[PATCH v5 1/9] uapi: virtio_ids: add a sound device type ID from OASIS spec

[PATCH v5 1/9] uapi: virtio_ids: add a sound device type ID from OASIS spec

[Anton Yakovlev]

The OASIS virtio spec defines a sound device type ID that is not
present in the header yet.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 include/uapi/linux/virtio_ids.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
index bc1c0621f5ed..029a2e07a7f9 100644
--- a/include/uapi/linux/virtio_ids.h
+++ b/include/uapi/linux/virtio_ids.h
@@ -51,6 +51,7 @@
 #define VIRTIO_ID_PSTORE		22 /* virtio pstore device */
 #define VIRTIO_ID_IOMMU			23 /* virtio IOMMU */
 #define VIRTIO_ID_MEM			24 /* virtio mem */
+#define VIRTIO_ID_SOUND			25 /* virtio sound */
 #define VIRTIO_ID_FS			26 /* virtio filesystem */
 #define VIRTIO_ID_PMEM			27 /* virtio pmem */
 #define VIRTIO_ID_MAC80211_HWSIM	29 /* virtio mac80211-hwsim */
-- 
2.30.0

[PATCH v5 2/9] ALSA: virtio: add virtio sound driver

[Anton Yakovlev]

Introduce skeleton of the virtio sound driver. The driver implements
the virtio sound device specification, which has become part of the
virtio standard.

Initial initialization of the device, virtqueues and creation of an
empty ALSA sound device. Also, handling DEVICE_NEEDS_RESET device
status.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 MAINTAINERS                     |   9 +
 include/uapi/linux/virtio_snd.h | 334 +++++++++++++++++++++++++++++++
 sound/Kconfig                   |   2 +
 sound/Makefile                  |   3 +-
 sound/virtio/Kconfig            |  10 +
 sound/virtio/Makefile           |   7 +
 sound/virtio/virtio_card.c      | 340 ++++++++++++++++++++++++++++++++
 sound/virtio/virtio_card.h      |  67 +++++++
 8 files changed, 771 insertions(+), 1 deletion(-)
 create mode 100644 include/uapi/linux/virtio_snd.h
 create mode 100644 sound/virtio/Kconfig
 create mode 100644 sound/virtio/Makefile
 create mode 100644 sound/virtio/virtio_card.c
 create mode 100644 sound/virtio/virtio_card.h

diff --git a/MAINTAINERS b/MAINTAINERS
index bfc1b86e3e73..599c1231214d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18945,6 +18945,15 @@ W:	https://virtio-mem.gitlab.io/
 F:	drivers/virtio/virtio_mem.c
 F:	include/uapi/linux/virtio_mem.h
 
+VIRTIO SOUND DRIVER
+M:	Anton Yakovlev <anton.yakovlev@opensynergy.com>
+M:	"Michael S. Tsirkin" <mst@redhat.com>
+L:	virtualization@lists.linux-foundation.org
+L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
+S:	Maintained
+F:	include/uapi/linux/virtio_snd.h
+F:	sound/virtio/*
+
 VIRTUAL BOX GUEST DEVICE DRIVER
 M:	Hans de Goede <hdegoede@redhat.com>
 M:	Arnd Bergmann <arnd@arndb.de>
diff --git a/include/uapi/linux/virtio_snd.h b/include/uapi/linux/virtio_snd.h
new file mode 100644
index 000000000000..dfe49547a7b0
--- /dev/null
+++ b/include/uapi/linux/virtio_snd.h
@@ -0,0 +1,334 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#ifndef VIRTIO_SND_IF_H
+#define VIRTIO_SND_IF_H
+
+#include <linux/virtio_types.h>
+
+/*******************************************************************************
+ * CONFIGURATION SPACE
+ */
+struct virtio_snd_config {
+	/* # of available physical jacks */
+	__le32 jacks;
+	/* # of available PCM streams */
+	__le32 streams;
+	/* # of available channel maps */
+	__le32 chmaps;
+};
+
+enum {
+	/* device virtqueue indexes */
+	VIRTIO_SND_VQ_CONTROL = 0,
+	VIRTIO_SND_VQ_EVENT,
+	VIRTIO_SND_VQ_TX,
+	VIRTIO_SND_VQ_RX,
+	/* # of device virtqueues */
+	VIRTIO_SND_VQ_MAX
+};
+
+/*******************************************************************************
+ * COMMON DEFINITIONS
+ */
+
+/* supported dataflow directions */
+enum {
+	VIRTIO_SND_D_OUTPUT = 0,
+	VIRTIO_SND_D_INPUT
+};
+
+enum {
+	/* jack control request types */
+	VIRTIO_SND_R_JACK_INFO = 1,
+	VIRTIO_SND_R_JACK_REMAP,
+
+	/* PCM control request types */
+	VIRTIO_SND_R_PCM_INFO = 0x0100,
+	VIRTIO_SND_R_PCM_SET_PARAMS,
+	VIRTIO_SND_R_PCM_PREPARE,
+	VIRTIO_SND_R_PCM_RELEASE,
+	VIRTIO_SND_R_PCM_START,
+	VIRTIO_SND_R_PCM_STOP,
+
+	/* channel map control request types */
+	VIRTIO_SND_R_CHMAP_INFO = 0x0200,
+
+	/* jack event types */
+	VIRTIO_SND_EVT_JACK_CONNECTED = 0x1000,
+	VIRTIO_SND_EVT_JACK_DISCONNECTED,
+
+	/* PCM event types */
+	VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED = 0x1100,
+	VIRTIO_SND_EVT_PCM_XRUN,
+
+	/* common status codes */
+	VIRTIO_SND_S_OK = 0x8000,
+	VIRTIO_SND_S_BAD_MSG,
+	VIRTIO_SND_S_NOT_SUPP,
+	VIRTIO_SND_S_IO_ERR
+};
+
+/* common header */
+struct virtio_snd_hdr {
+	__le32 code;
+};
+
+/* event notification */
+struct virtio_snd_event {
+	/* VIRTIO_SND_EVT_XXX */
+	struct virtio_snd_hdr hdr;
+	/* optional event data */
+	__le32 data;
+};
+
+/* common control request to query an item information */
+struct virtio_snd_query_info {
+	/* VIRTIO_SND_R_XXX_INFO */
+	struct virtio_snd_hdr hdr;
+	/* item start identifier */
+	__le32 start_id;
+	/* item count to query */
+	__le32 count;
+	/* item information size in bytes */
+	__le32 size;
+};
+
+/* common item information header */
+struct virtio_snd_info {
+	/* function group node id (High Definition Audio Specification 7.1.2) */
+	__le32 hda_fn_nid;
+};
+
+/*******************************************************************************
+ * JACK CONTROL MESSAGES
+ */
+struct virtio_snd_jack_hdr {
+	/* VIRTIO_SND_R_JACK_XXX */
+	struct virtio_snd_hdr hdr;
+	/* 0 ... virtio_snd_config::jacks - 1 */
+	__le32 jack_id;
+};
+
+/* supported jack features */
+enum {
+	VIRTIO_SND_JACK_F_REMAP = 0
+};
+
+struct virtio_snd_jack_info {
+	/* common header */
+	struct virtio_snd_info hdr;
+	/* supported feature bit map (1 << VIRTIO_SND_JACK_F_XXX) */
+	__le32 features;
+	/* pin configuration (High Definition Audio Specification 7.3.3.31) */
+	__le32 hda_reg_defconf;
+	/* pin capabilities (High Definition Audio Specification 7.3.4.9) */
+	__le32 hda_reg_caps;
+	/* current jack connection status (0: disconnected, 1: connected) */
+	__u8 connected;
+
+	__u8 padding[7];
+};
+
+/* jack remapping control request */
+struct virtio_snd_jack_remap {
+	/* .code = VIRTIO_SND_R_JACK_REMAP */
+	struct virtio_snd_jack_hdr hdr;
+	/* selected association number */
+	__le32 association;
+	/* selected sequence number */
+	__le32 sequence;
+};
+
+/*******************************************************************************
+ * PCM CONTROL MESSAGES
+ */
+struct virtio_snd_pcm_hdr {
+	/* VIRTIO_SND_R_PCM_XXX */
+	struct virtio_snd_hdr hdr;
+	/* 0 ... virtio_snd_config::streams - 1 */
+	__le32 stream_id;
+};
+
+/* supported PCM stream features */
+enum {
+	VIRTIO_SND_PCM_F_SHMEM_HOST = 0,
+	VIRTIO_SND_PCM_F_SHMEM_GUEST,
+	VIRTIO_SND_PCM_F_MSG_POLLING,
+	VIRTIO_SND_PCM_F_EVT_SHMEM_PERIODS,
+	VIRTIO_SND_PCM_F_EVT_XRUNS
+};
+
+/* supported PCM sample formats */
+enum {
+	/* analog formats (width / physical width) */
+	VIRTIO_SND_PCM_FMT_IMA_ADPCM = 0,	/*  4 /  4 bits */
+	VIRTIO_SND_PCM_FMT_MU_LAW,		/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_A_LAW,		/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_S8,			/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_U8,			/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_S16,			/* 16 / 16 bits */
+	VIRTIO_SND_PCM_FMT_U16,			/* 16 / 16 bits */
+	VIRTIO_SND_PCM_FMT_S18_3,		/* 18 / 24 bits */
+	VIRTIO_SND_PCM_FMT_U18_3,		/* 18 / 24 bits */
+	VIRTIO_SND_PCM_FMT_S20_3,		/* 20 / 24 bits */
+	VIRTIO_SND_PCM_FMT_U20_3,		/* 20 / 24 bits */
+	VIRTIO_SND_PCM_FMT_S24_3,		/* 24 / 24 bits */
+	VIRTIO_SND_PCM_FMT_U24_3,		/* 24 / 24 bits */
+	VIRTIO_SND_PCM_FMT_S20,			/* 20 / 32 bits */
+	VIRTIO_SND_PCM_FMT_U20,			/* 20 / 32 bits */
+	VIRTIO_SND_PCM_FMT_S24,			/* 24 / 32 bits */
+	VIRTIO_SND_PCM_FMT_U24,			/* 24 / 32 bits */
+	VIRTIO_SND_PCM_FMT_S32,			/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_U32,			/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_FLOAT,		/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_FLOAT64,		/* 64 / 64 bits */
+	/* digital formats (width / physical width) */
+	VIRTIO_SND_PCM_FMT_DSD_U8,		/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_DSD_U16,		/* 16 / 16 bits */
+	VIRTIO_SND_PCM_FMT_DSD_U32,		/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_IEC958_SUBFRAME	/* 32 / 32 bits */
+};
+
+/* supported PCM frame rates */
+enum {
+	VIRTIO_SND_PCM_RATE_5512 = 0,
+	VIRTIO_SND_PCM_RATE_8000,
+	VIRTIO_SND_PCM_RATE_11025,
+	VIRTIO_SND_PCM_RATE_16000,
+	VIRTIO_SND_PCM_RATE_22050,
+	VIRTIO_SND_PCM_RATE_32000,
+	VIRTIO_SND_PCM_RATE_44100,
+	VIRTIO_SND_PCM_RATE_48000,
+	VIRTIO_SND_PCM_RATE_64000,
+	VIRTIO_SND_PCM_RATE_88200,
+	VIRTIO_SND_PCM_RATE_96000,
+	VIRTIO_SND_PCM_RATE_176400,
+	VIRTIO_SND_PCM_RATE_192000,
+	VIRTIO_SND_PCM_RATE_384000
+};
+
+struct virtio_snd_pcm_info {
+	/* common header */
+	struct virtio_snd_info hdr;
+	/* supported feature bit map (1 << VIRTIO_SND_PCM_F_XXX) */
+	__le32 features;
+	/* supported sample format bit map (1 << VIRTIO_SND_PCM_FMT_XXX) */
+	__le64 formats;
+	/* supported frame rate bit map (1 << VIRTIO_SND_PCM_RATE_XXX) */
+	__le64 rates;
+	/* dataflow direction (VIRTIO_SND_D_XXX) */
+	__u8 direction;
+	/* minimum # of supported channels */
+	__u8 channels_min;
+	/* maximum # of supported channels */
+	__u8 channels_max;
+
+	__u8 padding[5];
+};
+
+/* set PCM stream format */
+struct virtio_snd_pcm_set_params {
+	/* .code = VIRTIO_SND_R_PCM_SET_PARAMS */
+	struct virtio_snd_pcm_hdr hdr;
+	/* size of the hardware buffer */
+	__le32 buffer_bytes;
+	/* size of the hardware period */
+	__le32 period_bytes;
+	/* selected feature bit map (1 << VIRTIO_SND_PCM_F_XXX) */
+	__le32 features;
+	/* selected # of channels */
+	__u8 channels;
+	/* selected sample format (VIRTIO_SND_PCM_FMT_XXX) */
+	__u8 format;
+	/* selected frame rate (VIRTIO_SND_PCM_RATE_XXX) */
+	__u8 rate;
+
+	__u8 padding;
+};
+
+/*******************************************************************************
+ * PCM I/O MESSAGES
+ */
+
+/* I/O request header */
+struct virtio_snd_pcm_xfer {
+	/* 0 ... virtio_snd_config::streams - 1 */
+	__le32 stream_id;
+};
+
+/* I/O request status */
+struct virtio_snd_pcm_status {
+	/* VIRTIO_SND_S_XXX */
+	__le32 status;
+	/* current device latency */
+	__le32 latency_bytes;
+};
+
+/*******************************************************************************
+ * CHANNEL MAP CONTROL MESSAGES
+ */
+struct virtio_snd_chmap_hdr {
+	/* VIRTIO_SND_R_CHMAP_XXX */
+	struct virtio_snd_hdr hdr;
+	/* 0 ... virtio_snd_config::chmaps - 1 */
+	__le32 chmap_id;
+};
+
+/* standard channel position definition */
+enum {
+	VIRTIO_SND_CHMAP_NONE = 0,	/* undefined */
+	VIRTIO_SND_CHMAP_NA,		/* silent */
+	VIRTIO_SND_CHMAP_MONO,		/* mono stream */
+	VIRTIO_SND_CHMAP_FL,		/* front left */
+	VIRTIO_SND_CHMAP_FR,		/* front right */
+	VIRTIO_SND_CHMAP_RL,		/* rear left */
+	VIRTIO_SND_CHMAP_RR,		/* rear right */
+	VIRTIO_SND_CHMAP_FC,		/* front center */
+	VIRTIO_SND_CHMAP_LFE,		/* low frequency (LFE) */
+	VIRTIO_SND_CHMAP_SL,		/* side left */
+	VIRTIO_SND_CHMAP_SR,		/* side right */
+	VIRTIO_SND_CHMAP_RC,		/* rear center */
+	VIRTIO_SND_CHMAP_FLC,		/* front left center */
+	VIRTIO_SND_CHMAP_FRC,		/* front right center */
+	VIRTIO_SND_CHMAP_RLC,		/* rear left center */
+	VIRTIO_SND_CHMAP_RRC,		/* rear right center */
+	VIRTIO_SND_CHMAP_FLW,		/* front left wide */
+	VIRTIO_SND_CHMAP_FRW,		/* front right wide */
+	VIRTIO_SND_CHMAP_FLH,		/* front left high */
+	VIRTIO_SND_CHMAP_FCH,		/* front center high */
+	VIRTIO_SND_CHMAP_FRH,		/* front right high */
+	VIRTIO_SND_CHMAP_TC,		/* top center */
+	VIRTIO_SND_CHMAP_TFL,		/* top front left */
+	VIRTIO_SND_CHMAP_TFR,		/* top front right */
+	VIRTIO_SND_CHMAP_TFC,		/* top front center */
+	VIRTIO_SND_CHMAP_TRL,		/* top rear left */
+	VIRTIO_SND_CHMAP_TRR,		/* top rear right */
+	VIRTIO_SND_CHMAP_TRC,		/* top rear center */
+	VIRTIO_SND_CHMAP_TFLC,		/* top front left center */
+	VIRTIO_SND_CHMAP_TFRC,		/* top front right center */
+	VIRTIO_SND_CHMAP_TSL,		/* top side left */
+	VIRTIO_SND_CHMAP_TSR,		/* top side right */
+	VIRTIO_SND_CHMAP_LLFE,		/* left LFE */
+	VIRTIO_SND_CHMAP_RLFE,		/* right LFE */
+	VIRTIO_SND_CHMAP_BC,		/* bottom center */
+	VIRTIO_SND_CHMAP_BLC,		/* bottom left center */
+	VIRTIO_SND_CHMAP_BRC		/* bottom right center */
+};
+
+/* maximum possible number of channels */
+#define VIRTIO_SND_CHMAP_MAX_SIZE	18
+
+struct virtio_snd_chmap_info {
+	/* common header */
+	struct virtio_snd_info hdr;
+	/* dataflow direction (VIRTIO_SND_D_XXX) */
+	__u8 direction;
+	/* # of valid channel position values */
+	__u8 channels;
+	/* channel position values (VIRTIO_SND_CHMAP_XXX) */
+	__u8 positions[VIRTIO_SND_CHMAP_MAX_SIZE];
+};
+
+#endif /* VIRTIO_SND_IF_H */
diff --git a/sound/Kconfig b/sound/Kconfig
index 36785410fbe1..e56d96d2b11c 100644
--- a/sound/Kconfig
+++ b/sound/Kconfig
@@ -99,6 +99,8 @@ source "sound/synth/Kconfig"
 
 source "sound/xen/Kconfig"
 
+source "sound/virtio/Kconfig"
+
 endif # SND
 
 endif # !UML
diff --git a/sound/Makefile b/sound/Makefile
index 797ecdcd35e2..04ef04b1168f 100644
--- a/sound/Makefile
+++ b/sound/Makefile
@@ -5,7 +5,8 @@
 obj-$(CONFIG_SOUND) += soundcore.o
 obj-$(CONFIG_DMASOUND) += oss/dmasound/
 obj-$(CONFIG_SND) += core/ i2c/ drivers/ isa/ pci/ ppc/ arm/ sh/ synth/ usb/ \
-	firewire/ sparc/ spi/ parisc/ pcmcia/ mips/ soc/ atmel/ hda/ x86/ xen/
+	firewire/ sparc/ spi/ parisc/ pcmcia/ mips/ soc/ atmel/ hda/ x86/ xen/ \
+	virtio/
 obj-$(CONFIG_SND_AOA) += aoa/
 
