Re: [PATCH v2 5/5] ALSA: xen-front: Implement ALSA virtual sound driver

[Juergen Gross]

On 17/04/18 14:26, Oleksandr Andrushchenko wrote:
> On 04/17/2018 02:32 PM, Oleksandr Andrushchenko wrote:
>> On 04/16/2018 05:09 PM, Juergen Gross wrote:
>>> On 16/04/18 08:24, Oleksandr Andrushchenko wrote:
>>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>>>>
>>>> Implement essential initialization of the sound driver:
>>>> ÂÂ - introduce required data structures
>>>> ÂÂ - handle driver registration
>>>> ÂÂ - handle sound card registration
>>>> ÂÂ - register sound driver on backend connection
>>>> ÂÂ - remove sound driver on backend disconnect
>>>>
>>>> Initialize virtual sound card with streams according to the
>>>> Xen store configuration.
>>>>
>>>> Implement ALSA driver operations including:
>>>> - manage frontend/backend shared buffers
>>>> - manage Xen bus event channel states
>>>>
>>>> Implement requests from front to back for ALSA
>>>> PCM operations.
>>>> Â - report ALSA period elapsed event: handle XENSND_EVT_CUR_POS
>>>> ÂÂÂ notifications from the backend when stream position advances
>>>> ÂÂÂ during playback/capture. The event carries a value of how
>>>> ÂÂÂ many octets were played/captured at the time of the event.
>>>> Â - implement explicit stream parameter negotiation between
>>>> ÂÂÂ backend and frontend: handle XENSND_OP_HW_PARAM_QUERY request
>>>> ÂÂÂ to read/update configuration space for the parameter given:
>>>> ÂÂÂ request passes desired parameter interval and the response to
>>>> ÂÂÂ this request returns min/max interval for the parameter to be used.
>>>>
>>>> Signed-off-by: Oleksandr Andrushchenko
>>>> <oleksandr_andrushchenko@xxxxxxxx>
>>>> ---
>>>> Â sound/xen/MakefileÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 3 +-
>>>> Â sound/xen/xen_snd_front.cÂÂÂÂÂÂÂÂ | 193 ++++++++-
>>>> Â sound/xen/xen_snd_front.hÂÂÂÂÂÂÂÂ |Â 28 ++
>>>> Â sound/xen/xen_snd_front_alsa.cÂÂÂ | 830
>>>> ++++++++++++++++++++++++++++++++++++++
>>>> Â sound/xen/xen_snd_front_alsa.hÂÂÂ |Â 23 ++
>>>> Â sound/xen/xen_snd_front_evtchnl.c |ÂÂ 6 +-
>>>> Â 6 files changed, 1080 insertions(+), 3 deletions(-)
>>>> Â create mode 100644 sound/xen/xen_snd_front_alsa.c
>>>> Â create mode 100644 sound/xen/xen_snd_front_alsa.h
>>>>
>>>> diff --git a/sound/xen/Makefile b/sound/xen/Makefile
>>>> index f028bc30af5d..1e6470ecc2f2 100644
>>>> --- a/sound/xen/Makefile
>>>> +++ b/sound/xen/Makefile
>>>> @@ -3,6 +3,7 @@
>>>> Â snd_xen_front-objs := xen_snd_front.o \
>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ xen_snd_front_cfg.o \
>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ xen_snd_front_evtchnl.o \
>>>> -ÂÂÂÂÂÂÂÂÂÂÂÂÂ xen_snd_front_shbuf.o
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂ xen_snd_front_shbuf.o \
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂ xen_snd_front_alsa.o
>>>> Â Â obj-$(CONFIG_SND_XEN_FRONTEND) += snd_xen_front.o
>>>> diff --git a/sound/xen/xen_snd_front.c b/sound/xen/xen_snd_front.c
>>>> index 0569c6c596a3..1fef253ea21a 100644
>>>> --- a/sound/xen/xen_snd_front.c
>>>> +++ b/sound/xen/xen_snd_front.c
>>>> @@ -19,10 +19,201 @@
>>>> Â #include <xen/interface/io/sndif.h>
>>>> Â Â #include "xen_snd_front.h"
>>>> +#include "xen_snd_front_alsa.h"
>>>> Â #include "xen_snd_front_evtchnl.h"
>>>> +#include "xen_snd_front_shbuf.h"
>>>> +
>>>> +static struct xensnd_req *
>>>> +be_stream_prepare_req(struct xen_snd_front_evtchnl *evtchnl, u8
>>>> operation)
>>>> +{
>>>> +ÂÂÂ struct xensnd_req *req;
>>>> +
>>>> +ÂÂÂ req = RING_GET_REQUEST(&evtchnl->u.req.ring,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ evtchnl->u.req.ring.req_prod_pvt);
>>>> +ÂÂÂ req->operation = operation;
