soundbus.h

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/*
 * soundbus generic definitions
 *
 * Copyright 2006 Johannes Berg <[email protected]>
 *
 * 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
 * and give it CLOCK_SWITCH_PREPARE_SLAVE!
 */
enum clock_switch {
    CLOCK_SWITCH_PREPARE_SLAVE,
    CLOCK_SWITCH_PREPARE_MASTER,
    CLOCK_SWITCH_SLAVE,
    CLOCK_SWITCH_MASTER,
    CLOCK_SWITCH_NOTIFY,
};

/* 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 */
        must_be_clock_source:1;
    /* 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, ofdev.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 (*suspend)(struct soundbus_dev* dev, pm_message_t state);
    int (*resume)(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 device_attribute soundbus_dev_attrs[];

#endif /* __SOUNDBUS_H */