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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /sound/core/vmaster.c
downloadlinux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz
linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
Diffstat (limited to '')
-rw-r--r--sound/core/vmaster.c522
1 files changed, 522 insertions, 0 deletions
diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
new file mode 100644
index 000000000..d0f11f378
--- /dev/null
+++ b/sound/core/vmaster.c
@@ -0,0 +1,522 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Virtual master and follower controls
+ *
+ * Copyright (c) 2008 by Takashi Iwai <tiwai@suse.de>
+ */
+
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <sound/core.h>
+#include <sound/control.h>
+#include <sound/tlv.h>
+
+/*
+ * a subset of information returned via ctl info callback
+ */
+struct link_ctl_info {
+ snd_ctl_elem_type_t type; /* value type */
+ int count; /* item count */
+ int min_val, max_val; /* min, max values */
+};
+
+/*
+ * link master - this contains a list of follower controls that are
+ * identical types, i.e. info returns the same value type and value
+ * ranges, but may have different number of counts.
+ *
+ * The master control is so far only mono volume/switch for simplicity.
+ * The same value will be applied to all followers.
+ */
+struct link_master {
+ struct list_head followers;
+ struct link_ctl_info info;
+ int val; /* the master value */
+ unsigned int tlv[4];
+ void (*hook)(void *private_data, int);
+ void *hook_private_data;
+};
+
+/*
+ * link follower - this contains a follower control element
+ *
+ * It fakes the control callbacks with additional attenuation by the
+ * master control. A follower may have either one or two channels.
+ */
+
+struct link_follower {
+ struct list_head list;
+ struct link_master *master;
+ struct link_ctl_info info;
+ int vals[2]; /* current values */
+ unsigned int flags;
+ struct snd_kcontrol *kctl; /* original kcontrol pointer */
+ struct snd_kcontrol follower; /* the copy of original control entry */
+};
+
+static int follower_update(struct link_follower *follower)
+{
+ struct snd_ctl_elem_value *uctl;
+ int err, ch;
+
+ uctl = kzalloc(sizeof(*uctl), GFP_KERNEL);
+ if (!uctl)
+ return -ENOMEM;
+ uctl->id = follower->follower.id;
+ err = follower->follower.get(&follower->follower, uctl);
+ if (err < 0)
+ goto error;
+ for (ch = 0; ch < follower->info.count; ch++)
+ follower->vals[ch] = uctl->value.integer.value[ch];
+ error:
+ kfree(uctl);
+ return err < 0 ? err : 0;
+}
+
+/* get the follower ctl info and save the initial values */
+static int follower_init(struct link_follower *follower)
+{
+ struct snd_ctl_elem_info *uinfo;
+ int err;
+
+ if (follower->info.count) {
+ /* already initialized */
+ if (follower->flags & SND_CTL_FOLLOWER_NEED_UPDATE)
+ return follower_update(follower);
+ return 0;
+ }
+
+ uinfo = kmalloc(sizeof(*uinfo), GFP_KERNEL);
+ if (!uinfo)
+ return -ENOMEM;
+ uinfo->id = follower->follower.id;
+ err = follower->follower.info(&follower->follower, uinfo);
+ if (err < 0) {
+ kfree(uinfo);
+ return err;
+ }
+ follower->info.type = uinfo->type;
+ follower->info.count = uinfo->count;
+ if (follower->info.count > 2 ||
+ (follower->info.type != SNDRV_CTL_ELEM_TYPE_INTEGER &&
+ follower->info.type != SNDRV_CTL_ELEM_TYPE_BOOLEAN)) {
+ pr_err("ALSA: vmaster: invalid follower element\n");
+ kfree(uinfo);
+ return -EINVAL;
+ }
+ follower->info.min_val = uinfo->value.integer.min;
+ follower->info.max_val = uinfo->value.integer.max;
+ kfree(uinfo);
+
+ return follower_update(follower);
+}
+
+/* initialize master volume */
