From 9da3489210fe1870491b0cc49c0304994baa7e96 Mon Sep 17 00:00:00 2001 From: Tyrel Datwyler Date: Wed, 19 Feb 2014 12:56:54 -0800 Subject: [PATCH] powerpc/pseries: Expose in kernel device tree update to drmgr 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 an update entirely in the kernel during the resume. Therefore, a mechanism is required to expose that information to drmgr. This patch adds a show function to the "hibernate" attribute that returns 1 if the kernel performs a device tree update after the resume and 0 otherwise. This allows newer versions of drmgr to avoid doing a second unnecessary device tree update. Signed-off-by: Tyrel Datwyler Signed-off-by: Benjamin Herrenschmidt --- 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 1d9c580ab772..b87b97849d4c 100644 --- a/arch/powerpc/platforms/pseries/suspend.c +++ b/arch/powerpc/platforms/pseries/suspend.c @@ -192,7 +192,30 @@ static ssize_t store_hibernate(struct device *dev, 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", -- GitLab