[media] dvb_frontend.h: Document struct dvb_tuner_ops

The struct dvb_tuner_ops contains lots of callbacks used
by tuners. Document them.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>

drivers/media/dvb-core/dvb_frontend.h

@@ -192,7 +192,53 @@ enum dvbfe_search {
 	DVBFE_ALGO_SEARCH_ERROR		= (1 << 31),
 };
 
-
+/**
+ * struct dvb_tuner_ops - Tuner information and callbacks
+ *
+ * @info:		embedded struct dvb_tuner_info with tuner properties
+ * @release:		callback function called when frontend is dettached.
+ *			drivers should free any allocated memory.
+ * @init:		callback function used to initialize the tuner device.
+ * @sleep:		callback function used to put the tuner to sleep.
+ * @suspend:		callback function used to inform that the Kernel will
+ *			suspend.
+ * @resume:		callback function used to inform that the Kernel is
+ *			resuming from suspend.
+ * @set_params:		callback function used to inform the tuner to tune
+ *			into a digital TV channel. The properties to be used
+ *			are stored at @dvb_frontend.dtv_property_cache;.
+ * @set_analog_params:	callback function used to tune into an analog TV
+ *			channel on hybrid tuners. It passes @analog_parameters;
+ *			to the driver.
+ * @calc_regs:		callback function used to pass register data settings
+ *			for simple tuners.
+ * @set_config:		callback function used to send some tuner-specific
+ *			parameters.
+ * @get_frequency:	get the actual tuned frequency
+ * @get_bandwidth:	get the bandwitdh used by the low pass filters
+ * @get_if_frequency:	get the Intermediate Frequency, in Hz. For baseband,
+ * 			should return 0.
+ * @get_status:		returns the frontend lock status
+ * @get_rf_strength:	returns the RF signal strengh. Used mostly to support
+ *			analog TV and radio. Digital TV should report, instead,
+ *			via DVBv5 API (@dvb_frontend.dtv_property_cache;).
+ * @get_afc:		Used only by analog TV core. Reports the frequency
+ *			drift due to AFC.
+ * @set_frequency:	Set a new frequency. Please notice that using
+ *			set_params is preferred.
+ * @set_bandwidth:	Set a new frequency. Please notice that using
+ *			set_params is preferred.
+ * @set_state:		callback function used on some legacy drivers that
+ * 			don't implement set_params in order to set properties.
+ * 			Shouldn't be used on new drivers.
+ * @get_state:		callback function used to get properties by some
+ * 			legacy drivers that don't implement set_params.
+ * 			Shouldn't be used on new drivers.
+ *
+ * NOTE: frequencies used on get_frequency and set_frequency are in Hz for
+ * terrestrial/cable or kHz for satellite.
+ *
+ */
 struct dvb_tuner_ops {
 
 	struct dvb_tuner_info info;