[PATCH 2/4] amba: Fix resource leak for drivers without .remove

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Consider an amba driver with a .probe but without a .remove callback (e.g.
pl061_gpio_driver). The function amba_probe() is called to bind a device
and so dev_pm_domain_attach() and others are called. As there is no remove
callback amba_remove() isn't called at unbind time however and so calling
dev_pm_domain_detach() is missed and the pm domain keeps active.

To fix this always use the core driver callbacks and handle missing amba
callbacks there. For probe refuse registration as a driver without probe
doesn't make sense.

Fixes: 7cfe249475fd ("ARM: AMBA: Add pclk support to AMBA bus infrastructure")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/amba/bus.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 8658e0533b67..8c4a42df47c6 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -300,10 +300,11 @@ static int amba_remove(struct device *dev)
 {
 	struct amba_device *pcdev = to_amba_device(dev);
 	struct amba_driver *drv = to_amba_driver(dev->driver);
-	int ret;
+	int ret = 0;
 
 	pm_runtime_get_sync(dev);
-	ret = drv->remove(pcdev);
+	if (drv->remove)
+		ret = drv->remove(pcdev);
 	pm_runtime_put_noidle(dev);
 
 	/* Undo the runtime PM settings in amba_probe() */
@@ -320,7 +321,9 @@ static int amba_remove(struct device *dev)
 static void amba_shutdown(struct device *dev)
 {
 	struct amba_driver *drv = to_amba_driver(dev->driver);
-	drv->shutdown(to_amba_device(dev));
+
+	if (drv->shutdown)
+		drv->shutdown(to_amba_device(dev));
 }
 
 /**
@@ -333,12 +336,13 @@ static void amba_shutdown(struct device *dev)
  */
 int amba_driver_register(struct amba_driver *drv)
 {
-	drv->drv.bus = &amba_bustype;
+	if (!drv->probe)
+		return -EINVAL;
 
-#define SETFN(fn)	if (drv->fn) drv->drv.fn = amba_##fn
-	SETFN(probe);
-	SETFN(remove);
-	SETFN(shutdown);
+	drv->drv.bus = &amba_bustype;
+	drv->drv.probe = amba_probe;
+	drv->drv.remove = amba_remove;
+	drv->drv.shutdown = amba_shutdown;
 
 	return driver_register(&drv->drv);
 }
-- 
2.29.2