This is used as a software WAR to offset shunt voltage reading
from INA3221 to increase its accuracy. This patch implements a
previous downstream feature by reading the offset information
from DT and apply it to current readings.
Signed-off-by: Ninad Malwade <nmalwade@xxxxxxxxxx>
---
drivers/hwmon/ina3221.c | 141 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 137 insertions(+), 4 deletions(-)
diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index e06186986444..726c8b99b8cd 100644
--- a/drivers/hwmon/ina3221.c
+++ b/drivers/hwmon/ina3221.c
@@ -94,13 +94,39 @@ enum ina3221_channels {
INA3221_NUM_CHANNELS
};
+/**
+ * struct shuntv_offset_range - [WAR] shunt voltage offset sub-range
+ * @start: range start (uV)
+ * @end: range end (uV)
+ * @offset: offset for the current sub-range
+ */
+struct shuntv_offset_range {
+ s32 start;
+ s32 end;
+ s32 offset;
+};
+
+/**
+ * struct shuntv_offset - [WAR] shunt voltage offset information
+ * @offset: general offset
+ * @range: pointer to a sub-range of shunt voltage offset (uV)
+ * @num_range: number of sub-ranges of shunt voltage offset
+ */
+struct shuntv_offset {
+ s32 offset;
+ struct shuntv_offset_range *range;
+ s32 num_range;
+};
+
/**
* struct ina3221_input - channel input source specific information
+ * @shuntv_offset: [WAR] shunt voltage offset information
* @label: label of channel input source
* @shunt_resistor: shunt resistor value of channel input source
* @disconnected: connection status of channel input source
*/
struct ina3221_input {
+ struct shuntv_offset *shuntv_offset;
const char *label;
int shunt_resistor;
bool disconnected;
@@ -329,7 +355,7 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
struct ina3221_data *ina = dev_get_drvdata(dev);
struct ina3221_input *input = ina->inputs;
u8 reg = ina3221_curr_reg[attr][channel];
- int resistance_uo, voltage_nv;
+ int resistance_uo, voltage_uv;
int regval, ret;
if (channel > INA3221_CHANNEL3)
@@ -362,10 +388,34 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
if (ret)
return ret;
- /* Scale of shunt voltage: LSB is 40uV (40000nV) */
- voltage_nv = regval * 40000;
+ /* Scale of shunt voltage: LSB is 40uV */
+ voltage_uv = regval * 40;
+
+ /* Apply software WAR to offset shunt voltage for accuracy */
+ if (input->shuntv_offset) {
+ struct shuntv_offset_range *range =
+ input->shuntv_offset->range;
+ int num_range = input->shuntv_offset->num_range;
+ int offset = input->shuntv_offset->offset;
+
+ while (num_range--) {
+ if (voltage_uv >= range->start &&
+ voltage_uv <= range->end) {
+ /* Use range offset instead */
+ offset = range->offset;
+ break;
+ }
+ range++;
+ }
+
+ if (voltage_uv < 0)
+ voltage_uv += offset;
+ else
+ voltage_uv -= offset;
+ }
+
/* Return current in mA */
- *val = DIV_ROUND_CLOSEST(voltage_nv, resistance_uo);
+ *val = DIV_ROUND_CLOSEST(voltage_uv * 1000, resistance_uo);
return 0;
case hwmon_curr_crit_alarm:
case hwmon_curr_max_alarm:
@@ -758,6 +808,84 @@ static const struct regmap_config ina3221_regmap_config = {
.volatile_table = &ina3221_volatile_table,
};
+static struct shuntv_offset *
+ina3221_probe_shuntv_offset_from_dt(struct device *dev,
+ struct device_node *child)
+{
+ struct device_node *np, *range_np;
+ struct shuntv_offset *shuntv_offset;
+ struct shuntv_offset_range *range;
+ s32 start, end, offset;
+ const __be32 *prop;
+ int ret, num_range;
+
+ prop = of_get_property(child, "shunt-volt-offset-uv", NULL);
+ /* Silently return for devices with no need of an offset WAR */
+ if (!prop)
+ return NULL;
+
+ np = of_find_node_by_phandle(be32_to_cpup(prop));
+ if (!np) {
+ dev_err(dev, "corrupted phandle for shunt-volt-offset-uv\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ ret = of_property_read_s32(np, "offset", &offset);
+ if (ret) {
+ dev_err(dev, "failed to read general shuntv offset\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ shuntv_offset = devm_kzalloc(dev, sizeof(*shuntv_offset), GFP_KERNEL);
+ if (!shuntv_offset)
+ return ERR_PTR(-ENOMEM);
+
+ shuntv_offset->offset = offset;
+
+ num_range = of_get_child_count(np);
+
+ /* Return upon no sub-range found */
+ if (!num_range)
+ return shuntv_offset;
+
+ range = devm_kzalloc(dev, sizeof(*range) * num_range, GFP_KERNEL);
+ if (!range)
+ return ERR_PTR(-ENOMEM);
+
+ shuntv_offset->range = range;
+ shuntv_offset->num_range = num_range;
+
+ for_each_child_of_node(np, range_np) {
+ ret = of_property_read_s32(range_np, "start", &start);
+ if (ret) {
+ dev_warn(dev, "missing start in range node\n");
+ range++;
+ continue;
+ }
+
+ ret = of_property_read_s32(range_np, "end", &end);
+ if (ret) {
+ dev_warn(dev, "missing end in range node\n");
+ range++;
+ continue;
+ }
+
+ ret = of_property_read_s32(range_np, "offset", &offset);
+ if (ret) {
+ dev_warn(dev, "missing offset in range node\n");
+ range++;
+ continue;
+ }
+
+ range->start = start;
+ range->end = end;
+ range->offset = offset;
+ range++;
+ }
+
+ return shuntv_offset;
+}
+
static int ina3221_probe_child_from_dt(struct device *dev,
struct device_node *child,
struct ina3221_data *ina)
@@ -796,6 +924,11 @@ static int ina3221_probe_child_from_dt(struct device *dev,
input->shunt_resistor = val;
}
+ /* Apply software WAR to offset shunt voltage for accuracy */
+ input->shuntv_offset = ina3221_probe_shuntv_offset_from_dt(dev, child);
+ if (IS_ERR(input->shuntv_offset))
+ return PTR_ERR(input->shuntv_offset);
+
return 0;
}
--
2.17.1
