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SubjectRe: [PATCH v1 3/4] ASoC: tda7802: Add enable device attribute
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On 2019-06-11 19:49, Thomas Preston wrote:
> Add a device attribute to control the enable regulator. Write 1 to
> enable, 0 to disable (ref-count minus one), or -1 to force disable the
> physical pin.
>
> To disable a set of amplifiers wired to the same enable gpio, each
> device must be disabled. For example:
>
> echo 0 > /sys/devices/.../device:00/enable
> echo 0 > /sys/devices/.../device:01/enable
>
> In an emergency, we can force disable from any device:
>
> echo -1 > /sys/devices/.../device:00/enable
>
> Signed-off-by: Thomas Preston <thomas.preston@codethink.co.uk>
> Cc: Patrick Glaser <pglaser@tesla.com>
> Cc: Rob Duncan <rduncan@tesla.com>
> Cc: Nate Case <ncase@tesla.com>
> ---
> sound/soc/codecs/tda7802.c | 65 +++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 64 insertions(+), 1 deletion(-)
>
> diff --git a/sound/soc/codecs/tda7802.c b/sound/soc/codecs/tda7802.c
> index 38ca52de85f0..62aae011d9f1 100644
> --- a/sound/soc/codecs/tda7802.c
> +++ b/sound/soc/codecs/tda7802.c
> @@ -458,6 +458,42 @@ static struct snd_soc_dai_driver tda7802_dai_driver = {
> .ops = &tda7802_dai_ops,
> };
>
> +static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct tda7802_priv *tda7802 = dev_get_drvdata(dev);
> + int enabled = regulator_is_enabled(tda7802->enable_reg) ? 1 : 0;
> +
> + return scnprintf(buf, PAGE_SIZE, "%d\n", enabled);
> +}
> +
> +static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct tda7802_priv *tda7802 = dev_get_drvdata(dev);
> + int err;
> +
> + if (sysfs_streq(buf, "1")) {
> + err = regulator_enable(tda7802->enable_reg);
> + if (err < 0)
> + dev_err(dev, "Could not enable (sysfs)\n");
> + } else if (sysfs_streq(buf, "0")) {
> + err = regulator_disable(tda7802->enable_reg);
> + if (err < 0)
> + dev_err(dev, "Could not disable (sysfs)\n");
> + } else if (sysfs_streq(buf, "-1")) {
> + err = regulator_force_disable(tda7802->enable_reg);
> + if (err < 0)
> + dev_err(dev, "Could not force disable (sysfs)\n");
> + } else {
> + return -EINVAL;
> + }
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR_RW(enable);
> +
> /* read device tree or ACPI properties from device */
> static int tda7802_read_properties(struct tda7802_priv *tda7802)
> {
> @@ -493,7 +529,34 @@ static int tda7802_read_properties(struct tda7802_priv *tda7802)
> return err;
> }
>
> -static const struct snd_soc_component_driver tda7802_component_driver;
> +static int tda7802_probe(struct snd_soc_component *component)
> +{
> + struct tda7802_priv *tda7802 = snd_soc_component_get_drvdata(component);
> + struct device *dev = &tda7802->i2c->dev;
> + int err;
> +
> + dev_dbg(dev, "%s\n", __func__);

Function name alone ain't very informational. Is this intended?

> +
> + err = device_create_file(dev, &dev_attr_enable);
> + if (err < 0) {
> + dev_err(dev, "Could not create enable attr\n");
> + return err;
> + }

Regardless of outcome, you'll be returning err here. Consider leaving
error message alone within if-statement. Remove redundant brackets if
you decide to do so.

> +
> + return err;
> +}
> +
> +static void tda7802_remove(struct snd_soc_component *component)
> +{
> + struct tda7802_priv *tda7802 = snd_soc_component_get_drvdata(component);
> +
> + device_remove_file(&tda7802->i2c->dev, &dev_attr_enable);
> +}
> +
> +static const struct snd_soc_component_driver tda7802_component_driver = {
> + .probe = tda7802_probe,
> + .remove = tda7802_remove,
> +};
>
> static int tda7802_i2c_probe(struct i2c_client *i2c,
> const struct i2c_device_id *id)
>

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