linux-kernel - Re: [PATCH V5 05/12] ACPI: check and enumerate CMOS RTC devices explicitly

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Date:	Mon, 28 Apr 2014 00:17:49 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Zhang Rui <rui.zhang@...el.com>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	bhelgaas@...gle.com, matthew.garrett@...ula.com,
	rafael.j.wysocki@...el.com, dmitry.torokhov@...il.com
Subject: Re: [PATCH V5 05/12] ACPI: check and enumerate CMOS RTC devices explicitly

On Tuesday, April 08, 2014 12:06:52 AM Zhang Rui wrote:
> For CMOS RTC devices, the acpi pnp scan handler does not work because
> there is already a cmos rtc scan handler installed, thus we need to
> check those devices and enumerate them to PNP bus explicitly.
> Plus, the cmos rtc scan handler needs to return 1 so that it will not
> be enumerated to platform bus.
> 
> Note: the CMOS RTC device id is not removed from ACPI pnp scan handler
>       id list, thus, if cmos rtc scan handler is compiled out, the ACPI
>       pnp scan handler will be attached to the CMOS RTC devices instead,
>       to prevent these devices from being created to platform bus.
> 
> Signed-off-by: Zhang Rui <rui.zhang@...el.com>
> ---
>  drivers/acpi/acpi_cmos_rtc.c |    2 +-
>  drivers/acpi/acpi_pnp.c      |   22 +++++++++++++++++++++-
>  2 files changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_cmos_rtc.c b/drivers/acpi/acpi_cmos_rtc.c
> index 961b45d..2da8660 100644
> --- a/drivers/acpi/acpi_cmos_rtc.c
> +++ b/drivers/acpi/acpi_cmos_rtc.c
> @@ -68,7 +68,7 @@ static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev,
>  		return -ENODEV;
>  	}
>  
> -	return 0;
> +	return 1;
>  }
>  
>  static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev)
> diff --git a/drivers/acpi/acpi_pnp.c b/drivers/acpi/acpi_pnp.c
> index 8cf7d9d..387b150 100644
> --- a/drivers/acpi/acpi_pnp.c
> +++ b/drivers/acpi/acpi_pnp.c
> @@ -349,9 +349,29 @@ static struct acpi_scan_handler acpi_pnp_handler = {
>  	.attach = acpi_pnp_scan_handler_attach,
>  };
>  
> +/*
> + * For CMOS RTC devices, the acpi pnp spcan handler does not work because
> + * there is already a cmos rtc scan handler installed, thus we need to
> + * check those devices and enumerate them to PNP bus explicitly.
> + */
> +static int is_cmos_rtc_device(struct acpi_device *adev)
> +{
> +	struct acpi_device_id ids[] = {
> +		{ "PNP0B00" },
> +		{ "PNP0B01" },
> +		{ "PNP0B02" },
> +		{""},
> +	};
> +	return !acpi_match_device_ids(adev, ids);
> +}
> +
>  bool acpi_is_pnp_device(struct acpi_device *device)
>  {
> -	return device->handler == &acpi_pnp_handler;
> +	if (device->handler == &acpi_pnp_handler)
> +		return true;
> +	if (is_cmos_rtc_device(device))
> +		return true;
> +	return false;

What about doing

	return device->handler == &acpi_pnp_handler || is_cmos_rtc_device(device);

instead?

>  }
>  EXPORT_SYMBOL_GPL(acpi_is_pnp_device);
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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