@@ -192,7 +192,30 @@ 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",
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 <tyreld@linux.vnet.ibm.com> --- arch/powerpc/platforms/pseries/suspend.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)