+static int master_init(struct link_master *master)
+{
+ struct link_follower *follower;
+
+ if (master->info.count)
+ return 0; /* already initialized */
+
+ list_for_each_entry(follower, &master->followers, list) {
+ int err = follower_init(follower);
+ if (err < 0)
+ return err;
+ master->info = follower->info;
+ master->info.count = 1; /* always mono */
+ /* set full volume as default (= no attenuation) */
+ master->val = master->info.max_val;
+ if (master->hook)
+ master->hook(master->hook_private_data, master->val);
+ return 1;
+ }
+ return -ENOENT;
+}
+
+static int follower_get_val(struct link_follower *follower,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ int err, ch;
+
+ err = follower_init(follower);
+ if (err < 0)
+ return err;
+ for (ch = 0; ch < follower->info.count; ch++)
+ ucontrol->value.integer.value[ch] = follower->vals[ch];
+ return 0;
+}
+
+static int follower_put_val(struct link_follower *follower,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ int err, ch, vol;
+
+ err = master_init(follower->master);
+ if (err < 0)
+ return err;
+
+ switch (follower->info.type) {
+ case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
+ for (ch = 0; ch < follower->info.count; ch++)
+ ucontrol->value.integer.value[ch] &=
+ !!follower->master->val;
+ break;
+ case SNDRV_CTL_ELEM_TYPE_INTEGER:
+ for (ch = 0; ch < follower->info.count; ch++) {
+ /* max master volume is supposed to be 0 dB */
+ vol = ucontrol->value.integer.value[ch];
+ vol += follower->master->val - follower->master->info.max_val;
+ if (vol < follower->info.min_val)
+ vol = follower->info.min_val;
+ else if (vol > follower->info.max_val)
+ vol = follower->info.max_val;
+ ucontrol->value.integer.value[ch] = vol;
+ }
+ break;
+ }
+ return follower->follower.put(&follower->follower, ucontrol);
+}
+
+/*
+ * ctl callbacks for followers
+ */
+static int follower_info(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_info *uinfo)
+{
+ struct link_follower *follower = snd_kcontrol_chip(kcontrol);
+ return follower->follower.info(&follower->follower, uinfo);
+}
+
+static int follower_get(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct link_follower *follower = snd_kcontrol_chip(kcontrol);
+ return follower_get_val(follower, ucontrol);
+}
+
+static int follower_put(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct link_follower *follower = snd_kcontrol_chip(kcontrol);
+ int err, ch, changed = 0;
+
+ err = follower_init(follower);
+ if (err < 0)
+ return err;
+ for (ch = 0; ch < follower->info.count; ch++) {
+ if (follower->vals[ch] != ucontrol->value.integer.value[ch]) {
+ changed = 1;
+ follower->vals[ch] = ucontrol->value.integer.value[ch];
+ }
+ }
+ if (!changed)
+ return 0;
+ err = follower_put_val(follower, ucontrol);
+ if (err < 0)
+ return err;
+ return 1;
+}
+
+static int follower_tlv_cmd(struct snd_kcontrol *kcontrol,
+ int op_flag, unsigned int size,
+ unsigned int __user *tlv)
+{
+ struct link_follower *follower = snd_kcontrol_chip(kcontrol);
+ /* FIXME: this assumes that the max volume is 0 dB */
+ return follower->follower.tlv.c(&follower->follower, op_flag, size, tlv);
+}
+
+static void follower_free(struct snd_kcontrol *kcontrol)
+{
+ struct link_follower *follower = snd_kcontrol_chip(kcontrol);
+ if (follower->follower.private_free)
+ follower->follower.private_free(&follower->follower);
+ if (follower->master)
+ list_del(&follower->list);
+ kfree(follower);
+}
+
+/*
+ * Add a follower control to the group with the given master control
+ *
+ * All followers must be the same type (returning the same information
+ * via info callback). The function doesn't check it, so it's your
+ * responsibility.
