From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com
In order to provide explicit synchronization between backend and frontend the following changes are introduced in the protocol: - add new ring buffer for sending asynchronous events from backend to frontend to report number of bytes played by the frontend (XENSND_EVT_CUR_POS) - introduce trigger events for playback control: start/stop/pause/resume - add "req-" prefix to event-channel and ring-ref to unify naming of the Xen event channels for requests and events
Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com Signed-off-by: Oleksandr Grytsov oleksandr_grytsov@epam.com Cc: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Cc: Takashi Iwai tiwai@suse.de Cc: Takashi Sakamoto o-takashi@sakamocchi.jp Cc: Clemens Ladisch clemens@ladisch.de --- xen/include/public/io/sndif.h | 162 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 161 insertions(+), 1 deletion(-)
diff --git a/xen/include/public/io/sndif.h b/xen/include/public/io/sndif.h index ec47ff990f2c..be8d7c83fa72 100644 --- a/xen/include/public/io/sndif.h +++ b/xen/include/public/io/sndif.h @@ -113,6 +113,8 @@ * * /local/domain/1/device/vsnd/0/0/0/ring-ref = "386" * /local/domain/1/device/vsnd/0/0/0/event-channel = "15" + * /local/domain/1/device/vsnd/0/0/0/evt-ring-ref = "1386" + * /local/domain/1/device/vsnd/0/0/0/evt-event-channel = "215" * *------------------------------ Stream 1, capture ---------------------------- * @@ -122,6 +124,8 @@ * * /local/domain/1/device/vsnd/0/0/1/ring-ref = "384" * /local/domain/1/device/vsnd/0/0/1/event-channel = "13" + * /local/domain/1/device/vsnd/0/0/1/evt-ring-ref = "1384" + * /local/domain/1/device/vsnd/0/0/1/evt-event-channel = "213" * *------------------------------- PCM device 1 -------------------------------- * @@ -135,6 +139,8 @@ * * /local/domain/1/device/vsnd/0/1/0/ring-ref = "387" * /local/domain/1/device/vsnd/0/1/0/event-channel = "151" + * /local/domain/1/device/vsnd/0/1/0/evt-ring-ref = "1387" + * /local/domain/1/device/vsnd/0/1/0/evt-event-channel = "351" * *------------------------------- PCM device 2 -------------------------------- * @@ -147,6 +153,8 @@ * * /local/domain/1/device/vsnd/0/2/0/ring-ref = "389" * /local/domain/1/device/vsnd/0/2/0/event-channel = "152" + * /local/domain/1/device/vsnd/0/2/0/evt-ring-ref = "1389" + * /local/domain/1/device/vsnd/0/2/0/evt-event-channel = "452" * ****************************************************************************** * Backend XenBus Nodes @@ -292,6 +300,23 @@ * The Xen grant reference granting permission for the backend to map * a sole page in a single page sized ring buffer. * + *--------------------- Stream Event Transport Parameters --------------------- + * + * This communication path is used to deliver asynchronous events from backend + * to frontend, set up per stream. + * + * evt-event-channel + * Values: <uint32_t> + * + * The identifier of the Xen event channel used to signal activity + * in the ring buffer. + * + * evt-ring-ref + * Values: <uint32_t> + * + * The Xen grant reference granting permission for the backend to map + * a sole page in a single page sized ring buffer. + * ****************************************************************************** * STATE DIAGRAMS ****************************************************************************** @@ -439,6 +464,19 @@ #define XENSND_OP_GET_VOLUME 5 #define XENSND_OP_MUTE 6 #define XENSND_OP_UNMUTE 7 +#define XENSND_OP_TRIGGER 8 + +#define XENSND_OP_TRIGGER_START 0 +#define XENSND_OP_TRIGGER_PAUSE 1 +#define XENSND_OP_TRIGGER_STOP 2 +#define XENSND_OP_TRIGGER_RESUME 3 + +/* + ****************************************************************************** + * EVENT CODES + ****************************************************************************** + */ +#define XENSND_EVT_CUR_POS 0
/* ****************************************************************************** @@ -455,6 +493,8 @@ #define XENSND_FIELD_VCARD_LONG_NAME "long-name" #define XENSND_FIELD_RING_REF "ring-ref" #define XENSND_FIELD_EVT_CHNL "event-channel" +#define XENSND_FIELD_EVT_RING_REF "evt-ring-ref" +#define XENSND_FIELD_EVT_EVT_CHNL "evt-event-channel" #define XENSND_FIELD_DEVICE_NAME "name" #define XENSND_FIELD_TYPE "type" #define XENSND_FIELD_STREAM_UNIQUE_ID "unique-id" @@ -566,7 +606,9 @@ * +----------------+----------------+----------------+----------------+ * | gref_directory | 24 * +----------------+----------------+----------------+----------------+ - * | reserved | 28 + * | period_sz | 28 + * +----------------+----------------+----------------+----------------+ + * | reserved | 32 * +----------------+----------------+----------------+----------------+ * |//////////////////////////////////| * +----------------+----------------+----------------+----------------+ @@ -578,6 +620,14 @@ * pcm_channels - uint8_t, number of channels of this stream, * [channels-min; channels-max] * buffer_sz - uint32_t, buffer size to be allocated, octets + * period_sz - uint32_t, event period size, octets + * This is the requested value of the period at which frontend would + * like to receive XENSND_EVT_CUR_POS notifications from the backend when + * stream position advances during playback/capture. + * It shows how many octets are expected to be played/captured before + * sending such an event. + * If set to 0 no XENSND_EVT_CUR_POS events are sent by the backend. + * * gref_directory - grant_ref_t, a reference to the first shared page * describing shared buffer references. At least one page exists. If shared * buffer size (buffer_sz) exceeds what can be addressed by this single page, @@ -592,6 +642,7 @@ struct xensnd_open_req { uint16_t reserved; uint32_t buffer_sz; grant_ref_t gref_directory; + uint32_t period_sz; };
