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Commit a2894e3f authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
Browse files

[media] tuner-core: Improve function documentation 



This driver is complex, and used by everyone. Better to have it
properly documented.

No functional changes are done in this patch.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent ad020dc2

drivers/media/video/tuner-core.c

+116 −23
Original line number Diff line number Diff line 
/*

 *

 * i2c tv tuner chip device driver

 * core core, i.e. kernel interfaces, registering and so on

 *

 * Copyright(c) by Ralph Metzler, Gerd Knorr, Gunther Mayer

 *

 * Copyright(c) 2005-2011 by Mauro Carvalho Chehab

 *	- Added support for a separate Radio tuner

 *	- Major rework and cleanups at the code

 *

 * This driver supports many devices and the idea is to let the driver

 * detect which device is present. So rather than listing all supported

 * devices here, we pretend to support a single, fake device type that will

 * handle both radio and analog TV tuning.

 */



#include <linux/module.h>
@@ -67,6 +77,7 @@ module_param_string(ntsc, ntsc, sizeof(ntsc), 0644); 
 */



static LIST_HEAD(tuner_list);

static const struct v4l2_subdev_ops tuner_ops;



/*

 * Debug macros
@@ -124,6 +135,13 @@ struct tuner { 
	const char          *name;

};



/*

 * Function prototypes

 */



static void set_tv_freq(struct i2c_client *c, unsigned int freq);

static void set_radio_freq(struct i2c_client *c, unsigned int freq);



/*

 * tuner attach/detach logic

 */
@@ -233,13 +251,24 @@ static struct analog_demod_ops tuner_analog_ops = { 
};



/*

 * Functions that are common to both TV and radio

 * Functions to select between radio and TV and tuner probe functions

 */



static void set_tv_freq(struct i2c_client *c, unsigned int freq);

static void set_radio_freq(struct i2c_client *c, unsigned int freq);

static const struct v4l2_subdev_ops tuner_ops;



/**

 * set_type - Sets the tuner type for a given device

 *

 * @c:			i2c_client descriptoy

 * @type:		type of the tuner (e. g. tuner number)

 * @new_mode_mask:	Indicates if tuner supports TV and/or Radio

 * @new_config:		an optional parameter ranging from 0-255 used by

			a few tuners to adjust an internal parameter,

			like LNA mode

 * @tuner_callback:	an optional function to be called when switching

 *			to analog mode

 *

 * This function applys the tuner config to tuner specified

 * by tun_setup structure. It contains several per-tuner initialization "magic"

 */

static void set_type(struct i2c_client *c, unsigned int type,

		     unsigned int new_mode_mask, unsigned int new_config,

		     int (*tuner_callback) (void *dev, int component, int cmd, int arg))
@@ -452,6 +481,15 @@ static int tuner_s_type_addr(struct v4l2_subdev *sd, 
	return 0;

}



/**

 * tuner_s_config - Sets tuner configuration

 *

 * @sd:		subdev descriptor

 * @cfg:	tuner configuration

 *

 * Calls tuner set_config() private function to set some tuner-internal

 * parameters

 */

static int tuner_s_config(struct v4l2_subdev *sd,

			  const struct v4l2_priv_tun_config *cfg)

{
@@ -470,10 +508,20 @@ static int tuner_s_config(struct v4l2_subdev *sd, 
	return 0;

}



/* Search for existing radio and/or TV tuners on the given I2C adapter.

   Note that when this function is called from tuner_probe you can be

   certain no other devices will be added/deleted at the same time, I2C

   core protects against that. */

/**

 * tuner_lookup - Seek for tuner adapters

 *

 * @adap:	i2c_adapter struct

 * @radio:	pointer to be filled if the adapter is radio

 * @tv:		pointer to be filled if the adapter is TV

 *

 * Search for existing radio and/or TV tuners on the given I2C adapter,

 * discarding demod-only adapters (tda9887).

 *

 * Note that when this function is called from tuner_probe you can be

 * certain no other devices will be added/deleted at the same time, I2C

 * core protects against that.

 */

static void tuner_lookup(struct i2c_adapter *adap,

		struct tuner **radio, struct tuner **tv)

{
@@ -502,8 +550,20 @@ static void tuner_lookup(struct i2c_adapter *adap, 
	}

}



/* During client attach, set_type is called by adapter's attach_inform callback.

   set_type must then be completed by tuner_probe.

