ASoC: SOF: add DAI_HW_FREE IPC command

There is an STREAM_PCM_FREE IPC command which is sent to a SOF
pipeline in trigger stop. Here we add an new DAI_HW_FREE command which
will be sent to SOF DAI component. The command is sent from BE DAI
link so codec driver has chance to run code in the mute_stream()
callback before the DAI_HW_FREE IPC command is sent.

This is the call flow of pcm playback:

DROP:
    sof's trigger()
        => send STREAM_TRIG_STOP
        => send STREAM_PCM_FREE
HW_FREE:
    sof's hw_free() (FE)
    codec's mute_stream()
    sof's hw_free() (BE)
        => send DAI_HW_FREE
    codec's hw_free()

Signed-off-by: Brent Lu <brent.lu@intel.com>

Author: brentlu

include/sound/sof/dai.h

@@ -85,4 +85,11 @@ struct sof_ipc_dai_config {
 	};
 } __packed;
 
+/* DAI hardware free */
+struct sof_ipc_dai_hw_free {
+	struct sof_ipc_cmd_hdr hdr;
+	uint32_t type;		/**< DAI type - enum sof_ipc_dai_type */
+	uint32_t dai_index;	/**< index of this type dai */
+} __packed;
+
 #endif

include/sound/sof/header.h

@@ -89,6 +89,7 @@
 /* DAI messages */
 #define SOF_IPC_DAI_CONFIG			SOF_CMD_TYPE(0x001)
 #define SOF_IPC_DAI_LOOPBACK			SOF_CMD_TYPE(0x002)
+#define SOF_IPC_DAI_HW_FREE			SOF_CMD_TYPE(0x004)
 
 /* stream */
 #define SOF_IPC_STREAM_PCM_PARAMS		SOF_CMD_TYPE(0x001)

sound/soc/sof/ipc.c

@@ -168,6 +168,8 @@ static void ipc_log_header(struct device *dev, u8 *text, u32 cmd)
 			str2 = "CONFIG"; break;
 		case SOF_IPC_DAI_LOOPBACK:
 			str2 = "LOOPBACK"; break;
+		case SOF_IPC_DAI_HW_FREE:
+			str2 = "HW_FREE"; break;
 		default:
 			str2 = "unknown type"; break;
 		}

sound/soc/sof/pcm.c

@@ -288,9 +288,41 @@ static int sof_pcm_hw_free(struct snd_soc_component *component,
 	struct snd_sof_pcm *spcm;
 	int ret, err = 0;
 
-	/* nothing to do for BE */
-	if (rtd->dai_link->no_pcm)
+	if (rtd->dai_link->no_pcm) {
+		struct snd_sof_dai *sdai;
+		struct sof_ipc_dai_config *dai_config;
+		struct sof_ipc_dai_hw_free dai_hw_free;
+		struct sof_ipc_reply reply;
+
+		sdai = snd_sof_find_dai(component, rtd->dai_link->name);
+		if (!sdai)
+			return -EINVAL;
+
+		dai_config = sdai->dai_config;
+
+		dev_dbg(component->dev, "dai: free dai type %d index %d\n",
+			dai_config->type, dai_config->dai_index);
+
+		memset(&dai_hw_free, 0, sizeof(dai_hw_free));
+
+		dai_hw_free.hdr.size = sizeof(dai_hw_free);
+		dai_hw_free.hdr.cmd = SOF_IPC_GLB_DAI_MSG | SOF_IPC_DAI_HW_FREE;
+		dai_hw_free.type = dai_config->type;
+		dai_hw_free.dai_index = dai_config->dai_index;
+
+		/* send IPC to the DSP */
+		ret = sof_ipc_tx_message(sdev->ipc, dai_hw_free.hdr.cmd,
+					 &dai_hw_free, sizeof(dai_hw_free),
+					 &reply, sizeof(reply));
+		if (ret < 0) {
+			dev_err(component->dev,
+				"error: hw free ipc failed for dai type %d index %d\n",
+				dai_config->type, dai_config->dai_index);
+			return ret;
+		}
+
 		return 0;
+	}
 
 	spcm = snd_sof_find_spcm_dai(component, rtd);
 	if (!spcm)