ALSA: scarlett2: Add power status control

Add a control to retrieve the power status from the interface
(bus-powered, external-powered, or insufficient power).

Mark the new scarlett2_notify_power_status() function with
__always_unused until it gets used when the Gen 4 notification
callback function arrays are added.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/d9806bc41adc45b1c19749562fec7765ba24351d.1703612638.git.g@b4.vu

diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c
index 6266f5d3fab85319272baf582b449ba3540a8edf..ce842c29be5ec4fb370681ad033d2ce04e048ffd 100644 (file)
--- a/sound/usb/mixer_scarlett2.c
+++ b/sound/usb/mixer_scarlett2.c
@@ -278,6 +278,14 @@ enum {
        SCARLETT2_AUTOGAIN_STATUS_COUNT
 };
 
+/* Power Status Values */
+enum {
+       SCARLETT2_POWER_STATUS_EXT,
+       SCARLETT2_POWER_STATUS_BUS,
+       SCARLETT2_POWER_STATUS_FAIL,
+       SCARLETT2_POWER_STATUS_COUNT
+};
+
 /* Notification callback functions */
 struct scarlett2_notification {
        u32 mask;
@@ -334,6 +342,8 @@ enum {
        SCARLETT2_CONFIG_SAFE_SWITCH,
        SCARLETT2_CONFIG_INPUT_SELECT_SWITCH,
        SCARLETT2_CONFIG_INPUT_LINK_SWITCH,
+       SCARLETT2_CONFIG_POWER_EXT,
+       SCARLETT2_CONFIG_POWER_STATUS,
        SCARLETT2_CONFIG_COUNT
 };
 
@@ -751,6 +761,7 @@ struct scarlett2_data {
        u8 direct_monitor_updated;
        u8 mux_updated;
        u8 speaker_switching_switched;
+       u8 power_status_updated;
        u8 sync;
        u8 master_vol;
        u8 vol[SCARLETT2_ANALOGUE_MAX];
@@ -774,6 +785,7 @@ struct scarlett2_data {
        u8 talkback_map[SCARLETT2_OUTPUT_MIX_MAX];
        u8 msd_switch;
        u8 standalone_switch;
+       u8 power_status;
        u8 meter_level_map[SCARLETT2_MAX_METERS];
        struct snd_kcontrol *sync_ctl;
        struct snd_kcontrol *master_vol_ctl;
@@ -795,6 +807,7 @@ struct scarlett2_data {
        struct snd_kcontrol *direct_monitor_ctl;
        struct snd_kcontrol *speaker_switching_ctl;
        struct snd_kcontrol *talkback_ctl;
+       struct snd_kcontrol *power_status_ctl;
        u8 mux[SCARLETT2_MUX_MAX];
        u8 mix[SCARLETT2_MIX_MAX];
 };
@@ -5526,6 +5539,91 @@ static int scarlett2_add_standalone_ctl(struct usb_mixer_interface *mixer)
                                     0, 1, "Standalone Switch", NULL);
 }
 
+/*** Power Status ***/
+
+static int scarlett2_update_power_status(struct usb_mixer_interface *mixer)
+{
+       struct scarlett2_data *private = mixer->private_data;
+       int err;
+       u8 power_ext;
+       u8 power_status;
+
+       private->power_status_updated = 0;
+
+       err = scarlett2_usb_get_config(mixer, SCARLETT2_CONFIG_POWER_EXT,
+                                      1, &power_ext);
+       if (err < 0)
+               return err;
+
+       err = scarlett2_usb_get_config(mixer, SCARLETT2_CONFIG_POWER_STATUS,
+                                      1, &power_status);
+       if (err < 0)
+               return err;
+
+       if (power_status > 1)
+               private->power_status = SCARLETT2_POWER_STATUS_FAIL;
+       else if (power_ext)
+               private->power_status = SCARLETT2_POWER_STATUS_EXT;
+       else
+               private->power_status = SCARLETT2_POWER_STATUS_BUS;
+
+       return 0;
+}
+
+static int scarlett2_power_status_ctl_get(struct snd_kcontrol *kctl,
+                                         struct snd_ctl_elem_value *ucontrol)
+{
+       struct usb_mixer_elem_info *elem = kctl->private_data;
+       struct usb_mixer_interface *mixer = elem->head.mixer;
+       struct scarlett2_data *private = mixer->private_data;
+       int err = 0;
+
+       mutex_lock(&private->data_mutex);
+
+       if (private->power_status_updated) {
+               err = scarlett2_update_power_status(mixer);
+               if (err < 0)
+                       goto unlock;
+       }
+       ucontrol->value.integer.value[0] = private->power_status;
+
+unlock:
+       mutex_unlock(&private->data_mutex);
+       return err;
+}
+
+static int scarlett2_power_status_ctl_info(
+       struct snd_kcontrol *kctl, struct snd_ctl_elem_info *uinfo)
+{
+       static const char *const values[3] = {
+               "External", "Bus", "Fail"
+       };
+
+       return snd_ctl_enum_info(uinfo, 1, 3, values);
+}
+
+static const struct snd_kcontrol_new scarlett2_power_status_ctl = {
+       .iface = SNDRV_CTL_ELEM_IFACE_CARD,
+       .access = SNDRV_CTL_ELEM_ACCESS_READ,
+       .name = "",
+       .info = scarlett2_power_status_ctl_info,
+       .get  = scarlett2_power_status_ctl_get,
+};
+
+static int scarlett2_add_power_status_ctl(struct usb_mixer_interface *mixer)
+{
+       struct scarlett2_data *private = mixer->private_data;
+
+       if (!scarlett2_has_config_item(private,
+                                      SCARLETT2_CONFIG_POWER_EXT))
+               return 0;
+
+       /* Add power status control */
+       return scarlett2_add_new_ctl(mixer, &scarlett2_power_status_ctl,
+                                    0, 1, "Power Status Card Enum",
+                                    &private->power_status_ctl);
+}
+
 /*** Cleanup/Suspend Callbacks ***/
 
 static void scarlett2_private_free(struct usb_mixer_interface *mixer)
@@ -5817,6 +5915,13 @@ static int scarlett2_read_configs(struct usb_mixer_interface *mixer)
                        return err;
        }
 
+       if (scarlett2_has_config_item(private,
+                                     SCARLETT2_CONFIG_POWER_EXT)) {
+               err = scarlett2_update_power_status(mixer);
+               if (err < 0)
+                       return err;
+       }
+
        err = scarlett2_update_sync(mixer);
        if (err < 0)
                return err;
@@ -6153,6 +6258,19 @@ static void scarlett2_notify_direct_monitor(struct usb_mixer_interface *mixer)
                       &private->direct_monitor_ctl->id);
 }
 
+/* Notify on power change */
+static __always_unused void scarlett2_notify_power_status(
+       struct usb_mixer_interface *mixer)
+{
+       struct snd_card *card = mixer->chip->card;
+       struct scarlett2_data *private = mixer->private_data;
+
+       private->power_status_updated = 1;
+
+       snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
+                      &private->power_status_ctl->id);
+}
+
 /* Interrupt callback */
 static void scarlett2_notify(struct urb *urb)
 {
@@ -6330,6 +6448,11 @@ static int snd_scarlett2_controls_create(
        if (err < 0)
                return err;
 
+       /* Create the power status control */
+       err = scarlett2_add_power_status_ctl(mixer);
+       if (err < 0)
+               return err;
+
        /* Set the access mode of controls disabled during
         * autogain/phantom power switching.
         */