of/reconfig: Add of_reconfig_get_state_change() of notifier helper.

Introduce of_reconfig_get_state_change() which allows an of notifier
to query about device state changes.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 661ad2f5c00c..6659c39ab3aa 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -85,6 +85,102 @@ int of_reconfig_notify(unsigned long action, void *p)
         return notifier_to_errno(rc);
 }
 
+/*
+ * of_reconfig_get_state_change()       - Returns new state of device
+ * @action      - action of the of notifier
+ * @arg         - argument of the of notifier
+ *
+ * Returns the new state of a device based on the notifier used.
+ * Returns 0 on device going from enabled to disabled, 1 on device
+ * going from disabled to enabled and -1 on no change.
+ */
+int of_reconfig_get_state_change(unsigned long action, void *arg)
+{
+        struct device_node *dn;
+        struct property *prop, *old_prop;
+        struct of_prop_reconfig *pr;
+        int is_status, status_state, old_status_state, prev_state, new_state;
+
+        /* figure out if a device should be created or destroyed */
+        dn = NULL;
+        prop = old_prop = NULL;
+        switch (action) {
+        case OF_RECONFIG_ATTACH_NODE:
+        case OF_RECONFIG_DETACH_NODE:
+                dn = arg;
+                prop = of_find_property(dn, "status", NULL);
+                break;
+        case OF_RECONFIG_ADD_PROPERTY:
+        case OF_RECONFIG_REMOVE_PROPERTY:
+                pr = arg;
+                dn = pr->dn;
+                prop = pr->prop;
+                break;
+        case OF_RECONFIG_UPDATE_PROPERTY:
+                pr = arg;
+                dn = pr->dn;
+                prop = pr->prop;
+                old_prop = pr->old_prop;
+                break;
+        default:
+                return OF_RECONFIG_NO_CHANGE;
+        }
+
+        is_status = 0;
+        status_state = -1;
+        old_status_state = -1;
+        prev_state = -1;
+        new_state = -1;
+
+        if (prop && !strcmp(prop->name, "status")) {
+                is_status = 1;
+                status_state = !strcmp(prop->value, "okay") ||
+                               !strcmp(prop->value, "ok");
+                if (old_prop)
+                        old_status_state = !strcmp(old_prop->value, "okay") ||
+                                           !strcmp(old_prop->value, "ok");
+        }
+
+        switch (action) {
+        case OF_RECONFIG_ATTACH_NODE:
+                prev_state = 0;
+                /* -1 & 0 status either missing or okay */
+                new_state = status_state != 0;
+                break;
+        case OF_RECONFIG_DETACH_NODE:
+                /* -1 & 0 status either missing or okay */
+                prev_state = status_state != 0;
+                new_state = 0;
+                break;
+        case OF_RECONFIG_ADD_PROPERTY:
+                if (is_status) {
+                        /* no status property -> enabled (legacy) */
+                        prev_state = 1;
+                        new_state = status_state;
+                }
+                break;
+        case OF_RECONFIG_REMOVE_PROPERTY:
+                if (is_status) {
+                        prev_state = status_state;
+                        /* no status property -> enabled (legacy) */
+                        new_state = 1;
+                }
+                break;
+        case OF_RECONFIG_UPDATE_PROPERTY:
+                if (is_status) {
+                        prev_state = old_status_state != 0;
+                        new_state = status_state != 0;
+                }
+                break;
+        }
+
+        if (prev_state == new_state)
+                return OF_RECONFIG_NO_CHANGE;
+
+        return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
+}
+EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);
+
 int of_property_notify(int action, struct device_node *np,
                        struct property *prop, struct property *oldprop)
 {