V4L/DVB (4665): Add frontend structure callback for bus acquisition.

This patch enables generic bus arbitration callbacks enabling
dvbcore frontend_open and frontend_release to pass 'acquire'
and 'release' hardware messages back into the DVB bridge frameworks.
Frameworks like cx88 can then implement single bus multiple demod
card sharing features, which would prohibit two frontends from attempting
to use a single transport bus at the same time.
Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/dvb/dvb-core/dvb_frontend.c

@@ -1014,6 +1014,13 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
 	if ((ret = dvb_generic_open (inode, file)) < 0)
 		return ret;
 
+	if (fe->ops.ts_bus_ctrl) {
+		if ((ret = fe->ops.ts_bus_ctrl (fe, 1)) < 0) {
+			dvb_generic_release (inode, file);
+			return ret;
+		}
+	}
+
 	if ((file->f_flags & O_ACCMODE) != O_RDONLY) {
 
 		/* normal tune mode when opened R/W */
@@ -1043,6 +1050,9 @@ static int dvb_frontend_release(struct inode *inode, struct file *file)
 	if ((file->f_flags & O_ACCMODE) != O_RDONLY)
 		fepriv->release_jiffies = jiffies;
 
+	if (fe->ops.ts_bus_ctrl)
+		fe->ops.ts_bus_ctrl (fe, 0);
+
 	return dvb_generic_release (inode, file);
 }
 

drivers/media/dvb/dvb-core/dvb_frontend.h

@@ -129,6 +129,7 @@ struct dvb_frontend_ops {
 	int (*enable_high_lnb_voltage)(struct dvb_frontend* fe, long arg);
 	int (*dishnetwork_send_legacy_command)(struct dvb_frontend* fe, unsigned long cmd);
 	int (*i2c_gate_ctrl)(struct dvb_frontend* fe, int enable);
+	int (*ts_bus_ctrl)(struct dvb_frontend* fe, int acquire);
 
 	struct dvb_tuner_ops tuner_ops;
 };