From 79f6c108c87b470aacf25fc25a86f48694d03ae8 Mon Sep 17 00:00:00 2001
From: Peter Ujfalusi <peter.ujfalusi@ti.com>
Date: Wed, 13 Nov 2019 14:47:34 +0200
Subject: [PATCH] ASoC: pcm3168a: Add support for optional RST gpio handling
Git-commit: 79f6c108c87b470aacf25fc25a86f48694d03ae8
Patch-mainline: v5.5-rc1
References: jsc#SLE-16518

In case the RST line is connected to a GPIO line it needs to be pulled high
when the driver probes to be able to use the codec.

Add support also for cases when more than one codec is is controlled by the
same GPIO line by requesting the gpio with GPIOD_FLAGS_BIT_NONEXCLUSIVE.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

Link: https://lore.kernel.org/r/20191113124734.27984-3-peter.ujfalusi@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 sound/soc/codecs/pcm3168a.c | 38 ++++++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/sound/soc/codecs/pcm3168a.c b/sound/soc/codecs/pcm3168a.c
index 313500ab36df..f3475134b519 100644
--- a/sound/soc/codecs/pcm3168a.c
+++ b/sound/soc/codecs/pcm3168a.c
@@ -9,7 +9,9 @@
 
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/module.h>
+#include <linux/of_gpio.h>
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 
@@ -59,6 +61,7 @@ struct pcm3168a_priv {
 	struct regulator_bulk_data supplies[PCM3168A_NUM_SUPPLIES];
 	struct regmap *regmap;
 	struct clk *scki;
+	struct gpio_desc *gpio_rst;
 	unsigned long sysclk;
 
 	struct pcm3168a_io_params io_params[2];
@@ -643,6 +646,7 @@ static bool pcm3168a_readable_register(struct device *dev, unsigned int reg)
 static bool pcm3168a_volatile_register(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
+	case PCM3168A_RST_SMODE:
 	case PCM3168A_DAC_ZERO:
 	case PCM3168A_ADC_OV:
 		return true;
@@ -702,6 +706,21 @@ int pcm3168a_probe(struct device *dev, struct regmap *regmap)
 
 	dev_set_drvdata(dev, pcm3168a);
 
+	/*
+	 * Request the RST gpio line as non exclusive as the same reset line
+	 * might be connected to multiple pcm3168a codec
+	 */
+	pcm3168a->gpio_rst = devm_gpiod_get_optional(dev, "rst",
+						GPIOD_OUT_HIGH |
+						GPIOD_FLAGS_BIT_NONEXCLUSIVE);
+	if (IS_ERR(pcm3168a->gpio_rst)) {
+		ret = PTR_ERR(pcm3168a->gpio_rst);
+		if (ret != -EPROBE_DEFER )
+			dev_err(dev, "failed to acquire RST gpio: %d\n", ret);
+
+		return ret;
+	}
+
 	pcm3168a->scki = devm_clk_get(dev, "scki");
 	if (IS_ERR(pcm3168a->scki)) {
 		ret = PTR_ERR(pcm3168a->scki);
@@ -743,10 +762,18 @@ int pcm3168a_probe(struct device *dev, struct regmap *regmap)
 		goto err_regulator;
 	}
 
-	ret = pcm3168a_reset(pcm3168a);
-	if (ret) {
-		dev_err(dev, "Failed to reset device: %d\n", ret);
-		goto err_regulator;
+	if (pcm3168a->gpio_rst) {
+		/*
+		 * The device is taken out from reset via GPIO line, wait for
+		 * 3846 SCKI clock cycles for the internal reset de-assertion
+		 */
+		msleep(DIV_ROUND_UP(3846 * 1000, pcm3168a->sysclk));
+	} else {
+		ret = pcm3168a_reset(pcm3168a);
+		if (ret) {
+			dev_err(dev, "Failed to reset device: %d\n", ret);
+			goto err_regulator;
+		}
 	}
 
 	pm_runtime_set_active(dev);
@@ -785,6 +812,9 @@ static void pcm3168a_disable(struct device *dev)
 
 void pcm3168a_remove(struct device *dev)
 {
+	struct pcm3168a_priv *pcm3168a = dev_get_drvdata(dev);
+
+	gpiod_set_value_cansleep(pcm3168a->gpio_rst, 0);
 	pm_runtime_disable(dev);
 #ifndef CONFIG_PM
 	pcm3168a_disable(dev);
-- 
2.16.4