Revert "driver core: Delete driver_deferred_probe_check_state()"

This reverts commit 9cbffc7.

There are a few more issues to fix that have been reported in the thread
for the original series [1]. We'll need to fix those before this will work.
So, revert it for now.

[1] - https://lore.kernel.org/lkml/[email protected]/

Fixes: 9cbffc7 ("driver core: Delete driver_deferred_probe_check_state()")
Tested-by: Tony Lindgren <[email protected]>
Tested-by: Peng Fan <[email protected]>
Tested-by: Douglas Anderson <[email protected]>
Tested-by: Alexander Stein <[email protected]>
Reviewed-by: Tony Lindgren <[email protected]>
Signed-off-by: Saravana Kannan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Saravana Kannan

drivers/base/dd.c

@@ -274,12 +274,42 @@ static int __init deferred_probe_timeout_setup(char *str)
 }
 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 
+/**
+ * driver_deferred_probe_check_state() - Check deferred probe state
+ * @dev: device to check
+ *
+ * Return:
+ * * -ENODEV if initcalls have completed and modules are disabled.
+ * * -ETIMEDOUT if the deferred probe timeout was set and has expired
+ *   and modules are enabled.
+ * * -EPROBE_DEFER in other cases.
+ *
+ * Drivers or subsystems can opt-in to calling this function instead of directly
+ * returning -EPROBE_DEFER.
+ */
+int driver_deferred_probe_check_state(struct device *dev)
+{
+	if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
+		dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
+		return -ENODEV;
+	}
+
+	if (!driver_deferred_probe_timeout && initcalls_done) {
+		dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
+		return -ETIMEDOUT;
+	}
+
+	return -EPROBE_DEFER;
+}
+EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
+
 static void deferred_probe_timeout_work_func(struct work_struct *work)
 {
 	struct device_private *p;
 
 	fw_devlink_drivers_done();
 
+	driver_deferred_probe_timeout = 0;
 	driver_deferred_probe_trigger();
 	flush_work(&deferred_probe_work);
 

include/linux/device/driver.h

@@ -242,6 +242,7 @@ driver_find_device_by_acpi_dev(struct device_driver *drv, const void *adev)
 
 extern int driver_deferred_probe_timeout;
 void driver_deferred_probe_add(struct device *dev);
+int driver_deferred_probe_check_state(struct device *dev);
 void driver_init(void);
 
 /**