 # This one must be compilable even if sound is configured out
diff --git a/sound/virtio/Kconfig b/sound/virtio/Kconfig
new file mode 100644
index 000000000000..094cba24ee5b
--- /dev/null
+++ b/sound/virtio/Kconfig
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Sound card driver for virtio
+
+config SND_VIRTIO
+	tristate "Virtio sound driver"
+	depends on VIRTIO
+	select SND_PCM
+	select SND_JACK
+	help
+          This is the virtual sound driver for virtio. Say Y or M.
diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
new file mode 100644
index 000000000000..8c87ebb9982b
--- /dev/null
+++ b/sound/virtio/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
+
+virtio_snd-objs := \
+	virtio_card.o
+
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
new file mode 100644
index 000000000000..b5f63b5b7db4
--- /dev/null
+++ b/sound/virtio/virtio_card.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/virtio_config.h>
+#include <sound/initval.h>
+#include <uapi/linux/virtio_ids.h>
+
+#include "virtio_card.h"
+
+static void virtsnd_remove(struct virtio_device *vdev);
+
+/**
+ * virtsnd_event_send() - Add an event to the event queue.
+ * @vqueue: Underlying event virtqueue.
+ * @event: Event.
+ * @notify: Indicates whether or not to send a notification to the device.
+ * @gfp: Kernel flags for memory allocation.
+ *
+ * Context: Any context.
+ */
+static void virtsnd_event_send(struct virtqueue *vqueue,
+			       struct virtio_snd_event *event, bool notify,
+			       gfp_t gfp)
+{
+	struct scatterlist sg;
+	struct scatterlist *psgs[1] = { &sg };
+
+	/* reset event content */
+	memset(event, 0, sizeof(*event));
+
+	sg_init_one(&sg, event, sizeof(*event));
+
+	if (virtqueue_add_sgs(vqueue, psgs, 0, 1, event, gfp) || !notify)
+		return;
+
+	if (virtqueue_kick_prepare(vqueue))
+		virtqueue_notify(vqueue);
+}
+
+/**
+ * virtsnd_event_notify_cb() - Dispatch all reported events from the event queue.
+ * @vqueue: Underlying event virtqueue.
+ *
+ * This callback function is called upon a vring interrupt request from the
+ * device.
+ *
+ * Context: Interrupt context.
+ */
+static void virtsnd_event_notify_cb(struct virtqueue *vqueue)
+{
+	struct virtio_snd *snd = vqueue->vdev->priv;
+	struct virtio_snd_queue *queue = virtsnd_event_queue(snd);
+	struct virtio_snd_event *event;
+	u32 length;
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	do {
+		virtqueue_disable_cb(vqueue);
+		while ((event = virtqueue_get_buf(vqueue, &length)))
+			virtsnd_event_send(vqueue, event, true, GFP_ATOMIC);
+		if (unlikely(virtqueue_is_broken(vqueue)))
+			break;
+	} while (!virtqueue_enable_cb(vqueue));
+	spin_unlock_irqrestore(&queue->lock, flags);
+}
+
+/**
+ * virtsnd_find_vqs() - Enumerate and initialize all virtqueues.
+ * @snd: VirtIO sound device.
+ *
+ * After calling this function, the event queue is disabled.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_find_vqs(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = {
+		[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb
+	};
+	const char *names[VIRTIO_SND_VQ_MAX] = {
+		[VIRTIO_SND_VQ_CONTROL] = "virtsnd-ctl",
+		[VIRTIO_SND_VQ_EVENT] = "virtsnd-event",
+		[VIRTIO_SND_VQ_TX] = "virtsnd-tx",
+		[VIRTIO_SND_VQ_RX] = "virtsnd-rx"
+	};
+	struct virtqueue *vqs[VIRTIO_SND_VQ_MAX] = { 0 };
+	unsigned int i;
+	unsigned int n;
+	int rc;
+
+	rc = virtio_find_vqs(vdev, VIRTIO_SND_VQ_MAX, vqs, callbacks, names,
+			     NULL);
+	if (rc) {
+		dev_err(&vdev->dev, "failed to initialize virtqueues\n");
+		return rc;
+	}
+
+	for (i = 0; i < VIRTIO_SND_VQ_MAX; ++i)
+		snd->queues[i].vqueue = vqs[i];
+
+	/* Allocate events and populate the event queue */
+	virtqueue_disable_cb(vqs[VIRTIO_SND_VQ_EVENT]);
+
+	n = virtqueue_get_vring_size(vqs[VIRTIO_SND_VQ_EVENT]);
+
+	snd->event_msgs = kmalloc_array(n, sizeof(*snd->event_msgs),
+					GFP_KERNEL);
+	if (!snd->event_msgs)
+		return -ENOMEM;
+
+	for (i = 0; i < n; ++i)
+		virtsnd_event_send(vqs[VIRTIO_SND_VQ_EVENT],
+				   &snd->event_msgs[i], false, GFP_KERNEL);
+
+	return 0;
+}
+
+/**
+ * virtsnd_enable_event_vq() - Enable the event virtqueue.
+ * @snd: VirtIO sound device.
+ *
+ * Context: Any context.
+ */
+static void virtsnd_enable_event_vq(struct virtio_snd *snd)
+{
+	struct virtio_snd_queue *queue = virtsnd_event_queue(snd);
+
+	if (!virtqueue_enable_cb(queue->vqueue))
+		virtsnd_event_notify_cb(queue->vqueue);
+}
+
+/**
+ * virtsnd_reset_fn() - Kernel worker's function to reset the device.
+ * @work: Reset device work.
+ *
+ * Context: Process context.
+ */
+static void virtsnd_reset_fn(struct work_struct *work)
+{
+	struct virtio_snd *snd =
+		container_of(work, struct virtio_snd, reset_work);
+	struct virtio_device *vdev = snd->vdev;
+	struct device *dev = &vdev->dev;
+	int rc;
+
+	dev_info(dev, "sound device needs reset\n");
+
+	/*
+	 * It seems that the only way to properly reset the device is to remove
+	 * and re-create the ALSA sound card device.
+	 */
+	rc = device_reprobe(dev);
+	if (rc)
+		dev_err(dev, "failed to reprobe sound device: %d\n", rc);
+}
+
+/**
+ * virtsnd_build_devs() - Read configuration and build ALSA devices.
+ * @snd: VirtIO sound device.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_build_devs(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct device *dev = &vdev->dev;
+	int rc;
+
+	rc = snd_card_new(dev, SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1,
+			  THIS_MODULE, 0, &snd->card);
+	if (rc < 0)
+		return rc;
+
+	snd->card->private_data = snd;
+
+	strscpy(snd->card->driver, VIRTIO_SND_CARD_DRIVER,
+		sizeof(snd->card->driver));
+	strscpy(snd->card->shortname, VIRTIO_SND_CARD_NAME,
+		sizeof(snd->card->shortname));
+	if (dev->parent->bus)
+		snprintf(snd->card->longname, sizeof(snd->card->longname),
+			 VIRTIO_SND_CARD_NAME " at %s/%s/%s",
+			 dev->parent->bus->name, dev_name(dev->parent),
+			 dev_name(dev));
+	else
+		snprintf(snd->card->longname, sizeof(snd->card->longname),
+			 VIRTIO_SND_CARD_NAME " at %s/%s",
+			 dev_name(dev->parent), dev_name(dev));
+
+	return snd_card_register(snd->card);
+}
+
+/**
+ * virtsnd_validate() - Validate if the device can be started.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -EINVAL on failure.
+ */
+static int virtsnd_validate(struct virtio_device *vdev)
+{
+	if (!vdev->config->get) {
+		dev_err(&vdev->dev, "configuration access disabled\n");
+		return -EINVAL;
+	}
+
+	if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+		dev_err(&vdev->dev,
+			"device does not comply with spec version 1.x\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * virtsnd_probe() - Create and initialize the device.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_probe(struct virtio_device *vdev)
+{
+	struct virtio_snd *snd;
+	unsigned int i;
+	int rc;
+
+	snd = devm_kzalloc(&vdev->dev, sizeof(*snd), GFP_KERNEL);
+	if (!snd)
+		return -ENOMEM;
+
+	snd->vdev = vdev;
+	INIT_WORK(&snd->reset_work, virtsnd_reset_fn);
+
+	vdev->priv = snd;
+
+	for (i = 0; i < VIRTIO_SND_VQ_MAX; ++i)
+		spin_lock_init(&snd->queues[i].lock);
+
+	rc = virtsnd_find_vqs(snd);
+	if (rc)
+		goto on_exit;
+
+	virtio_device_ready(vdev);
+
+	rc = virtsnd_build_devs(snd);
+	if (rc)
+		goto on_exit;
+
+	virtsnd_enable_event_vq(snd);
+
+on_exit:
+	if (rc)
+		virtsnd_remove(vdev);
+
+	return rc;
+}
+
+/**
+ * virtsnd_remove() - Remove VirtIO and ALSA devices.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context that permits to sleep.
+ */
+static void virtsnd_remove(struct virtio_device *vdev)
+{
+	struct virtio_snd *snd = vdev->priv;
+
+	/* Stop all the virtqueues. */
+	vdev->config->reset(vdev);
+
+	if (snd->card)
+		snd_card_free(snd->card);
+
+	vdev->config->del_vqs(vdev);
+
+	kfree(snd->event_msgs);
+}
+
+/**
+ * virtsnd_config_changed() - Handle configuration change notification.
+ * @vdev: VirtIO parent device.
+ *
+ * This callback function is called upon a configuration change interrupt
+ * request from the device. Currently only used to handle NEEDS_RESET device
+ * status.
+ *
+ * Context: Interrupt context.
+ */
+static void virtsnd_config_changed(struct virtio_device *vdev)
+{
+	struct virtio_snd *snd = vdev->priv;
+	unsigned int status = vdev->config->get_status(vdev);
+
+	if (status & VIRTIO_CONFIG_S_NEEDS_RESET)
+		schedule_work(&snd->reset_work);
+	else
+		dev_warn(&vdev->dev,
+			 "sound device configuration was changed\n");
+}
+
+static const struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_SOUND, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static struct virtio_driver virtsnd_driver = {
+	.driver.name = KBUILD_MODNAME,
+	.driver.owner = THIS_MODULE,
+	.id_table = id_table,
+	.validate = virtsnd_validate,
+	.probe = virtsnd_probe,
+	.remove = virtsnd_remove,
+	.config_changed = virtsnd_config_changed,
+};
+
+static int __init init(void)
+{
+	return register_virtio_driver(&virtsnd_driver);
+}
+module_init(init);
+
+static void __exit fini(void)
+{
+	unregister_virtio_driver(&virtsnd_driver);
+}
+module_exit(fini);
+
+MODULE_DEVICE_TABLE(virtio, id_table);
+MODULE_DESCRIPTION("Virtio sound card driver");
+MODULE_LICENSE("GPL");
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
new file mode 100644
index 000000000000..244381cc7a9b
--- /dev/null
+++ b/sound/virtio/virtio_card.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#ifndef VIRTIO_SND_CARD_H
+#define VIRTIO_SND_CARD_H
+
+#include <linux/slab.h>
+#include <linux/virtio.h>
+#include <sound/core.h>
+#include <uapi/linux/virtio_snd.h>
+
+#define VIRTIO_SND_CARD_DRIVER	"virtio-snd"
+#define VIRTIO_SND_CARD_NAME	"VirtIO SoundCard"
+
+/**
+ * struct virtio_snd_queue - Virtqueue wrapper structure.
+ * @lock: Used to synchronize access to a virtqueue.
+ * @vqueue: Underlying virtqueue.
+ */
+struct virtio_snd_queue {
+	spinlock_t lock;
+	struct virtqueue *vqueue;
+};
+
+/**
+ * struct virtio_snd - VirtIO sound card device.
+ * @vdev: Underlying virtio device.
+ * @queues: Virtqueue wrappers.
+ * @reset_work: Reset device work.
+ * @card: ALSA sound card.
+ * @event_msgs: Device events.
+ */
+struct virtio_snd {
+	struct virtio_device *vdev;
+	struct virtio_snd_queue queues[VIRTIO_SND_VQ_MAX];
+	struct work_struct reset_work;
+	struct snd_card *card;
+	struct virtio_snd_event *event_msgs;
+};
+
+static inline struct virtio_snd_queue *
+virtsnd_control_queue(struct virtio_snd *snd)
+{
+	return &snd->queues[VIRTIO_SND_VQ_CONTROL];
+}
+
+static inline struct virtio_snd_queue *
+virtsnd_event_queue(struct virtio_snd *snd)
+{
+	return &snd->queues[VIRTIO_SND_VQ_EVENT];
+}
+
+static inline struct virtio_snd_queue *
+virtsnd_tx_queue(struct virtio_snd *snd)
+{
+	return &snd->queues[VIRTIO_SND_VQ_TX];
+}
+
+static inline struct virtio_snd_queue *
+virtsnd_rx_queue(struct virtio_snd *snd)
+{
+	return &snd->queues[VIRTIO_SND_VQ_RX];
+}
+
+#endif /* VIRTIO_SND_CARD_H */
-- 
2.30.0

Re: [PATCH v5 2/9] ALSA: virtio: add virtio sound driver

[Takashi Iwai]

On Mon, 22 Feb 2021 16:34:37 +0100,
Anton Yakovlev wrote:
> +static int virtsnd_find_vqs(struct virtio_snd *snd)
> +{
> +	struct virtio_device *vdev = snd->vdev;
> +	vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = {
> +		[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb
> +	};
> +	const char *names[VIRTIO_SND_VQ_MAX] = {

Shouldn't be static?
Also it's often const char * const names[] = { ... }
unless you overwrite something.

> +/**
> + * virtsnd_reset_fn() - Kernel worker's function to reset the device.
> + * @work: Reset device work.
> + *
> + * Context: Process context.
> + */
> +static void virtsnd_reset_fn(struct work_struct *work)
> +{
> +	struct virtio_snd *snd =
> +		container_of(work, struct virtio_snd, reset_work);
> +	struct virtio_device *vdev = snd->vdev;
> +	struct device *dev = &vdev->dev;
> +	int rc;
> +
> +	dev_info(dev, "sound device needs reset\n");
> +
> +	/*
> +	 * It seems that the only way to properly reset the device is to remove
> +	 * and re-create the ALSA sound card device.
> +	 */
> +	rc = device_reprobe(dev);
> +	if (rc)
> +		dev_err(dev, "failed to reprobe sound device: %d\n", rc);

Now I'm wondering whether it's safe to do that from this place.
Basically device_reprobe() unbinds the device that releases the full
resources once including the devm_* stuff.  And this work itself is in
a part of devm allocated resource, so it'll be released there.  That
said, we might hit use-after-free...  This needs to be verified.


thanks,

Takashi

Re: [PATCH v5 2/9] ALSA: virtio: add virtio sound driver

[Takashi Iwai]

On Thu, 25 Feb 2021 11:38:35 +0100,
Takashi Iwai wrote:
> 
> On Mon, 22 Feb 2021 16:34:37 +0100,
> Anton Yakovlev wrote:
> > +static int virtsnd_find_vqs(struct virtio_snd *snd)
> > +{
> > +	struct virtio_device *vdev = snd->vdev;
> > +	vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = {
> > +		[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb
> > +	};
> > +	const char *names[VIRTIO_SND_VQ_MAX] = {
> 
> Shouldn't be static?

Also callbacks[] should be static (and maybe const), I suppose.


Takashi

Re: [PATCH v5 2/9] ALSA: virtio: add virtio sound driver

[Anton Yakovlev]

On 25.02.2021 11:38, Takashi Iwai wrote:
> On Mon, 22 Feb 2021 16:34:37 +0100,
> Anton Yakovlev wrote:
>> +static int virtsnd_find_vqs(struct virtio_snd *snd)
>> +{
>> +     struct virtio_device *vdev = snd->vdev;
>> +     vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = {
>> +             [VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb
>> +     };
>> +     const char *names[VIRTIO_SND_VQ_MAX] = {
> 
> Shouldn't be static?

Well, yes. Although in this particular case, I do not think it is that
critical. :)


> Also it's often const char * const names[] = { ... }
> unless you overwrite something.

I tried to use the same type names as in the function prototype.
Otherwise the compiler or static analyzer may complain.


>> +/**
>> + * virtsnd_reset_fn() - Kernel worker's function to reset the device.
>> + * @work: Reset device work.
>> + *
>> + * Context: Process context.
>> + */
>> +static void virtsnd_reset_fn(struct work_struct *work)
>> +{
>> +     struct virtio_snd *snd =
>> +             container_of(work, struct virtio_snd, reset_work);
>> +     struct virtio_device *vdev = snd->vdev;
>> +     struct device *dev = &vdev->dev;
>> +     int rc;
>> +
>> +     dev_info(dev, "sound device needs reset\n");
>> +
>> +     /*
>> +      * It seems that the only way to properly reset the device is to remove
>> +      * and re-create the ALSA sound card device.
>> +      */
>> +     rc = device_reprobe(dev);
>> +     if (rc)
>> +             dev_err(dev, "failed to reprobe sound device: %d\n", rc);
> 
> Now I'm wondering whether it's safe to do that from this place.
> Basically device_reprobe() unbinds the device that releases the full
> resources once including the devm_* stuff.  And this work itself is in
> a part of devm allocated resource, so it'll be released there.  That
> said, we might hit use-after-free...  This needs to be verified.

It's safe. Suicide kernel workers are funny but possible things. Since
the kernel itself (AFAIU) assumes such a situation and does not access
the worker structure after the callback function call.


> thanks,
> 
> Takashi
> 

-- 
Anton Yakovlev
Senior Software Engineer

OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin

Re: [PATCH v5 2/9] ALSA: virtio: add virtio sound driver

[Takashi Iwai]

On Thu, 25 Feb 2021 12:51:36 +0100,
Anton Yakovlev wrote:
> 
> > Now I'm wondering whether it's safe to do that from this place.
> > Basically device_reprobe() unbinds the device that releases the full
> > resources once including the devm_* stuff.  And this work itself is in
> > a part of devm allocated resource, so it'll be released there.  That
> > said, we might hit use-after-free...  This needs to be verified.
> 
> It's safe. Suicide kernel workers are funny but possible things. Since
> the kernel itself (AFAIU) assumes such a situation and does not access
> the worker structure after the callback function call.

Indeed, process_one_work() in workqueue.c assures no access to the
work object after the callback.  Then this must be fine.  Good to
know!


thanks,

Takashi

[PATCH v5 3/9] ALSA: virtio: handling control messages

[Anton Yakovlev]

The control queue can be used by different parts of the driver to send
commands to the device. Control messages can be either synchronous or
asynchronous. The lifetime of a message is controlled by a reference
count.

Introduce a module parameter to set the message completion timeout:
  msg_timeout_ms [=1000]

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/Makefile         |   3 +-
 sound/virtio/virtio_card.c    |  13 ++
 sound/virtio/virtio_card.h    |   7 +
 sound/virtio/virtio_ctl_msg.c | 310 ++++++++++++++++++++++++++++++++++
 sound/virtio/virtio_ctl_msg.h |  78 +++++++++
 5 files changed, 410 insertions(+), 1 deletion(-)
 create mode 100644 sound/virtio/virtio_ctl_msg.c
 create mode 100644 sound/virtio/virtio_ctl_msg.h

diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 8c87ebb9982b..dc551e637441 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -3,5 +3,6 @@
 obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
 
 virtio_snd-objs := \
-	virtio_card.o
+	virtio_card.o \
+	virtio_ctl_msg.o
 
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index b5f63b5b7db4..c62b3a2da148 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -11,6 +11,10 @@
 
 #include "virtio_card.h"
 
+int msg_timeout_ms = MSEC_PER_SEC;
+module_param(msg_timeout_ms, int, 0644);
+MODULE_PARM_DESC(msg_timeout_ms, "Message completion timeout in milliseconds");
+
 static void virtsnd_remove(struct virtio_device *vdev);
 
 /**
@@ -82,6 +86,7 @@ static int virtsnd_find_vqs(struct virtio_snd *snd)
 {
 	struct virtio_device *vdev = snd->vdev;
 	vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = {
+		[VIRTIO_SND_VQ_CONTROL] = virtsnd_ctl_notify_cb,
 		[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb
 	};
 	const char *names[VIRTIO_SND_VQ_MAX] = {
@@ -218,6 +223,11 @@ static int virtsnd_validate(struct virtio_device *vdev)
 		return -EINVAL;
 	}
 
+	if (!msg_timeout_ms) {
+		dev_err(&vdev->dev, "msg_timeout_ms value cannot be zero\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -240,6 +250,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
 
 	snd->vdev = vdev;
 	INIT_WORK(&snd->reset_work, virtsnd_reset_fn);
+	INIT_LIST_HEAD(&snd->ctl_msgs);
 
 	vdev->priv = snd;
 
@@ -278,6 +289,8 @@ static void virtsnd_remove(struct virtio_device *vdev)
 	/* Stop all the virtqueues. */
 	vdev->config->reset(vdev);
 
+	virtsnd_ctl_msg_cancel_all(snd);
+
 	if (snd->card)
 		snd_card_free(snd->card);
 
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index 244381cc7a9b..c51a71a79388 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -11,6 +11,8 @@
 #include <sound/core.h>
 #include <uapi/linux/virtio_snd.h>
 
+#include "virtio_ctl_msg.h"
+
 #define VIRTIO_SND_CARD_DRIVER	"virtio-snd"
 #define VIRTIO_SND_CARD_NAME	"VirtIO SoundCard"
 
@@ -30,6 +32,7 @@ struct virtio_snd_queue {
  * @queues: Virtqueue wrappers.
  * @reset_work: Reset device work.
  * @card: ALSA sound card.
+ * @ctl_msgs: Pending control request list.
  * @event_msgs: Device events.
  */
 struct virtio_snd {
@@ -37,9 +40,13 @@ struct virtio_snd {
 	struct virtio_snd_queue queues[VIRTIO_SND_VQ_MAX];
 	struct work_struct reset_work;
 	struct snd_card *card;
+	struct list_head ctl_msgs;
 	struct virtio_snd_event *event_msgs;
 };
 
