[PATCH v4 2/2] ASoC: codecs: wsa883x: Handle shared reset GPIO for WSA883x speakers

[Mohammad Rafi Shaik <mohammad.rafi.shaik@xxxxxxxxxxxxxxxx>]

From: Mohammad Rafi Shaik <quic_mohs@xxxxxxxxxxx>

On some Qualcomm platforms such as QCS6490-RB3Gen2, the multiple
WSA8830/WSA8835 speaker amplifiers share a common reset (shutdown) GPIO.

To handle such scenario, use the reset controller framework and its
"reset-gpio" driver to handle such case. This allows proper handling
of all WSA883x speaker amplifiers on QCS6490-RB3Gen2 board.

Signed-off-by: Mohammad Rafi Shaik <quic_mohs@xxxxxxxxxxx>
---
 sound/soc/codecs/wsa883x.c | 57 +++++++++++++++++++++++++++++++++-----
 1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/wsa883x.c b/sound/soc/codecs/wsa883x.c
index 188363b03b93..ec7a55d88576 100644
--- a/sound/soc/codecs/wsa883x.c
+++ b/sound/soc/codecs/wsa883x.c
@@ -14,6 +14,7 @@
 #include <linux/printk.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/soundwire/sdw.h>
 #include <linux/soundwire/sdw_registers.h>
@@ -468,6 +469,7 @@ struct wsa883x_priv {
 	struct sdw_stream_runtime *sruntime;
 	struct sdw_port_config port_config[WSA883X_MAX_SWR_PORTS];
 	struct gpio_desc *sd_n;
+	struct reset_control *sd_reset;
 	bool port_prepared[WSA883X_MAX_SWR_PORTS];
 	bool port_enable[WSA883X_MAX_SWR_PORTS];
 	int active_ports;
@@ -1546,6 +1548,46 @@ static const struct hwmon_chip_info wsa883x_hwmon_chip_info = {
 	.info	= wsa883x_hwmon_info,
 };
 
+static void wsa883x_reset_assert(void *data)
+{
+	struct wsa883x_priv *wsa883x = data;
+
+	if (wsa883x->sd_reset)
+		reset_control_assert(wsa883x->sd_reset);
+	else
+		gpiod_direction_output(wsa883x->sd_n, 1);
+}
+
+static void wsa883x_reset_deassert(struct wsa883x_priv *wsa883x)
+{
+	if (wsa883x->sd_reset)
+		reset_control_deassert(wsa883x->sd_reset);
+	else
+		gpiod_direction_output(wsa883x->sd_n, 0);
+}
+
+static int wsa883x_get_reset(struct device *dev, struct wsa883x_priv *wsa883x)
+{
+	wsa883x->sd_reset = devm_reset_control_get_optional_shared_deasserted(dev, NULL);
+	if (IS_ERR(wsa883x->sd_reset))
+		return dev_err_probe(dev, PTR_ERR(wsa883x->sd_reset),
+				     "Failed to get reset\n");
+	/*
+	 * if sd_reset: NULL, so use the backwards compatible way for powerdown-gpios,
+	 * which does not handle sharing GPIO properly.
+	 */
+	if (!wsa883x->sd_reset) {
+		wsa883x->sd_n = devm_gpiod_get_optional(dev, "powerdown",
+							GPIOD_FLAGS_BIT_NONEXCLUSIVE |
+							GPIOD_OUT_HIGH);
+		if (IS_ERR(wsa883x->sd_n))
+			return dev_err_probe(dev, PTR_ERR(wsa883x->sd_n),
+					     "Shutdown Control GPIO not found\n");
+	}
+
+	return 0;
+}
+
 static int wsa883x_probe(struct sdw_slave *pdev,
 			 const struct sdw_device_id *id)
 {
@@ -1566,11 +1608,9 @@ static int wsa883x_probe(struct sdw_slave *pdev,
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to enable vdd regulator\n");
 
-	wsa883x->sd_n = devm_gpiod_get_optional(dev, "powerdown",
-						GPIOD_FLAGS_BIT_NONEXCLUSIVE | GPIOD_OUT_HIGH);
-	if (IS_ERR(wsa883x->sd_n)) {
-		ret = dev_err_probe(dev, PTR_ERR(wsa883x->sd_n),
-				    "Shutdown Control GPIO not found\n");
+	ret = wsa883x_get_reset(dev, wsa883x);
+	if (ret) {
+		dev_dbg(dev, "Failed to get reset powerdown GPIO: %d\n", ret);
 		goto err;
 	}
 
@@ -1595,11 +1635,14 @@ static int wsa883x_probe(struct sdw_slave *pdev,
 	pdev->prop.simple_clk_stop_capable = true;
 	pdev->prop.sink_dpn_prop = wsa_sink_dpn_prop;
 	pdev->prop.scp_int1_mask = SDW_SCP_INT1_BUS_CLASH | SDW_SCP_INT1_PARITY;
-	gpiod_direction_output(wsa883x->sd_n, 0);
+
+	wsa883x_reset_deassert(wsa883x);
+	ret = devm_add_action_or_reset(dev, wsa883x_reset_assert, wsa883x);
+	if (ret)
+		return ret;
 
 	wsa883x->regmap = devm_regmap_init_sdw(pdev, &wsa883x_regmap_config);
 	if (IS_ERR(wsa883x->regmap)) {
-		gpiod_direction_output(wsa883x->sd_n, 1);
 		ret = dev_err_probe(dev, PTR_ERR(wsa883x->regmap),
 				    "regmap_init failed\n");
 		goto err;
-- 
2.34.1