[PATCH 2/2] nvmem: core: add OF_RECONFIG handler for nvmem cells

[Michael Auchter]

CONFIG_OF_DYNAMIC allows runtime changes to the device tree. This patch
adds a OF_RECONFIG handler to receive notifications on tree changes to
support adding/removing cells from an nvmem device based on these
changes.

Signed-off-by: Michael Auchter <michael.auch...@ni.com>
---
 drivers/nvmem/core.c | 61 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 91979529cb07..859431c15d5b 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1629,6 +1629,53 @@ void nvmem_del_cell_lookups(struct nvmem_cell_lookup 
*entries, size_t nentries)
 }
 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
 
+#if IS_ENABLED(CONFIG_OF_DYNAMIC)
+static int of_nvmem_notify(struct notifier_block *nb, unsigned long action,
+                          void *arg)
+{
+
+       struct of_reconfig_data *rd = arg;
+       struct nvmem_device *nvmem;
+       struct nvmem_cell *cell;
+       int rval;
+
+       switch (of_reconfig_get_state_change(action, rd)) {
+       case OF_RECONFIG_CHANGE_ADD:
+               if (of_node_test_and_set_flag(rd->dn, OF_POPULATED))
+                       return NOTIFY_OK;
+
+               nvmem = __nvmem_device_get(rd->dn->parent, 
device_match_of_node);
+               if (IS_ERR(nvmem))
+                       return NOTIFY_OK;
+
+               rval = nvmem_add_cell_from_of(nvmem, rd->dn);
+               return notifier_from_errno(rval);
+               break;
+       case OF_RECONFIG_CHANGE_REMOVE:
+               if (!of_node_check_flag(rd->dn, OF_POPULATED))
+                       return NOTIFY_OK;
+
+               nvmem = __nvmem_device_get(rd->dn->parent, 
device_match_of_node);
+               if (IS_ERR(nvmem))
+                       return NOTIFY_OK;
+
+               cell = nvmem_find_cell_by_node(nvmem, rd->dn);
+               if (!cell)
+                       return NOTIFY_OK;
+
+               nvmem_cell_drop(cell);
+               of_node_clear_flag(rd->dn, OF_POPULATED);
+               break;
+       }
+
+       return NOTIFY_OK;
+}
+
+struct notifier_block nvmem_of_notifier = {
+       .notifier_call = of_nvmem_notify,
+};
+#endif /* CONFIG_OF_DYNAMIC */
+
 /**
  * nvmem_dev_name() - Get the name of a given nvmem device.
  *
@@ -1644,11 +1691,23 @@ EXPORT_SYMBOL_GPL(nvmem_dev_name);
 
 static int __init nvmem_init(void)
 {
-       return bus_register(&nvmem_bus_type);
+       int rval;
+
+       rval = bus_register(&nvmem_bus_type);
+       if (rval)
+               return rval;
+
+       if (IS_ENABLED(CONFIG_OF_DYNAMIC))
+               WARN_ON(of_reconfig_notifier_register(&nvmem_of_notifier));
+
+       return 0;
 }
 
 static void __exit nvmem_exit(void)
 {
+       if (IS_ENABLED(CONFIG_OF_DYNAMIC))
+               WARN_ON(of_reconfig_notifier_unregister(&nvmem_of_notifier));
+
        bus_unregister(&nvmem_bus_type);
 }
 
-- 
2.25.4