+/* Message completion timeout in milliseconds (module parameter). */
+extern int msg_timeout_ms;
+
 static inline struct virtio_snd_queue *
 virtsnd_control_queue(struct virtio_snd *snd)
 {
diff --git a/sound/virtio/virtio_ctl_msg.c b/sound/virtio/virtio_ctl_msg.c
new file mode 100644
index 000000000000..67a5a0301ba3
--- /dev/null
+++ b/sound/virtio/virtio_ctl_msg.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#include <linux/moduleparam.h>
+#include <linux/virtio_config.h>
+
+#include "virtio_card.h"
+
+/**
+ * struct virtio_snd_msg - Control message.
+ * @sg_request: Scattergather list containing a device request (header).
+ * @sg_response: Scattergather list containing a device response (status).
+ * @list: Pending message list entry.
+ * @notify: Request completed notification.
+ * @ref_count: Reference count used to manage a message lifetime.
+ */
+struct virtio_snd_msg {
+	struct scatterlist sg_request;
+	struct scatterlist sg_response;
+	struct list_head list;
+	struct completion notify;
+	refcount_t ref_count;
+};
+
+/**
+ * virtsnd_ctl_msg_ref() - Increment reference counter for the message.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ */
+void virtsnd_ctl_msg_ref(struct virtio_snd_msg *msg)
+{
+	refcount_inc(&msg->ref_count);
+}
+
+/**
+ * virtsnd_ctl_msg_unref() - Decrement reference counter for the message.
+ * @msg: Control message.
+ *
+ * The message will be freed when the ref_count value is 0.
+ *
+ * Context: Any context.
+ */
+void virtsnd_ctl_msg_unref(struct virtio_snd_msg *msg)
+{
+	if (refcount_dec_and_test(&msg->ref_count))
+		kfree(msg);
+}
+
+/**
+ * virtsnd_ctl_msg_request() - Get a pointer to the request header.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ */
+void *virtsnd_ctl_msg_request(struct virtio_snd_msg *msg)
+{
+	return sg_virt(&msg->sg_request);
+}
+
+/**
+ * virtsnd_ctl_msg_request() - Get a pointer to the response header.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ */
+void *virtsnd_ctl_msg_response(struct virtio_snd_msg *msg)
+{
+	return sg_virt(&msg->sg_response);
+}
+
+/**
+ * virtsnd_ctl_msg_alloc() - Allocate and initialize a control message.
+ * @request_size: Size of request header.
+ * @response_size: Size of response header.
+ * @gfp: Kernel flags for memory allocation.
+ *
+ * The message will be automatically freed when the ref_count value is 0.
+ *
+ * Context: Any context. May sleep if @gfp flags permit.
+ * Return: Allocated message on success, NULL on failure.
+ */
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc(size_t request_size,
+					     size_t response_size, gfp_t gfp)
+{
+	struct virtio_snd_msg *msg;
+
+	if (!request_size || !response_size)
+		return NULL;
+
+	msg = kzalloc(sizeof(*msg) + request_size + response_size, gfp);
+	if (!msg)
+		return NULL;
+
+	sg_init_one(&msg->sg_request, (u8 *)msg + sizeof(*msg), request_size);
+	sg_init_one(&msg->sg_response, (u8 *)msg + sizeof(*msg) + request_size,
+		    response_size);
+
+	INIT_LIST_HEAD(&msg->list);
+	init_completion(&msg->notify);
+	/* This reference is dropped in virtsnd_ctl_msg_complete(). */
+	refcount_set(&msg->ref_count, 1);
+
+	return msg;
+}
+
+/**
+ * virtsnd_ctl_msg_send() - Send a control message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ * @out_sgs: Additional sg-list to attach to the request header (may be NULL).
+ * @in_sgs: Additional sg-list to attach to the response header (may be NULL).
+ * @nowait: Flag indicating whether to wait for completion.
+ *
+ * Context: Any context. Takes and releases the control queue spinlock.
+ *          May sleep if @nowait is false.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg,
+			 struct scatterlist *out_sgs,
+			 struct scatterlist *in_sgs, bool nowait)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
+	unsigned int js = msecs_to_jiffies(msg_timeout_ms);
+	struct virtio_snd_hdr *request = virtsnd_ctl_msg_request(msg);
+	struct virtio_snd_hdr *response = virtsnd_ctl_msg_response(msg);
+	unsigned int nouts = 0;
+	unsigned int nins = 0;
+	struct scatterlist *psgs[4];
+	bool notify = false;
+	unsigned long flags;
+	int rc;
+
+	virtsnd_ctl_msg_ref(msg);
+
+	/* Set the default status in case the message was canceled. */
+	response->code = cpu_to_le32(VIRTIO_SND_S_IO_ERR);
+
+	psgs[nouts++] = &msg->sg_request;
+	if (out_sgs)
+		psgs[nouts++] = out_sgs;
+
+	psgs[nouts + nins++] = &msg->sg_response;
+	if (in_sgs)
+		psgs[nouts + nins++] = in_sgs;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	rc = virtqueue_add_sgs(queue->vqueue, psgs, nouts, nins, msg,
+			       GFP_ATOMIC);
+	if (!rc) {
+		notify = virtqueue_kick_prepare(queue->vqueue);
+
+		list_add_tail(&msg->list, &snd->ctl_msgs);
+	}
+	spin_unlock_irqrestore(&queue->lock, flags);
+
+	if (rc) {
+		dev_err(&vdev->dev, "failed to send control message (0x%08x)\n",
+			le32_to_cpu(request->code));
+
+		/*
+		 * Since in this case virtsnd_ctl_msg_complete() will not be
+		 * called, it is necessary to decrement the reference count.
+		 */
+		virtsnd_ctl_msg_unref(msg);
+
+		goto on_exit;
+	}
+
+	if (notify)
+		virtqueue_notify(queue->vqueue);
+
+	if (nowait)
+		goto on_exit;
+
+	rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
+	if (rc <= 0) {
+		if (!rc) {
+			dev_err(&vdev->dev,
+				"control message (0x%08x) timeout\n",
+				le32_to_cpu(request->code));
+			rc = -ETIMEDOUT;
+		}
+
+		goto on_exit;
+	}
+
+	switch (le32_to_cpu(response->code)) {
+	case VIRTIO_SND_S_OK:
+		rc = 0;
+		break;
+	case VIRTIO_SND_S_NOT_SUPP:
+		rc = -EOPNOTSUPP;
+		break;
+	case VIRTIO_SND_S_IO_ERR:
+		rc = -EIO;
+		break;
+	default:
+		rc = -EINVAL;
+		break;
+	}
+
+on_exit:
+	virtsnd_ctl_msg_unref(msg);
+
+	return rc;
+}
+
+/**
+ * virtsnd_ctl_msg_complete() - Complete a control message.
+ * @msg: Control message.
+ *
+ * Context: Any context. Expects the control queue spinlock to be held by
+ *          caller.
+ */
+void virtsnd_ctl_msg_complete(struct virtio_snd_msg *msg)
+{
+	list_del(&msg->list);
+	complete(&msg->notify);
+
+	virtsnd_ctl_msg_unref(msg);
+}
+
+/**
+ * virtsnd_ctl_msg_cancel_all() - Cancel all pending control messages.
+ * @snd: VirtIO sound device.
+ *
+ * Context: Any context.
+ */
+void virtsnd_ctl_msg_cancel_all(struct virtio_snd *snd)
+{
+	struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	while (!list_empty(&snd->ctl_msgs)) {
+		struct virtio_snd_msg *msg =
+			list_first_entry(&snd->ctl_msgs, struct virtio_snd_msg,
+					 list);
+
+		virtsnd_ctl_msg_complete(msg);
+	}
+	spin_unlock_irqrestore(&queue->lock, flags);
+}
+
+/**
+ * virtsnd_ctl_query_info() - Query the item configuration from the device.
+ * @snd: VirtIO sound device.
+ * @command: Control request code (VIRTIO_SND_R_XXX_INFO).
+ * @start_id: Item start identifier.
+ * @count: Item count to query.
+ * @size: Item information size in bytes.
+ * @info: Buffer for storing item information.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
+			   int count, size_t size, void *info)
+{
+	struct virtio_snd_msg *msg;
+	struct virtio_snd_query_info *query;
+	struct scatterlist sg;
+
+	msg = virtsnd_ctl_msg_alloc(sizeof(*query),
+				    sizeof(struct virtio_snd_hdr), GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	query = virtsnd_ctl_msg_request(msg);
+	query->hdr.code = cpu_to_le32(command);
+	query->start_id = cpu_to_le32(start_id);
+	query->count = cpu_to_le32(count);
+	query->size = cpu_to_le32(size);
+
+	sg_init_one(&sg, info, count * size);
+
+	return virtsnd_ctl_msg_send(snd, msg, NULL, &sg, false);
+}
+
+/**
+ * virtsnd_ctl_notify_cb() - Process all completed control messages.
+ * @vqueue: Underlying control virtqueue.
+ *
+ * This callback function is called upon a vring interrupt request from the
+ * device.
+ *
+ * Context: Interrupt context. Takes and releases the control queue spinlock.
+ */
+void virtsnd_ctl_notify_cb(struct virtqueue *vqueue)
+{
+	struct virtio_snd *snd = vqueue->vdev->priv;
+	struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
+	struct virtio_snd_msg *msg;
+	u32 length;
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	do {
+		virtqueue_disable_cb(vqueue);
+		while ((msg = virtqueue_get_buf(vqueue, &length)))
+			virtsnd_ctl_msg_complete(msg);
+		if (unlikely(virtqueue_is_broken(vqueue)))
+			break;
+	} while (!virtqueue_enable_cb(vqueue));
+	spin_unlock_irqrestore(&queue->lock, flags);
+}
diff --git a/sound/virtio/virtio_ctl_msg.h b/sound/virtio/virtio_ctl_msg.h
new file mode 100644
index 000000000000..7f4db044f28e
--- /dev/null
+++ b/sound/virtio/virtio_ctl_msg.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#ifndef VIRTIO_SND_MSG_H
+#define VIRTIO_SND_MSG_H
+
+#include <linux/atomic.h>
+#include <linux/virtio.h>
+
+struct virtio_snd;
+struct virtio_snd_msg;
+
+void virtsnd_ctl_msg_ref(struct virtio_snd_msg *msg);
+
+void virtsnd_ctl_msg_unref(struct virtio_snd_msg *msg);
+
+void *virtsnd_ctl_msg_request(struct virtio_snd_msg *msg);
+
+void *virtsnd_ctl_msg_response(struct virtio_snd_msg *msg);
+
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc(size_t request_size,
+					     size_t response_size, gfp_t gfp);
+
+int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg,
+			 struct scatterlist *out_sgs,
+			 struct scatterlist *in_sgs, bool nowait);
+
+/**
+ * virtsnd_ctl_msg_send_sync() - Simplified sending of synchronous message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * After returning from this function, the message will be deleted. If message
+ * content is still needed, the caller must additionally to
+ * virtsnd_ctl_msg_ref/unref() it.
+ *
+ * The msg_timeout_ms module parameter defines the message completion timeout.
+ * If the message is not completed within this time, the function will return an
+ * error.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ *
+ * The return value is a message status code (VIRTIO_SND_S_XXX) converted to an
+ * appropriate -errno value.
+ */
+static inline int virtsnd_ctl_msg_send_sync(struct virtio_snd *snd,
+					    struct virtio_snd_msg *msg)
+{
+	return virtsnd_ctl_msg_send(snd, msg, NULL, NULL, false);
+}
+
+/**
+ * virtsnd_ctl_msg_send_async() - Simplified sending of asynchronous message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static inline int virtsnd_ctl_msg_send_async(struct virtio_snd *snd,
+					     struct virtio_snd_msg *msg)
+{
+	return virtsnd_ctl_msg_send(snd, msg, NULL, NULL, true);
+}
+
+void virtsnd_ctl_msg_cancel_all(struct virtio_snd *snd);
+
+void virtsnd_ctl_msg_complete(struct virtio_snd_msg *msg);
+
+int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
+			   int count, size_t size, void *info);
+
+void virtsnd_ctl_notify_cb(struct virtqueue *vqueue);
+
+#endif /* VIRTIO_SND_MSG_H */
-- 
2.30.0

[PATCH v5 4/9] ALSA: virtio: build PCM devices and substream hardware descriptors

[Anton Yakovlev]

Like the HDA specification, the virtio sound device specification links
PCM substreams, jacks and PCM channel maps into functional groups. For
each discovered group, a PCM device is created, the number of which
coincides with the group number.

Introduce the module parameters for setting the hardware buffer
parameters:
  pcm_buffer_ms [=160]
  pcm_periods_min [=2]
  pcm_periods_max [=16]
  pcm_period_ms_min [=10]
  pcm_period_ms_max [=80]

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/Makefile      |   3 +-
 sound/virtio/virtio_card.c |  14 ++
 sound/virtio/virtio_card.h |  10 +
 sound/virtio/virtio_pcm.c  | 463 +++++++++++++++++++++++++++++++++++++
 sound/virtio/virtio_pcm.h  |  70 ++++++
 5 files changed, 559 insertions(+), 1 deletion(-)
 create mode 100644 sound/virtio/virtio_pcm.c
 create mode 100644 sound/virtio/virtio_pcm.h

diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index dc551e637441..69162a545a41 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -4,5 +4,6 @@ obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
 
 virtio_snd-objs := \
 	virtio_card.o \
-	virtio_ctl_msg.o
+	virtio_ctl_msg.o \
+	virtio_pcm.o
 
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index c62b3a2da148..235afc25fce7 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -200,6 +200,16 @@ static int virtsnd_build_devs(struct virtio_snd *snd)
 			 VIRTIO_SND_CARD_NAME " at %s/%s",
 			 dev_name(dev->parent), dev_name(dev));
 
+	rc = virtsnd_pcm_parse_cfg(snd);
+	if (rc)
+		return rc;
+
+	if (snd->nsubstreams) {
+		rc = virtsnd_pcm_build_devs(snd);
+		if (rc)
+			return rc;
+	}
+
 	return snd_card_register(snd->card);
 }
 
@@ -228,6 +238,9 @@ static int virtsnd_validate(struct virtio_device *vdev)
 		return -EINVAL;
 	}
 
+	if (virtsnd_pcm_validate(vdev))
+		return -EINVAL;
+
 	return 0;
 }
 
@@ -251,6 +264,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
 	snd->vdev = vdev;
 	INIT_WORK(&snd->reset_work, virtsnd_reset_fn);
 	INIT_LIST_HEAD(&snd->ctl_msgs);
+	INIT_LIST_HEAD(&snd->pcm_list);
 
 	vdev->priv = snd;
 
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index c51a71a79388..f5e06a1ec033 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -12,9 +12,13 @@
 #include <uapi/linux/virtio_snd.h>
 
 #include "virtio_ctl_msg.h"
+#include "virtio_pcm.h"
 
 #define VIRTIO_SND_CARD_DRIVER	"virtio-snd"
 #define VIRTIO_SND_CARD_NAME	"VirtIO SoundCard"
+#define VIRTIO_SND_PCM_NAME	"VirtIO PCM"
+
+struct virtio_pcm_substream;
 
 /**
  * struct virtio_snd_queue - Virtqueue wrapper structure.
@@ -34,6 +38,9 @@ struct virtio_snd_queue {
  * @card: ALSA sound card.
  * @ctl_msgs: Pending control request list.
  * @event_msgs: Device events.
+ * @pcm_list: VirtIO PCM device list.
+ * @substreams: VirtIO PCM substreams.
+ * @nsubstreams: Number of PCM substreams.
  */
 struct virtio_snd {
 	struct virtio_device *vdev;
@@ -42,6 +49,9 @@ struct virtio_snd {
 	struct snd_card *card;
 	struct list_head ctl_msgs;
 	struct virtio_snd_event *event_msgs;
+	struct list_head pcm_list;
+	struct virtio_pcm_substream *substreams;
+	u32 nsubstreams;
 };
 
