[PATCH 17/22] ASoC: rsnd: Add system suspend/resume support

[John Madieu]

On RZ/G3E and similar SoCs, the audio subsystem loses its state during
deep sleep, due to lacking of proper clock and reset management in the
PM path.

Implement suspend/resume callbacks that save and restore the hardware
state by managing clocks and reset controls in the correct order:
- Suspend follows reverse probe order
- Resume follows probe order

Note that module clocks (mod->clk) are left in "prepared but disabled"
state after rsnd_mod_init(), so suspend only needs to unprepare them
and resume only needs to prepare them.

Signed-off-by: John Madieu <john.madieu.xa@xxxxxxxxxxxxxx>
---
 sound/soc/renesas/rcar/core.c | 108 +++++++++++++++++++++++++++++++++-
 1 file changed, 106 insertions(+), 2 deletions(-)

diff --git a/sound/soc/renesas/rcar/core.c b/sound/soc/renesas/rcar/core.c
index 6a25580b9c6a..eb504551e410 100644
--- a/sound/soc/renesas/rcar/core.c
+++ b/sound/soc/renesas/rcar/core.c
@@ -962,7 +962,8 @@ static int rsnd_soc_hw_rule_channels(struct snd_pcm_hw_params *params,
 static const struct snd_pcm_hardware rsnd_pcm_hardware = {
 	.info =		SNDRV_PCM_INFO_INTERLEAVED	|
 			SNDRV_PCM_INFO_MMAP		|
-			SNDRV_PCM_INFO_MMAP_VALID,
+			SNDRV_PCM_INFO_MMAP_VALID	|
+			SNDRV_PCM_INFO_RESUME,
 	.buffer_bytes_max	= 64 * 1024,
 	.period_bytes_min	= 32,
 	.period_bytes_max	= 8192,
@@ -2059,11 +2060,70 @@ static void rsnd_remove(struct platform_device *pdev)
 		remove_func[i](priv);
 }
 
+static void rsnd_suspend_mod(struct rsnd_mod *mod)
+{
+	if (!mod)
+		return;
+
+	clk_unprepare(mod->clk);
+	reset_control_assert(mod->rstc);
+}
+
+static void rsnd_resume_mod(struct rsnd_mod *mod)
+{
+	if (!mod)
+		return;
+
+	reset_control_deassert(mod->rstc);
+	clk_prepare(mod->clk);
+}
+
 static int rsnd_suspend(struct device *dev)
 {
 	struct rsnd_priv *priv = dev_get_drvdata(dev);
+	int i;
+
+	/*
+	 * Reverse order of probe:
+	 * ADG -> DVC -> MIX -> CTU -> SRC -> SSIU -> SSI -> DMA
+	 */
 
+	/* ADG */
+	/* ADG clock disabled via rsnd_adg_clk_disable() -> adg->adg */
 	rsnd_adg_clk_disable(priv);
+	rsnd_suspend_mod(rsnd_adg_mod_get(priv));
+
+	/* DVC */
+	for (i = priv->dvc_nr - 1; i >= 0; i--)
+		rsnd_suspend_mod(rsnd_dvc_mod_get(priv, i));
+
+	/* MIX */
+	for (i = priv->mix_nr - 1; i >= 0; i--)
+		rsnd_suspend_mod(rsnd_mix_mod_get(priv, i));
+
+	/* CTU */
+	for (i = priv->ctu_nr - 1; i >= 0; i--)
+		rsnd_suspend_mod(rsnd_ctu_mod_get(priv, i));
+
+	/* SRC */
+	for (i = priv->src_nr - 1; i >= 0; i--)
+		rsnd_suspend_mod(rsnd_src_mod_get(priv, i));
+
+	clk_disable_unprepare(priv->clk_scu_x2);
+	clk_disable_unprepare(priv->clk_scu);
+
+	/* SSIU */
+	for (i = priv->ssiu_nr - 1; i >= 0; i--)
+		rsnd_suspend_mod(rsnd_ssiu_mod_get(priv, i));
+
+	/* SSI */
+	for (i = priv->ssi_nr - 1; i >= 0; i--)
+		rsnd_suspend_mod(rsnd_ssi_mod_get(priv, i));
+
+	/* DMA */
+	clk_disable_unprepare(priv->clk_audmac_pp);
+	if (priv->rstc_audmac_pp)
+		reset_control_assert(priv->rstc_audmac_pp);
 
 	return 0;
 }
@@ -2071,8 +2131,52 @@ static int rsnd_suspend(struct device *dev)
 static int rsnd_resume(struct device *dev)
 {
 	struct rsnd_priv *priv = dev_get_drvdata(dev);
+	int i;
+
+	/*
+	 * Same order as probe:
+	 * DMA -> SSI -> SSIU -> SRC -> CTU -> MIX -> DVC -> ADG
+	 */
+
+	/* DMA */
+	if (priv->rstc_audmac_pp)
+		reset_control_deassert(priv->rstc_audmac_pp);
 
-	return rsnd_adg_clk_enable(priv);
+	clk_prepare_enable(priv->clk_audmac_pp);
+
+	/* SSI */
+	for (i = 0; i < priv->ssi_nr; i++)
+		rsnd_resume_mod(rsnd_ssi_mod_get(priv, i));
+
+	/* SSIU */
+	for (i = 0; i < priv->ssiu_nr; i++)
+		rsnd_resume_mod(rsnd_ssiu_mod_get(priv, i));
+
+	/* SRC */
+	clk_prepare_enable(priv->clk_scu);
+	clk_prepare_enable(priv->clk_scu_x2);
+
+	for (i = 0; i < priv->src_nr; i++)
+		rsnd_resume_mod(rsnd_src_mod_get(priv, i));
+
+	/* CTU */
+	for (i = 0; i < priv->ctu_nr; i++)
+		rsnd_resume_mod(rsnd_ctu_mod_get(priv, i));
+
+	/* MIX */
+	for (i = 0; i < priv->mix_nr; i++)
+		rsnd_resume_mod(rsnd_mix_mod_get(priv, i));
+
+	/* DVC */
+	for (i = 0; i < priv->dvc_nr; i++)
+		rsnd_resume_mod(rsnd_dvc_mod_get(priv, i));
+
+	/* ADG */
+	rsnd_resume_mod(rsnd_adg_mod_get(priv));
+	/* ADG clock enabled via rsnd_adg_clk_enable() -> adg->adg */
+	rsnd_adg_clk_enable(priv);
+
+	return 0;
 }
 
 static const struct dev_pm_ops rsnd_pm_ops = {
-- 
2.25.1