/* @@ -754,8 +805,32 @@ struct xensnd_rw_req { * * The 'struct xensnd_rw_req' is also used for XENSND_OP_SET_VOLUME, * XENSND_OP_GET_VOLUME, XENSND_OP_MUTE, XENSND_OP_UNMUTE. + * + * Request stream running state change - trigger PCM stream running state + * to start, stop, pause or resume: + * + * 0 1 2 3 octet + * +----------------+----------------+----------------+----------------+ + * | id | _OP_TRIGGER | reserved | 4 + * +----------------+----------------+----------------+----------------+ + * | reserved | 8 + * +----------------+----------------+----------------+----------------+ + * | type | reserved | 12 + * +----------------+----------------+----------------+----------------+ + * | reserved | 16 + * +----------------+----------------+----------------+----------------+ + * |//////////////////////////////////| + * +----------------+----------------+----------------+----------------+ + * | reserved | 64 + * +----------------+----------------+----------------+----------------+ + * + * type - uint8_t, XENSND_OP_TRIGGER_XXX value */
+struct xensnd_trigger_req { + uint8_t type; +}; + /* *---------------------------------- Responses -------------------------------- * @@ -778,8 +853,51 @@ struct xensnd_rw_req { * id - uint16_t, copied from the request * operation - uint8_t, XENSND_OP_* - copied from request * status - int32_t, response status, zero on success and -XEN_EXX on failure + * + *----------------------------------- Events ---------------------------------- + * + * Events are sent via shared page allocated by the front and propagated by + * evt-event-channel/evt-ring-ref XenStore entries + * All event packets have the same length (64 octets) + * All event packets have common header: + * 0 1 2 3 octet + * +----------------+----------------+----------------+----------------+ + * | id | type | reserved | 4 + * +----------------+----------------+----------------+----------------+ + * | reserved | 8 + * +----------------+----------------+----------------+----------------+ + * + * id - uint16_t, event id, may be used by front + * type - uint8_t, type of the event + * + * + * Current stream position - event from back to front when stream's + * playback/capture position has advanced: + * 0 1 2 3 octet + * +----------------+----------------+----------------+----------------+ + * | id | _EVT_CUR_POS | reserved | 4 + * +----------------+----------------+----------------+----------------+ + * | reserved | 8 + * +----------------+----------------+----------------+----------------+ + * | position low 32-bit | 12 + * +----------------+----------------+----------------+----------------+ + * | position high 32-bit | 16 + * +----------------+----------------+----------------+----------------+ + * | reserved | 20 + * +----------------+----------------+----------------+----------------+ + * |//////////////////////////////////| + * +----------------+----------------+----------------+----------------+ + * | reserved | 64 + * +----------------+----------------+----------------+----------------+ + * + * position - current value of stream's playback/capture position, octets + * */
+struct xensnd_cur_pos_evt { + uint64_t position; +}; + struct xensnd_req { uint16_t id; uint8_t operation; @@ -787,6 +905,7 @@ struct xensnd_req { union { struct xensnd_open_req open; struct xensnd_rw_req rw; + struct xensnd_trigger_req trigger; uint8_t reserved[56]; } op; }; @@ -799,8 +918,49 @@ struct xensnd_resp { uint8_t reserved1[56]; };
+struct xensnd_evt { + uint16_t id; + uint8_t type; + uint8_t reserved[5]; + union { + struct xensnd_cur_pos_evt cur_pos; + uint8_t reserved[56]; + } op; +}; + DEFINE_RING_TYPES(xen_sndif, struct xensnd_req, struct xensnd_resp);
+/* + ****************************************************************************** + * Back to front events delivery + ****************************************************************************** + * In order to deliver asynchronous events from back to front a shared page is + * allocated by front and its granted reference propagated to back via + * XenStore entries (evt-ring-ref/evt-event-channel). + * This page has a common header used by both front and back to synchronize + * access and control event's ring buffer, while back being a producer of the + * events and front being a consumer. The rest of the page after the header + * is used for event packets. + * + * Upon reception of an event(s) front may confirm its reception + * for either each event, group of events or none. + */ + +struct xensnd_event_page { + uint32_t in_cons; + uint32_t in_prod; + uint8_t reserved[56]; +}; + +#define XENSND_EVENT_PAGE_SIZE 4096 +#define XENSND_IN_RING_OFFS (sizeof(struct xensnd_event_page)) +#define XENSND_IN_RING_SIZE (XENSND_EVENT_PAGE_SIZE - XENSND_IN_RING_OFFS) +#define XENSND_IN_RING_LEN (XENSND_IN_RING_SIZE / sizeof(struct xensnd_evt)) +#define XENSND_IN_RING(page) \ + ((struct xensnd_evt *)((char *)(page) + XENSND_IN_RING_OFFS)) +#define XENSND_IN_RING_REF(page, idx) \ + (XENSND_IN_RING((page))[(idx) % XENSND_IN_RING_LEN]) + #endif /* __XEN_PUBLIC_IO_SNDIF_H__ */
/*