 /* Message completion timeout in milliseconds (module parameter). */
diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
new file mode 100644
index 000000000000..4348ead63c14
--- /dev/null
+++ b/sound/virtio/virtio_pcm.c
@@ -0,0 +1,463 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#include <linux/moduleparam.h>
+#include <linux/virtio_config.h>
+
+#include "virtio_card.h"
+
+static unsigned int pcm_buffer_ms = 160;
+module_param(pcm_buffer_ms, uint, 0644);
+MODULE_PARM_DESC(pcm_buffer_ms, "PCM substream buffer time in milliseconds");
+
+static unsigned int pcm_periods_min = 2;
+module_param(pcm_periods_min, uint, 0644);
+MODULE_PARM_DESC(pcm_periods_min, "Minimum number of PCM periods");
+
+static unsigned int pcm_periods_max = 16;
+module_param(pcm_periods_max, uint, 0644);
+MODULE_PARM_DESC(pcm_periods_max, "Maximum number of PCM periods");
+
+static unsigned int pcm_period_ms_min = 10;
+module_param(pcm_period_ms_min, uint, 0644);
+MODULE_PARM_DESC(pcm_period_ms_min, "Minimum PCM period time in milliseconds");
+
+static unsigned int pcm_period_ms_max = 80;
+module_param(pcm_period_ms_max, uint, 0644);
+MODULE_PARM_DESC(pcm_period_ms_max, "Maximum PCM period time in milliseconds");
+
+/* Map for converting VirtIO format to ALSA format. */
+static const snd_pcm_format_t g_v2a_format_map[] = {
+	[VIRTIO_SND_PCM_FMT_IMA_ADPCM] = SNDRV_PCM_FORMAT_IMA_ADPCM,
+	[VIRTIO_SND_PCM_FMT_MU_LAW] = SNDRV_PCM_FORMAT_MU_LAW,
+	[VIRTIO_SND_PCM_FMT_A_LAW] = SNDRV_PCM_FORMAT_A_LAW,
+	[VIRTIO_SND_PCM_FMT_S8] = SNDRV_PCM_FORMAT_S8,
+	[VIRTIO_SND_PCM_FMT_U8] = SNDRV_PCM_FORMAT_U8,
+	[VIRTIO_SND_PCM_FMT_S16] = SNDRV_PCM_FORMAT_S16_LE,
+	[VIRTIO_SND_PCM_FMT_U16] = SNDRV_PCM_FORMAT_U16_LE,
+	[VIRTIO_SND_PCM_FMT_S18_3] = SNDRV_PCM_FORMAT_S18_3LE,
+	[VIRTIO_SND_PCM_FMT_U18_3] = SNDRV_PCM_FORMAT_U18_3LE,
+	[VIRTIO_SND_PCM_FMT_S20_3] = SNDRV_PCM_FORMAT_S20_3LE,
+	[VIRTIO_SND_PCM_FMT_U20_3] = SNDRV_PCM_FORMAT_U20_3LE,
+	[VIRTIO_SND_PCM_FMT_S24_3] = SNDRV_PCM_FORMAT_S24_3LE,
+	[VIRTIO_SND_PCM_FMT_U24_3] = SNDRV_PCM_FORMAT_U24_3LE,
+	[VIRTIO_SND_PCM_FMT_S20] = SNDRV_PCM_FORMAT_S20_LE,
+	[VIRTIO_SND_PCM_FMT_U20] = SNDRV_PCM_FORMAT_U20_LE,
+	[VIRTIO_SND_PCM_FMT_S24] = SNDRV_PCM_FORMAT_S24_LE,
+	[VIRTIO_SND_PCM_FMT_U24] = SNDRV_PCM_FORMAT_U24_LE,
+	[VIRTIO_SND_PCM_FMT_S32] = SNDRV_PCM_FORMAT_S32_LE,
+	[VIRTIO_SND_PCM_FMT_U32] = SNDRV_PCM_FORMAT_U32_LE,
+	[VIRTIO_SND_PCM_FMT_FLOAT] = SNDRV_PCM_FORMAT_FLOAT_LE,
+	[VIRTIO_SND_PCM_FMT_FLOAT64] = SNDRV_PCM_FORMAT_FLOAT64_LE,
+	[VIRTIO_SND_PCM_FMT_DSD_U8] = SNDRV_PCM_FORMAT_DSD_U8,
+	[VIRTIO_SND_PCM_FMT_DSD_U16] = SNDRV_PCM_FORMAT_DSD_U16_LE,
+	[VIRTIO_SND_PCM_FMT_DSD_U32] = SNDRV_PCM_FORMAT_DSD_U32_LE,
+	[VIRTIO_SND_PCM_FMT_IEC958_SUBFRAME] =
+		SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE
+};
+
+/* Map for converting VirtIO frame rate to ALSA frame rate. */
+struct virtsnd_v2a_rate {
+	unsigned int alsa_bit;
+	unsigned int rate;
+};
+
+static const struct virtsnd_v2a_rate g_v2a_rate_map[] = {
+	[VIRTIO_SND_PCM_RATE_5512] = { SNDRV_PCM_RATE_5512, 5512 },
+	[VIRTIO_SND_PCM_RATE_8000] = { SNDRV_PCM_RATE_8000, 8000 },
+	[VIRTIO_SND_PCM_RATE_11025] = { SNDRV_PCM_RATE_11025, 11025 },
+	[VIRTIO_SND_PCM_RATE_16000] = { SNDRV_PCM_RATE_16000, 16000 },
+	[VIRTIO_SND_PCM_RATE_22050] = { SNDRV_PCM_RATE_22050, 22050 },
+	[VIRTIO_SND_PCM_RATE_32000] = { SNDRV_PCM_RATE_32000, 32000 },
+	[VIRTIO_SND_PCM_RATE_44100] = { SNDRV_PCM_RATE_44100, 44100 },
+	[VIRTIO_SND_PCM_RATE_48000] = { SNDRV_PCM_RATE_48000, 48000 },
+	[VIRTIO_SND_PCM_RATE_64000] = { SNDRV_PCM_RATE_64000, 64000 },
+	[VIRTIO_SND_PCM_RATE_88200] = { SNDRV_PCM_RATE_88200, 88200 },
+	[VIRTIO_SND_PCM_RATE_96000] = { SNDRV_PCM_RATE_96000, 96000 },
+	[VIRTIO_SND_PCM_RATE_176400] = { SNDRV_PCM_RATE_176400, 176400 },
+	[VIRTIO_SND_PCM_RATE_192000] = { SNDRV_PCM_RATE_192000, 192000 }
+};
+
+/**
+ * virtsnd_pcm_build_hw() - Parse substream config and build HW descriptor.
+ * @vss: VirtIO substream.
+ * @info: VirtIO substream information entry.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -EINVAL if configuration is invalid.
+ */
+static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss,
+				struct virtio_snd_pcm_info *info)
+{
+	struct virtio_device *vdev = vss->snd->vdev;
+	unsigned int i;
+	u64 values;
+	size_t sample_max = 0;
+	size_t sample_min = 0;
+
+	vss->features = le32_to_cpu(info->features);
+
+	/*
+	 * TODO: set SNDRV_PCM_INFO_{BATCH,BLOCK_TRANSFER} if device supports
+	 * only message-based transport.
+	 */
+	vss->hw.info =
+		SNDRV_PCM_INFO_MMAP |
+		SNDRV_PCM_INFO_MMAP_VALID |
+		SNDRV_PCM_INFO_BATCH |
+		SNDRV_PCM_INFO_BLOCK_TRANSFER |
+		SNDRV_PCM_INFO_INTERLEAVED |
+		SNDRV_PCM_INFO_PAUSE;
+
+	if (!info->channels_min || info->channels_min > info->channels_max) {
+		dev_err(&vdev->dev,
+			"SID %u: invalid channel range [%u %u]\n",
+			vss->sid, info->channels_min, info->channels_max);
+		return -EINVAL;
+	}
+
+	vss->hw.channels_min = info->channels_min;
+	vss->hw.channels_max = info->channels_max;
+
+	values = le64_to_cpu(info->formats);
+
+	vss->hw.formats = 0;
+
+	for (i = 0; i < ARRAY_SIZE(g_v2a_format_map); ++i)
+		if (values & (1ULL << i)) {
+			snd_pcm_format_t alsa_fmt = g_v2a_format_map[i];
+			int bytes = snd_pcm_format_physical_width(alsa_fmt) / 8;
+
+			if (!sample_min || sample_min > bytes)
+				sample_min = bytes;
+
+			if (sample_max < bytes)
+				sample_max = bytes;
+
+			vss->hw.formats |= (1ULL << (__force int)alsa_fmt);
+		}
+
+	if (!vss->hw.formats) {
+		dev_err(&vdev->dev,
+			"SID %u: no supported PCM sample formats found\n",
+			vss->sid);
+		return -EINVAL;
+	}
+
+	values = le64_to_cpu(info->rates);
+
+	vss->hw.rates = 0;
+
+	for (i = 0; i < ARRAY_SIZE(g_v2a_rate_map); ++i)
+		if (values & (1ULL << i)) {
+			if (!vss->hw.rate_min ||
+			    vss->hw.rate_min > g_v2a_rate_map[i].rate)
+				vss->hw.rate_min = g_v2a_rate_map[i].rate;
+
+			if (vss->hw.rate_max < g_v2a_rate_map[i].rate)
+				vss->hw.rate_max = g_v2a_rate_map[i].rate;
+
+			vss->hw.rates |= g_v2a_rate_map[i].alsa_bit;
+		}
+
+	if (!vss->hw.rates) {
+		dev_err(&vdev->dev,
+			"SID %u: no supported PCM frame rates found\n",
+			vss->sid);
+		return -EINVAL;
+	}
+
+	vss->hw.periods_min = pcm_periods_min;
+	vss->hw.periods_max = pcm_periods_max;
+
+	/*
+	 * We must ensure that there is enough space in the buffer to store
+	 * pcm_buffer_ms ms for the combination (Cmax, Smax, Rmax), where:
+	 *   Cmax = maximum supported number of channels,
+	 *   Smax = maximum supported sample size in bytes,
+	 *   Rmax = maximum supported frame rate.
+	 */
+	vss->hw.buffer_bytes_max =
+		sample_max * vss->hw.channels_max * pcm_buffer_ms *
+		(vss->hw.rate_max / MSEC_PER_SEC);
+
+	/* Align the buffer size to the page size */
+	vss->hw.buffer_bytes_max =
+		(vss->hw.buffer_bytes_max + PAGE_SIZE - 1) & -PAGE_SIZE;
+
+	/*
+	 * We must ensure that the minimum period size is enough to store
+	 * pcm_period_ms_min ms for the combination (Cmin, Smin, Rmin), where:
+	 *   Cmin = minimum supported number of channels,
+	 *   Smin = minimum supported sample size in bytes,
+	 *   Rmin = minimum supported frame rate.
+	 */
+	vss->hw.period_bytes_min =
+		sample_min * vss->hw.channels_min * pcm_period_ms_min *
+		(vss->hw.rate_min / MSEC_PER_SEC);
+
+	/*
+	 * We must ensure that the maximum period size is enough to store
+	 * pcm_period_ms_max ms for the combination (Cmax, Smax, Rmax).
+	 */
+	vss->hw.period_bytes_max =
+		sample_max * vss->hw.channels_max * pcm_period_ms_max *
+		(vss->hw.rate_max / MSEC_PER_SEC);
+
+	return 0;
+}
+
+/**
+ * virtsnd_pcm_find() - Find the PCM device for the specified node ID.
+ * @snd: VirtIO sound device.
+ * @nid: Function node ID.
+ *
+ * Context: Any context.
+ * Return: a pointer to the PCM device or ERR_PTR(-ENOENT).
+ */
+struct virtio_pcm *virtsnd_pcm_find(struct virtio_snd *snd, u32 nid)
+{
+	struct virtio_pcm *vpcm;
+
+	list_for_each_entry(vpcm, &snd->pcm_list, list)
+		if (vpcm->nid == nid)
+			return vpcm;
+
+	return ERR_PTR(-ENOENT);
+}
+
+/**
+ * virtsnd_pcm_find_or_create() - Find or create the PCM device for the
+ *                                specified node ID.
+ * @snd: VirtIO sound device.
+ * @nid: Function node ID.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: a pointer to the PCM device or ERR_PTR(-errno).
+ */
+struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, u32 nid)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_pcm *vpcm;
+
+	vpcm = virtsnd_pcm_find(snd, nid);
+	if (!IS_ERR(vpcm))
+		return vpcm;
+
+	vpcm = devm_kzalloc(&vdev->dev, sizeof(*vpcm), GFP_KERNEL);
+	if (!vpcm)
+		return ERR_PTR(-ENOMEM);
+
+	vpcm->nid = nid;
+	list_add_tail(&vpcm->list, &snd->pcm_list);
+
+	return vpcm;
+}
+
+/**
+ * virtsnd_pcm_validate() - Validate if the device can be started.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -EINVAL on failure.
+ */
+int virtsnd_pcm_validate(struct virtio_device *vdev)
+{
+	if (pcm_periods_min < 2 || pcm_periods_min > pcm_periods_max) {
+		dev_err(&vdev->dev,
+			"invalid range [%u %u] of the number of PCM periods\n",
+			pcm_periods_min, pcm_periods_max);
+		return -EINVAL;
+	}
+
+	if (!pcm_period_ms_min || pcm_period_ms_min > pcm_period_ms_max) {
+		dev_err(&vdev->dev,
+			"invalid range [%u %u] of the size of the PCM period\n",
+			pcm_period_ms_min, pcm_period_ms_max);
+		return -EINVAL;
+	}
+
+	if (pcm_buffer_ms < pcm_periods_min * pcm_period_ms_min) {
+		dev_err(&vdev->dev,
+			"pcm_buffer_ms(=%u) value cannot be < %u ms\n",
+			pcm_buffer_ms, pcm_periods_min * pcm_period_ms_min);
+		return -EINVAL;
+	}
+
+	if (pcm_period_ms_max > pcm_buffer_ms / 2) {
+		dev_err(&vdev->dev,
+			"pcm_period_ms_max(=%u) value cannot be > %u ms\n",
+			pcm_period_ms_max, pcm_buffer_ms / 2);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * virtsnd_pcm_parse_cfg() - Parse the stream configuration.
+ * @snd: VirtIO sound device.
+ *
+ * This function is called during initial device initialization.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_pcm_parse_cfg(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_snd_pcm_info *info;
+	u32 i;
+	int rc;
+
+	virtio_cread_le(vdev, struct virtio_snd_config, streams,
+			&snd->nsubstreams);
+	if (!snd->nsubstreams)
+		return 0;
+
+	snd->substreams = devm_kcalloc(&vdev->dev, snd->nsubstreams,
+				       sizeof(*snd->substreams), GFP_KERNEL);
+	if (!snd->substreams)
+		return -ENOMEM;
+
+	info = kcalloc(snd->nsubstreams, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_PCM_INFO, 0,
+				    snd->nsubstreams, sizeof(*info), info);
+	if (rc)
+		goto on_exit;
+
+	for (i = 0; i < snd->nsubstreams; ++i) {
+		struct virtio_pcm_substream *vss = &snd->substreams[i];
+		struct virtio_pcm *vpcm;
+
+		vss->snd = snd;
+		vss->sid = i;
+
+		rc = virtsnd_pcm_build_hw(vss, &info[i]);
+		if (rc)
+			goto on_exit;
+
+		vss->nid = le32_to_cpu(info[i].hdr.hda_fn_nid);
+
+		vpcm = virtsnd_pcm_find_or_create(snd, vss->nid);
+		if (IS_ERR(vpcm)) {
+			rc = PTR_ERR(vpcm);
+			goto on_exit;
+		}
+
+		switch (info[i].direction) {
+		case VIRTIO_SND_D_OUTPUT:
+			vss->direction = SNDRV_PCM_STREAM_PLAYBACK;
+			break;
+		case VIRTIO_SND_D_INPUT:
+			vss->direction = SNDRV_PCM_STREAM_CAPTURE;
+			break;
+		default:
+			dev_err(&vdev->dev, "SID %u: unknown direction (%u)\n",
+				vss->sid, info[i].direction);
+			rc = -EINVAL;
+			goto on_exit;
+		}
+
+		vpcm->streams[vss->direction].nsubstreams++;
+	}
+
+on_exit:
+	kfree(info);
+
+	return rc;
+}
+
+/**
+ * virtsnd_pcm_build_devs() - Build ALSA PCM devices.
+ * @snd: VirtIO sound device.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_pcm_build_devs(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_pcm *vpcm;
+	u32 i;
+	int rc;
+
+	list_for_each_entry(vpcm, &snd->pcm_list, list) {
+		unsigned int npbs =
+			vpcm->streams[SNDRV_PCM_STREAM_PLAYBACK].nsubstreams;
+		unsigned int ncps =
+			vpcm->streams[SNDRV_PCM_STREAM_CAPTURE].nsubstreams;
+
+		if (!npbs && !ncps)
+			continue;
+
+		rc = snd_pcm_new(snd->card, VIRTIO_SND_CARD_DRIVER, vpcm->nid,
+				 npbs, ncps, &vpcm->pcm);
+		if (rc) {
+			dev_err(&vdev->dev, "snd_pcm_new[%u] failed: %d\n",
+				vpcm->nid, rc);
+			return rc;
+		}
+
+		vpcm->pcm->info_flags = 0;
+		vpcm->pcm->dev_class = SNDRV_PCM_CLASS_GENERIC;
+		vpcm->pcm->dev_subclass = SNDRV_PCM_SUBCLASS_GENERIC_MIX;
+		snprintf(vpcm->pcm->name, sizeof(vpcm->pcm->name),
+			 VIRTIO_SND_PCM_NAME " %u", vpcm->pcm->device);
+		vpcm->pcm->private_data = vpcm;
+		vpcm->pcm->nonatomic = true;
+
+		for (i = 0; i < ARRAY_SIZE(vpcm->streams); ++i) {
+			struct virtio_pcm_stream *stream = &vpcm->streams[i];
+
+			if (!stream->nsubstreams)
+				continue;
+
+			stream->substreams =
+				devm_kcalloc(&vdev->dev, stream->nsubstreams,
+					     sizeof(*stream->substreams),
+					     GFP_KERNEL);
+			if (!stream->substreams)
+				return -ENOMEM;
+
+			stream->nsubstreams = 0;
+		}
+	}
+
+	for (i = 0; i < snd->nsubstreams; ++i) {
+		struct virtio_pcm_stream *vs;
+		struct virtio_pcm_substream *vss = &snd->substreams[i];
+
+		vpcm = virtsnd_pcm_find(snd, vss->nid);
+		if (IS_ERR(vpcm))
+			return PTR_ERR(vpcm);
+
+		vs = &vpcm->streams[vss->direction];
+		vs->substreams[vs->nsubstreams++] = vss;
+	}
+
+	list_for_each_entry(vpcm, &snd->pcm_list, list) {
+		for (i = 0; i < ARRAY_SIZE(vpcm->streams); ++i) {
+			struct virtio_pcm_stream *vs = &vpcm->streams[i];
+			struct snd_pcm_str *ks = &vpcm->pcm->streams[i];
+			struct snd_pcm_substream *kss;
+
+			if (!vs->nsubstreams)
+				continue;
+
+			for (kss = ks->substream; kss; kss = kss->next)
+				vs->substreams[kss->number]->substream = kss;
+		}
+
+		snd_pcm_set_managed_buffer_all(vpcm->pcm,
+					       SNDRV_DMA_TYPE_VMALLOC, NULL,
+					       0, 0);
+	}
+
+	return 0;
+}
diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
new file mode 100644
index 000000000000..a2aadc44dce9
--- /dev/null
+++ b/sound/virtio/virtio_pcm.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#ifndef VIRTIO_SND_PCM_H
+#define VIRTIO_SND_PCM_H
+
+#include <linux/atomic.h>
+#include <linux/virtio_config.h>
+#include <sound/pcm.h>
+
+struct virtio_pcm;
+struct virtio_pcm_msg;
+
+/**
+ * struct virtio_pcm_substream - VirtIO PCM substream.
+ * @snd: VirtIO sound device.
+ * @nid: Function group node identifier.
+ * @sid: Stream identifier.
+ * @direction: Stream data flow direction (SNDRV_PCM_STREAM_XXX).
+ * @features: Stream VirtIO feature bit map (1 << VIRTIO_SND_PCM_F_XXX).
+ * @substream: Kernel ALSA substream.
+ * @hw: Kernel ALSA substream hardware descriptor.
+ */
+struct virtio_pcm_substream {
+	struct virtio_snd *snd;
+	u32 nid;
+	u32 sid;
+	u32 direction;
+	u32 features;
+	struct snd_pcm_substream *substream;
+	struct snd_pcm_hardware hw;
+};
+
+/**
+ * struct virtio_pcm_stream - VirtIO PCM stream.
+ * @substreams: VirtIO substreams belonging to the stream.
+ * @nsubstreams: Number of substreams.
+ */
+struct virtio_pcm_stream {
+	struct virtio_pcm_substream **substreams;
+	u32 nsubstreams;
+};
+
+/**
+ * struct virtio_pcm - VirtIO PCM device.
+ * @list: VirtIO PCM list entry.
+ * @nid: Function group node identifier.
+ * @pcm: Kernel PCM device.
+ * @streams: VirtIO PCM streams (playback and capture).
+ */
+struct virtio_pcm {
+	struct list_head list;
+	u32 nid;
+	struct snd_pcm *pcm;
+	struct virtio_pcm_stream streams[SNDRV_PCM_STREAM_LAST + 1];
+};
+
+int virtsnd_pcm_validate(struct virtio_device *vdev);
+
+int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
+
+int virtsnd_pcm_build_devs(struct virtio_snd *snd);
+
+struct virtio_pcm *virtsnd_pcm_find(struct virtio_snd *snd, u32 nid);
+
+struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, u32 nid);
+
+#endif /* VIRTIO_SND_PCM_H */
-- 
2.30.0

[PATCH v5 5/9] ALSA: virtio: handling control and I/O messages for the PCM device

[Anton Yakovlev]

The driver implements a message-based transport for I/O substream
operations. Before the start of the substream, the hardware buffer is
sliced into I/O messages, the number of which is equal to the current
number of periods. The size of each message is equal to the current
size of one period.

I/O messages are organized in an ordered queue. The completion of the
I/O message indicates an elapsed period (the only exception is the end
of the stream for the capture substream). Upon completion, the message
is automatically re-added to the end of the queue.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/Makefile         |   3 +-
 sound/virtio/virtio_card.c    |  18 +-
 sound/virtio/virtio_card.h    |   9 +
 sound/virtio/virtio_pcm.c     |  32 +++
 sound/virtio/virtio_pcm.h     |  42 ++++
 sound/virtio/virtio_pcm_msg.c | 392 ++++++++++++++++++++++++++++++++++
 6 files changed, 493 insertions(+), 3 deletions(-)
 create mode 100644 sound/virtio/virtio_pcm_msg.c

diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 69162a545a41..626af3cc3ed7 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -5,5 +5,6 @@ obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
 virtio_snd-objs := \
 	virtio_card.o \
 	virtio_ctl_msg.o \
-	virtio_pcm.o
+	virtio_pcm.o \
+	virtio_pcm_msg.o
 
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index 235afc25fce7..a845978111d6 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -65,8 +65,16 @@ static void virtsnd_event_notify_cb(struct virtqueue *vqueue)
 	spin_lock_irqsave(&queue->lock, flags);
 	do {
 		virtqueue_disable_cb(vqueue);
-		while ((event = virtqueue_get_buf(vqueue, &length)))
+		while ((event = virtqueue_get_buf(vqueue, &length))) {
+			switch (le32_to_cpu(event->hdr.code)) {
+			case VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED:
+			case VIRTIO_SND_EVT_PCM_XRUN:
+				virtsnd_pcm_event(snd, event);
+				break;
+			}
+
 			virtsnd_event_send(vqueue, event, true, GFP_ATOMIC);
+		}
 		if (unlikely(virtqueue_is_broken(vqueue)))
 			break;
 	} while (!virtqueue_enable_cb(vqueue));
@@ -87,7 +95,9 @@ static int virtsnd_find_vqs(struct virtio_snd *snd)
 	struct virtio_device *vdev = snd->vdev;
 	vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = {
 		[VIRTIO_SND_VQ_CONTROL] = virtsnd_ctl_notify_cb,
-		[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb
+		[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb,
+		[VIRTIO_SND_VQ_TX] = virtsnd_pcm_tx_notify_cb,
+		[VIRTIO_SND_VQ_RX] = virtsnd_pcm_rx_notify_cb
 	};
 	const char *names[VIRTIO_SND_VQ_MAX] = {
 		[VIRTIO_SND_VQ_CONTROL] = "virtsnd-ctl",
@@ -299,6 +309,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
 static void virtsnd_remove(struct virtio_device *vdev)
 {
 	struct virtio_snd *snd = vdev->priv;
+	unsigned int i;
 
 	/* Stop all the virtqueues. */
 	vdev->config->reset(vdev);
@@ -310,6 +321,9 @@ static void virtsnd_remove(struct virtio_device *vdev)
 
 	vdev->config->del_vqs(vdev);
 
+	for (i = 0; snd->substreams && i < snd->nsubstreams; ++i)
+		virtsnd_pcm_msg_free(&snd->substreams[i]);
+
 	kfree(snd->event_msgs);
 }
 
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index f5e06a1ec033..3d8f5ad92f79 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -81,4 +81,13 @@ virtsnd_rx_queue(struct virtio_snd *snd)
 	return &snd->queues[VIRTIO_SND_VQ_RX];
 }
 
+static inline struct virtio_snd_queue *
+virtsnd_pcm_queue(struct virtio_pcm_substream *vss)
+{
+	if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK)
+		return virtsnd_tx_queue(vss->snd);
+	else
+		return virtsnd_rx_queue(vss->snd);
+}
+
 #endif /* VIRTIO_SND_CARD_H */
diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
index 4348ead63c14..3cfd3520a9c0 100644
--- a/sound/virtio/virtio_pcm.c
+++ b/sound/virtio/virtio_pcm.c
@@ -337,6 +337,8 @@ int virtsnd_pcm_parse_cfg(struct virtio_snd *snd)
 
 		vss->snd = snd;
 		vss->sid = i;
+		init_waitqueue_head(&vss->msg_empty);
+		spin_lock_init(&vss->lock);
 
 		rc = virtsnd_pcm_build_hw(vss, &info[i]);
 		if (rc)
@@ -461,3 +463,33 @@ int virtsnd_pcm_build_devs(struct virtio_snd *snd)
 
 	return 0;
 }
+
+/**
+ * virtsnd_pcm_event() - Handle the PCM device event notification.
+ * @snd: VirtIO sound device.
+ * @event: VirtIO sound event.
+ *
+ * Context: Interrupt context.
+ */
+void virtsnd_pcm_event(struct virtio_snd *snd, struct virtio_snd_event *event)
+{
+	struct virtio_pcm_substream *vss;
+	u32 sid = le32_to_cpu(event->data);
+
+	if (sid >= snd->nsubstreams)
+		return;
+
+	vss = &snd->substreams[sid];
+
+	switch (le32_to_cpu(event->hdr.code)) {
+	case VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED:
+		/* TODO: deal with shmem elapsed period */
+		break;
+	case VIRTIO_SND_EVT_PCM_XRUN:
+		spin_lock(&vss->lock);
+		if (vss->xfer_enabled)
+			vss->xfer_xrun = true;
+		spin_unlock(&vss->lock);
+		break;
+	}
+}
diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
index a2aadc44dce9..c70e4fed9044 100644
--- a/sound/virtio/virtio_pcm.h
+++ b/sound/virtio/virtio_pcm.h
@@ -22,6 +22,19 @@ struct virtio_pcm_msg;
  * @features: Stream VirtIO feature bit map (1 << VIRTIO_SND_PCM_F_XXX).
  * @substream: Kernel ALSA substream.
  * @hw: Kernel ALSA substream hardware descriptor.
+ * @frame_bytes: Current frame size in bytes.
+ * @period_size: Current period size in frames.
+ * @buffer_size: Current buffer size in frames.
+ * @lock: Spinlock that protects fields shared by interrupt handlers and
+ *        substream operators.
+ * @hw_ptr: Substream hardware pointer value in frames [0 ... buffer_size).
+ * @xfer_enabled: Data transfer state (0 - off, 1 - on).
+ * @xfer_xrun: Data underflow/overflow state (0 - no xrun, 1 - xrun).
+ * @msgs: Allocated I/O messages.
+ * @nmsgs: Number of allocated I/O messages.
+ * @msg_last_enqueued: Index of the last I/O message added to the virtqueue.
+ * @msg_count: Number of pending I/O messages in the virtqueue.
+ * @msg_empty: Notify when msg_count is zero.
  */
 struct virtio_pcm_substream {
 	struct virtio_snd *snd;
@@ -31,6 +44,18 @@ struct virtio_pcm_substream {
 	u32 features;
 	struct snd_pcm_substream *substream;
 	struct snd_pcm_hardware hw;
+	unsigned int frame_bytes;
+	snd_pcm_uframes_t period_size;
+	snd_pcm_uframes_t buffer_size;
+	spinlock_t lock;
+	snd_pcm_uframes_t hw_ptr;
+	bool xfer_enabled;
+	bool xfer_xrun;
+	struct virtio_pcm_msg **msgs;
+	unsigned int nmsgs;
+	int msg_last_enqueued;
+	unsigned int msg_count;
+	wait_queue_head_t msg_empty;
 };
 
 /**
@@ -63,8 +88,25 @@ int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
 
 int virtsnd_pcm_build_devs(struct virtio_snd *snd);
 
+void virtsnd_pcm_event(struct virtio_snd *snd, struct virtio_snd_event *event);
+
+void virtsnd_pcm_tx_notify_cb(struct virtqueue *vqueue);
+
+void virtsnd_pcm_rx_notify_cb(struct virtqueue *vqueue);
+
 struct virtio_pcm *virtsnd_pcm_find(struct virtio_snd *snd, u32 nid);
 
 struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, u32 nid);
 