>>>> +ÂÂÂ req->id = evtchnl->evt_next_id++;
>>>> +ÂÂÂ evtchnl->evt_id = req->id;
>>>> +ÂÂÂ return req;
>>>> +}
>>>> +
>>>> +static int be_stream_do_io(struct xen_snd_front_evtchnl *evtchnl)
>>>> +{
>>>> +ÂÂÂ if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
>>>> +ÂÂÂÂÂÂÂ return -EIO;
>>>> +
>>>> +ÂÂÂ reinit_completion(&evtchnl->u.req.completion);
>>>> +ÂÂÂ xen_snd_front_evtchnl_flush(evtchnl);
>>>> +ÂÂÂ return 0;
>>>> +}
>>>> +
>>>> +static int be_stream_wait_io(struct xen_snd_front_evtchnl *evtchnl)
>>>> +{
>>>> +ÂÂÂ if (wait_for_completion_timeout(&evtchnl->u.req.completion,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂ msecs_to_jiffies(VSND_WAIT_BACK_MS)) <= 0)
>>>> +ÂÂÂÂÂÂÂ return -ETIMEDOUT;
>>>> +
>>>> +ÂÂÂ return evtchnl->u.req.resp_status;
>>>> +}
>>>> +
>>>> +int xen_snd_front_stream_query_hw_param(struct
>>>> xen_snd_front_evtchnl *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct xensnd_query_hw_param *hw_param_req,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct xensnd_query_hw_param *hw_param_resp)
>>>> +{
>>>> +ÂÂÂ struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>> +ÂÂÂ struct xensnd_req *req;
>>>> +ÂÂÂ unsigned long flags;
>>>> +ÂÂÂ int ret;
>>>> +
>>>> +ÂÂÂ mutex_lock(&evtchnl->u.req.req_io_lock);
>>>> +
>>>> +ÂÂÂ spin_lock_irqsave(&front_info->io_lock, flags);
>>>> +ÂÂÂ req = be_stream_prepare_req(evtchnl, XENSND_OP_HW_PARAM_QUERY);
>>>> +ÂÂÂ req->op.hw_param = *hw_param_req;
>>>> +
>>>> +ÂÂÂ ret = be_stream_do_io(evtchnl);
>>>> +ÂÂÂ spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> +ÂÂÂ if (ret == 0)
>>>> +ÂÂÂÂÂÂÂ ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> +ÂÂÂ if (ret == 0)
>>>> +ÂÂÂÂÂÂÂ *hw_param_resp = evtchnl->u.req.resp.hw_param;
>>>> +
>>>> +ÂÂÂ mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>> +ÂÂÂ return ret;
>>>> +}
>>>> +
>>>> +int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl
>>>> *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct xen_snd_front_shbuf *sh_buf,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u8 format, unsigned int channels,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned int rate, u32 buffer_sz,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u32 period_sz)
>>>> +{
>>>> +ÂÂÂ struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>> +ÂÂÂ struct xensnd_req *req;
>>>> +ÂÂÂ unsigned long flags;
>>>> +ÂÂÂ int ret;
>>>> +
>>>> +ÂÂÂ mutex_lock(&evtchnl->u.req.req_io_lock);
>>>> +
>>>> +ÂÂÂ spin_lock_irqsave(&front_info->io_lock, flags);
>>>> +ÂÂÂ req = be_stream_prepare_req(evtchnl, XENSND_OP_OPEN);
>>>> +ÂÂÂ req->op.open.pcm_format = format;
>>>> +ÂÂÂ req->op.open.pcm_channels = channels;
>>>> +ÂÂÂ req->op.open.pcm_rate = rate;
>>>> +ÂÂÂ req->op.open.buffer_sz = buffer_sz;
>>>> +ÂÂÂ req->op.open.period_sz = period_sz;
>>>> +ÂÂÂ req->op.open.gref_directory =
>>>> xen_snd_front_shbuf_get_dir_start(sh_buf);
>>>> +
>>>> +ÂÂÂ ret = be_stream_do_io(evtchnl);
>>>> +ÂÂÂ spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> +ÂÂÂ if (ret == 0)
>>>> +ÂÂÂÂÂÂÂ ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> +ÂÂÂ mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>> +ÂÂÂ return ret;
>>>> +}
>>>> +
>>>> +int xen_snd_front_stream_close(struct xen_snd_front_evtchnl *evtchnl)
>>>> +{
>>>> +ÂÂÂ struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>> +ÂÂÂ struct xensnd_req *req;
>>>> +ÂÂÂ unsigned long flags;
>>>> +ÂÂÂ int ret;
>>>> +
>>>> +ÂÂÂ mutex_lock(&evtchnl->u.req.req_io_lock);
>>>> +
>>>> +ÂÂÂ spin_lock_irqsave(&front_info->io_lock, flags);
>>>> +ÂÂÂ req = be_stream_prepare_req(evtchnl, XENSND_OP_CLOSE);
>>>> +
>>>> +ÂÂÂ ret = be_stream_do_io(evtchnl);
