On 01/22/2014 01:58 PM, Tyrel Datwyler wrote:
> Traditionally it has been drmgr's responsibilty to update the device tree
> through the /proc/ppc64/ofdt interface after a suspend/resume operation.
> This patchset however has modified suspend/resume ops to preform that update
> entirely in the kernel during the resume. Therefore, a mechanism is required
> for drmgr to determine who is responsible for the update. This patch adds a
> show function to the "hibernate" attribute that returns 1 if the kernel
> updates the device tree after the resume and 0 if drmgr is responsible.
>
> Signed-off-by: Tyrel Datwyler <tyr...@linux.vnet.ibm.com>
Acked-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/pseries/suspend.c | 25 ++++++++++++++++++++++++-
> 1 file changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/pseries/suspend.c
> b/arch/powerpc/platforms/pseries/suspend.c
> index 16a2552..723115d 100644
> --- a/arch/powerpc/platforms/pseries/suspend.c
> +++ b/arch/powerpc/platforms/pseries/suspend.c
> @@ -174,7 +174,30 @@ out:
> return rc;
> }
>
> -static DEVICE_ATTR(hibernate, S_IWUSR, NULL, store_hibernate);
> +#define USER_DT_UPDATE 0
> +#define KERN_DT_UPDATE 1
> +
> +/**
> + * show_hibernate - Report device tree update responsibilty
> + * @dev: subsys root device
> + * @attr: device attribute struct
> + * @buf: buffer
> + *
> + * Report whether a device tree update is performed by the kernel after a
> + * resume, or if drmgr must coordinate the update from user space.
> + *
> + * Return value:
> + * 0 if drmgr is to initiate update, and 1 otherwise
> + **/
> +static ssize_t show_hibernate(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + return sprintf(buf, "%d\n", KERN_DT_UPDATE);
> +}
> +
> +static DEVICE_ATTR(hibernate, S_IWUSR | S_IRUGO,
> + show_hibernate, store_hibernate);
>
> static struct bus_type suspend_subsys = {
> .name = "power",
>
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