/**

 *tuner_probe - Probes the existing tuners on an I2C bus

 *

 * @client:	i2c_client descriptor

 * @id:		not used

 *

 * This routine probes for tuners at the expected I2C addresses. On most

 * cases, if a device answers to a given I2C address, it assumes that the

 * device is a tuner. On a few cases, however, an additional logic is needed

 * to double check if the device is really a tuner, or to identify the tuner

 * type, like on tea5767/5761 devices.

 *

 * During client attach, set_type is called by adapter's attach_inform callback.

 * set_type must then be completed by tuner_probe.

 */

static int tuner_probe(struct i2c_client *client,

		       const struct i2c_device_id *id)
@@ -618,6 +678,12 @@ static int tuner_probe(struct i2c_client *client, 
	return 0;

}



/**

 * tuner_remove - detaches a tuner

 *

 * @client:	i2c_client descriptor

 */



static int tuner_remove(struct i2c_client *client)

{

	struct tuner *t = to_tuner(i2c_get_clientdata(client));
@@ -635,7 +701,12 @@ static int tuner_remove(struct i2c_client *client) 
 * Functions that are specific for TV mode

 */



/* Set tuner frequency,  freq in Units of 62.5kHz = 1/16MHz */

/**

 * set_tv_freq - Set tuner frequency,  freq in Units of 62.5 kHz = 1/16MHz

 *

 * @c:	i2c_client descriptor

 * @freq: frequency

 */

static void set_tv_freq(struct i2c_client *c, unsigned int freq)

{

	struct tuner *t = to_tuner(i2c_get_clientdata(c));
@@ -675,7 +746,19 @@ static void set_tv_freq(struct i2c_client *c, unsigned int freq) 
	analog_ops->set_params(&t->fe, &params);

}



/* get more precise norm info from insmod option */

/**

 * tuner_fixup_std - force a given video standard variant

 *

 * @t:	tuner internal struct

 *

 * A few devices or drivers have problem to detect some standard variations.

 * On other operational systems, the drivers generally have a per-country

 * code, and some logic to apply per-country hacks. V4L2 API doesn't provide

 * such hacks. Instead, it relies on a proper video standard selection from

 * the userspace application. However, as some apps are buggy, not allowing

 * to distinguish all video standard variations, a modprobe parameter can

 * be used to force a video standard match.

 */

static int tuner_fixup_std(struct tuner *t)

{

	if ((t->std & V4L2_STD_PAL) == V4L2_STD_PAL) {
@@ -797,6 +880,12 @@ static int tuner_fixup_std(struct tuner *t) 
 * Functions that are specific for Radio mode

 */



/**

 * set_radio_freq - Set tuner frequency,  freq in Units of 62.5 Hz  = 1/16kHz

 *

 * @c:	i2c_client descriptor

 * @freq: frequency

 */

static void set_radio_freq(struct i2c_client *c, unsigned int freq)

{

	struct tuner *t = to_tuner(i2c_get_clientdata(c));
@@ -972,7 +1061,9 @@ static int tuner_s_power(struct v4l2_subdev *sd, int on) 
	return 0;

}



/* ---------------------------------------------------------------------- */

/*

 * Function to splicitly change mode to radio. Probably not needed anymore

 */



static int tuner_s_radio(struct v4l2_subdev *sd)

{
@@ -984,9 +1075,10 @@ static int tuner_s_radio(struct v4l2_subdev *sd) 
	return 0;

}



/* --- v4l ioctls --- */

/* take care: bttv does userspace copying, we'll get a

   kernel pointer here... */

/*

 * Tuner callbacks to handle userspace ioctl's

 */



static int tuner_s_std(struct v4l2_subdev *sd, v4l2_std_id std)

{

	struct tuner *t = to_tuner(sd);
@@ -1137,7 +1229,9 @@ static int tuner_command(struct i2c_client *client, unsigned cmd, void *arg) 
	return -ENOIOCTLCMD;

}



/* ----------------------------------------------------------------------- */

/*

 * Callback structs

 */



static const struct v4l2_subdev_core_ops tuner_core_ops = {

	.log_status = tuner_log_status,
@@ -1160,11 +1254,10 @@ static const struct v4l2_subdev_ops tuner_ops = { 
	.tuner = &tuner_tuner_ops,

};



/* ----------------------------------------------------------------------- */

/*

 * I2C structs and module init functions

 */



/* This driver supports many devices and the idea is to let the driver

   detect which device is present. So rather than listing all supported

   devices here, we pretend to support a single, fake device type. */

static const struct i2c_device_id tuner_id[] = {

	{ "tuner", }, /* autodetect */

	{ }