>>>> +ÂÂÂ spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> +ÂÂÂ if (ret == 0)
>>>> +ÂÂÂÂÂÂÂ ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> +ÂÂÂ mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>> +ÂÂÂ return ret;
>>>> +}
>>>> +
>>>> +int xen_snd_front_stream_write(struct xen_snd_front_evtchnl *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long pos, unsigned long count)
>>>> +{
>>>> +ÂÂÂ struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>> +ÂÂÂ struct xensnd_req *req;
>>>> +ÂÂÂ unsigned long flags;
>>>> +ÂÂÂ int ret;
>>>> +
>>>> +ÂÂÂ mutex_lock(&evtchnl->u.req.req_io_lock);
>>>> +
>>>> +ÂÂÂ spin_lock_irqsave(&front_info->io_lock, flags);
>>>> +ÂÂÂ req = be_stream_prepare_req(evtchnl, XENSND_OP_WRITE);
>>>> +ÂÂÂ req->op.rw.length = count;
>>>> +ÂÂÂ req->op.rw.offset = pos;
>>>> +
>>>> +ÂÂÂ ret = be_stream_do_io(evtchnl);
>>>> +ÂÂÂ spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> +ÂÂÂ if (ret == 0)
>>>> +ÂÂÂÂÂÂÂ ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> +ÂÂÂ mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>> +ÂÂÂ return ret;
>>>> +}
>>>> +
>>>> +int xen_snd_front_stream_read(struct xen_snd_front_evtchnl *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long pos, unsigned long count)
>>>> +{
>>>> +ÂÂÂ struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>> +ÂÂÂ struct xensnd_req *req;
>>>> +ÂÂÂ unsigned long flags;
>>>> +ÂÂÂ int ret;
>>>> +
>>>> +ÂÂÂ mutex_lock(&evtchnl->u.req.req_io_lock);
>>>> +
>>>> +ÂÂÂ spin_lock_irqsave(&front_info->io_lock, flags);
>>>> +ÂÂÂ req = be_stream_prepare_req(evtchnl, XENSND_OP_READ);
>>>> +ÂÂÂ req->op.rw.length = count;
>>>> +ÂÂÂ req->op.rw.offset = pos;
>>>> +
>>>> +ÂÂÂ ret = be_stream_do_io(evtchnl);
>>>> +ÂÂÂ spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> +ÂÂÂ if (ret == 0)
>>>> +ÂÂÂÂÂÂÂ ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> +ÂÂÂ mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>> +ÂÂÂ return ret;
>>>> +}
>>>> +
>>>> +int xen_snd_front_stream_trigger(struct xen_snd_front_evtchnl
>>>> *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ int type)
>>>> +{
>>>> +ÂÂÂ struct xen_snd_front_info *front_info = evtchnl->front_info;
>>>> +ÂÂÂ struct xensnd_req *req;
>>>> +ÂÂÂ unsigned long flags;
>>>> +ÂÂÂ int ret;
>>>> +
>>>> +ÂÂÂ mutex_lock(&evtchnl->u.req.req_io_lock);
>>>> +
>>>> +ÂÂÂ spin_lock_irqsave(&front_info->io_lock, flags);
>>>> +ÂÂÂ req = be_stream_prepare_req(evtchnl, XENSND_OP_TRIGGER);
>>>> +ÂÂÂ req->op.trigger.type = type;
>>>> +
>>>> +ÂÂÂ ret = be_stream_do_io(evtchnl);
>>>> +ÂÂÂ spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> +ÂÂÂ if (ret == 0)
>>>> +ÂÂÂÂÂÂÂ ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> +ÂÂÂ mutex_unlock(&evtchnl->u.req.req_io_lock);
>>>> +ÂÂÂ return ret;
>>>> +}
>>>> Â Â static void xen_snd_drv_fini(struct xen_snd_front_info *front_info)
>>>> Â {
>>>> +ÂÂÂ xen_snd_front_alsa_fini(front_info);
>>>> ÂÂÂÂÂ xen_snd_front_evtchnl_free_all(front_info);
>>>> Â }
>>>> Â @@ -45,7 +236,7 @@ static int sndback_initwait(struct
>>>> xen_snd_front_info *front_info)
>>>> Â Â static int sndback_connect(struct xen_snd_front_info *front_info)
>>>> Â {
>>>> -ÂÂÂ return 0;
>>>> +ÂÂÂ return xen_snd_front_alsa_init(front_info);
>>>> Â }
>>>> Â Â static void sndback_disconnect(struct xen_snd_front_info
>>>> *front_info)
>>>> diff --git a/sound/xen/xen_snd_front.h b/sound/xen/xen_snd_front.h
>>>> index 9c2ffbb4e4b8..7adbdb4d2019 100644
>>>> --- a/sound/xen/xen_snd_front.h
>>>> +++ b/sound/xen/xen_snd_front.h
>>>> @@ -13,17 +13,45 @@
>>>> Â Â #include "xen_snd_front_cfg.h"
>>>> Â +struct card_info;
>>>> +struct xen_snd_front_evtchnl;
>>>> Â struct xen_snd_front_evtchnl_pair;
