hwmon: (ina3221) Add suspend and resume functions

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>
[groeck: Moved call to dev_set_drvdata()]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index e0c4f4d..1e38b4c 100644 (file)
--- 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,
@@ -407,6 +411,8 @@ static int ina3221_probe(struct i2c_client *client,
                return ret;
        }
 
+       dev_set_drvdata(dev, ina);
+
        hwmon_dev = devm_hwmon_device_register_with_groups(dev,
                                                           client->name,
                                                           ina, ina3221_groups);
@@ -418,6 +424,62 @@ static int ina3221_probe(struct i2c_client *client,
        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,
 };