+struct virtio_snd_msg *
+virtsnd_pcm_ctl_msg_alloc(struct virtio_pcm_substream *vss,
+			  unsigned int command, gfp_t gfp);
+
+int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss,
+			  unsigned int periods, unsigned int period_bytes);
+
+void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss);
+
+int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss);
+
 #endif /* VIRTIO_SND_PCM_H */
diff --git a/sound/virtio/virtio_pcm_msg.c b/sound/virtio/virtio_pcm_msg.c
new file mode 100644
index 000000000000..8f29a9baf806
--- /dev/null
+++ b/sound/virtio/virtio_pcm_msg.c
@@ -0,0 +1,392 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#include <sound/pcm_params.h>
+
+#include "virtio_card.h"
+
+/**
+ * struct virtio_pcm_msg - VirtIO I/O message.
+ * @substream: VirtIO PCM substream.
+ * @xfer: Request header payload.
+ * @status: Response header payload.
+ * @sgs: Payload scatter-gather table.
+ */
+struct virtio_pcm_msg {
+	struct virtio_pcm_substream *substream;
+	struct virtio_snd_pcm_xfer xfer;
+	struct virtio_snd_pcm_status status;
+	struct scatterlist sgs[0];
+};
+
+/**
+ * enum pcm_msg_sg_index - Index values for the virtio_pcm_msg->sgs field in
+ *                         an I/O message.
+ * @PCM_MSG_SG_XFER: Element containing a virtio_snd_pcm_xfer structure.
+ * @PCM_MSG_SG_STATUS: Element containing a virtio_snd_pcm_status structure.
+ * @PCM_MSG_SG_DATA: The first element containing a data buffer.
+ */
+enum pcm_msg_sg_index {
+	PCM_MSG_SG_XFER = 0,
+	PCM_MSG_SG_STATUS,
+	PCM_MSG_SG_DATA
+};
+
+/**
+ * virtsnd_pcm_sg_num() - Count the number of sg-elements required to represent
+ *                        vmalloc'ed buffer.
+ * @data: Pointer to vmalloc'ed buffer.
+ * @length: Buffer size.
+ *
+ * Context: Any context.
+ * Return: Number of physically contiguous parts in the @data.
+ */
+static int virtsnd_pcm_sg_num(u8 *data, unsigned int length)
+{
+	phys_addr_t sg_address;
+	unsigned int sg_length;
+	int num = 0;
+
+	while (length) {
+		struct page *pg = vmalloc_to_page(data);
+		phys_addr_t pg_address = page_to_phys(pg);
+		size_t pg_length;
+
+		pg_length = PAGE_SIZE - offset_in_page(data);
+		if (pg_length > length)
+			pg_length = length;
+
+		if (!num || sg_address + sg_length != pg_address) {
+			sg_address = pg_address;
+			sg_length = pg_length;
+			num++;
+		} else {
+			sg_length += pg_length;
+		}
+
+		data += pg_length;
+		length -= pg_length;
+	}
+
+	return num;
+}
+
+/**
+ * virtsnd_pcm_sg_from() - Build sg-list from vmalloc'ed buffer.
+ * @sgs: Preallocated sg-list to populate.
+ * @nsgs: The maximum number of elements in the @sgs.
+ * @data: Pointer to vmalloc'ed buffer.
+ * @length: Buffer size.
+ *
+ * Splits the buffer into physically contiguous parts and makes an sg-list of
+ * such parts.
+ *
+ * Context: Any context.
+ */
+static void virtsnd_pcm_sg_from(struct scatterlist *sgs, int nsgs, u8 *data,
+				unsigned int length)
+{
+	int idx = -1;
+
+	while (length) {
+		struct page *pg = vmalloc_to_page(data);
+		size_t pg_length;
+
+		pg_length = PAGE_SIZE - offset_in_page(data);
+		if (pg_length > length)
+			pg_length = length;
+
+		if (idx == -1 ||
+		    sg_phys(&sgs[idx]) + sgs[idx].length != page_to_phys(pg)) {
+			if (idx + 1 == nsgs)
+				break;
+			sg_set_page(&sgs[++idx], pg, pg_length,
+				    offset_in_page(data));
+		} else {
+			sgs[idx].length += pg_length;
+		}
+
+		data += pg_length;
+		length -= pg_length;
+	}
+
+	sg_mark_end(&sgs[idx]);
+}
+
+/**
+ * virtsnd_pcm_msg_alloc() - Allocate I/O messages.
+ * @vss: VirtIO PCM substream.
+ * @periods: Current number of periods.
+ * @period_bytes: Current period size in bytes.
+ *
+ * The function slices the buffer into @periods parts (each with the size of
+ * @period_bytes), and creates @periods corresponding I/O messages.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -ENOMEM on failure.
+ */
+int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss,
+			  unsigned int periods, unsigned int period_bytes)
+{
+	struct snd_pcm_runtime *runtime = vss->substream->runtime;
+	unsigned int i;
+
+	/* Free previously allocated messages (if any). */
+	virtsnd_pcm_msg_free(vss);
+
+	vss->msgs = kcalloc(periods, sizeof(*vss->msgs), GFP_KERNEL);
+	if (!vss->msgs)
+		return -ENOMEM;
+
+	vss->nmsgs = periods;
+
+	for (i = 0; i < periods; ++i) {
+		u8 *data = runtime->dma_area + period_bytes * i;
+		int sg_num = virtsnd_pcm_sg_num(data, period_bytes);
+		struct virtio_pcm_msg *msg;
+
+		msg = kzalloc(sizeof(*msg) + sizeof(*msg->sgs) * (sg_num + 2),
+			      GFP_KERNEL);
+		if (!msg)
+			return -ENOMEM;
+
+		msg->substream = vss;
+		sg_init_one(&msg->sgs[PCM_MSG_SG_XFER], &msg->xfer,
+			    sizeof(msg->xfer));
+		sg_init_one(&msg->sgs[PCM_MSG_SG_STATUS], &msg->status,
+			    sizeof(msg->status));
+		virtsnd_pcm_sg_from(&msg->sgs[PCM_MSG_SG_DATA], sg_num, data,
+				    period_bytes);
+
+		vss->msgs[i] = msg;
+	}
+
+	return 0;
+}
+
+/**
+ * virtsnd_pcm_msg_free() - Free all allocated I/O messages.
+ * @vss: VirtIO PCM substream.
+ *
+ * Context: Any context.
+ */
+void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss)
+{
+	unsigned int i;
+
+	for (i = 0; i < vss->nmsgs; ++i)
+		kfree(vss->msgs[i]);
+	kfree(vss->msgs);
+
+	vss->msgs = NULL;
+	vss->nmsgs = 0;
+}
+
+/**
+ * virtsnd_pcm_msg_send() - Send asynchronous I/O messages.
+ * @vss: VirtIO PCM substream.
+ *
+ * All messages are organized in an ordered circular list. Each time the
+ * function is called, all currently non-enqueued messages are added to the
+ * virtqueue. For this, the function keeps track of two values:
+ *
+ *   msg_last_enqueued = index of the last enqueued message,
+ *   msg_count = # of pending messages in the virtqueue.
+ *
+ * Context: Any context. Expects the tx/rx queue and the VirtIO substream
+ *          spinlocks to be held by caller.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss)
+{
+	struct snd_pcm_runtime *runtime = vss->substream->runtime;
+	struct virtio_snd *snd = vss->snd;
+	struct virtio_device *vdev = snd->vdev;
+	struct virtqueue *vqueue = virtsnd_pcm_queue(vss)->vqueue;
+	int i;
+	int n;
+	bool notify = false;
+
+	i = (vss->msg_last_enqueued + 1) % runtime->periods;
+	n = runtime->periods - vss->msg_count;
+
+	for (; n; --n, i = (i + 1) % runtime->periods) {
+		struct virtio_pcm_msg *msg = vss->msgs[i];
+		struct scatterlist *psgs[] = {
+			&msg->sgs[PCM_MSG_SG_XFER],
+			&msg->sgs[PCM_MSG_SG_DATA],
+			&msg->sgs[PCM_MSG_SG_STATUS]
+		};
+		int rc;
+
+		msg->xfer.stream_id = cpu_to_le32(vss->sid);
+		memset(&msg->status, 0, sizeof(msg->status));
+
+		if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK)
+			rc = virtqueue_add_sgs(vqueue, psgs, 2, 1, msg,
+					       GFP_ATOMIC);
+		else
+			rc = virtqueue_add_sgs(vqueue, psgs, 1, 2, msg,
+					       GFP_ATOMIC);
+
+		if (rc) {
+			dev_err(&vdev->dev,
+				"SID %u: failed to send I/O message\n",
+				vss->sid);
+			return rc;
+		}
+
+		vss->msg_last_enqueued = i;
+		vss->msg_count++;
+	}
+
+	if (!(vss->features & (1U << VIRTIO_SND_PCM_F_MSG_POLLING)))
+		notify = virtqueue_kick_prepare(vqueue);
+
+	if (notify)
+		virtqueue_notify(vqueue);
+
+	return 0;
+}
+
+/**
+ * virtsnd_pcm_msg_complete() - Complete an I/O message.
+ * @msg: I/O message.
+ * @size: Number of bytes written.
+ *
+ * Completion of the message means the elapsed period.
+ *
+ * Context: Interrupt context. Takes and releases the VirtIO substream spinlock.
+ */
+static void virtsnd_pcm_msg_complete(struct virtio_pcm_msg *msg, size_t size)
+{
+	struct virtio_pcm_substream *vss = msg->substream;
+
+	/*
+	 * hw_ptr always indicates the buffer position of the first I/O message
+	 * in the virtqueue. Therefore, on each completion of an I/O message,
+	 * the hw_ptr value is unconditionally advanced.
+	 */
+	spin_lock(&vss->lock);
+	/*
+	 * If the capture substream returned an incorrect status, then just
+	 * increase the hw_ptr by the period size.
+	 */
+	if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK ||
+	    size <= sizeof(msg->status)) {
+		vss->hw_ptr += vss->period_size;
+	} else {
+		size -= sizeof(msg->status);
+		vss->hw_ptr += size / vss->frame_bytes;
+	}
+
+	vss->hw_ptr %= vss->buffer_size;
+	vss->xfer_xrun = false;
+	vss->msg_count--;
+
+	if (vss->xfer_enabled) {
+		struct snd_pcm_runtime *runtime = vss->substream->runtime;
+
+		runtime->delay =
+			bytes_to_frames(runtime,
+					le32_to_cpu(msg->status.latency_bytes));
+
+		spin_unlock(&vss->lock);
+		snd_pcm_period_elapsed(vss->substream);
+		spin_lock(&vss->lock);
+
+		virtsnd_pcm_msg_send(vss);
+	} else if (!vss->msg_count) {
+		wake_up_all(&vss->msg_empty);
+	}
+	spin_unlock(&vss->lock);
+}
+
+/**
+ * virtsnd_pcm_notify_cb() - Process all completed I/O messages.
+ * @queue: Underlying tx/rx virtqueue.
+ *
+ * If transmission is allowed, then each completed message is immediately placed
+ * back at the end of the queue.
+ *
+ * Context: Interrupt context. Takes and releases the tx/rx queue spinlock.
+ */
+static inline void virtsnd_pcm_notify_cb(struct virtio_snd_queue *queue)
+{
+	struct virtio_pcm_msg *msg;
+	u32 length;
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	do {
+		virtqueue_disable_cb(queue->vqueue);
+		while ((msg = virtqueue_get_buf(queue->vqueue, &length)))
+			virtsnd_pcm_msg_complete(msg, length);
+		if (unlikely(virtqueue_is_broken(queue->vqueue)))
+			break;
+	} while (!virtqueue_enable_cb(queue->vqueue));
+	spin_unlock_irqrestore(&queue->lock, flags);
+}
+
+/**
+ * virtsnd_pcm_tx_notify_cb() - Process all completed TX messages.
+ * @vqueue: Underlying tx virtqueue.
+ *
+ * Context: Interrupt context.
+ */
+void virtsnd_pcm_tx_notify_cb(struct virtqueue *vqueue)
+{
+	struct virtio_snd *snd = vqueue->vdev->priv;
+
+	virtsnd_pcm_notify_cb(virtsnd_tx_queue(snd));
+}
+
+/**
+ * virtsnd_pcm_rx_notify_cb() - Process all completed RX messages.
+ * @vqueue: Underlying rx virtqueue.
+ *
+ * Context: Interrupt context.
+ */
+void virtsnd_pcm_rx_notify_cb(struct virtqueue *vqueue)
+{
+	struct virtio_snd *snd = vqueue->vdev->priv;
+
+	virtsnd_pcm_notify_cb(virtsnd_rx_queue(snd));
+}
+
+/**
+ * virtsnd_pcm_ctl_msg_alloc() - Allocate and initialize the PCM device control
+ *                               message for the specified substream.
+ * @vss: VirtIO PCM substream.
+ * @command: Control request code (VIRTIO_SND_R_PCM_XXX).
+ * @gfp: Kernel flags for memory allocation.
+ *
+ * Context: Any context. May sleep if @gfp flags permit.
+ * Return: Allocated message on success, NULL on failure.
+ */
+struct virtio_snd_msg *
+virtsnd_pcm_ctl_msg_alloc(struct virtio_pcm_substream *vss,
+			  unsigned int command, gfp_t gfp)
+{
+	size_t request_size = sizeof(struct virtio_snd_pcm_hdr);
+	size_t response_size = sizeof(struct virtio_snd_hdr);
+	struct virtio_snd_msg *msg;
+
+	switch (command) {
+	case VIRTIO_SND_R_PCM_SET_PARAMS:
+		request_size = sizeof(struct virtio_snd_pcm_set_params);
+		break;
+	}
+
+	msg = virtsnd_ctl_msg_alloc(request_size, response_size, gfp);
+	if (msg) {
+		struct virtio_snd_pcm_hdr *hdr = virtsnd_ctl_msg_request(msg);
+
+		hdr->hdr.code = cpu_to_le32(command);
+		hdr->stream_id = cpu_to_le32(vss->sid);
+	}
+
+	return msg;
+}
-- 
2.30.0

Re: [PATCH v5 5/9] ALSA: virtio: handling control and I/O messages for the PCM device

[Takashi Iwai]

On Mon, 22 Feb 2021 16:34:40 +0100,
Anton Yakovlev wrote:
> 
> +void virtsnd_pcm_event(struct virtio_snd *snd, struct virtio_snd_event *event)
> +{
> +	struct virtio_pcm_substream *vss;
> +	u32 sid = le32_to_cpu(event->data);
> +
> +	if (sid >= snd->nsubstreams)
> +		return;
> +
> +	vss = &snd->substreams[sid];
> +
> +	switch (le32_to_cpu(event->hdr.code)) {
> +	case VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED:
> +		/* TODO: deal with shmem elapsed period */
> +		break;
> +	case VIRTIO_SND_EVT_PCM_XRUN:
> +		spin_lock(&vss->lock);
> +		if (vss->xfer_enabled)
> +			vss->xfer_xrun = true;
> +		spin_unlock(&vss->lock);

You can stop the stream at xrun, too.

But it often messes up with the locking, so it's no mandatory
implementation.  You seem to pass the xrun state at the pointer
callback, and this should be enough for normal uses.


thanks,

Takashi

[PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Anton Yakovlev]

Introduce the operators required for the operation of substreams.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/Makefile         |   3 +-
 sound/virtio/virtio_pcm.c     |   2 +
 sound/virtio/virtio_pcm.h     |   4 +
 sound/virtio/virtio_pcm_ops.c | 469 ++++++++++++++++++++++++++++++++++
 4 files changed, 477 insertions(+), 1 deletion(-)
 create mode 100644 sound/virtio/virtio_pcm_ops.c

diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 626af3cc3ed7..34493226793f 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -6,5 +6,6 @@ virtio_snd-objs := \
 	virtio_card.o \
 	virtio_ctl_msg.o \
 	virtio_pcm.o \
-	virtio_pcm_msg.o
+	virtio_pcm_msg.o \
+	virtio_pcm_ops.o
 
diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
index 3cfd3520a9c0..3605151860f2 100644
--- a/sound/virtio/virtio_pcm.c
+++ b/sound/virtio/virtio_pcm.c
@@ -454,6 +454,8 @@ int virtsnd_pcm_build_devs(struct virtio_snd *snd)
 
 			for (kss = ks->substream; kss; kss = kss->next)
 				vs->substreams[kss->number]->substream = kss;
+
+			snd_pcm_set_ops(vpcm->pcm, i, &virtsnd_pcm_ops);
 		}
 
 		snd_pcm_set_managed_buffer_all(vpcm->pcm,
diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
index c70e4fed9044..c48d00acee2e 100644
--- a/sound/virtio/virtio_pcm.h
+++ b/sound/virtio/virtio_pcm.h
@@ -35,6 +35,7 @@ struct virtio_pcm_msg;
  * @msg_last_enqueued: Index of the last I/O message added to the virtqueue.
  * @msg_count: Number of pending I/O messages in the virtqueue.
  * @msg_empty: Notify when msg_count is zero.
+ * @msg_flushing: True if the I/O queue is in flushing state.
  */
 struct virtio_pcm_substream {
 	struct virtio_snd *snd;
@@ -56,6 +57,7 @@ struct virtio_pcm_substream {
 	int msg_last_enqueued;
 	unsigned int msg_count;
 	wait_queue_head_t msg_empty;
+	bool msg_flushing;
 };
 
 /**
@@ -82,6 +84,8 @@ struct virtio_pcm {
 	struct virtio_pcm_stream streams[SNDRV_PCM_STREAM_LAST + 1];
 };
 
+extern const struct snd_pcm_ops virtsnd_pcm_ops;
+
 int virtsnd_pcm_validate(struct virtio_device *vdev);
 
