	if (button->type == ACPI_BUTTON_TYPE_LID)
> +	if (button->type == ACPI_BUTTON_TYPE_LID) {
>  		acpi_lid_send_state(device);
> +		/*
> +		 * This assumes there's only one lid device, or if there are
> +		 * more we only care about the last one...
> +		 */
> +		lid_device = device;
> +	}
>  
>  	if (device->wakeup.flags.valid) {
>  		/* Button's GPE is run-wake GPE */
> diff --git a/include/acpi/button.h b/include/acpi/button.h
> new file mode 100644
> index 0000000..bb643a7
> --- /dev/null
> +++ b/include/acpi/button.h
> @@ -0,0 +1,10 @@
> +#ifndef ACPI_BUTTON_H
> +#define ACPI_BUTTON_H
> +
> +#include <linux/notifier.h>
Maybe sometimes the CONFIG_ACPI is disabled in kernel configuration. 
So it will be better that we define another function set when
CONFIG_ACPI is disabled in kernel configuration.

Thanks.
   Yakui
> +
> +extern int acpi_lid_notifier_register(struct notifier_block *nb);
> +extern int acpi_lid_notifier_unregister(struct notifier_block *nb);
> +extern int acpi_lid_open(void);
> +
> +#endif /* ACPI_BUTTON_H */