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Subject[PATCH 2/2] nvmem: core: add OF_RECONFIG handler for nvmem cells
Date
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.auchter@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
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