platform/x86: wmi: Add driver_override support

Add support for forcing the WMI driver core to bind
a certain WMI driver to a WMI device. This will be
necessary to support generic WMI drivers without an
ID table

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240624173116.31314-2-W_Armin@gmx.de
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index d21f3fa25823..6bfae28b962a 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -772,11 +772,39 @@ static ssize_t expensive_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(expensive);
 
+static ssize_t driver_override_show(struct device *dev, struct device_attribute *attr,
+				    char *buf)
+{
+	struct wmi_device *wdev = to_wmi_device(dev);
+	ssize_t ret;
+
+	device_lock(dev);
+	ret = sysfs_emit(buf, "%s\n", wdev->driver_override);
+	device_unlock(dev);
+
+	return ret;
+}
+
+static ssize_t driver_override_store(struct device *dev, struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct wmi_device *wdev = to_wmi_device(dev);
+	int ret;
+
+	ret = driver_set_override(dev, &wdev->driver_override, buf, count);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+static DEVICE_ATTR_RW(driver_override);
+
 static struct attribute *wmi_attrs[] = {
 	&dev_attr_modalias.attr,
 	&dev_attr_guid.attr,
 	&dev_attr_instance_count.attr,
 	&dev_attr_expensive.attr,
+	&dev_attr_driver_override.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(wmi);
@@ -845,6 +873,7 @@ static void wmi_dev_release(struct device *dev)
 {
 	struct wmi_block *wblock = dev_to_wblock(dev);
 
+	kfree(wblock->dev.driver_override);
 	kfree(wblock);
 }
 
@@ -854,6 +883,10 @@ static int wmi_dev_match(struct device *dev, struct device_driver *driver)
 	struct wmi_block *wblock = dev_to_wblock(dev);
 	const struct wmi_device_id *id = wmi_driver->id_table;
 
+	/* When driver_override is set, only bind to the matching driver */
+	if (wblock->dev.driver_override)
+		return !strcmp(wblock->dev.driver_override, driver->name);
+
 	if (id == NULL)
 		return 0;