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SubjectRe: [alsa-devel] [PATCH 2/2] ASoC: max98927: Add reset-gpio support
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On 9/12/2018 5:49 PM, Cheng-Yi Chiang wrote:
> 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>
Reviewed-and-tested-by: Rohit kumar <rohitkr@codeaurora.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

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