>>>> +struct xen_snd_front_shbuf;
>>>> +struct xensnd_query_hw_param;
>>>> Â Â struct xen_snd_front_info {
>>>> ÂÂÂÂÂ struct xenbus_device *xb_dev;
>>>> Â +ÂÂÂ struct card_info *card_info;
>>>> +
>>>> ÂÂÂÂÂ /* serializer for backend IO: request/response */
>>>> ÂÂÂÂÂ spinlock_t io_lock;
>>>> +
>>>> ÂÂÂÂÂ int num_evt_pairs;
>>>> ÂÂÂÂÂ struct xen_snd_front_evtchnl_pair *evt_pairs;
>>>> Â ÂÂÂÂÂ struct xen_front_cfg_card cfg;
>>>> Â };
>>>> Â +int xen_snd_front_stream_query_hw_param(struct
>>>> xen_snd_front_evtchnl *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct xensnd_query_hw_param *hw_param_req,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct xensnd_query_hw_param *hw_param_resp);
>>>> +
>>>> +int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl
>>>> *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ struct xen_snd_front_shbuf *sh_buf,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u8 format, unsigned int channels,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned int rate, u32 buffer_sz,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u32 period_sz);
>>>> +
>>>> +int xen_snd_front_stream_close(struct xen_snd_front_evtchnl *evtchnl);
>>>> +
>>>> +int xen_snd_front_stream_write(struct xen_snd_front_evtchnl *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long pos, unsigned long count);
>>>> +
>>>> +int xen_snd_front_stream_read(struct xen_snd_front_evtchnl *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned long pos, unsigned long count);
>>>> +
>>>> +int xen_snd_front_stream_trigger(struct xen_snd_front_evtchnl
>>>> *evtchnl,
>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ int type);
>>>> +
>>>> Â #endif /* __XEN_SND_FRONT_H */
>>>> diff --git a/sound/xen/xen_snd_front_alsa.c
>>>> b/sound/xen/xen_snd_front_alsa.c
>>>> new file mode 100644
>>>> index 000000000000..f524b172750e
>>>> --- /dev/null
>>>> +++ b/sound/xen/xen_snd_front_alsa.c
>>>> @@ -0,0 +1,830 @@
>>>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>>>> +
>>>> +/*
>>>> + * Xen para-virtual sound device
>>>> + *
>>>> + * Copyright (C) 2016-2018 EPAM Systems Inc.
>>>> + *
>>>> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>>>> + */
>>>> +
>>>> +#include <linux/platform_device.h>
>>>> +
>>>> +#include <sound/core.h>
>>>> +#include <sound/pcm.h>
>>>> +#include <sound/pcm_params.h>
>>>> +
>>>> +#include <xen/xenbus.h>
>>>> +
>>>> +#include "xen_snd_front.h"
>>>> +#include "xen_snd_front_alsa.h"
>>>> +#include "xen_snd_front_cfg.h"
>>>> +#include "xen_snd_front_evtchnl.h"
>>>> +#include "xen_snd_front_shbuf.h"
>>>> +
>>>> +struct pcm_stream_info {
>>> Not sure how this is generally handled in the sound drivers, but when
>>> reviewing the code using those structures I repeatedly tried to find
>>> their definitions in the sound headers instead of here. Same applies to
>>> the alsa_* names.
>>>
>>> I'd prefer names which don't poison the name space.
>> I'll try to do something about naming
> One question still remains wrt alsa_* names: if this is for structures
> I have (alsa_sndif_sample_format/alsa_sndif_hw_param), then
> those already have sndif in their name which clearly says these are
> Xen related ones (sndif is a Xen protocol).
> If you also don't like the alsa_* function names then those are all
> static and defined in this same file, so see no confusion here.
> 
> I have changed other non-obvious struct names:
> 
> -struct pcm_stream_info {
> +struct xen_snd_front_pcm_stream_info {
> 
> -struct pcm_instance_info {
> +struct xen_snd_front_pcm_instance_info {
> 
> -struct card_info {
> +struct xen_snd_front_card_info {
> 
> Does the above work for you?

Yes, this seems to be okay.

Thanks,

Juergen