[PATCH v6 03/16] power: sequencing: Add pwrseq_power_is_on()

The power sequencing consumer API already does power on state tracking
internally. Expose the state to consumers through pwrseq_power_is_on()
so that they don't have to reimplement it locally.

Acked-by: Bartosz Golaszewski <[email protected]>
Signed-off-by: Chen-Yu Tsai <[email protected]>
---
Changes since v5:
- Reverted back to returning -EINVAL if descriptor is NULL

Changes since v4:
- Make pwrseq_power_is_on() return 1 if descriptor is NULL, i.e. if
  the descriptor is optional, matching the other pwrseq consumer APIs

Changes since v3:
- Added missing stub function for !POWER_SEQUENCING

Changes since v2:
- New patch

Needs to go in with "usb: hub: Power on connected M.2 E-key connectors"
as it is a build time dependency. Bartosz wants the change on an
immutable branch to pull into the pwrseq tree.
---
 drivers/power/sequencing/core.c | 18 ++++++++++++++++++
 include/linux/pwrseq/consumer.h |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/power/sequencing/core.c b/drivers/power/sequencing/core.c
index 02f42da91598..72b96d36920e 100644
--- a/drivers/power/sequencing/core.c
+++ b/drivers/power/sequencing/core.c
@@ -968,6 +968,24 @@ int pwrseq_power_off(struct pwrseq_desc *desc)
 }
 EXPORT_SYMBOL_GPL(pwrseq_power_off);
 
+/**
+ * pwrseq_power_is_on() - Queries the last requested state of the power sequencer.
+ * @desc: Descriptor referencing the power sequencer.
+ *
+ * This returns the last requested state of the power sequencer.
+ *
+ * Returns:
+ * On success, 1 for on and 0 for off; negative error number on failure.
+ */
+int pwrseq_power_is_on(struct pwrseq_desc *desc)
+{
+	if (!desc)
+		return -EINVAL;
+
+	return desc->powered_on;
+}
+EXPORT_SYMBOL_GPL(pwrseq_power_is_on);
+
 /**
  * pwrseq_to_device() - Get the pwrseq device pointer from a descriptor.
  * @desc: Descriptor referencing the power sequencer.
diff --git a/include/linux/pwrseq/consumer.h b/include/linux/pwrseq/consumer.h
index 3c907c9e1885..3c6122bd0205 100644
--- a/include/linux/pwrseq/consumer.h
+++ b/include/linux/pwrseq/consumer.h
@@ -22,6 +22,7 @@ devm_pwrseq_get(struct device *dev, const char *target);
 
 int pwrseq_power_on(struct pwrseq_desc *desc);
 int pwrseq_power_off(struct pwrseq_desc *desc);
+int pwrseq_power_is_on(struct pwrseq_desc *desc);
 
 struct device *pwrseq_to_device(struct pwrseq_desc *desc);
 
@@ -53,6 +54,11 @@ static inline int pwrseq_power_off(struct pwrseq_desc *desc)
 	return -ENOSYS;
 }
 
+static inline int pwrseq_power_is_on(struct pwrseq_desc *desc)
+{
+	return -ENOSYS;
+}
+
 static inline struct device *pwrseq_to_device(struct pwrseq_desc *desc)
 {
 	return NULL;
-- 
2.55.0.229.g6434b31f56-goog