power: supply: core: Add resistance power supply property

Some battery drivers provide the ability to export internal resistance
as a parameter. Add internal_resistance power supply property for that
purpose.

Signed-off-by: Fenglin Wu <fenglin.wu@oss.qualcomm.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
index 87a058e..e6cce42 100644 (file)
--- a/Documentation/ABI/testing/sysfs-class-power
+++ b/Documentation/ABI/testing/sysfs-class-power
@@ -553,6 +553,22 @@ Description:
                        Integer > 0: representing full cycles
                        Integer = 0: cycle_count info is not available
 
+What:          /sys/class/power_supply/<supply_name>/internal_resistance
+Date:          August 2025
+Contact:       linux-arm-msm@vger.kernel.org
+Description:
+               Represent the battery's internal resistance, often referred
+               to as Equivalent Series Resistance (ESR). It is a dynamic
+               parameter that reflects the opposition to current flow within
+               the cell. It is not a fixed value but varies significantly
+               based on several operational conditions, including battery
+               state of charge (SoC), temperature, and whether the battery
+               is in a charging or discharging state.
+
+               Access: Read
+
+               Valid values: Represented in microohms
+
 **USB Properties**
 
 What:          /sys/class/power_supply/<supply_name>/input_current_limit

diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index 18e5e84..8ba08d4 100644 (file)
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -223,6 +223,7 @@ static struct power_supply_attr power_supply_attrs[] __ro_after_init = {
        POWER_SUPPLY_ATTR(MANUFACTURE_YEAR),
        POWER_SUPPLY_ATTR(MANUFACTURE_MONTH),
        POWER_SUPPLY_ATTR(MANUFACTURE_DAY),
+       POWER_SUPPLY_ATTR(INTERNAL_RESISTANCE),
        /* Properties of type `const char *' */
        POWER_SUPPLY_ATTR(MODEL_NAME),
        POWER_SUPPLY_ATTR(MANUFACTURER),

diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index f21f806..f38da7c 100644 (file)
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -176,6 +176,7 @@ enum power_supply_property {
        POWER_SUPPLY_PROP_MANUFACTURE_YEAR,
        POWER_SUPPLY_PROP_MANUFACTURE_MONTH,
        POWER_SUPPLY_PROP_MANUFACTURE_DAY,
+       POWER_SUPPLY_PROP_INTERNAL_RESISTANCE,
        /* Properties of type `const char *' */
        POWER_SUPPLY_PROP_MODEL_NAME,
        POWER_SUPPLY_PROP_MANUFACTURER,