 int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
diff --git a/sound/virtio/virtio_pcm_ops.c b/sound/virtio/virtio_pcm_ops.c
new file mode 100644
index 000000000000..07510778b555
--- /dev/null
+++ b/sound/virtio/virtio_pcm_ops.c
@@ -0,0 +1,469 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#include <sound/pcm_params.h>
+
+#include "virtio_card.h"
+
+/* Map for converting ALSA format to VirtIO format. */
+struct virtsnd_a2v_format {
+	snd_pcm_format_t alsa_bit;
+	unsigned int vio_bit;
+};
+
+static const struct virtsnd_a2v_format g_a2v_format_map[] = {
+	{ SNDRV_PCM_FORMAT_IMA_ADPCM, VIRTIO_SND_PCM_FMT_IMA_ADPCM },
+	{ SNDRV_PCM_FORMAT_MU_LAW, VIRTIO_SND_PCM_FMT_MU_LAW },
+	{ SNDRV_PCM_FORMAT_A_LAW, VIRTIO_SND_PCM_FMT_A_LAW },
+	{ SNDRV_PCM_FORMAT_S8, VIRTIO_SND_PCM_FMT_S8 },
+	{ SNDRV_PCM_FORMAT_U8, VIRTIO_SND_PCM_FMT_U8 },
+	{ SNDRV_PCM_FORMAT_S16_LE, VIRTIO_SND_PCM_FMT_S16 },
+	{ SNDRV_PCM_FORMAT_U16_LE, VIRTIO_SND_PCM_FMT_U16 },
+	{ SNDRV_PCM_FORMAT_S18_3LE, VIRTIO_SND_PCM_FMT_S18_3 },
+	{ SNDRV_PCM_FORMAT_U18_3LE, VIRTIO_SND_PCM_FMT_U18_3 },
+	{ SNDRV_PCM_FORMAT_S20_3LE, VIRTIO_SND_PCM_FMT_S20_3 },
+	{ SNDRV_PCM_FORMAT_U20_3LE, VIRTIO_SND_PCM_FMT_U20_3 },
+	{ SNDRV_PCM_FORMAT_S24_3LE, VIRTIO_SND_PCM_FMT_S24_3 },
+	{ SNDRV_PCM_FORMAT_U24_3LE, VIRTIO_SND_PCM_FMT_U24_3 },
+	{ SNDRV_PCM_FORMAT_S20_LE, VIRTIO_SND_PCM_FMT_S20 },
+	{ SNDRV_PCM_FORMAT_U20_LE, VIRTIO_SND_PCM_FMT_U20 },
+	{ SNDRV_PCM_FORMAT_S24_LE, VIRTIO_SND_PCM_FMT_S24 },
+	{ SNDRV_PCM_FORMAT_U24_LE, VIRTIO_SND_PCM_FMT_U24 },
+	{ SNDRV_PCM_FORMAT_S32_LE, VIRTIO_SND_PCM_FMT_S32 },
+	{ SNDRV_PCM_FORMAT_U32_LE, VIRTIO_SND_PCM_FMT_U32 },
+	{ SNDRV_PCM_FORMAT_FLOAT_LE, VIRTIO_SND_PCM_FMT_FLOAT },
+	{ SNDRV_PCM_FORMAT_FLOAT64_LE, VIRTIO_SND_PCM_FMT_FLOAT64 },
+	{ SNDRV_PCM_FORMAT_DSD_U8, VIRTIO_SND_PCM_FMT_DSD_U8 },
+	{ SNDRV_PCM_FORMAT_DSD_U16_LE, VIRTIO_SND_PCM_FMT_DSD_U16 },
+	{ SNDRV_PCM_FORMAT_DSD_U32_LE, VIRTIO_SND_PCM_FMT_DSD_U32 },
+	{ SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE,
+	  VIRTIO_SND_PCM_FMT_IEC958_SUBFRAME }
+};
+
+/* Map for converting ALSA frame rate to VirtIO frame rate. */
+struct virtsnd_a2v_rate {
+	unsigned int rate;
+	unsigned int vio_bit;
+};
+
+static const struct virtsnd_a2v_rate g_a2v_rate_map[] = {
+	{ 5512, VIRTIO_SND_PCM_RATE_5512 },
+	{ 8000, VIRTIO_SND_PCM_RATE_8000 },
+	{ 11025, VIRTIO_SND_PCM_RATE_11025 },
+	{ 16000, VIRTIO_SND_PCM_RATE_16000 },
+	{ 22050, VIRTIO_SND_PCM_RATE_22050 },
+	{ 32000, VIRTIO_SND_PCM_RATE_32000 },
+	{ 44100, VIRTIO_SND_PCM_RATE_44100 },
+	{ 48000, VIRTIO_SND_PCM_RATE_48000 },
+	{ 64000, VIRTIO_SND_PCM_RATE_64000 },
+	{ 88200, VIRTIO_SND_PCM_RATE_88200 },
+	{ 96000, VIRTIO_SND_PCM_RATE_96000 },
+	{ 176400, VIRTIO_SND_PCM_RATE_176400 },
+	{ 192000, VIRTIO_SND_PCM_RATE_192000 }
+};
+
+static int virtsnd_pcm_sync_stop(struct snd_pcm_substream *substream);
+
+/**
+ * virtsnd_pcm_open() - Open the PCM substream.
+ * @substream: Kernel ALSA substream.
+ *
+ * Context: Process context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
+{
+	struct virtio_pcm *vpcm = snd_pcm_substream_chip(substream);
+	struct virtio_pcm_substream *vss = NULL;
+
+	if (vpcm) {
+		switch (substream->stream) {
+		case SNDRV_PCM_STREAM_PLAYBACK:
+		case SNDRV_PCM_STREAM_CAPTURE: {
+			struct virtio_pcm_stream *vs =
+				&vpcm->streams[substream->stream];
+
+			if (substream->number < vs->nsubstreams)
+				vss = vs->substreams[substream->number];
+			break;
+		}
+		}
+	}
+
+	if (!vss)
+		return -EBADFD;
+
+	substream->runtime->hw = vss->hw;
+	substream->private_data = vss;
+
+	snd_pcm_hw_constraint_integer(substream->runtime,
+				      SNDRV_PCM_HW_PARAM_PERIODS);
+
+	/*
+	 * If the substream has already been used, then the I/O queue may be in
+	 * an invalid state. Just in case, we do a check and try to return the
+	 * queue to its original state, if necessary.
+	 */
+	vss->msg_flushing = true;
+
+	return virtsnd_pcm_sync_stop(substream);
+}
+
+/**
+ * virtsnd_pcm_close() - Close the PCM substream.
+ * @substream: Kernel ALSA substream.
+ *
+ * Context: Process context.
+ * Return: 0.
+ */
+static int virtsnd_pcm_close(struct snd_pcm_substream *substream)
+{
+	return 0;
+}
+
+/**
+ * virtsnd_pcm_hw_params() - Set the parameters of the PCM substream.
+ * @substream: Kernel ALSA substream.
+ * @hw_params: Hardware parameters (can be NULL).
+ *
+ * The function can be called both from the upper level (in this case,
+ * @hw_params is not NULL) or from the driver itself (in this case, @hw_params
+ * is NULL, and the parameter values are taken from the runtime structure).
+ *
+ * Context: Process context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
+				 struct snd_pcm_hw_params *hw_params)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream);
+	struct virtio_device *vdev = vss->snd->vdev;
+	struct virtio_snd_msg *msg;
+	struct virtio_snd_pcm_set_params *request;
+	snd_pcm_format_t format;
+	unsigned int channels;
+	unsigned int rate;
+	unsigned int buffer_bytes;
+	unsigned int period_bytes;
+	unsigned int periods;
+	unsigned int i;
+	int vformat = -1;
+	int vrate = -1;
+	int rc;
+
+	if (vss->msg_flushing) {
+		dev_err(&vdev->dev, "SID %u: invalid I/O queue state\n",
+			vss->sid);
+		return -EBADFD;
+	}
+
+	/* Set hardware parameters in device */
+	if (hw_params) {
+		format = params_format(hw_params);
+		channels = params_channels(hw_params);
+		rate = params_rate(hw_params);
+		buffer_bytes = params_buffer_bytes(hw_params);
+		period_bytes = params_period_bytes(hw_params);
+		periods = params_periods(hw_params);
+	} else {
+		format = runtime->format;
+		channels = runtime->channels;
+		rate = runtime->rate;
+		buffer_bytes = frames_to_bytes(runtime, runtime->buffer_size);
+		period_bytes = frames_to_bytes(runtime, runtime->period_size);
+		periods = runtime->periods;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(g_a2v_format_map); ++i)
+		if (g_a2v_format_map[i].alsa_bit == format) {
+			vformat = g_a2v_format_map[i].vio_bit;
+
+			break;
+		}
+
+	for (i = 0; i < ARRAY_SIZE(g_a2v_rate_map); ++i)
+		if (g_a2v_rate_map[i].rate == rate) {
+			vrate = g_a2v_rate_map[i].vio_bit;
+
+			break;
+		}
+
+	if (vformat == -1 || vrate == -1)
+		return -EINVAL;
+
+	msg = virtsnd_pcm_ctl_msg_alloc(vss, VIRTIO_SND_R_PCM_SET_PARAMS,
+					GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	request = virtsnd_ctl_msg_request(msg);
+	request->buffer_bytes = cpu_to_le32(buffer_bytes);
+	request->period_bytes = cpu_to_le32(period_bytes);
+	request->channels = channels;
+	request->format = vformat;
+	request->rate = vrate;
+
+	if (vss->features & (1U << VIRTIO_SND_PCM_F_MSG_POLLING))
+		request->features |=
+			cpu_to_le32(1U << VIRTIO_SND_PCM_F_MSG_POLLING);
+
+	if (vss->features & (1U << VIRTIO_SND_PCM_F_EVT_XRUNS))
+		request->features |=
+			cpu_to_le32(1U << VIRTIO_SND_PCM_F_EVT_XRUNS);
+
+	rc = virtsnd_ctl_msg_send_sync(vss->snd, msg);
+	if (rc)
+		return rc;
+
+	return virtsnd_pcm_msg_alloc(vss, periods, period_bytes);
+}
+
+/**
+ * virtsnd_pcm_hw_free() - Reset the parameters of the PCM substream.
+ * @substream: Kernel ALSA substream.
+ *
+ * Context: Process context.
+ * Return: 0
+ */
+static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+	return 0;
+}
+
+/**
+ * virtsnd_pcm_prepare() - Prepare the PCM substream.
+ * @substream: Kernel ALSA substream.
+ *
+ * The function can be called both from the upper level or from the driver
+ * itself.
+ *
+ * Context: Process context. Takes and releases the VirtIO substream spinlock.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream);
+	struct virtio_device *vdev = vss->snd->vdev;
+	struct virtio_snd_msg *msg;
+	unsigned long flags;
+
+	if (vss->msg_flushing) {
+		dev_err(&vdev->dev, "SID %u: invalid I/O queue state\n",
+			vss->sid);
+		return -EBADFD;
+	}
+
+	spin_lock_irqsave(&vss->lock, flags);
+	/*
+	 * Since I/O messages are asynchronous, they can be completed
+	 * when the runtime structure no longer exists. Since each
+	 * completion implies incrementing the hw_ptr, we cache all the
+	 * current values needed to compute the new hw_ptr value.
+	 */
+	vss->frame_bytes = runtime->frame_bits >> 3;
+	vss->period_size = runtime->period_size;
+	vss->buffer_size = runtime->buffer_size;
+
+	vss->hw_ptr = 0;
+	vss->xfer_xrun = false;
+	vss->msg_last_enqueued = -1;
+	vss->msg_count = 0;
+	spin_unlock_irqrestore(&vss->lock, flags);
+
+	msg = virtsnd_pcm_ctl_msg_alloc(vss, VIRTIO_SND_R_PCM_PREPARE,
+					GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	return virtsnd_ctl_msg_send_sync(vss->snd, msg);
+}
+
+/**
+ * virtsnd_pcm_trigger() - Process command for the PCM substream.
+ * @substream: Kernel ALSA substream.
+ * @command: Substream command (SNDRV_PCM_TRIGGER_XXX).
+ *
+ * Context: Any context. Takes and releases the VirtIO substream spinlock.
+ *          May take and release the tx/rx queue spinlock.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
+{
+	struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream);
+	struct virtio_snd *snd = vss->snd;
+	struct virtio_snd_msg *msg;
+	unsigned long flags;
+	int rc;
+
+	switch (command) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: {
+		struct virtio_snd_queue *queue = virtsnd_pcm_queue(vss);
+
+		spin_lock_irqsave(&queue->lock, flags);
+		spin_lock(&vss->lock);
+		rc = virtsnd_pcm_msg_send(vss);
+		if (!rc)
+			vss->xfer_enabled = true;
+		spin_unlock(&vss->lock);
+		spin_unlock_irqrestore(&queue->lock, flags);
+		if (rc)
+			return rc;
+
+		msg = virtsnd_pcm_ctl_msg_alloc(vss, VIRTIO_SND_R_PCM_START,
+						GFP_KERNEL);
+		if (!msg) {
+			spin_lock_irqsave(&vss->lock, flags);
+			vss->xfer_enabled = false;
+			spin_unlock_irqrestore(&vss->lock, flags);
+
+			return -ENOMEM;
+		}
+
+		return virtsnd_ctl_msg_send_sync(snd, msg);
+	}
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: {
+		spin_lock_irqsave(&vss->lock, flags);
+		vss->xfer_enabled = false;
+		spin_unlock_irqrestore(&vss->lock, flags);
+
+		/*
+		 * The I/O queue needs to be flushed only when the substream is
+		 * completely stopped.
+		 */
+		if (command == SNDRV_PCM_TRIGGER_STOP)
+			vss->msg_flushing = true;
+
+		/*
+		 * The STOP command can be issued in an atomic context after
+		 * the drain is complete. Therefore, in general, we cannot sleep
+		 * here.
+		 */
+		msg = virtsnd_pcm_ctl_msg_alloc(vss, VIRTIO_SND_R_PCM_STOP,
+						GFP_ATOMIC);
+		if (!msg)
+			return -ENOMEM;
+
+		return virtsnd_ctl_msg_send_async(snd, msg);
+	}
+	default: {
+		return -EINVAL;
+	}
+	}
+}
+
+/**
+ * virtsnd_pcm_msg_count() - Returns the number of pending I/O messages.
+ * @vss: VirtIO substream.
+ *
+ * Context: Any context.
+ * Return: Number of messages.
+ */
+static inline
+unsigned int virtsnd_pcm_msg_count(struct virtio_pcm_substream *vss)
+{
+	unsigned int msg_count;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vss->lock, flags);
+	msg_count = vss->msg_count;
+	spin_unlock_irqrestore(&vss->lock, flags);
+
+	return msg_count;
+}
+
+/**
+ * virtsnd_pcm_sync_stop() - Synchronous PCM substream stop.
+ * @substream: Kernel ALSA substream.
+ *
+ * The function can be called both from the upper level or from the driver
+ * itself.
+ *
+ * Context: Process context. Takes and releases the VirtIO substream spinlock.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_pcm_sync_stop(struct snd_pcm_substream *substream)
+{
+	struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream);
+	struct virtio_snd *snd = vss->snd;
+	struct virtio_snd_msg *msg;
+	unsigned int js = msecs_to_jiffies(msg_timeout_ms);
+	int rc;
+
+	if (!vss->msg_flushing)
+		return 0;
+
+	if (!virtsnd_pcm_msg_count(vss))
+		goto on_exit;
+
+	msg = virtsnd_pcm_ctl_msg_alloc(vss, VIRTIO_SND_R_PCM_RELEASE,
+					GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	rc = virtsnd_ctl_msg_send_sync(snd, msg);
+	if (rc)
+		return rc;
+
+	/*
+	 * The spec states that upon receipt of the RELEASE command "the device
+	 * MUST complete all pending I/O messages for the specified stream ID".
+	 * Thus, we consider the absence of I/O messages in the queue as an
+	 * indication that the substream has been released.
+	 */
+	rc = wait_event_interruptible_timeout(vss->msg_empty,
+					      !virtsnd_pcm_msg_count(vss),
+					      js);
+	if (rc <= 0) {
+		dev_warn(&snd->vdev->dev, "SID %u: failed to flush I/O queue\n",
+			 vss->sid);
+
+		return !rc ? -ETIMEDOUT : rc;
+	}
+
+on_exit:
+	vss->msg_flushing = false;
+
+	return 0;
+}
+
+/**
+ * virtsnd_pcm_pointer() - Get the current hardware position for the PCM
+ *                         substream.
+ * @substream: Kernel ALSA substream.
+ *
+ * Context: Any context. Takes and releases the VirtIO substream spinlock.
+ * Return: Hardware position in frames inside [0 ... buffer_size) range.
+ */
+static snd_pcm_uframes_t
+virtsnd_pcm_pointer(struct snd_pcm_substream *substream)
+{
+	struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream);
+	snd_pcm_uframes_t hw_ptr = SNDRV_PCM_POS_XRUN;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vss->lock, flags);
+	if (!vss->xfer_xrun)
+		hw_ptr = vss->hw_ptr;
+	spin_unlock_irqrestore(&vss->lock, flags);
+
+	return hw_ptr;
+}
+
+/* PCM substream operators map. */
+const struct snd_pcm_ops virtsnd_pcm_ops = {
+	.open = virtsnd_pcm_open,
+	.close = virtsnd_pcm_close,
+	.ioctl = snd_pcm_lib_ioctl,
+	.hw_params = virtsnd_pcm_hw_params,
+	.hw_free = virtsnd_pcm_hw_free,
+	.prepare = virtsnd_pcm_prepare,
+	.trigger = virtsnd_pcm_trigger,
+	.sync_stop = virtsnd_pcm_sync_stop,
+	.pointer = virtsnd_pcm_pointer,
+};
-- 
2.30.0

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Takashi Iwai]

On Mon, 22 Feb 2021 16:34:41 +0100,
Anton Yakovlev wrote:
> +static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
> +{
> +	struct virtio_pcm *vpcm = snd_pcm_substream_chip(substream);
> +	struct virtio_pcm_substream *vss = NULL;
> +
> +	if (vpcm) {
> +		switch (substream->stream) {
> +		case SNDRV_PCM_STREAM_PLAYBACK:
> +		case SNDRV_PCM_STREAM_CAPTURE: {

The switch() here looks superfluous.  The substream->stream must be a
good value in the callback.  If any, you can put WARN_ON() there, but
I don't think it worth.

> +static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
> +				 struct snd_pcm_hw_params *hw_params)
> +{
....
> +	return virtsnd_pcm_msg_alloc(vss, periods, period_bytes);

We have the allocation, but...

> +static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
> +{
> +	return 0;

... no release at hw_free()?
I know that the free is present in the allocator, but it's only for
re-allocation case, I suppose.


thanks,

Takashi

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Anton Yakovlev]

On 25.02.2021 11:55, Takashi Iwai wrote:
> On Mon, 22 Feb 2021 16:34:41 +0100,
> Anton Yakovlev wrote:
>> +static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
>> +{
>> +     struct virtio_pcm *vpcm = snd_pcm_substream_chip(substream);
>> +     struct virtio_pcm_substream *vss = NULL;
>> +
>> +     if (vpcm) {
>> +             switch (substream->stream) {
>> +             case SNDRV_PCM_STREAM_PLAYBACK:
>> +             case SNDRV_PCM_STREAM_CAPTURE: {
> 
> The switch() here looks superfluous.  The substream->stream must be a
> good value in the callback.  If any, you can put WARN_ON() there, but
> I don't think it worth.

At least it doesn't do any harm. If something really went wrong, we can
check it right in the open callback, which is called the very first.


>> +static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
>> +                              struct snd_pcm_hw_params *hw_params)
>> +{
> ....
>> +     return virtsnd_pcm_msg_alloc(vss, periods, period_bytes);
> 
> We have the allocation, but...
> 
>> +static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
>> +{
>> +     return 0;
> 
> ... no release at hw_free()?
> I know that the free is present in the allocator, but it's only for
> re-allocation case, I suppose.

When the substream stops, sync_ptr waits until the device has completed
all pending messages. This wait can be interrupted either by a signal or
due to a timeout. In this case, the device can still access messages
even after calling hw_free(). It can also issue an interrupt, and the
interrupt handler will also try to access message structures. Therefore,
freeing of already allocated messages occurs either in hw_params() or in
dev->release(), since there it is 100% safe.


> thanks,
> 
> Takashi
> 

-- 
Anton Yakovlev
Senior Software Engineer

OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Takashi Iwai]

On Thu, 25 Feb 2021 13:14:37 +0100,
Anton Yakovlev wrote:
> 
> On 25.02.2021 11:55, Takashi Iwai wrote:
> > On Mon, 22 Feb 2021 16:34:41 +0100,
> > Anton Yakovlev wrote:
> >> +static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
> >> +{
> >> +     struct virtio_pcm *vpcm = snd_pcm_substream_chip(substream);
> >> +     struct virtio_pcm_substream *vss = NULL;
> >> +
> >> +     if (vpcm) {
> >> +             switch (substream->stream) {
> >> +             case SNDRV_PCM_STREAM_PLAYBACK:
> >> +             case SNDRV_PCM_STREAM_CAPTURE: {
> >
> > The switch() here looks superfluous.  The substream->stream must be a
> > good value in the callback.  If any, you can put WARN_ON() there, but
> > I don't think it worth.
> 
> At least it doesn't do any harm.

It does -- it makes the readability worse, and that's a very important
point.

> >> +static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
> >> +                              struct snd_pcm_hw_params *hw_params)
> >> +{
> > ....
> >> +     return virtsnd_pcm_msg_alloc(vss, periods, period_bytes);
> >
> > We have the allocation, but...
> >
> >> +static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
> >> +{
> >> +     return 0;
> >
> > ... no release at hw_free()?
> > I know that the free is present in the allocator, but it's only for
> > re-allocation case, I suppose.
> 
> When the substream stops, sync_ptr waits until the device has completed
> all pending messages. This wait can be interrupted either by a signal or
> due to a timeout. In this case, the device can still access messages
> even after calling hw_free(). It can also issue an interrupt, and the
> interrupt handler will also try to access message structures. Therefore,
> freeing of already allocated messages occurs either in hw_params() or in
> dev->release(), since there it is 100% safe.

OK, then it's worth to document it about this object lifecycle.
The buffer management of this driver is fairly unique, so otherwise it
confuses readers.


thanks,

Takashi

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Michael S. Tsirkin]

On Thu, Feb 25, 2021 at 01:51:16PM +0100, Takashi Iwai wrote:
> On Thu, 25 Feb 2021 13:14:37 +0100,
> Anton Yakovlev wrote:
> > 
> > On 25.02.2021 11:55, Takashi Iwai wrote:
> > > On Mon, 22 Feb 2021 16:34:41 +0100,
> > > Anton Yakovlev wrote:
> > >> +static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
> > >> +{
> > >> +     struct virtio_pcm *vpcm = snd_pcm_substream_chip(substream);
> > >> +     struct virtio_pcm_substream *vss = NULL;
> > >> +
> > >> +     if (vpcm) {
> > >> +             switch (substream->stream) {
> > >> +             case SNDRV_PCM_STREAM_PLAYBACK:
> > >> +             case SNDRV_PCM_STREAM_CAPTURE: {
> > >
> > > The switch() here looks superfluous.  The substream->stream must be a
> > > good value in the callback.  If any, you can put WARN_ON() there, but
> > > I don't think it worth.
> > 
> > At least it doesn't do any harm.
> 
> It does -- it makes the readability worse, and that's a very important
> point.
> 
> > >> +static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
> > >> +                              struct snd_pcm_hw_params *hw_params)
> > >> +{
> > > ....
> > >> +     return virtsnd_pcm_msg_alloc(vss, periods, period_bytes);
> > >
> > > We have the allocation, but...
> > >
> > >> +static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
> > >> +{
> > >> +     return 0;
> > >
> > > ... no release at hw_free()?
> > > I know that the free is present in the allocator, but it's only for
> > > re-allocation case, I suppose.
> > 
> > When the substream stops, sync_ptr waits until the device has completed
> > all pending messages. This wait can be interrupted either by a signal or
> > due to a timeout. In this case, the device can still access messages
> > even after calling hw_free(). It can also issue an interrupt, and the
> > interrupt handler will also try to access message structures. Therefore,
> > freeing of already allocated messages occurs either in hw_params() or in
> > dev->release(), since there it is 100% safe.
> 
> OK, then it's worth to document it about this object lifecycle.
> The buffer management of this driver is fairly unique, so otherwise it
> confuses readers.
> 
> 
> thanks,
> 
> Takashi

Takashi given I was in my tree for a while and I planned to merge
it this merge window. I can still drop it but there are
unrelated patches behind these in the tree so that's a rebase
which will invalidate my testing, I'm just concerned about
meeting the merge window.

Would it be ok to merge this as is and then address
readability stuff by patches on top?
If yes please send acks!
If you want to merge it yourself instead, also please say so.