+ *
+ * Also, some additional limitations:
+ * - at most two channels
+ * - logarithmic volume control (dB level), no linear volume
+ * - master can only attenuate the volume, no gain
+ */
+int _snd_ctl_add_follower(struct snd_kcontrol *master,
+ struct snd_kcontrol *follower,
+ unsigned int flags)
+{
+ struct link_master *master_link = snd_kcontrol_chip(master);
+ struct link_follower *srec;
+
+ srec = kzalloc(struct_size(srec, follower.vd, follower->count),
+ GFP_KERNEL);
+ if (!srec)
+ return -ENOMEM;
+ srec->kctl = follower;
+ srec->follower = *follower;
+ memcpy(srec->follower.vd, follower->vd, follower->count * sizeof(*follower->vd));
+ srec->master = master_link;
+ srec->flags = flags;
+
+ /* override callbacks */
+ follower->info = follower_info;
+ follower->get = follower_get;
+ follower->put = follower_put;
+ if (follower->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK)
+ follower->tlv.c = follower_tlv_cmd;
+ follower->private_data = srec;
+ follower->private_free = follower_free;
+
+ list_add_tail(&srec->list, &master_link->followers);
+ return 0;
+}
+EXPORT_SYMBOL(_snd_ctl_add_follower);
+
+/*
+ * ctl callbacks for master controls
+ */
+static int master_info(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_info *uinfo)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ int ret;
+
+ ret = master_init(master);
+ if (ret < 0)
+ return ret;
+ uinfo->type = master->info.type;
+ uinfo->count = master->info.count;
+ uinfo->value.integer.min = master->info.min_val;
+ uinfo->value.integer.max = master->info.max_val;
+ return 0;
+}
+
+static int master_get(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ int err = master_init(master);
+ if (err < 0)
+ return err;
+ ucontrol->value.integer.value[0] = master->val;
+ return 0;
+}
+
+static int sync_followers(struct link_master *master, int old_val, int new_val)
+{
+ struct link_follower *follower;
+ struct snd_ctl_elem_value *uval;
+
+ uval = kmalloc(sizeof(*uval), GFP_KERNEL);
+ if (!uval)
+ return -ENOMEM;
+ list_for_each_entry(follower, &master->followers, list) {
+ master->val = old_val;
+ uval->id = follower->follower.id;
+ follower_get_val(follower, uval);
+ master->val = new_val;
+ follower_put_val(follower, uval);
+ }
+ kfree(uval);
+ return 0;
+}
+
+static int master_put(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ int err, new_val, old_val;
+ bool first_init;
+
+ err = master_init(master);
+ if (err < 0)
+ return err;
+ first_init = err;
+ old_val = master->val;
+ new_val = ucontrol->value.integer.value[0];
+ if (new_val == old_val)
+ return 0;
+
+ err = sync_followers(master, old_val, new_val);
+ if (err < 0)
+ return err;
+ if (master->hook && !first_init)
+ master->hook(master->hook_private_data, master->val);
+ return 1;
+}
+
+static void master_free(struct snd_kcontrol *kcontrol)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ struct link_follower *follower, *n;
+
+ /* free all follower links and retore the original follower kctls */
+ list_for_each_entry_safe(follower, n, &master->followers, list) {
+ struct snd_kcontrol *sctl = follower->kctl;
+ struct list_head olist = sctl->list;
+ memcpy(sctl, &follower->follower, sizeof(*sctl));
+ memcpy(sctl->vd, follower->follower.vd,
+ sctl->count * sizeof(*sctl->vd));
+ sctl->list = olist; /* keep the current linked-list */
+ kfree(follower);
+ }
+ kfree(master);
+}
+
+
+/**
+ * snd_ctl_make_virtual_master - Create a virtual master control
+ * @name: name string of the control element to create
+ * @tlv: optional TLV int array for dB information
+ *
+ * Creates a virtual master control with the given name string.
+ *
+ * After creating a vmaster element, you can add the follower controls
+ * via snd_ctl_add_follower() or snd_ctl_add_follower_uncached().
+ *
+ * The optional argument @tlv can be used to specify the TLV information
+ * for dB scale of the master control. It should be a single element
+ * with #SNDRV_CTL_TLVT_DB_SCALE, #SNDRV_CTL_TLV_DB_MINMAX or
+ * #SNDRV_CTL_TLVT_DB_MINMAX_MUTE type, and should be the max 0dB.
+ *
+ * Return: The created control element, or %NULL for errors (ENOMEM).
