Re: [patch 2.6.25-rc2-git] crosslink ACPI and "real" device nodes

Zhang, Rui
2008-02-26T06:34:11Z

On Sat, 2008-02-23 at 13:54 +0800, David Brownell wrote:
> Add cross-links between ACPI device and "real" devices in sysfs,
> exposing otherwise-hidden interrelationships between the various
> device nodes for ACPI stuff. As a representative example, one
> hardware device is exposed as two logical devices (PNP and ACPI):
>
> .../pnp0/00:06/
> .../LNXSYSTM:00/device:00/PNP0A03:00/device:15/PNP0B00:00/
>
> The PNP device gets a "firmware_node" link pointing to the ACPI
> device,
> and is what a Linux device driver binds to. The ACPI device has
> instead
> a "physical_node" link pointing back to the PNP device. Other
> firmware
> frameworks, like OpenFirmware, could do the same thing to couple their
> firmware tables to the rest of the system.
>
> (Based on a patch from Zhang Rui. This version is modified to not
> depend on the patch makig ACPI initialize driver model wakeup flags.)
>
> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
> Cc: Zhang Rui <rui.zhang@intel.com>
> ---
> Another extract from the "teach ACPI how to use driver model wakeup
> flags" patch series. The linkage helps sort out confusion about which
> devices are wakeup-capable, among other things, and can help when
> interpreting /proc/acpi/wakeup contents.
>
> drivers/acpi/glue.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> --- g26.orig/drivers/acpi/glue.c 2008-02-22 20:39:19.000000000
> -0800
> +++ g26/drivers/acpi/glue.c 2008-02-22 20:46:40.000000000 -0800
> @@ -142,6 +142,7 @@ EXPORT_SYMBOL(acpi_get_physical_device);
>
> static int acpi_bind_one(struct device *dev, acpi_handle handle)
> {
> + struct acpi_device *acpi_dev;
> acpi_status status;
>
> if (dev->archdata.acpi_handle) {
> @@ -157,6 +158,16 @@ static int acpi_bind_one(struct device *
> }
> dev->archdata.acpi_handle = handle;
>
> + status = acpi_bus_get_device(handle, &acpi_dev);
> + if (!ACPI_FAILURE(status)) {
> + int ret;
> +
> + ret = sysfs_create_link(&dev->kobj,
> &acpi_dev->dev.kobj,
> + "firmware_node");
> + ret = sysfs_create_link(&acpi_dev->dev.kobj,
> &dev->kobj,
> + "physical_node");
> + }
ret is not needed here...

> return 0;
> }
>
> @@ -165,8 +176,17 @@ static int acpi_unbind_one(struct device
> if (!dev->archdata.acpi_handle)
> return 0;
> if (dev ==
> acpi_get_physical_device(dev->archdata.acpi_handle)) {
> + struct acpi_device *acpi_dev;
> +
> /* acpi_get_physical_device increase refcnt by one */
> put_device(dev);
> +
> + if (!acpi_bus_get_device(dev->archdata.acpi_handle,
> + &acpi_dev)) {
> + sysfs_remove_link(&dev->kobj,
> "firmware_node");
> + sysfs_remove_link(&acpi_dev->dev.kobj,
> "physical_node");
> + }
> +
> acpi_detach_data(dev->archdata.acpi_handle,
> acpi_glue_data_handler);
> dev->archdata.acpi_handle = NULL;
>
>