V4L/DVB (13103): create a standard method for dvb adapter drivers to override frontend ioctls

Signed-off-by: Michael Krufky <mkrufky@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 47 insertions, 1 deletions

diff --git a/drivers/media/dvb/dvb-core/dvb_frontend.c b/drivers/media/dvb/dvb-core/dvb_frontend.c
index 9808241..e9ec8e9 100644
--- a/drivers/media/dvb/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb/dvb-core/dvb_frontend.c
@@ -1712,7 +1712,18 @@ static int dvb_frontend_ioctl_legacy(struct inode *inode, struct file *file,
 	struct dvb_device *dvbdev = file->private_data;
 	struct dvb_frontend *fe = dvbdev->priv;
 	struct dvb_frontend_private *fepriv = fe->frontend_priv;
-	int err = -EOPNOTSUPP;
+	int cb_err, err = -EOPNOTSUPP;
+
+	if (fe->dvb->fe_ioctl_override) {
+		cb_err = fe->dvb->fe_ioctl_override(fe, cmd, parg,
+						    DVB_FE_IOCTL_PRE);
+		if (cb_err < 0)
+			return cb_err;
+		if (cb_err > 0)
+			return 0;
+		/* fe_ioctl_override returning 0 allows
+		 * dvb-core to continue handling the ioctl */
+	}
 
 	switch (cmd) {
 	case FE_GET_INFO: {
@@ -1978,6 +1989,13 @@ static int dvb_frontend_ioctl_legacy(struct inode *inode, struct file *file,
 		break;
 	};
 
+	if (fe->dvb->fe_ioctl_override) {
+		cb_err = fe->dvb->fe_ioctl_override(fe, cmd, parg,
+						    DVB_FE_IOCTL_POST);
+		if (cb_err < 0)
+			return cb_err;
+	}
+
 	return err;
 }
 
diff --git a/drivers/media/dvb/dvb-core/dvbdev.h b/drivers/media/dvb/dvb-core/dvbdev.h
index 01fc704..f7b499d 100644
--- a/drivers/media/dvb/dvb-core/dvbdev.h
+++ b/drivers/media/dvb/dvb-core/dvbdev.h
@@ -54,6 +54,8 @@
 	module_param_array(adapter_nr, short, NULL, 0444); \
 	MODULE_PARM_DESC(adapter_nr, "DVB adapter numbers")
 
+struct dvb_frontend;
+
 struct dvb_adapter {
 	int num;
 	struct list_head list_head;
@@ -69,6 +71,32 @@ struct dvb_adapter {
 	int mfe_shared;			/* indicates mutually exclusive frontends */
 	struct dvb_device *mfe_dvbdev;	/* frontend device in use */
 	struct mutex mfe_lock;		/* access lock for thread creation */
+
+	/* Allow the adapter/bridge driver to perform an action before and/or
+	 * after the core handles an ioctl:
+	 *
+	 * DVB_FE_IOCTL_PRE indicates that the ioctl has not yet been handled.
+	 * DVB_FE_IOCTL_POST indicates that the ioctl has been handled.
+	 *
+	 * When DVB_FE_IOCTL_PRE is passed to the callback as the stage arg:
+	 *
+	 * return 0 to allow dvb-core to handle the ioctl.
+	 * return a positive int to prevent dvb-core from handling the ioctl,
+	 * 	and exit without error.
+	 * return a negative int to prevent dvb-core from handling the ioctl,
+	 * 	and return that value as an error.
+	 *
+	 * When DVB_FE_IOCTL_POST is passed to the callback as the stage arg:
+	 *
+	 * return 0 to allow the dvb_frontend ioctl handler to exit normally.
+	 * return a negative int to cause the dvb_frontend ioctl handler to
+	 * 	return that value as an error.
+	 */
+#define DVB_FE_IOCTL_PRE 0
+#define DVB_FE_IOCTL_POST 1
+	int (*fe_ioctl_override)(struct dvb_frontend *fe,
+				 unsigned int cmd, void *parg,
+				 unsigned int stage);
 };