ASoC: rsnd: src: Add SRC reset support for RZ/G3E

The RZ/G3E SoC exposes a shared SCU reset controller used by all SRC
modules. Acquire it once and pass it through per-instance's
rsnd_mod_init() so it is wired into the rsnd_mod->rstc plumbing.

devm_reset_control_get_optional_shared() returns NULL when no reset
is described in DT, leaving existing R-Car generations unaffected.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/20260525110230.4014435-17-john.madieu.xa@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: John Madieu

sound/soc/renesas/rcar/src.c

@@ -720,6 +720,7 @@ int rsnd_src_probe(struct rsnd_priv *priv)
 {
 	struct device_node *node;
 	struct device *dev = rsnd_priv_to_dev(priv);
+	struct reset_control *rstc;
 	struct rsnd_src_ctrl *src_ctrl;
 	struct rsnd_src *src;
 	struct clk *clk;
@@ -772,6 +773,16 @@ int rsnd_src_probe(struct rsnd_priv *priv)
 		goto rsnd_src_probe_done;
 	}
 
+	/*
+	 * Shared SCU reset for every SRC module; acquire once.
+	 * R-Car platforms typically don't have SRC reset controls.
+	 */
+	rstc = devm_reset_control_get_optional_shared(dev, "scu");
+	if (IS_ERR(rstc)) {
+		ret = PTR_ERR(rstc);
+		goto rsnd_src_probe_done;
+	}
+
 	i = 0;
 	for_each_child_of_node_scoped(node, np) {
 		if (!of_device_is_available(np))
@@ -798,7 +809,7 @@ int rsnd_src_probe(struct rsnd_priv *priv)
 		}
 
 		ret = rsnd_mod_init(priv, rsnd_mod_get(src),
-				    &rsnd_src_ops, clk, NULL, RSND_MOD_SRC, i);
+				    &rsnd_src_ops, clk, rstc, RSND_MOD_SRC, i);
 		if (ret)
 			goto rsnd_src_probe_done;