+ */
+struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
+ const unsigned int *tlv)
+{
+ struct link_master *master;
+ struct snd_kcontrol *kctl;
+ struct snd_kcontrol_new knew;
+
+ memset(&knew, 0, sizeof(knew));
+ knew.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
+ knew.name = name;
+ knew.info = master_info;
+
+ master = kzalloc(sizeof(*master), GFP_KERNEL);
+ if (!master)
+ return NULL;
+ INIT_LIST_HEAD(&master->followers);
+
+ kctl = snd_ctl_new1(&knew, master);
+ if (!kctl) {
+ kfree(master);
+ return NULL;
+ }
+ /* override some callbacks */
+ kctl->info = master_info;
+ kctl->get = master_get;
+ kctl->put = master_put;
+ kctl->private_free = master_free;
+
+ /* additional (constant) TLV read */
+ if (tlv) {
+ unsigned int type = tlv[SNDRV_CTL_TLVO_TYPE];
+ if (type == SNDRV_CTL_TLVT_DB_SCALE ||
+ type == SNDRV_CTL_TLVT_DB_MINMAX ||
+ type == SNDRV_CTL_TLVT_DB_MINMAX_MUTE) {
+ kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
+ memcpy(master->tlv, tlv, sizeof(master->tlv));
+ kctl->tlv.p = master->tlv;
+ }
+ }
+
+ return kctl;
+}
+EXPORT_SYMBOL(snd_ctl_make_virtual_master);
+
+/**
+ * snd_ctl_add_vmaster_hook - Add a hook to a vmaster control
+ * @kcontrol: vmaster kctl element
+ * @hook: the hook function
+ * @private_data: the private_data pointer to be saved
+ *
+ * Adds the given hook to the vmaster control element so that it's called
+ * at each time when the value is changed.
+ *
+ * Return: Zero.
+ */
+int snd_ctl_add_vmaster_hook(struct snd_kcontrol *kcontrol,
+ void (*hook)(void *private_data, int),
+ void *private_data)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ master->hook = hook;
+ master->hook_private_data = private_data;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_ctl_add_vmaster_hook);
+
+/**
+ * snd_ctl_sync_vmaster - Sync the vmaster followers and hook
+ * @kcontrol: vmaster kctl element
+ * @hook_only: sync only the hook
+ *
+ * Forcibly call the put callback of each follower and call the hook function
+ * to synchronize with the current value of the given vmaster element.
+ * NOP when NULL is passed to @kcontrol.
+ */
+void snd_ctl_sync_vmaster(struct snd_kcontrol *kcontrol, bool hook_only)
+{
+ struct link_master *master;
+ bool first_init = false;
+
+ if (!kcontrol)
+ return;
+ master = snd_kcontrol_chip(kcontrol);
+ if (!hook_only) {
+ int err = master_init(master);
+ if (err < 0)
+ return;
+ first_init = err;
+ err = sync_followers(master, master->val, master->val);
+ if (err < 0)
+ return;
+ }
+
+ if (master->hook && !first_init)
+ master->hook(master->hook_private_data, master->val);
+}
+EXPORT_SYMBOL_GPL(snd_ctl_sync_vmaster);
+
+/**
+ * snd_ctl_apply_vmaster_followers - Apply function to each vmaster follower
+ * @kctl: vmaster kctl element
+ * @func: function to apply
+ * @arg: optional function argument
+ *
+ * Apply the function @func to each follower kctl of the given vmaster kctl.
+ *
+ * Return: 0 if successful, or a negative error code
+ */
+int snd_ctl_apply_vmaster_followers(struct snd_kcontrol *kctl,
+ int (*func)(struct snd_kcontrol *vfollower,
+ struct snd_kcontrol *follower,
+ void *arg),
+ void *arg)
+{
+ struct link_master *master;
+ struct link_follower *follower;
+ int err;
+
+ master = snd_kcontrol_chip(kctl);
+ err = master_init(master);
+ if (err < 0)
+ return err;
+ list_for_each_entry(follower, &master->followers, list) {
+ err = func(follower->kctl, &follower->follower, arg);
+ if (err < 0)
+ return err;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(snd_ctl_apply_vmaster_followers);