[RFC PATCH] ASoC: simple-card-utils: support system-clock-id DT property

[Sen Wang <sen@ti.com>]

Looking for feedbacks & on this before I draft a proper series w/
dt-binding.

The generic machine driver never had a mechanism to adjust for various
clk_ids that is tailored for individual codec & cpu peripherial driver.
simple_util_dai_init() has hardcoded 0, thus making non-default clock IDs
unreachable from DTS. Boards needing a specific clk_id have had no choice
but to write dedicated machine drivers.

This adds an optional "system-clock-id" u32 property to the cpu/codec
sub-node. When absent clk_id stays 0, preserving identical behaviour
for all existing boards.

Signed-off-by: Sen Wang <sen@ti.com>
---
 include/sound/simple_card_utils.h      | 1 +
 sound/soc/generic/simple-card-utils.c | 6 +++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/sound/simple_card_utils.h b/include/sound/simple_card_utils.h
index XXXXXXX..XXXXXXX 100644
--- a/include/sound/simple_card_utils.h
+++ b/include/sound/simple_card_utils.h
@@ -25,6 +25,7 @@ struct simple_util_dai {
 	const char *name;
 	unsigned int sysclk;
 	int clk_direction;
+	int clk_id;
 	int slots;
 	int slot_width;
 	unsigned int tx_slot_mask;
diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c
index XXXXXXX..XXXXXXX 100644
--- a/sound/soc/generic/simple-card-utils.c
+++ b/sound/soc/generic/simple-card-utils.c
@@ -290,6 +290,10 @@ int simple_util_parse_clk(struct device *dev,
 	if (of_property_read_bool(node, "system-clock-direction-out"))
 		simple_dai->clk_direction = SND_SOC_CLOCK_OUT;

+	if (!of_property_read_u32(node, "system-clock-id", &val))
+		simple_dai->clk_id = val;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(simple_util_parse_clk);
@@ -589,7 +593,7 @@ static int simple_init_dai(struct simple_util_priv *priv,

 	if (simple_dai->sysclk) {
-		ret = snd_soc_dai_set_sysclk(dai, 0, simple_dai->sysclk,
+		ret = snd_soc_dai_set_sysclk(dai, simple_dai->clk_id,
+					     simple_dai->sysclk,
 					     simple_dai->clk_direction);
 		if (ret && ret != -ENOTSUPP) {
 			dev_err(dai->dev, "simple-card: set_sysclk error\n");
--
2.43.0