Merge tag 'tags/mute-led-rework' into for-next

ALSA: control - add generic LED API

This patchset tries to resolve the diversity in the audio LED
control among the ALSA drivers. A new control layer registration
is introduced which allows to run additional operations on
top of the elementary ALSA sound controls.

A new control access group (three bits in the access flags)
was introduced to carry the LED group information for
the sound controls. The low-level sound drivers can just
mark those controls using this access group. This information
is not exported to the user space, but user space can
manage the LED sound control associations through sysfs
(last patch) per Mark's request. It makes things fully
configurable in the kernel and user space (UCM).

The actual state ('route') evaluation is really easy
(the minimal value check for all channels / controls / cards).
If there's more complicated logic for a given hardware,
the card driver may eventually export a new read-only
sound control for the LED group and do the logic itself.

The new LED trigger control code is completely separated
and possibly optional (there's no symbol dependency).
The full code separation allows eventually to move this
LED trigger control to the user space in future.
Actually it replaces the already present functionality
in the kernel space (HDA drivers) and allows a quick adoption
for the recent hardware (ASoC codecs including SoundWire).

snd_ctl_led            24576  0

The sound driver implementation is really easy:

1) call snd_ctl_led_request() when control LED layer should be
   automatically activated
   / it calls module_request("snd-ctl-led") on demand /
2) mark all related kcontrols with
        SNDRV_CTL_ELEM_ACCESS_SPK_LED or
        SNDRV_CTL_ELEM_ACCESS_MIC_LED

Link: https://lore.kernel.org/r/20210317172945.842280-1-perex@perex.cz
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 32 insertions, 3 deletions

diff --git a/include/sound/control.h b/include/sound/control.h
index 77d9fa10812d..985c51a8fb74 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -24,7 +24,7 @@ typedef int (snd_kcontrol_tlv_rw_t)(struct snd_kcontrol *kcontrol,
 
 /* internal flag for skipping validations */
 #ifdef CONFIG_SND_CTL_VALIDATION
-#define SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK	(1 << 27)
+#define SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK	(1 << 24)
 #define snd_ctl_skip_validation(info) \
 	((info)->access & SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK)
 #else
@@ -32,6 +32,12 @@ typedef int (snd_kcontrol_tlv_rw_t)(struct snd_kcontrol *kcontrol,
 #define snd_ctl_skip_validation(info)		true
 #endif
 
+/* kernel only - LED bits */
+#define SNDRV_CTL_ELEM_ACCESS_LED_SHIFT		25
+#define SNDRV_CTL_ELEM_ACCESS_LED_MASK		(7<<25) /* kernel three bits - LED group */
+#define SNDRV_CTL_ELEM_ACCESS_SPK_LED		(1<<25) /* kernel speaker (output) LED flag */
+#define SNDRV_CTL_ELEM_ACCESS_MIC_LED		(2<<25) /* kernel microphone (input) LED flag */
+
 enum {
 	SNDRV_CTL_TLV_OP_READ = 0,
 	SNDRV_CTL_TLV_OP_WRITE = 1,
@@ -108,6 +114,14 @@ struct snd_ctl_file {
 	struct list_head events;	/* waiting events for read */
 };
 
+struct snd_ctl_layer_ops {
+	struct snd_ctl_layer_ops *next;
+	const char *module_name;
+	void (*lregister)(struct snd_card *card);
+	void (*ldisconnect)(struct snd_card *card);
+	void (*lnotify)(struct snd_card *card, unsigned int mask, struct snd_kcontrol *kctl, unsigned int ioff);
+};
+
 #define snd_ctl_file(n) list_entry(n, struct snd_ctl_file, list)
 
 typedef int (*snd_kctl_ioctl_func_t) (struct snd_card * card,
@@ -115,6 +129,7 @@ typedef int (*snd_kctl_ioctl_func_t) (struct snd_card * card,
 				      unsigned int cmd, unsigned long arg);
 
 void snd_ctl_notify(struct snd_card * card, unsigned int mask, struct snd_ctl_elem_id * id);
+void snd_ctl_notify_one(struct snd_card * card, unsigned int mask, struct snd_kcontrol * kctl, unsigned int ioff);
 
 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new * kcontrolnew, void * private_data);
 void snd_ctl_free_one(struct snd_kcontrol * kcontrol);
@@ -123,8 +138,7 @@ int snd_ctl_remove(struct snd_card * card, struct snd_kcontrol * kcontrol);
 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol, bool add_on_replace);
 int snd_ctl_remove_id(struct snd_card * card, struct snd_ctl_elem_id *id);
 int snd_ctl_rename_id(struct snd_card * card, struct snd_ctl_elem_id *src_id, struct snd_ctl_elem_id *dst_id);
-int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
-			int active);
+int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id, int active);
 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card * card, unsigned int numid);
 struct snd_kcontrol *snd_ctl_find_id(struct snd_card * card, struct snd_ctl_elem_id *id);
 
@@ -140,6 +154,10 @@ int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn);
 #define snd_ctl_unregister_ioctl_compat(fcn)
 #endif
 
+int snd_ctl_request_layer(const char *module_name);
+void snd_ctl_register_layer(struct snd_ctl_layer_ops *lops);
+void snd_ctl_disconnect_layer(struct snd_ctl_layer_ops *lops);
+
 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type);
 
 static inline unsigned int snd_ctl_get_ioffnum(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)
@@ -254,6 +272,17 @@ int snd_ctl_apply_vmaster_followers(struct snd_kcontrol *kctl,
 				    void *arg);
 
 /*
+ * Control LED trigger layer
+ */
+#define SND_CTL_LAYER_MODULE_LED	"snd-ctl-led"
+
+#if IS_MODULE(CONFIG_SND_CTL_LED)
+static inline int snd_ctl_led_request(void) { return snd_ctl_request_layer(SND_CTL_LAYER_MODULE_LED); }
+#else
+static inline int snd_ctl_led_request(void) { return 0; }
+#endif
+
+/*
  * Helper functions for jack-detection controls
  */
 struct snd_kcontrol *