-- 
MST

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Takashi Iwai]

On Thu, 25 Feb 2021 20:02:50 +0100,
Michael S. Tsirkin wrote:
> 
> On Thu, Feb 25, 2021 at 01:51:16PM +0100, Takashi Iwai wrote:
> > On Thu, 25 Feb 2021 13:14:37 +0100,
> > Anton Yakovlev wrote:
> > > 
> > > On 25.02.2021 11:55, Takashi Iwai wrote:
> > > > On Mon, 22 Feb 2021 16:34:41 +0100,
> > > > Anton Yakovlev wrote:
> > > >> +static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
> > > >> +{
> > > >> +     struct virtio_pcm *vpcm = snd_pcm_substream_chip(substream);
> > > >> +     struct virtio_pcm_substream *vss = NULL;
> > > >> +
> > > >> +     if (vpcm) {
> > > >> +             switch (substream->stream) {
> > > >> +             case SNDRV_PCM_STREAM_PLAYBACK:
> > > >> +             case SNDRV_PCM_STREAM_CAPTURE: {
> > > >
> > > > The switch() here looks superfluous.  The substream->stream must be a
> > > > good value in the callback.  If any, you can put WARN_ON() there, but
> > > > I don't think it worth.
> > > 
> > > At least it doesn't do any harm.
> > 
> > It does -- it makes the readability worse, and that's a very important
> > point.
> > 
> > > >> +static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
> > > >> +                              struct snd_pcm_hw_params *hw_params)
> > > >> +{
> > > > ....
> > > >> +     return virtsnd_pcm_msg_alloc(vss, periods, period_bytes);
> > > >
> > > > We have the allocation, but...
> > > >
> > > >> +static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
> > > >> +{
> > > >> +     return 0;
> > > >
> > > > ... no release at hw_free()?
> > > > I know that the free is present in the allocator, but it's only for
> > > > re-allocation case, I suppose.
> > > 
> > > When the substream stops, sync_ptr waits until the device has completed
> > > all pending messages. This wait can be interrupted either by a signal or
> > > due to a timeout. In this case, the device can still access messages
> > > even after calling hw_free(). It can also issue an interrupt, and the
> > > interrupt handler will also try to access message structures. Therefore,
> > > freeing of already allocated messages occurs either in hw_params() or in
> > > dev->release(), since there it is 100% safe.
> > 
> > OK, then it's worth to document it about this object lifecycle.
> > The buffer management of this driver is fairly unique, so otherwise it
> > confuses readers.
> > 
> > 
> > thanks,
> > 
> > Takashi
> 
> Takashi given I was in my tree for a while and I planned to merge
> it this merge window.

Hmm, that's too quick, I'm afraid.  I see still a few rough edges in
the code.  e.g. the reset work should be canceled at the driver
removal, but it's missing right now.  And that'll become tricky
because the reset work itself unbinds the device, hence it'll get
stuck if calling cancel_work_sync() at remove callback.

> I can still drop it but there are
> unrelated patches behind these in the tree so that's a rebase
> which will invalidate my testing, I'm just concerned about
> meeting the merge window.
> 
> Would it be ok to merge this as is and then address
> readability stuff by patches on top?
> If yes please send acks!
> If you want to merge it yourself instead, also please say so.

I don't mind who take the patches, although it looks more fitting to
merge through sound git tree if judging from the changes put in
sound/* directory.


thanks,

Takashi

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Anton Yakovlev]

On 25.02.2021 21:30, Takashi Iwai wrote:> On Thu, 25 Feb 2021 20:02:50 
+0100,
> Michael S. Tsirkin wrote:
>>
>> On Thu, Feb 25, 2021 at 01:51:16PM +0100, Takashi Iwai wrote:
>>> On Thu, 25 Feb 2021 13:14:37 +0100,
>>> Anton Yakovlev wrote:


[snip]


>> Takashi given I was in my tree for a while and I planned to merge
>> it this merge window.
> 
> Hmm, that's too quick, I'm afraid.  I see still a few rough edges in
> the code.  e.g. the reset work should be canceled at the driver
> removal, but it's missing right now.  And that'll become tricky
> because the reset work itself unbinds the device, hence it'll get
> stuck if calling cancel_work_sync() at remove callback.

Yes, you made a good point here! In this case, we need some external
mutex for synchronization. This is just a rough idea, but maybe
something like this might work:

struct reset_work {
     struct mutex mutex;
     struct work_struct work;
     struct virtio_snd *snd;
     bool resetting;
};

static struct reset_work reset_works[SNDRV_CARDS];

init()
     // init mutexes and workers


virtsnd_probe()
     snd_card_new(snd->card)
     reset_works[snd->card->number].snd = snd;


virtsnd_remove()
     mutex_lock(reset_works[snd->card->number].mutex)
     reset_works[snd->card->number].snd = NULL;
     resetting = reset_works[snd->card->number].resetting;
     mutex_unlock(reset_works[snd->card->number].mutex)

     if (!resetting)
         // cancel worker reset_works[snd->card->number].work
     // remove device


virtsnd_reset_fn(work)
     mutex_lock(work->mutex)
     if (!work->snd)
         // do nothing and take an exit path
     work->resetting = true;
     mutex_unlock(work->mutex)

     device_reprobe()

     work->resetting = false;


interrupt_handler()
     schedule_work(reset_works[snd->card->number].work);


What do you think?


-- 
Anton Yakovlev
Senior Software Engineer

OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Takashi Iwai]

On Thu, 25 Feb 2021 23:19:31 +0100,
Anton Yakovlev wrote:
> 
> On 25.02.2021 21:30, Takashi Iwai wrote:> On Thu, 25 Feb 2021 20:02:50
> +0100,
> > Michael S. Tsirkin wrote:
> >>
> >> On Thu, Feb 25, 2021 at 01:51:16PM +0100, Takashi Iwai wrote:
> >>> On Thu, 25 Feb 2021 13:14:37 +0100,
> >>> Anton Yakovlev wrote:
> 
> 
> [snip]
> 
> 
> >> Takashi given I was in my tree for a while and I planned to merge
> >> it this merge window.
> >
> > Hmm, that's too quick, I'm afraid.  I see still a few rough edges in
> > the code.  e.g. the reset work should be canceled at the driver
> > removal, but it's missing right now.  And that'll become tricky
> > because the reset work itself unbinds the device, hence it'll get
> > stuck if calling cancel_work_sync() at remove callback.
> 
> Yes, you made a good point here! In this case, we need some external
> mutex for synchronization. This is just a rough idea, but maybe
> something like this might work:
> 
> struct reset_work {
>     struct mutex mutex;
>     struct work_struct work;
>     struct virtio_snd *snd;
>     bool resetting;
> };
> 
> static struct reset_work reset_works[SNDRV_CARDS];
> 
> init()
>     // init mutexes and workers
> 
> 
> virtsnd_probe()
>     snd_card_new(snd->card)
>     reset_works[snd->card->number].snd = snd;
> 
> 
> virtsnd_remove()
>     mutex_lock(reset_works[snd->card->number].mutex)
>     reset_works[snd->card->number].snd = NULL;
>     resetting = reset_works[snd->card->number].resetting;
>     mutex_unlock(reset_works[snd->card->number].mutex)
> 
>     if (!resetting)
>         // cancel worker reset_works[snd->card->number].work
>     // remove device
> 
> 
> virtsnd_reset_fn(work)
>     mutex_lock(work->mutex)
>     if (!work->snd)
>         // do nothing and take an exit path
>     work->resetting = true;
>     mutex_unlock(work->mutex)
> 
>     device_reprobe()
> 
>     work->resetting = false;
> 
> 
> interrupt_handler()
>     schedule_work(reset_works[snd->card->number].work);
> 
> 
> What do you think?

I think it's still somehow racy.  Suppose that the reset_work is
already running right before entering virtsnd_remove(): it sets
reset_works[].resetting flag, virtsnd_remove() skips canceling, and
both reset work and virtsnd_remove() perform at the very same time.
(I don't know whether this may happen, but I assume it's possible.)

In that case, maybe a better check is to check current_work(), and
perform cancel_work_sync() unless it's &reset_works[].work itself.
Then the recursive cancel call can be avoided.

After that point, the reset must be completed, and we can (again)
process the rest release procedure.  (But also snd object itself might
have been changed again, so it needs to be re-evaluated.)

One remaining concern is that the card number of the sound instance
may change after reprobe.  That is, we may want to another persistent
object instead of accessing via an array index of sound card number.
So, we might need reset_works[] associated with virtio_snd object
instead.

In anyway, this is damn complex.  I sincerely hope that we can avoid
this kind of things.  Wouldn't it be better to shift the reset stuff
up to the virtio core layer?  Or drop the feature in the first
version.  Shooting itself (and revival) is a dangerous magic spell,
after all.


thanks,

Takashi

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Anton Yakovlev]

On 26.02.2021 15:23, Takashi Iwai wrote:
> On Thu, 25 Feb 2021 23:19:31 +0100,
> Anton Yakovlev wrote:
>>
>> On 25.02.2021 21:30, Takashi Iwai wrote:> On Thu, 25 Feb 2021 20:02:50
>> +0100,
>>> Michael S. Tsirkin wrote:
>>>>
>>>> On Thu, Feb 25, 2021 at 01:51:16PM +0100, Takashi Iwai wrote:
>>>>> On Thu, 25 Feb 2021 13:14:37 +0100,
>>>>> Anton Yakovlev wrote:
>>
>>
>> [snip]
>>
>>
>>>> Takashi given I was in my tree for a while and I planned to merge
>>>> it this merge window.
>>>
>>> Hmm, that's too quick, I'm afraid.  I see still a few rough edges in
>>> the code.  e.g. the reset work should be canceled at the driver
>>> removal, but it's missing right now.  And that'll become tricky
>>> because the reset work itself unbinds the device, hence it'll get
>>> stuck if calling cancel_work_sync() at remove callback.
>>
>> Yes, you made a good point here! In this case, we need some external
>> mutex for synchronization. This is just a rough idea, but maybe
>> something like this might work:
>>
>> struct reset_work {
>>      struct mutex mutex;
>>      struct work_struct work;
>>      struct virtio_snd *snd;
>>      bool resetting;
>> };
>>
>> static struct reset_work reset_works[SNDRV_CARDS];
>>
>> init()
>>      // init mutexes and workers
>>
>>
>> virtsnd_probe()
>>      snd_card_new(snd->card)
>>      reset_works[snd->card->number].snd = snd;
>>
>>
>> virtsnd_remove()
>>      mutex_lock(reset_works[snd->card->number].mutex)
>>      reset_works[snd->card->number].snd = NULL;
>>      resetting = reset_works[snd->card->number].resetting;
>>      mutex_unlock(reset_works[snd->card->number].mutex)
>>
>>      if (!resetting)
>>          // cancel worker reset_works[snd->card->number].work
>>      // remove device
>>
>>
>> virtsnd_reset_fn(work)
>>      mutex_lock(work->mutex)
>>      if (!work->snd)
>>          // do nothing and take an exit path
>>      work->resetting = true;
>>      mutex_unlock(work->mutex)
>>
>>      device_reprobe()
>>
>>      work->resetting = false;
>>
>>
>> interrupt_handler()
>>      schedule_work(reset_works[snd->card->number].work);
>>
>>
>> What do you think?
> 
> I think it's still somehow racy.  Suppose that the reset_work is
> already running right before entering virtsnd_remove(): it sets
> reset_works[].resetting flag, virtsnd_remove() skips canceling, and
> both reset work and virtsnd_remove() perform at the very same time.
> (I don't know whether this may happen, but I assume it's possible.)
> 
> In that case, maybe a better check is to check current_work(), and
> perform cancel_work_sync() unless it's &reset_works[].work itself.
> Then the recursive cancel call can be avoided.
> 
> After that point, the reset must be completed, and we can (again)
> process the rest release procedure.  (But also snd object itself might
> have been changed again, so it needs to be re-evaluated.)
> 
> One remaining concern is that the card number of the sound instance
> may change after reprobe.  That is, we may want to another persistent
> object instead of accessing via an array index of sound card number.
> So, we might need reset_works[] associated with virtio_snd object
> instead.
> 
> In anyway, this is damn complex.  I sincerely hope that we can avoid
> this kind of things.  Wouldn't it be better to shift the reset stuff
> up to the virtio core layer?  Or drop the feature in the first
> version.  Shooting itself (and revival) is a dangerous magic spell,
> after all.

Yes, I also got an impression, that without some assistance somewhere
from the bus it will hardly be possible to find a suitable solution.
Ok, then I will postpone this feature at the moment.


> 
> thanks,
> 
> Takashi
> 

-- 
Anton Yakovlev
Senior Software Engineer

OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Anton Yakovlev]

On 25.02.2021 21:30, Takashi Iwai wrote:> On Thu, 25 Feb 2021 20:02:50 
+0100,
> Michael S. Tsirkin wrote:
>>

[snip]

>> If you want to merge it yourself instead, also please say so.
> 
> I don't mind who take the patches, although it looks more fitting to
> merge through sound git tree if judging from the changes put in
> sound/* directory.

Then should I update the MAINTAINERS and add Takashi instead of
Michael, or should I put both of you there?


-- 
Anton Yakovlev
Senior Software Engineer

OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin

Re: [PATCH v5 6/9] ALSA: virtio: PCM substream operators

[Takashi Iwai]

On Fri, 26 Feb 2021 21:19:58 +0100,
Anton Yakovlev wrote:
> 
> On 25.02.2021 21:30, Takashi Iwai wrote:> On Thu, 25 Feb 2021 20:02:50
> +0100,
> > Michael S. Tsirkin wrote:
> >>
> 
> [snip]
> 
> >> If you want to merge it yourself instead, also please say so.
> >
> > I don't mind who take the patches, although it looks more fitting to
> > merge through sound git tree if judging from the changes put in
> > sound/* directory.
> 
> Then should I update the MAINTAINERS and add Takashi instead of
> Michael, or should I put both of you there?

No need for that, I'm already named as the generic sound/* stuff
maintainer.  And, it's rather more about how the merge gets pushed up
to upstream.  In general, the stuff belonging to a subsystem goes via
the subsystem tree, e.g. Mark has been maintaining ASoC stuff in his 
tree while it gets merged sound.git tree to Linus.  Similarly, it's
fine if Michael wants to keep a sub-subsystem tree for virtio_snd,
too.  But keeping a dedicated git repo for a single driver isn't often
worthwhile.

Of course, it's no strict rule, and I don't mind if anybody has a
strong reason to process in other ways, too.  Just let me know.


thanks,

Takashi

[PATCH v5 7/9] ALSA: virtio: introduce jack support

[Anton Yakovlev]

Enumerate all available jacks and create ALSA controls.

At the moment jacks have a simple implementation and can only be used
to receive notifications about a plugged in/out device.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/Makefile      |   1 +
 sound/virtio/virtio_card.c |  14 +++
 sound/virtio/virtio_card.h |  12 ++
 sound/virtio/virtio_jack.c | 233 +++++++++++++++++++++++++++++++++++++
 4 files changed, 260 insertions(+)
 create mode 100644 sound/virtio/virtio_jack.c

diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 34493226793f..09f485291285 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
 virtio_snd-objs := \
 	virtio_card.o \
 	virtio_ctl_msg.o \
+	virtio_jack.o \
 	virtio_pcm.o \
 	virtio_pcm_msg.o \
 	virtio_pcm_ops.o
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index a845978111d6..4578d0ce0726 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -67,6 +67,10 @@ static void virtsnd_event_notify_cb(struct virtqueue *vqueue)
 		virtqueue_disable_cb(vqueue);
 		while ((event = virtqueue_get_buf(vqueue, &length))) {
 			switch (le32_to_cpu(event->hdr.code)) {
+			case VIRTIO_SND_EVT_JACK_CONNECTED:
+			case VIRTIO_SND_EVT_JACK_DISCONNECTED:
+				virtsnd_jack_event(snd, event);
+				break;
 			case VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED:
 			case VIRTIO_SND_EVT_PCM_XRUN:
 				virtsnd_pcm_event(snd, event);
@@ -210,10 +214,20 @@ static int virtsnd_build_devs(struct virtio_snd *snd)
 			 VIRTIO_SND_CARD_NAME " at %s/%s",
 			 dev_name(dev->parent), dev_name(dev));
 
+	rc = virtsnd_jack_parse_cfg(snd);
+	if (rc)
+		return rc;
+
 	rc = virtsnd_pcm_parse_cfg(snd);
 	if (rc)
 		return rc;
 
+	if (snd->njacks) {
+		rc = virtsnd_jack_build_devs(snd);
+		if (rc)
+			return rc;
+	}
+
 	if (snd->nsubstreams) {
 		rc = virtsnd_pcm_build_devs(snd);
 		if (rc)
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index 3d8f5ad92f79..37896a030e10 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -18,6 +18,7 @@
 #define VIRTIO_SND_CARD_NAME	"VirtIO SoundCard"
 #define VIRTIO_SND_PCM_NAME	"VirtIO PCM"
 
+struct virtio_jack;
 struct virtio_pcm_substream;
 
 /**
@@ -39,6 +40,8 @@ struct virtio_snd_queue {
  * @ctl_msgs: Pending control request list.
  * @event_msgs: Device events.
  * @pcm_list: VirtIO PCM device list.
+ * @jacks: VirtIO jacks.
+ * @njacks: Number of jacks.
  * @substreams: VirtIO PCM substreams.
  * @nsubstreams: Number of PCM substreams.
  */
@@ -50,6 +53,8 @@ struct virtio_snd {
 	struct list_head ctl_msgs;
 	struct virtio_snd_event *event_msgs;
 	struct list_head pcm_list;
+	struct virtio_jack *jacks;
+	u32 njacks;
 	struct virtio_pcm_substream *substreams;
 	u32 nsubstreams;
 };
@@ -90,4 +95,11 @@ virtsnd_pcm_queue(struct virtio_pcm_substream *vss)
 		return virtsnd_rx_queue(vss->snd);
 }
 
+int virtsnd_jack_parse_cfg(struct virtio_snd *snd);
+
+int virtsnd_jack_build_devs(struct virtio_snd *snd);
+
+void virtsnd_jack_event(struct virtio_snd *snd,
+			struct virtio_snd_event *event);
+
 #endif /* VIRTIO_SND_CARD_H */
diff --git a/sound/virtio/virtio_jack.c b/sound/virtio/virtio_jack.c
new file mode 100644
index 000000000000..c69f1dcdcc84
--- /dev/null
+++ b/sound/virtio/virtio_jack.c
@@ -0,0 +1,233 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#include <linux/virtio_config.h>
+#include <sound/jack.h>
+#include <sound/hda_verbs.h>
+
+#include "virtio_card.h"
+
+/**
+ * DOC: Implementation Status
+ *
+ * At the moment jacks have a simple implementation and can only be used to
+ * receive notifications about a plugged in/out device.
+ *
+ * VIRTIO_SND_R_JACK_REMAP
+ *   is not supported
+ */
+
+/**
+ * struct virtio_jack - VirtIO jack.
+ * @jack: Kernel jack control.
+ * @nid: Functional group node identifier.
+ * @features: Jack virtio feature bit map (1 << VIRTIO_SND_JACK_F_XXX).
+ * @defconf: Pin default configuration value.
+ * @caps: Pin capabilities value.
+ * @connected: Current jack connection status.
+ * @type: Kernel jack type (SND_JACK_XXX).
+ */
+struct virtio_jack {
+	struct snd_jack *jack;
+	u32 nid;
+	u32 features;
+	u32 defconf;
+	u32 caps;
+	bool connected;
+	int type;
+};
+
+/**
+ * virtsnd_jack_get_label() - Get the name string for the jack.
+ * @vjack: VirtIO jack.
+ *
+ * Returns the jack name based on the default pin configuration value (see HDA
+ * specification).
+ *
+ * Context: Any context.
+ * Return: Name string.
+ */
+static const char *virtsnd_jack_get_label(struct virtio_jack *vjack)
+{
+	unsigned int defconf = vjack->defconf;
+	unsigned int device =
+		(defconf & AC_DEFCFG_DEVICE) >> AC_DEFCFG_DEVICE_SHIFT;
+	unsigned int location =
+		(defconf & AC_DEFCFG_LOCATION) >> AC_DEFCFG_LOCATION_SHIFT;
+
+	switch (device) {
+	case AC_JACK_LINE_OUT:
+		return "Line Out";
+	case AC_JACK_SPEAKER:
+		return "Speaker";
+	case AC_JACK_HP_OUT:
+		return "Headphone";
+	case AC_JACK_CD:
+		return "CD";
+	case AC_JACK_SPDIF_OUT:
+	case AC_JACK_DIG_OTHER_OUT:
+		if (location == AC_JACK_LOC_HDMI)
+			return "HDMI Out";
+		else
+			return "SPDIF Out";
+	case AC_JACK_LINE_IN:
+		return "Line";
+	case AC_JACK_AUX:
+		return "Aux";
+	case AC_JACK_MIC_IN:
+		return "Mic";
+	case AC_JACK_SPDIF_IN:
+		return "SPDIF In";
+	case AC_JACK_DIG_OTHER_IN:
+		return "Digital In";
+	default:
+		return "Misc";
+	}
+}
+
+/**
+ * virtsnd_jack_get_type() - Get the type for the jack.
+ * @vjack: VirtIO jack.
+ *
+ * Returns the jack type based on the default pin configuration value (see HDA
+ * specification).
+ *
+ * Context: Any context.
+ * Return: SND_JACK_XXX value.
+ */
+static int virtsnd_jack_get_type(struct virtio_jack *vjack)
+{
+	unsigned int defconf = vjack->defconf;
+	unsigned int device =
+		(defconf & AC_DEFCFG_DEVICE) >> AC_DEFCFG_DEVICE_SHIFT;
+
+	switch (device) {
+	case AC_JACK_LINE_OUT:
+	case AC_JACK_SPEAKER:
+		return SND_JACK_LINEOUT;
+	case AC_JACK_HP_OUT:
+		return SND_JACK_HEADPHONE;
+	case AC_JACK_SPDIF_OUT:
+	case AC_JACK_DIG_OTHER_OUT:
+		return SND_JACK_AVOUT;
+	case AC_JACK_MIC_IN:
+		return SND_JACK_MICROPHONE;
+	default:
+		return SND_JACK_LINEIN;
+	}
+}
+
+/**
+ * virtsnd_jack_parse_cfg() - Parse the jack configuration.
+ * @snd: VirtIO sound device.
+ *
+ * This function is called during initial device initialization.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_jack_parse_cfg(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_snd_jack_info *info;
+	u32 i;
+	int rc;
+
+	virtio_cread_le(vdev, struct virtio_snd_config, jacks, &snd->njacks);
+	if (!snd->njacks)
+		return 0;
+
+	snd->jacks = devm_kcalloc(&vdev->dev, snd->njacks, sizeof(*snd->jacks),
+				  GFP_KERNEL);
+	if (!snd->jacks)
+		return -ENOMEM;
+
+	info = kcalloc(snd->njacks, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_JACK_INFO, 0, snd->njacks,
+				    sizeof(*info), info);
+	if (rc)
+		goto on_exit;
+
+	for (i = 0; i < snd->njacks; ++i) {
+		struct virtio_jack *vjack = &snd->jacks[i];
+
+		vjack->nid = le32_to_cpu(info[i].hdr.hda_fn_nid);
+		vjack->features = le32_to_cpu(info[i].features);
+		vjack->defconf = le32_to_cpu(info[i].hda_reg_defconf);
+		vjack->caps = le32_to_cpu(info[i].hda_reg_caps);
+		vjack->connected = info[i].connected;
+	}
+
+on_exit:
+	kfree(info);
+
+	return rc;
+}
+
+/**
+ * virtsnd_jack_build_devs() - Build ALSA controls for jacks.
+ * @snd: VirtIO sound device.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_jack_build_devs(struct virtio_snd *snd)
+{
+	u32 i;
+	int rc;
+
+	for (i = 0; i < snd->njacks; ++i) {
+		struct virtio_jack *vjack = &snd->jacks[i];
+
+		vjack->type = virtsnd_jack_get_type(vjack);
+
+		rc = snd_jack_new(snd->card, virtsnd_jack_get_label(vjack),
+				  vjack->type, &vjack->jack, true, true);
+		if (rc)
+			return rc;
+
+		if (vjack->jack)
+			vjack->jack->private_data = vjack;
+
+		snd_jack_report(vjack->jack,
+				vjack->connected ? vjack->type : 0);
+	}
+
+	return 0;
+}
+
+/**
+ * virtsnd_jack_event() - Handle the jack event notification.
+ * @snd: VirtIO sound device.
+ * @event: VirtIO sound event.
+ *
+ * Context: Interrupt context.
+ */
+void virtsnd_jack_event(struct virtio_snd *snd, struct virtio_snd_event *event)
+{
+	u32 jack_id = le32_to_cpu(event->data);
+	struct virtio_jack *vjack;
+
+	if (jack_id >= snd->njacks)
+		return;
+
+	vjack = &snd->jacks[jack_id];
+
+	switch (le32_to_cpu(event->hdr.code)) {
+	case VIRTIO_SND_EVT_JACK_CONNECTED:
+		vjack->connected = true;
+		break;
+	case VIRTIO_SND_EVT_JACK_DISCONNECTED:
+		vjack->connected = false;
+		break;
+	default:
+		return;
+	}
+
+	snd_jack_report(vjack->jack, vjack->connected ? vjack->type : 0);
+}
-- 
2.30.0

