--- /dev/null
+/*
+ * Virtual master and slave controls
+ *
+ * Copyright (c) 2008 by Takashi Iwai <tiwai@suse.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2.
+ *
+ */
+
+#include <linux/slab.h>
+#include <sound/core.h>
+#include <sound/control.h>
+
+/*
+ * a subset of information returned via ctl info callback
+ */
+struct link_ctl_info {
+ int type; /* value type */
+ int count; /* item count */
+ int min_val, max_val; /* min, max values */
+};
+
+/*
+ * link master - this contains a list of slave 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 slaves.
+ */
+struct link_master {
+ struct list_head slaves;
+ struct link_ctl_info info;
+ int val; /* the master value */
+};
+
+/*
+ * link slave - this contains a slave control element
+ *
+ * It fakes the control callbacsk with additional attenuation by the
+ * master control. A slave may have either one or two channels.
+ */
+
+struct link_slave {
+ struct list_head list;
+ struct link_master *master;
+ struct link_ctl_info info;
+ int vals[2]; /* current values */
+ struct snd_kcontrol slave; /* the copy of original control entry */
+};
+
+/* get the slave ctl info and save the initial values */
+static int slave_init(struct link_slave *slave)
+{
+ struct snd_ctl_elem_info *uinfo;
+ struct snd_ctl_elem_value *uctl;
+ int err, ch;
+
+ if (slave->info.count)
+ return 0; /* already initialized */
+
+ uinfo = kmalloc(sizeof(*uinfo), GFP_KERNEL);
+ if (!uinfo)
+ return -ENOMEM;
+ uinfo->id = slave->slave.id;
+ err = slave->slave.info(&slave->slave, uinfo);
+ if (err < 0) {
+ kfree(uinfo);
+ return err;
+ }
+ slave->info.type = uinfo->type;
+ slave->info.count = uinfo->count;
+ if (slave->info.count > 2 ||
+ (slave->info.type != SNDRV_CTL_ELEM_TYPE_INTEGER &&
+ slave->info.type != SNDRV_CTL_ELEM_TYPE_BOOLEAN)) {
+ snd_printk(KERN_ERR "invalid slave element\n");
+ kfree(uinfo);
+ return -EINVAL;
+ }
+ slave->info.min_val = uinfo->value.integer.min;
+ slave->info.max_val = uinfo->value.integer.max;
+ kfree(uinfo);
+
+ uctl = kmalloc(sizeof(*uctl), GFP_KERNEL);
+ if (!uctl)
+ return -ENOMEM;
+ uctl->id = slave->slave.id;
+ err = slave->slave.get(&slave->slave, uctl);
+ for (ch = 0; ch < slave->info.count; ch++)
+ slave->vals[ch] = uctl->value.integer.value[ch];
+ kfree(uctl);
+ return 0;
+}
+
+/* initialize master volume */
+static int master_init(struct link_master *master)
+{
+ struct link_slave *slave;
+
+ if (master->info.count)
+ return 0; /* already initialized */
+
+ list_for_each_entry(slave, &master->slaves, list) {
+ int err = slave_init(slave);
+ if (err < 0)
+ return err;
+ master->info = slave->info;
+ master->info.count = 1; /* always mono */
+ /* set full volume as default (= no attenuation) */
+ master->val = master->info.max_val;
+ return 0;
+ }
+ return -ENOENT;
+}
+
+static int slave_get_val(struct link_slave *slave,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ int err, ch;
+
+ err = slave_init(slave);
+ if (err < 0)
+ return err;
+ for (ch = 0; ch < slave->info.count; ch++)
+ ucontrol->value.integer.value[ch] = slave->vals[ch];
+ return 0;
+}
+
+static int slave_put_val(struct link_slave *slave,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ int err, ch, vol;
+
+ err = master_init(slave->master);
+ if (err < 0)
+ return err;
+
+ switch (slave->info.type) {
+ case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
+ for (ch = 0; ch < slave->info.count; ch++)
+ ucontrol->value.integer.value[ch] &=
+ !!slave->master->val;
+ break;
+ case SNDRV_CTL_ELEM_TYPE_INTEGER:
+ for (ch = 0; ch < slave->info.count; ch++) {
+ /* max master volume is supposed to be 0 dB */
+ vol = ucontrol->value.integer.value[ch];
+ vol += slave->master->val - slave->master->info.max_val;
+ if (vol < slave->info.min_val)
+ vol = slave->info.min_val;
+ else if (vol > slave->info.max_val)
+ vol = slave->info.max_val;
