Re: [patch 2.6.25-rc6 1/7] crosslink ACPI and "real" device nodes

Zhao Yakui
2008-03-21T06:55:35Z

On Thu, 2008-03-20 at 14:09 -0700, David Brownell wrote:
> From: David Brownell <dbrownell@users.sourceforge.net>
>
> Add cross-links between ACPI device and "real" devices in sysfs,
> exposing otherwise-hidden interrelationships between the various
> device nodes which ACPI creates. 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.
> The ACPI device has a "physical_node" link pointing to the PNP device.
> Linux drivers currently bind only to the "physical" device nodes.
Very good idea.
But maybe there is a lot of ACPI devices on the laptops. And we take a
little care about the association between the acpi device and "real"
device.
Maybe it is more useful if the link is set up for the acpi device with
the _PRW object. Maybe the link that points to ACPI device with the _PRW
object is created in the /sys/power/.
>
> Other device trees provided by firmware tables could be exported
> using the same scheme; these names aren't ACPI-specific.
>
> (Based on a patch from Zhang Rui. This version is modified to not
> depend on the patch teaching ACPI about driver model wakeup flags.)
> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
> Cc: Zhang Rui <rui.zhang@intel.com>
> ---
> Change from previous version: if creating the link fails, a
> pr_debug level message is emitted.
>
> drivers/acpi/glue.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> --- g26.orig/drivers/acpi/glue.c 2008-03-08 11:11:18.000000000 -0800
> +++ g26/drivers/acpi/glue.c 2008-03-08 11:29:07.000000000 -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 +158,23 @@ 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");
> + if (ret != 0)
> + pr_debug(PREFIX "Can't create %s link for %s\n",
> + "firmware_node", dev->bus_id);
> +
> + ret = sysfs_create_link(&acpi_dev->dev.kobj, &dev->kobj,
> + "physical_node");
> + if (ret != 0)
> + pr_debug(PREFIX "Can't create %s link for %s\n",
> + "physical_node", acpi_dev->dev.bus_id);
> + }
> +
> return 0;
> }
>
> @@ -165,8 +183,17 @@ 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;
> --
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