[PATCH v3] software node: Implement device_get_match_data fwnode callback

[Sui Jingfeng <sui.jingfeng@linux.dev>]

Because the software node backend of the fwnode API framework lacks an
implementation for the .device_get_match_data function callback. This
makes it difficult to use(and/or test) a few drivers that originates
from DT world on the non-DT platform.

Implement the .device_get_match_data fwnode callback, which helps to keep
the three backends of the fwnode API aligned as much as possible. This is
also a fundamental step to make a few drivers OF-independent truely
possible.

Device drivers or platform setup codes are expected to provide a software
node string property, named as "compatible". At this moment, the value of
this string property is being used to match against the compatible entries
in the of_device_id table. It can be extended in the future though.

Fixes: ffb42e64561e ("drm/tiny/repaper: Make driver OF-independent")
Fixes: 5703d6ae9573 ("drm/tiny/st7735r: Make driver OF-independent")
Signed-off-by: Sui Jingfeng <sui.jingfeng@linux.dev>
---
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Daniel Scally <djrscally@gmail.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
---
v1 -> v2: Update commit message
v2 -> v3: Move a loop invariant conditional out of while clause
---
 drivers/base/swnode.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index eb6eb25b343b..b6f40715c4f8 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -15,6 +15,7 @@
 #include <linux/kobject.h>
 #include <linux/kstrtox.h>
 #include <linux/list.h>
+#include <linux/mod_devicetable.h>
 #include <linux/property.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
@@ -390,6 +391,33 @@ static void software_node_put(struct fwnode_handle *fwnode)
 	kobject_put(&swnode->kobj);
 }
 
+static const void *
+software_node_get_match_data(const struct fwnode_handle *fwnode,
+			     const struct device *dev)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+	const struct of_device_id *matches = dev->driver->of_match_table;
+	const char *val = NULL;
+	int ret;
+
+	ret = property_entry_read_string_array(swnode->node->properties,
+					       "compatible", &val, 1);
+	if (ret < 0 || !val)
+		return NULL;
+
+	if (!matches)
+		return NULL;
+
+	while (matches->compatible[0]) {
+		if (!strcmp(matches->compatible, val))
+			return matches->data;
+
+		++matches;
+	}
+
+	return NULL;
+}
+
 static bool software_node_property_present(const struct fwnode_handle *fwnode,
 					   const char *propname)
 {
@@ -676,6 +704,7 @@ software_node_graph_parse_endpoint(const struct fwnode_handle *fwnode,
 static const struct fwnode_operations software_node_ops = {
 	.get = software_node_get,
 	.put = software_node_put,
+	.device_get_match_data = software_node_get_match_data,
 	.property_present = software_node_property_present,
 	.property_read_int_array = software_node_read_int_array,
 	.property_read_string_array = software_node_read_string_array,
-- 
2.34.1