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Subject[PATCH 2/2] ASoC: max98927: Add reset-gpio support
Date
Toggle reset line in max98927_i2c_probe.
Use a list to store max98927 instances so we do not toggle reset line
again if more than one instances share the same reset line.

Signed-off-by: Cheng-Yi Chiang <cychiang@chromium.org>
---
sound/soc/codecs/max98927.c | 78 +++++++++++++++++++++++++++++++++++++++++++++
sound/soc/codecs/max98927.h | 2 ++
2 files changed, 80 insertions(+)

diff --git a/sound/soc/codecs/max98927.c b/sound/soc/codecs/max98927.c
index 941712058a8f5..789b27cdfd9e0 100644
--- a/sound/soc/codecs/max98927.c
+++ b/sound/soc/codecs/max98927.c
@@ -11,6 +11,7 @@
*/

#include <linux/acpi.h>
+#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/regmap.h>
@@ -24,6 +25,11 @@
#include <sound/tlv.h>
#include "max98927.h"

+#define MAX98927_MIN_RESET_US 1
+#define MAX98927_RELEASE_RESET_DELAY_US 500
+
+static LIST_HEAD(reset_list);
+
static struct reg_default max98927_reg[] = {
{MAX98927_R0001_INT_RAW1, 0x00},
{MAX98927_R0002_INT_RAW2, 0x00},
@@ -877,6 +883,54 @@ static void max98927_slot_config(struct i2c_client *i2c,
max98927->i_l_slot = 1;
}

+static int max98927_i2c_toggle_reset(struct device *dev,
+ struct max98927_priv *max98927)
+{
+ /*
+ * If we do not have reset gpio, assume platform firmware
+ * controls the regulator and toggles it for us.
+ */
+ if (!max98927->reset_gpio)
+ return 0;
+
+ gpiod_set_value_cansleep(max98927->reset_gpio, 1);
+
+ /*
+ * We need to wait a bit before we are allowed to release reset GPIO.
+ */
+ usleep_range(MAX98927_MIN_RESET_US, MAX98927_MIN_RESET_US + 5);
+
+ gpiod_set_value_cansleep(max98927->reset_gpio, 0);
+
+ /*
+ * We need to wait a bit before I2C communication is available.
+ */
+ usleep_range(MAX98927_RELEASE_RESET_DELAY_US,
+ MAX98927_RELEASE_RESET_DELAY_US + 5);
+
+ /*
+ * Release reset GPIO because we are not going to use it.
+ */
+ devm_gpiod_put(dev, max98927->reset_gpio);
+
+ return 0;
+}
+
+static bool max98927_is_first_to_reset(struct max98927_priv *max98927)
+{
+ struct max98927_priv *p;
+
+ if (!max98927->reset_gpio)
+ return false;
+
+ list_for_each_entry(p, &reset_list, list) {
+ if (max98927->reset_gpio == p->reset_gpio)
+ return false;
+ }
+
+ return true;
+}
+
static int max98927_i2c_probe(struct i2c_client *i2c,
const struct i2c_device_id *id)
{
@@ -904,6 +958,28 @@ static int max98927_i2c_probe(struct i2c_client *i2c,
} else
max98927->interleave_mode = 0;

+ /* Gets optional GPIO for reset line. */
+ max98927->reset_gpio = devm_gpiod_get_optional(
+ &i2c->dev, "reset", GPIOD_OUT_LOW);
+ if (IS_ERR(max98927->reset_gpio)) {
+ ret = PTR_ERR(max98927->reset_gpio);
+ dev_err(&i2c->dev, "error getting reset gpio: %d\n", ret);
+ return ret;
+ }
+
+ /*
+ * Only toggle reset line for the first instance when the
+ * reset line is shared among instances. For example,
+ * left and right amplifier share the same reset line, and
+ * we should only toggle the reset line once.
+ */
+ if (max98927_is_first_to_reset(max98927)) {
+ dev_info(&i2c->dev, "%s: toggle reset line\n", __func__);
+ ret = max98927_i2c_toggle_reset(&i2c->dev, max98927);
+ if (ret)
+ return ret;
+ }
+
/* regmap initialization */
max98927->regmap
= devm_regmap_init_i2c(i2c, &max98927_regmap);
@@ -934,6 +1010,8 @@ static int max98927_i2c_probe(struct i2c_client *i2c,
if (ret < 0)
dev_err(&i2c->dev, "Failed to register component: %d\n", ret);

+ list_add(&max98927->list, &reset_list);
+
return ret;
}

diff --git a/sound/soc/codecs/max98927.h b/sound/soc/codecs/max98927.h
index 538992a238b28..d48f61f6c3ba5 100644
--- a/sound/soc/codecs/max98927.h
+++ b/sound/soc/codecs/max98927.h
@@ -275,5 +275,7 @@ struct max98927_priv {
unsigned int master;
unsigned int digital_gain;
bool tdm_mode;
+ struct gpio_desc *reset_gpio;
+ struct list_head list;
};
#endif
--
2.16.4
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