ALSA: hdac: add link pm and ref counting

The HDA links can be switched off when not is use, similarly
command DMA can be stopped as well. This calls for a reference
counting mechanism on the link by it's users to manage the link
power. The DMA can be turned off when all links are off

For this we add two APIs
	snd_hdac_ext_bus_link_get
	snd_hdac_ext_bus_link_put

They help users to turn up/down link and manage the DMA as well

Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 69 insertions, 0 deletions

diff --git a/sound/hda/ext/hdac_ext_bus.c b/sound/hda/ext/hdac_ext_bus.c
index 2433f7c81472..3b7ae24900fd 100644
--- a/sound/hda/ext/hdac_ext_bus.c
+++ b/sound/hda/ext/hdac_ext_bus.c
@@ -105,6 +105,9 @@ int snd_hdac_ext_bus_init(struct hdac_ext_bus *ebus, struct device *dev,
 	INIT_LIST_HEAD(&ebus->hlink_list);
 	ebus->idx = idx++;
 
+	mutex_init(&ebus->lock);
+	ebus->cmd_dma_state = true;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_hdac_ext_bus_init);
diff --git a/sound/hda/ext/hdac_ext_controller.c b/sound/hda/ext/hdac_ext_controller.c
index 548cc1e4114b..860f8cad6602 100644
--- a/sound/hda/ext/hdac_ext_controller.c
+++ b/sound/hda/ext/hdac_ext_controller.c
@@ -186,6 +186,9 @@ int snd_hdac_ext_bus_get_ml_capabilities(struct hdac_ext_bus *ebus)
 		hlink->lcaps  = readl(hlink->ml_addr + AZX_REG_ML_LCAP);
 		hlink->lsdiid = readw(hlink->ml_addr + AZX_REG_ML_LSDIID);
 
+		/* since link in On, update the ref */
+		hlink->ref_count = 1;
+
 		list_add_tail(&hlink->list, &ebus->hlink_list);
 	}
 
@@ -327,3 +330,66 @@ int snd_hdac_ext_bus_link_power_down_all(struct hdac_ext_bus *ebus)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_hdac_ext_bus_link_power_down_all);
+
+int snd_hdac_ext_bus_link_get(struct hdac_ext_bus *ebus,
+				struct hdac_ext_link *link)
+{
+	int ret = 0;
+
+	mutex_lock(&ebus->lock);
+
+	/*
+	 * if we move from 0 to 1, count will be 1 so power up this link
+	 * as well, also check the dma status and trigger that
+	 */
+	if (++link->ref_count == 1) {
+		if (!ebus->cmd_dma_state) {
+			snd_hdac_bus_init_cmd_io(&ebus->bus);
+			ebus->cmd_dma_state = true;
+		}
+
+		ret = snd_hdac_ext_bus_link_power_up(link);
+	}
+
+	mutex_unlock(&ebus->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(snd_hdac_ext_bus_link_get);
+
+int snd_hdac_ext_bus_link_put(struct hdac_ext_bus *ebus,
+				struct hdac_ext_link *link)
+{
+	int ret = 0;
+	struct hdac_ext_link *hlink;
+	bool link_up = false;
+
+	mutex_lock(&ebus->lock);
+
+	/*
+	 * if we move from 1 to 0, count will be 0
+	 * so power down this link as well
+	 */
+	if (--link->ref_count == 0) {
+		ret = snd_hdac_ext_bus_link_power_down(link);
+
+		/*
+		 * now check if all links are off, if so turn off
+		 * cmd dma as well
+		 */
+		list_for_each_entry(hlink, &ebus->hlink_list, list) {
+			if (hlink->ref_count) {
+				link_up = true;
+				break;
+			}
+		}
+
+		if (!link_up) {
+			snd_hdac_bus_stop_cmd_io(&ebus->bus);
+			ebus->cmd_dma_state = false;
+		}
+	}
+
+	mutex_unlock(&ebus->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(snd_hdac_ext_bus_link_put);