ASoC: SOF: imx8: Add runtime PM / System PM support

Handle clocks and mailbox channels at runtime suspend/resume
in order to save power.

DSP runtime PM uses a timeout of 2s. If device
is idle for 2s system will enter runtime suspend.

Because SOF state machine assumes that even if the DSP wasn't previously
active at a System resume, will re-load the firmware we need to make sure
that all needed resources are active.

Kernel core will take care of enabling the PD, we need to make sure that
we request the MU channels.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20211119094319.81674-3-daniel.baluta@oss.nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/imx/imx8.c

@@ -320,7 +320,9 @@ static int imx8_probe(struct snd_sof_dev *sdev)
 	if (ret < 0)
 		goto exit_pdev_unregister;
 
-	imx8_enable_clocks(sdev, priv->clks);
+	ret = imx8_enable_clocks(sdev, priv->clks);
+	if (ret < 0)
+		goto exit_pdev_unregister;
 
 	return 0;
 
@@ -364,6 +366,92 @@ static int imx8_get_bar_index(struct snd_sof_dev *sdev, u32 type)
 	}
 }
 
+static void imx8_suspend(struct snd_sof_dev *sdev)
+{
+	int i;
+	struct imx8_priv *priv = (struct imx8_priv *)sdev->pdata->hw_pdata;
+
+	for (i = 0; i < DSP_MU_CHAN_NUM; i++)
+		imx_dsp_free_channel(priv->dsp_ipc, i);
+
+	imx8_disable_clocks(sdev, priv->clks);
+}
+
+static int imx8_resume(struct snd_sof_dev *sdev)
+{
+	struct imx8_priv *priv = (struct imx8_priv *)sdev->pdata->hw_pdata;
+	int ret;
+	int i;
+
+	ret = imx8_enable_clocks(sdev, priv->clks);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < DSP_MU_CHAN_NUM; i++)
+		imx_dsp_request_channel(priv->dsp_ipc, i);
+
+	return 0;
+}
+
+static int imx8_dsp_runtime_resume(struct snd_sof_dev *sdev)
+{
+	int ret;
+	const struct sof_dsp_power_state target_dsp_state = {
+		.state = SOF_DSP_PM_D0,
+	};
+
+	ret = imx8_resume(sdev);
+	if (ret < 0)
+		return ret;
+
+	return snd_sof_dsp_set_power_state(sdev, &target_dsp_state);
+}
+
+static int imx8_dsp_runtime_suspend(struct snd_sof_dev *sdev)
+{
+	const struct sof_dsp_power_state target_dsp_state = {
+		.state = SOF_DSP_PM_D3,
+	};
+
+	imx8_suspend(sdev);
+
+	return snd_sof_dsp_set_power_state(sdev, &target_dsp_state);
+}
+
+static int imx8_dsp_suspend(struct snd_sof_dev *sdev, unsigned int target_state)
+{
+	const struct sof_dsp_power_state target_dsp_state = {
+		.state = target_state,
+	};
+
+	if (!pm_runtime_suspended(sdev->dev))
+		imx8_suspend(sdev);
+
+	return snd_sof_dsp_set_power_state(sdev, &target_dsp_state);
+}
+
+static int imx8_dsp_resume(struct snd_sof_dev *sdev)
+{
+	int ret;
+	const struct sof_dsp_power_state target_dsp_state = {
+		.state = SOF_DSP_PM_D0,
+	};
+
+	ret = imx8_resume(sdev);
+	if (ret < 0)
+		return ret;
+
+	if (pm_runtime_suspended(sdev->dev)) {
+		pm_runtime_disable(sdev->dev);
+		pm_runtime_set_active(sdev->dev);
+		pm_runtime_mark_last_busy(sdev->dev);
+		pm_runtime_enable(sdev->dev);
+		pm_runtime_idle(sdev->dev);
+	}
+
+	return snd_sof_dsp_set_power_state(sdev, &target_dsp_state);
+}
+
 static struct snd_soc_dai_driver imx8_dai[] = {
 {
 	.name = "esai0",
@@ -389,6 +477,14 @@ static struct snd_soc_dai_driver imx8_dai[] = {
 },
 };
 
+static int imx8_dsp_set_power_state(struct snd_sof_dev *sdev,
+				    const struct sof_dsp_power_state *target_state)
+{
+	sdev->dsp_power_state = *target_state;
+
+	return 0;
+}
+
 /* i.MX8 ops */
 struct snd_sof_dsp_ops sof_imx8_ops = {
 	/* probe and remove */
@@ -441,6 +537,15 @@ struct snd_sof_dsp_ops sof_imx8_ops = {
 			SNDRV_PCM_INFO_INTERLEAVED |
 			SNDRV_PCM_INFO_PAUSE |
 			SNDRV_PCM_INFO_NO_PERIOD_WAKEUP,
+
+	/* PM */
+	.runtime_suspend	= imx8_dsp_runtime_suspend,
+	.runtime_resume		= imx8_dsp_runtime_resume,
+
+	.suspend	= imx8_dsp_suspend,
+	.resume		= imx8_dsp_resume,
+
+	.set_power_state	= imx8_dsp_set_power_state,
 };
 EXPORT_SYMBOL(sof_imx8_ops);
 
@@ -490,6 +595,15 @@ struct snd_sof_dsp_ops sof_imx8x_ops = {
 	.drv = imx8_dai,
 	.num_drv = ARRAY_SIZE(imx8_dai),
 
+	/* PM */
+	.runtime_suspend	= imx8_dsp_runtime_suspend,
+	.runtime_resume		= imx8_dsp_runtime_resume,
+
+	.suspend	= imx8_dsp_suspend,
+	.resume		= imx8_dsp_resume,
+
+	.set_power_state	= imx8_dsp_set_power_state,
+
 	/* ALSA HW info flags */
 	.hw_info =	SNDRV_PCM_INFO_MMAP |
 			SNDRV_PCM_INFO_MMAP_VALID |