[PATCH v2 12/24] ASoC: rsnd: Add SSI reset support for RZ/G3E platforms

[John Madieu <john.madieu.xa@bp.renesas.com>]

Add SSI reset support for the Renesas RZ/G3E SoC, which differs from earlier
generations in several ways:

 - The SSI block always operates in BUSIF mode; RZ/G3E does not implement
   the SSITDR/SSIRDR registers used by R-Car Gen2/Gen3/Gen4 for direct SSI
   DMA. Consequently, all audio data must pass through BUSIF.
 - Each SSI instance has its own reset line, exposed using per-SSI names
   such as "ssi0", "ssi1", etc., rather than a single shared reset.

To support these differences, rsnd_ssi_use_busif() always return 1 on
RZ/G3E, ensuring that the driver consistently selects the BUSIF DMA path.
While at it, update the reset acquisition logic to request the appropriate
per-SSI reset controller based on the SSI instance name.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
---

Changes:

v2:
 - Drop rsnd_dma_detach() from rsnd_ssi_common_remove() upon NULL pointer
   dereference on R-Car Gen3/Gen4 (reported by Geert)
 - Drop RSND_SSI_ALWAYS_BUSIF flag; use direct rsnd_is_rzg3e() check instead


 sound/soc/renesas/rcar/ssi.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/sound/soc/renesas/rcar/ssi.c b/sound/soc/renesas/rcar/ssi.c
index c06cebb36170..c65435551283 100644
--- a/sound/soc/renesas/rcar/ssi.c
+++ b/sound/soc/renesas/rcar/ssi.c
@@ -1158,6 +1158,7 @@ int __rsnd_ssi_is_pin_sharing(struct rsnd_mod *mod)
 
 int rsnd_ssi_probe(struct rsnd_priv *priv)
 {
+	struct reset_control *rstc;
 	struct device_node *node;
 	struct device *dev = rsnd_priv_to_dev(priv);
 	struct rsnd_mod_ops *ops;
@@ -1207,6 +1208,16 @@ int rsnd_ssi_probe(struct rsnd_priv *priv)
 			goto rsnd_ssi_probe_done;
 		}
 
+		/*
+		 * RZ/G3E uses per-SSI reset controllers.
+		 * R-Car platforms typically don't have SSI reset controls.
+		 */
+		rstc = devm_reset_control_get_optional(dev, name);
+		if (IS_ERR(rstc)) {
+			ret = PTR_ERR(rstc);
+			goto rsnd_ssi_probe_done;
+		}
+
 		if (of_property_read_bool(np, "shared-pin"))
 			rsnd_flags_set(ssi, RSND_SSI_CLK_PIN_SHARE);
 
@@ -1225,7 +1236,7 @@ int rsnd_ssi_probe(struct rsnd_priv *priv)
 			ops = &rsnd_ssi_dma_ops;
 
 		ret = rsnd_mod_init(priv, rsnd_mod_get(ssi), ops, clk,
-				    NULL, RSND_MOD_SSI, i);
+				    rstc, RSND_MOD_SSI, i);
 		if (ret)
 			goto rsnd_ssi_probe_done;
 
-- 
2.25.1