[PATCH 1/3] w1: use match() callback instead of hardwiring dev->driver

[Danilo Krummrich <dakr@kernel.org>]

w1 hardwires dev->driver before calling device_register(), relying on
the if (dev->driver) special case in __device_attach() to call
device_bind_driver() and skip normal matching. This is a legacy pattern
that should be replaced with proper match() logic.

Add device types for master and slave devices and implement a w1_match()
callback that routes each device type to its corresponding driver. This
lets the driver core bind w1 devices through the normal
__device_attach_driver() path.

Link: https://lore.kernel.org/driver-core/DKU2J83B6IX6.2CG1WOB66WC39@kernel.org/
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
Compile-tested only, no hardware available.
---
 drivers/w1/w1.c | 37 +++++++++++++++++++++++++------------
 1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 486f321eadc8..faa1c03f4807 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -58,11 +58,6 @@ MODULE_PARM_DESC(slave_ttl,
 DEFINE_MUTEX(w1_mlock);
 LIST_HEAD(w1_masters);
 
-static int w1_master_probe(struct device *dev)
-{
-	return -ENODEV;
-}
-
 static void w1_master_release(struct device *dev)
 {
 	struct w1_master *md = dev_to_w1_master(dev);
@@ -165,24 +160,42 @@ static struct w1_family w1_default_family = {
 	.fops = &w1_default_fops,
 };
 
+static const struct device_type w1_master_device_type = {
+	.name = "w1_master",
+};
+
+static const struct device_type w1_slave_device_type = {
+	.name = "w1_slave",
+};
+
 static int w1_uevent(const struct device *dev, struct kobj_uevent_env *env);
+static struct device_driver w1_slave_driver;
+
+static int w1_match(struct device *dev, const struct device_driver *drv)
+{
+	if (dev->type == &w1_master_device_type)
+		return drv == &w1_master_driver;
+	if (dev->type == &w1_slave_device_type)
+		return drv == &w1_slave_driver;
+	return 0;
+}
 
 static const struct bus_type w1_bus_type = {
 	.name = "w1",
+	.match = w1_match,
 	.uevent = w1_uevent,
 };
 
 struct device_driver w1_master_driver = {
 	.name = "w1_master_driver",
 	.bus = &w1_bus_type,
-	.probe = w1_master_probe,
 };
 
 struct device w1_master_device = {
 	.parent = NULL,
 	.bus = &w1_bus_type,
+	.type = &w1_master_device_type,
 	.init_name = "w1 bus master",
-	.driver = &w1_master_driver,
 	.release = &w1_master_release
 };
 
@@ -195,8 +208,8 @@ static struct device_driver w1_slave_driver = {
 struct device w1_slave_device = {
 	.parent = NULL,
 	.bus = &w1_bus_type,
+	.type = &w1_slave_device_type,
 	.init_name = "w1 bus slave",
-	.driver = &w1_slave_driver,
 	.release = &w1_slave_release
 };
 #endif  /*  0  */
@@ -574,11 +587,11 @@ static int w1_uevent(const struct device *dev, struct kobj_uevent_env *env)
 	const char *event_owner, *name;
 	int err = 0;
 
-	if (dev->driver == &w1_master_driver) {
+	if (dev->type == &w1_master_device_type) {
 		md = container_of(dev, struct w1_master, dev);
 		event_owner = "master";
 		name = md->name;
-	} else if (dev->driver == &w1_slave_driver) {
+	} else if (dev->type == &w1_slave_device_type) {
 		sl = container_of(dev, struct w1_slave, dev);
 		event_owner = "slave";
 		name = sl->name;
@@ -590,7 +603,7 @@ static int w1_uevent(const struct device *dev, struct kobj_uevent_env *env)
 	dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
 			event_owner, name, dev_name(dev));
 
-	if (dev->driver != &w1_slave_driver || !sl)
+	if (dev->type != &w1_slave_device_type || !sl)
 		goto end;
 
 	err = add_uevent_var(env, "W1_FID=%02X", sl->reg_num.family);
@@ -666,8 +679,8 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
 	int err;
 
 	sl->dev.parent = &sl->master->dev;
-	sl->dev.driver = &w1_slave_driver;
 	sl->dev.bus = &w1_bus_type;
+	sl->dev.type = &w1_slave_device_type;
 	sl->dev.release = &w1_slave_release;
 	sl->dev.groups = w1_slave_groups;
 	sl->dev.of_node = of_find_matching_node(sl->master->dev.of_node,

base-commit: 073e62fd33fe9cec754cb89e60c0ebbab781a50a
-- 
2.55.0