[PATCH v2 04/13] power: bq24257: Add SW-based approach for Power Good determination

Andreas Dannenberg
2015-09-09T00:13:43Z

A software-based approach for determining the charger's input voltage
"Power Good" state is introduced for devices like the bq24250 which
don't have a dedicated hardware pin for that purpose. This SW-based
approach is also used for other devices (with dedicated PG pin) as a
fall back solution if that pin is not configured to be used through
"pg-gpios".

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
---
drivers/power/bq24257_charger.c | 49 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 6 deletions(-)

diff --git a/drivers/power/bq24257_charger.c b/drivers/power/bq24257_charger.c
index d83898f..e309ae8 100644
--- a/drivers/power/bq24257_charger.c
+++ b/drivers/power/bq24257_charger.c
@@ -103,6 +103,7 @@ struct bq24257_device {
struct mutex lock; /* protect state data */

bool in_ilimit_autoset_disable;
+ bool pg_gpio_disable;
};

static bool bq24257_is_volatile_reg(struct device *dev, unsigned int reg)
@@ -356,7 +357,26 @@ static int bq24257_get_chip_state(struct bq24257_device *bq,

state->fault = ret;

- state->power_good = !gpiod_get_value_cansleep(bq->pg);
+ if (bq->pg_gpio_disable)
+ /*
+ * If we have a chip without a dedicated power-good GPIO or
+ * some other explicit bit that would provide this information
+ * assume the power is good if there is no supply related
+ * fault - and not good otherwise. There is a possibility for
+ * other errors to mask that power in fact is not good but this
+ * is probably the best we can do here.
+ */
+ switch (state->fault) {
+ case FAULT_INPUT_OVP:
+ case FAULT_INPUT_UVLO:
+ case FAULT_INPUT_LDO_LOW:
+ state->power_good = false;
+ break;
+ default:
+ state->power_good = true;
+ }
+ else
+ state->power_good = !gpiod_get_value_cansleep(bq->pg);

return 0;
}
@@ -676,7 +696,7 @@ static int bq24257_pg_gpio_probe(struct bq24257_device *bq)
{
bq->pg = devm_gpiod_get_index(bq->dev, BQ24257_PG_GPIO, 0, GPIOD_IN);
if (IS_ERR(bq->pg)) {
- dev_err(bq->dev, "could not probe PG pin\n");
+ dev_info(bq->dev, "could not probe PG pin\n");
return PTR_ERR(bq->pg);
}

@@ -808,10 +828,27 @@ static int bq24257_probe(struct i2c_client *client,
INIT_DELAYED_WORK(&bq->iilimit_setup_work,
bq24257_iilimit_setup_work);

- /* we can only check Power Good status by probing the PG pin */
- ret = bq24257_pg_gpio_probe(bq);
- if (ret < 0)
- return ret;
+ /*
+ * The BQ24250 doesn't have a dedicated Power Good (PG) pin so we
+ * explicitly disable this feature for this device and instead use
+ * a SW-based approach to determine the PG state.
+ */
+ if (bq->chip == BQ24250)
+ bq->pg_gpio_disable = true;
+
+ /*
+ * For devices that do have a dedicated PG pin go ahead and probe it,
+ * using the SW-based approach as a fall back solution. Note that the
+ * use of the dedicated pin is preferred.
+ */
+ if (!bq->pg_gpio_disable) {
+ ret = bq24257_pg_gpio_probe(bq);
+ if (ret < 0) {
+ dev_info(bq->dev,
+ "using SW-based power-good detection\n");
+ bq->pg_gpio_disable = true;
+ }
+ }

/* reset all registers to defaults */
ret = bq24257_field_write(bq, F_RESET, 1);
--
1.9.1