uwb: don't unbind the radio controller driver when resetting

Use pre_reset and post_reset methods to avoid unbinding the radio
controller driver after a uwb_rc_reset_all() call.  This avoids a
deadlock in uwb_rc_rm() when waiting for the uwb event thread to stop.

Signed-off-by: David Vrabel <david.vrabel@csr.com>

1 files changed, 43 insertions, 19 deletions

diff --git a/drivers/uwb/umc-bus.c b/drivers/uwb/umc-bus.c
index 2d8d62d..5ad3616 100644
--- a/drivers/uwb/umc-bus.c
+++ b/drivers/uwb/umc-bus.c
@@ -11,23 +11,48 @@
 #include <linux/uwb/umc.h>
 #include <linux/pci.h>
 
-static int umc_bus_unbind_helper(struct device *dev, void *data)
+static int umc_bus_pre_reset_helper(struct device *dev, void *data)
 {
-	struct device *parent = data;
+	int ret = 0;
 
-	if (dev->parent == parent && dev->driver)
-		device_release_driver(dev);
-	return 0;
+	if (dev->driver) {
+		struct umc_dev *umc = to_umc_dev(dev);
+		struct umc_driver *umc_drv = to_umc_driver(dev->driver);
+
+		if (umc_drv->pre_reset)
+			ret = umc_drv->pre_reset(umc);
+		else
+			device_release_driver(dev);
+	}
+	return ret;
+}
+
+static int umc_bus_post_reset_helper(struct device *dev, void *data)
+{
+	int ret = 0;
+
+	if (dev->driver) {
+		struct umc_dev *umc = to_umc_dev(dev);
+		struct umc_driver *umc_drv = to_umc_driver(dev->driver);
+
+		if (umc_drv->post_reset)
+			ret = umc_drv->post_reset(umc);
+	} else
+		ret = device_attach(dev);
+
+	return ret;
 }
 
 /**
  * umc_controller_reset - reset the whole UMC controller
  * @umc: the UMC device for the radio controller.
  *
- * Drivers will be unbound from all UMC devices belonging to the
- * controller and then the radio controller will be rebound.  The
- * radio controller is expected to do a full hardware reset when it is
- * probed.
+ * Drivers or all capabilities of the controller will have their
+ * pre_reset methods called or be unbound from their device.  Then all
+ * post_reset methods will be called or the drivers will be rebound.
+ *
+ * Radio controllers must provide pre_reset and post_reset methods and
+ * reset the hardware in their start method.
  *
  * If this is called while a probe() or remove() is in progress it
  * will return -EAGAIN and not perform the reset.
@@ -35,14 +60,13 @@ static int umc_bus_unbind_helper(struct device *dev, void *data)
 int umc_controller_reset(struct umc_dev *umc)
 {
 	struct device *parent = umc->dev.parent;
-	int ret;
+	int ret = 0;
 
-	if (down_trylock(&parent->sem))
+	if(down_trylock(&parent->sem))
 		return -EAGAIN;
-	bus_for_each_dev(&umc_bus_type, NULL, parent, umc_bus_unbind_helper);
-	ret = device_attach(&umc->dev);
-	if (ret == 1)
-		ret = 0;
+	ret = device_for_each_child(parent, parent, umc_bus_pre_reset_helper);
+	if (ret >= 0)
+		device_for_each_child(parent, parent, umc_bus_post_reset_helper);
 	up(&parent->sem);
 
 	return ret;
@@ -75,10 +99,10 @@ static int umc_bus_rescan_helper(struct device *dev, void *data)
 	if (!dev->driver)
 		ret = device_attach(dev);
 
-	return ret < 0 ? ret : 0;
+	return ret;
 }
 
-static void umc_bus_rescan(void)
+static void umc_bus_rescan(struct device *parent)
 {
 	int err;
 
@@ -86,7 +110,7 @@ static void umc_bus_rescan(void)
 	 * We can't use bus_rescan_devices() here as it deadlocks when
 	 * it tries to retake the dev->parent semaphore.
 	 */
-	err = bus_for_each_dev(&umc_bus_type, NULL, NULL, umc_bus_rescan_helper);
+	err = device_for_each_child(parent, NULL, umc_bus_rescan_helper);
 	if (err < 0)
 		printk(KERN_WARNING "%s: rescan of bus failed: %d\n",
 		       KBUILD_MODNAME, err);
@@ -120,7 +144,7 @@ static int umc_device_probe(struct device *dev)
 	if (err)
 		put_device(dev);
 	else
-		umc_bus_rescan();
+		umc_bus_rescan(dev->parent);
 
 	return err;
 }