[PATCH v5 8/9] ALSA: virtio: introduce PCM channel map support

[Anton Yakovlev]

Enumerate all available PCM channel maps and create ALSA controls.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/Makefile       |   1 +
 sound/virtio/virtio_card.c  |  10 ++
 sound/virtio/virtio_card.h  |   8 ++
 sound/virtio/virtio_chmap.c | 219 ++++++++++++++++++++++++++++++++++++
 sound/virtio/virtio_pcm.h   |   4 +
 5 files changed, 242 insertions(+)
 create mode 100644 sound/virtio/virtio_chmap.c

diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 09f485291285..2742bddb8874 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
 
 virtio_snd-objs := \
 	virtio_card.o \
+	virtio_chmap.o \
 	virtio_ctl_msg.o \
 	virtio_jack.o \
 	virtio_pcm.o \
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index 4578d0ce0726..787a4dec1da8 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -222,6 +222,10 @@ static int virtsnd_build_devs(struct virtio_snd *snd)
 	if (rc)
 		return rc;
 
+	rc = virtsnd_chmap_parse_cfg(snd);
+	if (rc)
+		return rc;
+
 	if (snd->njacks) {
 		rc = virtsnd_jack_build_devs(snd);
 		if (rc)
@@ -234,6 +238,12 @@ static int virtsnd_build_devs(struct virtio_snd *snd)
 			return rc;
 	}
 
+	if (snd->nchmaps) {
+		rc = virtsnd_chmap_build_devs(snd);
+		if (rc)
+			return rc;
+	}
+
 	return snd_card_register(snd->card);
 }
 
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index 37896a030e10..817508b3e9b4 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -44,6 +44,8 @@ struct virtio_snd_queue {
  * @njacks: Number of jacks.
  * @substreams: VirtIO PCM substreams.
  * @nsubstreams: Number of PCM substreams.
+ * @chmaps: VirtIO channel maps.
+ * @nchmaps: Number of channel maps.
  */
 struct virtio_snd {
 	struct virtio_device *vdev;
@@ -57,6 +59,8 @@ struct virtio_snd {
 	u32 njacks;
 	struct virtio_pcm_substream *substreams;
 	u32 nsubstreams;
+	struct virtio_snd_chmap_info *chmaps;
+	u32 nchmaps;
 };
 
 /* Message completion timeout in milliseconds (module parameter). */
@@ -102,4 +106,8 @@ int virtsnd_jack_build_devs(struct virtio_snd *snd);
 void virtsnd_jack_event(struct virtio_snd *snd,
 			struct virtio_snd_event *event);
 
+int virtsnd_chmap_parse_cfg(struct virtio_snd *snd);
+
+int virtsnd_chmap_build_devs(struct virtio_snd *snd);
+
 #endif /* VIRTIO_SND_CARD_H */
diff --git a/sound/virtio/virtio_chmap.c b/sound/virtio/virtio_chmap.c
new file mode 100644
index 000000000000..5bc924933a59
--- /dev/null
+++ b/sound/virtio/virtio_chmap.c
@@ -0,0 +1,219 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * virtio-snd: Virtio sound device
+ * Copyright (C) 2021 OpenSynergy GmbH
+ */
+#include <linux/virtio_config.h>
+
+#include "virtio_card.h"
+
+/* VirtIO->ALSA channel position map */
+static const u8 g_v2a_position_map[] = {
+	[VIRTIO_SND_CHMAP_NONE] = SNDRV_CHMAP_UNKNOWN,
+	[VIRTIO_SND_CHMAP_NA] = SNDRV_CHMAP_NA,
+	[VIRTIO_SND_CHMAP_MONO] = SNDRV_CHMAP_MONO,
+	[VIRTIO_SND_CHMAP_FL] = SNDRV_CHMAP_FL,
+	[VIRTIO_SND_CHMAP_FR] = SNDRV_CHMAP_FR,
+	[VIRTIO_SND_CHMAP_RL] = SNDRV_CHMAP_RL,
+	[VIRTIO_SND_CHMAP_RR] = SNDRV_CHMAP_RR,
+	[VIRTIO_SND_CHMAP_FC] = SNDRV_CHMAP_FC,
+	[VIRTIO_SND_CHMAP_LFE] = SNDRV_CHMAP_LFE,
+	[VIRTIO_SND_CHMAP_SL] = SNDRV_CHMAP_SL,
+	[VIRTIO_SND_CHMAP_SR] = SNDRV_CHMAP_SR,
+	[VIRTIO_SND_CHMAP_RC] = SNDRV_CHMAP_RC,
+	[VIRTIO_SND_CHMAP_FLC] = SNDRV_CHMAP_FLC,
+	[VIRTIO_SND_CHMAP_FRC] = SNDRV_CHMAP_FRC,
+	[VIRTIO_SND_CHMAP_RLC] = SNDRV_CHMAP_RLC,
+	[VIRTIO_SND_CHMAP_RRC] = SNDRV_CHMAP_RRC,
+	[VIRTIO_SND_CHMAP_FLW] = SNDRV_CHMAP_FLW,
+	[VIRTIO_SND_CHMAP_FRW] = SNDRV_CHMAP_FRW,
+	[VIRTIO_SND_CHMAP_FLH] = SNDRV_CHMAP_FLH,
+	[VIRTIO_SND_CHMAP_FCH] = SNDRV_CHMAP_FCH,
+	[VIRTIO_SND_CHMAP_FRH] = SNDRV_CHMAP_FRH,
+	[VIRTIO_SND_CHMAP_TC] = SNDRV_CHMAP_TC,
+	[VIRTIO_SND_CHMAP_TFL] = SNDRV_CHMAP_TFL,
+	[VIRTIO_SND_CHMAP_TFR] = SNDRV_CHMAP_TFR,
+	[VIRTIO_SND_CHMAP_TFC] = SNDRV_CHMAP_TFC,
+	[VIRTIO_SND_CHMAP_TRL] = SNDRV_CHMAP_TRL,
+	[VIRTIO_SND_CHMAP_TRR] = SNDRV_CHMAP_TRR,
+	[VIRTIO_SND_CHMAP_TRC] = SNDRV_CHMAP_TRC,
+	[VIRTIO_SND_CHMAP_TFLC] = SNDRV_CHMAP_TFLC,
+	[VIRTIO_SND_CHMAP_TFRC] = SNDRV_CHMAP_TFRC,
+	[VIRTIO_SND_CHMAP_TSL] = SNDRV_CHMAP_TSL,
+	[VIRTIO_SND_CHMAP_TSR] = SNDRV_CHMAP_TSR,
+	[VIRTIO_SND_CHMAP_LLFE] = SNDRV_CHMAP_LLFE,
+	[VIRTIO_SND_CHMAP_RLFE] = SNDRV_CHMAP_RLFE,
+	[VIRTIO_SND_CHMAP_BC] = SNDRV_CHMAP_BC,
+	[VIRTIO_SND_CHMAP_BLC] = SNDRV_CHMAP_BLC,
+	[VIRTIO_SND_CHMAP_BRC] = SNDRV_CHMAP_BRC
+};
+
+/**
+ * virtsnd_chmap_parse_cfg() - Parse the channel map configuration.
+ * @snd: VirtIO sound device.
+ *
+ * This function is called during initial device initialization.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_chmap_parse_cfg(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	u32 i;
+	int rc;
+
+	virtio_cread_le(vdev, struct virtio_snd_config, chmaps, &snd->nchmaps);
+	if (!snd->nchmaps)
+		return 0;
+
+	snd->chmaps = devm_kcalloc(&vdev->dev, snd->nchmaps,
+				   sizeof(*snd->chmaps), GFP_KERNEL);
+	if (!snd->chmaps)
+		return -ENOMEM;
+
+	rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_CHMAP_INFO, 0,
+				    snd->nchmaps, sizeof(*snd->chmaps),
+				    snd->chmaps);
+	if (rc)
+		return rc;
+
+	/* Count the number of channel maps per each PCM device/stream. */
+	for (i = 0; i < snd->nchmaps; ++i) {
+		struct virtio_snd_chmap_info *info = &snd->chmaps[i];
+		u32 nid = le32_to_cpu(info->hdr.hda_fn_nid);
+		struct virtio_pcm *vpcm;
+		struct virtio_pcm_stream *vs;
+
+		vpcm = virtsnd_pcm_find_or_create(snd, nid);
+		if (IS_ERR(vpcm))
+			return PTR_ERR(vpcm);
+
+		switch (info->direction) {
+		case VIRTIO_SND_D_OUTPUT:
+			vs = &vpcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
+			break;
+		case VIRTIO_SND_D_INPUT:
+			vs = &vpcm->streams[SNDRV_PCM_STREAM_CAPTURE];
+			break;
+		default:
+			dev_err(&vdev->dev,
+				"chmap #%u: unknown direction (%u)\n", i,
+				info->direction);
+			return -EINVAL;
+		}
+
+		vs->nchmaps++;
+	}
+
+	return 0;
+}
+
+/**
+ * virtsnd_chmap_add_ctls() - Create an ALSA control for channel maps.
+ * @pcm: ALSA PCM device.
+ * @direction: PCM stream direction (SNDRV_PCM_STREAM_XXX).
+ * @vs: VirtIO PCM stream.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_chmap_add_ctls(struct snd_pcm *pcm, int direction,
+				  struct virtio_pcm_stream *vs)
+{
+	u32 i;
+	int max_channels = 0;
+
+	for (i = 0; i < vs->nchmaps; i++)
+		if (max_channels < vs->chmaps[i].channels)
+			max_channels = vs->chmaps[i].channels;
+
+	return snd_pcm_add_chmap_ctls(pcm, direction, vs->chmaps, max_channels,
+				      0, NULL);
+}
+
+/**
+ * virtsnd_chmap_build_devs() - Build ALSA controls for channel maps.
+ * @snd: VirtIO sound device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_chmap_build_devs(struct virtio_snd *snd)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_pcm *vpcm;
+	struct virtio_pcm_stream *vs;
+	u32 i;
+	int rc;
+
+	/* Allocate channel map elements per each PCM device/stream. */
+	list_for_each_entry(vpcm, &snd->pcm_list, list) {
+		for (i = 0; i < ARRAY_SIZE(vpcm->streams); ++i) {
+			vs = &vpcm->streams[i];
+
+			if (!vs->nchmaps)
+				continue;
+
+			vs->chmaps = devm_kcalloc(&vdev->dev, vs->nchmaps + 1,
+						  sizeof(*vs->chmaps),
+						  GFP_KERNEL);
+			if (!vs->chmaps)
+				return -ENOMEM;
+
+			vs->nchmaps = 0;
+		}
+	}
+
+	/* Initialize channel maps per each PCM device/stream. */
+	for (i = 0; i < snd->nchmaps; ++i) {
+		struct virtio_snd_chmap_info *info = &snd->chmaps[i];
+		unsigned int channels = info->channels;
+		unsigned int ch;
+		struct snd_pcm_chmap_elem *chmap;
+
+		vpcm = virtsnd_pcm_find(snd, le32_to_cpu(info->hdr.hda_fn_nid));
+		if (IS_ERR(vpcm))
+			return PTR_ERR(vpcm);
+
+		if (info->direction == VIRTIO_SND_D_OUTPUT)
+			vs = &vpcm->streams[SNDRV_PCM_STREAM_PLAYBACK];
+		else
+			vs = &vpcm->streams[SNDRV_PCM_STREAM_CAPTURE];
+
+		chmap = &vs->chmaps[vs->nchmaps++];
+
+		if (channels > ARRAY_SIZE(chmap->map))
+			channels = ARRAY_SIZE(chmap->map);
+
+		chmap->channels = channels;
+
+		for (ch = 0; ch < channels; ++ch) {
+			u8 position = info->positions[ch];
+
+			if (position >= ARRAY_SIZE(g_v2a_position_map))
+				return -EINVAL;
+
+			chmap->map[ch] = g_v2a_position_map[position];
+		}
+	}
+
+	/* Create an ALSA control per each PCM device/stream. */
+	list_for_each_entry(vpcm, &snd->pcm_list, list) {
+		if (!vpcm->pcm)
+			continue;
+
+		for (i = 0; i < ARRAY_SIZE(vpcm->streams); ++i) {
+			vs = &vpcm->streams[i];
+
+			if (!vs->nchmaps)
+				continue;
+
+			rc = virtsnd_chmap_add_ctls(vpcm->pcm, i, vs);
+			if (rc)
+				return rc;
+		}
+	}
+
+	return 0;
+}
diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
index c48d00acee2e..379052e2fbf9 100644
--- a/sound/virtio/virtio_pcm.h
+++ b/sound/virtio/virtio_pcm.h
@@ -64,10 +64,14 @@ struct virtio_pcm_substream {
  * struct virtio_pcm_stream - VirtIO PCM stream.
  * @substreams: VirtIO substreams belonging to the stream.
  * @nsubstreams: Number of substreams.
+ * @chmaps: Kernel channel maps belonging to the stream.
+ * @nchmaps: Number of channel maps.
  */
 struct virtio_pcm_stream {
 	struct virtio_pcm_substream **substreams;
 	u32 nsubstreams;
+	struct snd_pcm_chmap_elem *chmaps;
+	u32 nchmaps;
 };
 
 /**
-- 
2.30.0

[PATCH v5 9/9] ALSA: virtio: introduce device suspend/resume support

[Anton Yakovlev]

All running PCM substreams are stopped on device suspend and restarted
on device resume.

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
---
 sound/virtio/virtio_card.c    | 57 +++++++++++++++++++++++++++++++++++
 sound/virtio/virtio_pcm.c     |  1 +
 sound/virtio/virtio_pcm_ops.c | 44 ++++++++++++++++++++-------
 3 files changed, 91 insertions(+), 11 deletions(-)

diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index 787a4dec1da8..1f0a0fa7bbc0 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -373,6 +373,59 @@ static void virtsnd_config_changed(struct virtio_device *vdev)
 			 "sound device configuration was changed\n");
 }
 
+#ifdef CONFIG_PM_SLEEP
+/**
+ * virtsnd_freeze() - Suspend device.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_freeze(struct virtio_device *vdev)
+{
+	struct virtio_snd *snd = vdev->priv;
+
+	/* Stop all the virtqueues. */
+	vdev->config->reset(vdev);
+	vdev->config->del_vqs(vdev);
+
+	virtsnd_ctl_msg_cancel_all(snd);
+
+	kfree(snd->event_msgs);
+
+	/*
+	 * If the virtsnd_restore() fails before re-allocating events, then we
+	 * get a dangling pointer here.
+	 */
+	snd->event_msgs = NULL;
+
+	return 0;
+}
+
+/**
+ * virtsnd_restore() - Resume device.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_restore(struct virtio_device *vdev)
+{
+	struct virtio_snd *snd = vdev->priv;
+	int rc;
+
+	rc = virtsnd_find_vqs(snd);
+	if (rc)
+		return rc;
+
+	virtio_device_ready(vdev);
+
+	virtsnd_enable_event_vq(snd);
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
 static const struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_SOUND, VIRTIO_DEV_ANY_ID },
 	{ 0 },
@@ -386,6 +439,10 @@ static struct virtio_driver virtsnd_driver = {
 	.probe = virtsnd_probe,
 	.remove = virtsnd_remove,
 	.config_changed = virtsnd_config_changed,
+#ifdef CONFIG_PM_SLEEP
+	.freeze = virtsnd_freeze,
+	.restore = virtsnd_restore,
+#endif
 };
 
 static int __init init(void)
diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
index 3605151860f2..4a4a6583b002 100644
--- a/sound/virtio/virtio_pcm.c
+++ b/sound/virtio/virtio_pcm.c
@@ -109,6 +109,7 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss,
 		SNDRV_PCM_INFO_BATCH |
 		SNDRV_PCM_INFO_BLOCK_TRANSFER |
 		SNDRV_PCM_INFO_INTERLEAVED |
+		SNDRV_PCM_INFO_RESUME |
 		SNDRV_PCM_INFO_PAUSE;
 
 	if (!info->channels_min || info->channels_min > info->channels_max) {
diff --git a/sound/virtio/virtio_pcm_ops.c b/sound/virtio/virtio_pcm_ops.c
index 07510778b555..ccef64502c13 100644
--- a/sound/virtio/virtio_pcm_ops.c
+++ b/sound/virtio/virtio_pcm_ops.c
@@ -218,6 +218,10 @@ static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
 	if (rc)
 		return rc;
 
+	/* If messages have already been allocated before, do nothing. */
+	if (runtime->status->state == SNDRV_PCM_STATE_SUSPENDED)
+		return 0;
+
 	return virtsnd_pcm_msg_alloc(vss, periods, period_bytes);
 }
 
@@ -258,19 +262,21 @@ static int virtsnd_pcm_prepare(struct snd_pcm_substream *substream)
 	}
 
 	spin_lock_irqsave(&vss->lock, flags);
-	/*
-	 * Since I/O messages are asynchronous, they can be completed
-	 * when the runtime structure no longer exists. Since each
-	 * completion implies incrementing the hw_ptr, we cache all the
-	 * current values needed to compute the new hw_ptr value.
-	 */
-	vss->frame_bytes = runtime->frame_bits >> 3;
-	vss->period_size = runtime->period_size;
-	vss->buffer_size = runtime->buffer_size;
+	if (runtime->status->state != SNDRV_PCM_STATE_SUSPENDED) {
+		/*
+		 * Since I/O messages are asynchronous, they can be completed
+		 * when the runtime structure no longer exists. Since each
+		 * completion implies incrementing the hw_ptr, we cache all the
+		 * current values needed to compute the new hw_ptr value.
+		 */
+		vss->frame_bytes = runtime->frame_bits >> 3;
+		vss->period_size = runtime->period_size;
+		vss->buffer_size = runtime->buffer_size;
 
-	vss->hw_ptr = 0;
+		vss->hw_ptr = 0;
+		vss->msg_last_enqueued = -1;
+	}
 	vss->xfer_xrun = false;
-	vss->msg_last_enqueued = -1;
 	vss->msg_count = 0;
 	spin_unlock_irqrestore(&vss->lock, flags);
 
@@ -300,6 +306,21 @@ static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
 	int rc;
 
 	switch (command) {
+	case SNDRV_PCM_TRIGGER_RESUME: {
+		/*
+		 * We restart the substream by executing the standard command
+		 * sequence.
+		 */
+		rc = virtsnd_pcm_hw_params(substream, NULL);
+		if (rc)
+			return rc;
+
+		rc = virtsnd_pcm_prepare(substream);
+		if (rc)
+			return rc;
+
+		fallthrough;
+	}
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: {
 		struct virtio_snd_queue *queue = virtsnd_pcm_queue(vss);
@@ -326,6 +347,7 @@ static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
 
 		return virtsnd_ctl_msg_send_sync(snd, msg);
 	}
+	case SNDRV_PCM_TRIGGER_SUSPEND:
 	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: {
 		spin_lock_irqsave(&vss->lock, flags);
-- 
2.30.0