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    Subject[PATCH v2 3/3] hwmon: ina3221: Add suspend and resume functions
    Date
    Depending on the hardware design, an INA3221 chip might lose
    its power during system suspend/resume. So this patch adds
    a set of suspend and resume functions to cache the register
    values including config register value and limit settings.

    Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
    ---
    Changelog
    v1->v2:
    * Added power-down setting during suspend for power saving

    drivers/hwmon/ina3221.c | 63 +++++++++++++++++++++++++++++++++++++++++
    1 file changed, 63 insertions(+)

    diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
    index e0c4f4d83f4e..877952efaa88 100644
    --- a/drivers/hwmon/ina3221.c
    +++ b/drivers/hwmon/ina3221.c
    @@ -38,6 +38,8 @@
    #define INA3221_WARN3 0x0c
    #define INA3221_MASK_ENABLE 0x0f

    +#define INA3221_CONFIG_MODE_MASK GENMASK(2, 0)
    +#define INA3221_CONFIG_MODE_POWERDOWN 0
    #define INA3221_CONFIG_MODE_SHUNT BIT(0)
    #define INA3221_CONFIG_MODE_BUS BIT(1)
    #define INA3221_CONFIG_MODE_CONTINUOUS BIT(2)
    @@ -91,11 +93,13 @@ static const unsigned int register_channel[] = {
    * @regmap: Register map of the device
    * @fields: Register fields of the device
    * @shunt_resistors: Array of resistor values per channel
    + * @reg_config: Register value of INA3221_CONFIG
    */
    struct ina3221_data {
    struct regmap *regmap;
    struct regmap_field *fields[F_MAX_FIELDS];
    int shunt_resistors[INA3221_NUM_CHANNELS];
    + u32 reg_config;
    };

    static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
    @@ -415,9 +419,67 @@ static int ina3221_probe(struct i2c_client *client,
    return PTR_ERR(hwmon_dev);
    }

    + dev_set_drvdata(dev, ina);
    +
    return 0;
    }

    +#ifdef CONFIG_PM
    +static int ina3221_suspend(struct device *dev)
    +{
    + struct ina3221_data *ina = dev_get_drvdata(dev);
    + int ret;
    +
    + /* Save config register value and enable cache-only */
    + ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
    + if (ret)
    + return ret;
    +
    + /* Set to power-down mode for power saving */
    + ret = regmap_update_bits(ina->regmap, INA3221_CONFIG,
    + INA3221_CONFIG_MODE_MASK,
    + INA3221_CONFIG_MODE_POWERDOWN);
    + if (ret)
    + return ret;
    +
    + regcache_cache_only(ina->regmap, true);
    + regcache_mark_dirty(ina->regmap);
    +
    + return 0;
    +}
    +
    +static int ina3221_resume(struct device *dev)
    +{
    + struct ina3221_data *ina = dev_get_drvdata(dev);
    + int ret;
    +
    + regcache_cache_only(ina->regmap, false);
    +
    + /* Software reset the chip */
    + ret = regmap_field_write(ina->fields[F_RST], true);
    + if (ret) {
    + dev_err(dev, "Unable to reset device\n");
    + return ret;
    + }
    +
    + /* Restore cached register values to hardware */
    + ret = regcache_sync(ina->regmap);
    + if (ret)
    + return ret;
    +
    + /* Restore config register value to hardware */
    + ret = regmap_write(ina->regmap, INA3221_CONFIG, ina->reg_config);
    + if (ret)
    + return ret;
    +
    + return 0;
    +}
    +#endif
    +
    +static const struct dev_pm_ops ina3221_pm = {
    + SET_SYSTEM_SLEEP_PM_OPS(ina3221_suspend, ina3221_resume)
    +};
    +
    static const struct of_device_id ina3221_of_match_table[] = {
    { .compatible = "ti,ina3221", },
    { /* sentinel */ }
    @@ -435,6 +497,7 @@ static struct i2c_driver ina3221_i2c_driver = {
    .driver = {
    .name = INA3221_DRIVER_NAME,
    .of_match_table = ina3221_of_match_table,
    + .pm = &ina3221_pm,
    },
    .id_table = ina3221_ids,
    };
    --
    2.17.1
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