+ ucontrol->value.integer.value[ch] = vol;
+ }
+ break;
+ }
+ return slave->slave.put(&slave->slave, ucontrol);
+}
+
+/*
+ * ctl callbacks for slaves
+ */
+static int slave_info(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_info *uinfo)
+{
+ struct link_slave *slave = snd_kcontrol_chip(kcontrol);
+ return slave->slave.info(&slave->slave, uinfo);
+}
+
+static int slave_get(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct link_slave *slave = snd_kcontrol_chip(kcontrol);
+ return slave_get_val(slave, ucontrol);
+}
+
+static int slave_put(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct link_slave *slave = snd_kcontrol_chip(kcontrol);
+ int err, ch, changed = 0;
+
+ err = slave_init(slave);
+ if (err < 0)
+ return err;
+ for (ch = 0; ch < slave->info.count; ch++) {
+ if (slave->vals[ch] != ucontrol->value.integer.value[ch]) {
+ changed = 1;
+ slave->vals[ch] = ucontrol->value.integer.value[ch];
+ }
+ }
+ if (!changed)
+ return 0;
+ return slave_put_val(slave, ucontrol);
+}
+
+static int slave_tlv_cmd(struct snd_kcontrol *kcontrol,
+ int op_flag, unsigned int size,
+ unsigned int __user *tlv)
+{
+ struct link_slave *slave = snd_kcontrol_chip(kcontrol);
+ /* FIXME: this assumes that the max volume is 0 dB */
+ return slave->slave.tlv.c(&slave->slave, op_flag, size, tlv);
+}
+
+static void slave_free(struct snd_kcontrol *kcontrol)
+{
+ struct link_slave *slave = snd_kcontrol_chip(kcontrol);
+ if (slave->slave.private_free)
+ slave->slave.private_free(&slave->slave);
+ if (slave->master)
+ list_del(&slave->list);
+ kfree(slave);
+}
+
+/*
+ * Add a slave control to the group with the given master control
+ *
+ * All slaves must be the same type (returning the same information
+ * via info callback). The fucntion 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_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave)
+{
+ struct link_master *master_link = snd_kcontrol_chip(master);
+ struct link_slave *srec;
+
+ srec = kzalloc(sizeof(*srec) +
+ slave->count * sizeof(*slave->vd), GFP_KERNEL);
+ if (!srec)
+ return -ENOMEM;
+ srec->slave = *slave;
+ memcpy(srec->slave.vd, slave->vd, slave->count * sizeof(*slave->vd));
+ srec->master = master_link;
+
+ /* override callbacks */
+ slave->info = slave_info;
+ slave->get = slave_get;
+ slave->put = slave_put;
+ if (slave->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK)
+ slave->tlv.c = slave_tlv_cmd;
+ slave->private_data = srec;
+ slave->private_free = slave_free;
+
+ list_add_tail(&srec->list, &master_link->slaves);
+ return 0;
+}
+
+/*
+ * 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 master_put(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ struct link_slave *slave;
+ struct snd_ctl_elem_value *uval;
+ int err, old_val;
+
+ err = master_init(master);
+ if (err < 0)
+ return err;
+ old_val = master->val;
+ if (ucontrol->value.integer.value[0] == old_val)
+ return 0;
+
+ uval = kmalloc(sizeof(*uval), GFP_KERNEL);
+ if (!uval)
+ return -ENOMEM;
+ list_for_each_entry(slave, &master->slaves, list) {
+ master->val = old_val;
+ uval->id = slave->slave.id;
+ slave_get_val(slave, uval);
+ master->val = ucontrol->value.integer.value[0];
+ slave_put_val(slave, uval);
+ }
+ kfree(uval);
+ return 1;
+}
+
+static void master_free(struct snd_kcontrol *kcontrol)
+{
+ struct link_master *master = snd_kcontrol_chip(kcontrol);
+ struct link_slave *slave;
+
+ list_for_each_entry(slave, &master->slaves, list)
+ slave->master = NULL;
+ kfree(master);
+}
+
+
+/*
+ * Create a virtual master control with the given name
+ */
+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->slaves);
+
+ 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) {
+ /* FIXME: this assumes that the max volume is 0 dB */
+ kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
+ kctl->tlv.p = tlv;
+ }
+ return kctl;
+}
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