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* soundbus generic definitions
* Copyright 2006 Johannes Berg <>
* GPL v2, can be found in COPYING.
#ifndef __SOUNDBUS_H
#define __SOUNDBUS_H
#include <linux/of_device.h>
#include <sound/pcm.h>
#include <linux/list.h>
/* When switching from master to slave or the other way around,
* you don't want to have the codec chip acting as clock source
* while the bus still is.
* More importantly, while switch from slave to master, you need
* to turn off the chip's master function first, but then there's
* no clock for a while and other chips might reset, so we notify
* their drivers after having switched.
* The constants here are codec-point of view, so when we switch
* the soundbus to master we tell the codec we're going to switch
enum clock_switch {
/* information on a transfer the codec can take */
struct transfer_info {
u64 formats; /* SNDRV_PCM_FMTBIT_* */
unsigned int rates; /* SNDRV_PCM_RATE_* */
/* flags */
u32 transfer_in:1, /* input = 1, output = 0 */
/* for codecs to distinguish among their TIs */
int tag;
struct codec_info_item {
struct codec_info *codec;
void *codec_data;
struct soundbus_dev *sdev;
/* internal, to be used by the soundbus provider */
struct list_head list;
/* for prepare, where the codecs need to know
* what we're going to drive the bus with */
struct bus_info {
/* see below */
int sysclock_factor;
int bus_factor;
/* information on the codec itself, plus function pointers */
struct codec_info {
/* the module this lives in */
struct module *owner;
/* supported transfer possibilities, array terminated by
* formats or rates being 0. */
struct transfer_info *transfers;
/* Master clock speed factor
* to be used (master clock speed = sysclock_factor * sampling freq)
* Unused if the soundbus provider has no such notion.
int sysclock_factor;
/* Bus factor, bus clock speed = bus_factor * sampling freq)
* Unused if the soundbus provider has no such notion.
int bus_factor;
/* operations */
/* clock switching, see above */
int (*switch_clock)(struct codec_info_item *cii,
enum clock_switch clock);
/* called for each transfer_info when the user
* opens the pcm device to determine what the
* hardware can support at this point in time.
* That can depend on other user-switchable controls.
* Return 1 if usable, 0 if not.
* out points to another instance of a transfer_info
* which is initialised to the values in *ti, and
* it's format and rate values can be modified by
* the callback if it is necessary to further restrict
* the formats that can be used at the moment, for
* example when one codec has multiple logical codec
* info structs for multiple inputs.
int (*usable)(struct codec_info_item *cii,
struct transfer_info *ti,
struct transfer_info *out);
/* called when pcm stream is opened, probably not implemented
* most of the time since it isn't too useful */
int (*open)(struct codec_info_item *cii,
struct snd_pcm_substream *substream);
/* called when the pcm stream is closed, at this point
* the user choices can all be unlocked (see below) */
int (*close)(struct codec_info_item *cii,
struct snd_pcm_substream *substream);
/* if the codec must forbid some user choices because
* they are not valid with the substream/transfer info,
* it must do so here. Example: no digital output for
* incompatible framerate, say 8KHz, on Onyx.
* If the selected stuff in the substream is NOT
* compatible, you have to reject this call! */
int (*prepare)(struct codec_info_item *cii,
struct bus_info *bi,
struct snd_pcm_substream *substream);
/* start() is called before data is pushed to the codec.
* Note that start() must be atomic! */
int (*start)(struct codec_info_item *cii,
struct snd_pcm_substream *substream);
/* stop() is called after data is no longer pushed to the codec.
* Note that stop() must be atomic! */
int (*stop)(struct codec_info_item *cii,
struct snd_pcm_substream *substream);
int (*suspend)(struct codec_info_item *cii, pm_message_t state);
int (*resume)(struct codec_info_item *cii);
/* information on a soundbus device */
struct soundbus_dev {
/* the bus it belongs to */
struct list_head onbuslist;
/* the of device it represents */
struct platform_device ofdev;
/* what modules go by */
char modalias[32];
/* These fields must be before attach_codec can be called.
* They should be set by the owner of the alsa card object
* that is needed, and whoever sets them must make sure
* that they are unique within that alsa card object. */
char *pcmname;
int pcmid;
/* this is assigned by the soundbus provider in attach_codec */
struct snd_pcm *pcm;
/* operations */
/* attach a codec to this soundbus, give the alsa
* card object the PCMs for this soundbus should be in.
* The 'data' pointer must be unique, it is used as the
* key for detach_codec(). */
int (*attach_codec)(struct soundbus_dev *dev, struct snd_card *card,
struct codec_info *ci, void *data);
void (*detach_codec)(struct soundbus_dev *dev, void *data);
/* TODO: suspend/resume */
/* private for the soundbus provider */
struct list_head codec_list;
u32 have_out:1, have_in:1;
#define to_soundbus_device(d) container_of(d, struct soundbus_dev,
#define of_to_soundbus_device(d) container_of(d, struct soundbus_dev, ofdev)
extern int soundbus_add_one(struct soundbus_dev *dev);
extern void soundbus_remove_one(struct soundbus_dev *dev);
extern struct soundbus_dev *soundbus_dev_get(struct soundbus_dev *dev);
extern void soundbus_dev_put(struct soundbus_dev *dev);
struct soundbus_driver {
char *name;
struct module *owner;
/* we don't implement any matching at all */
int (*probe)(struct soundbus_dev* dev);
int (*remove)(struct soundbus_dev* dev);
int (*shutdown)(struct soundbus_dev* dev);
struct device_driver driver;
#define to_soundbus_driver(drv) container_of(drv,struct soundbus_driver, driver)
extern int soundbus_register_driver(struct soundbus_driver *drv);
extern void soundbus_unregister_driver(struct soundbus_driver *drv);
extern struct attribute *soundbus_dev_attrs[];
#endif /* __SOUNDBUS_H */