regulator: Add support for power budget

Introduce power budget management for the regulator device. Enable tracking
of available power capacity by providing helpers to request and release
power budget allocations.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20250115-feature_regulator_pw_budget-v2-1-0a44b949e6bc@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: kmaincent

drivers/regulator/core.c

@@ -917,6 +917,26 @@ static ssize_t bypass_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(bypass);
 
+static ssize_t power_budget_milliwatt_show(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct regulator_dev *rdev = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", rdev->constraints->pw_budget_mW);
+}
+static DEVICE_ATTR_RO(power_budget_milliwatt);
+
+static ssize_t power_requested_milliwatt_show(struct device *dev,
+					      struct device_attribute *attr,
+					      char *buf)
+{
+	struct regulator_dev *rdev = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", rdev->pw_requested_mW);
+}
+static DEVICE_ATTR_RO(power_requested_milliwatt);
+
 #define REGULATOR_ERROR_ATTR(name, bit)							\
 	static ssize_t name##_show(struct device *dev, struct device_attribute *attr,	\
 				   char *buf)						\
@@ -1149,6 +1169,10 @@ static void print_constraints_debug(struct regulator_dev *rdev)
 	if (constraints->valid_modes_mask & REGULATOR_MODE_STANDBY)
 		count += scnprintf(buf + count, len - count, "standby ");
 
+	if (constraints->pw_budget_mW)
+		count += scnprintf(buf + count, len - count, "%d mW budget",
+				   constraints->pw_budget_mW);
+
 	if (!count)
 		count = scnprintf(buf, len, "no parameters");
 	else
@@ -1627,6 +1651,9 @@ static int set_machine_constraints(struct regulator_dev *rdev)
 		rdev->last_off = ktime_get();
 	}
 
+	if (!rdev->constraints->pw_budget_mW)
+		rdev->constraints->pw_budget_mW = INT_MAX;
+
 	print_constraints(rdev);
 	return 0;
 }
@@ -4601,6 +4628,87 @@ int regulator_get_current_limit(struct regulator *regulator)
 }
 EXPORT_SYMBOL_GPL(regulator_get_current_limit);
 
+/**
+ * regulator_get_unclaimed_power_budget - get regulator unclaimed power budget
+ * @regulator: regulator source
+ *
+ * Return: Unclaimed power budget of the regulator in mW.
+ */
+int regulator_get_unclaimed_power_budget(struct regulator *regulator)
+{
+	return regulator->rdev->constraints->pw_budget_mW -
+	       regulator->rdev->pw_requested_mW;
+}
+EXPORT_SYMBOL_GPL(regulator_get_unclaimed_power_budget);
+
+/**
+ * regulator_request_power_budget - request power budget on a regulator
+ * @regulator: regulator source
+ * @pw_req: Power requested
+ *
+ * Return: 0 on success or a negative error number on failure.
+ */
+int regulator_request_power_budget(struct regulator *regulator,
+				   unsigned int pw_req)
+{
+	struct regulator_dev *rdev = regulator->rdev;
+	int ret = 0, pw_tot_req;
+
+	regulator_lock(rdev);
+	if (rdev->supply) {
+		ret = regulator_request_power_budget(rdev->supply, pw_req);
+		if (ret < 0)
+			goto out;
+	}
+
+	pw_tot_req = rdev->pw_requested_mW + pw_req;
+	if (pw_tot_req > rdev->constraints->pw_budget_mW) {
+		rdev_warn(rdev, "power requested %d mW out of budget %d mW",
+			  pw_req,
+			  rdev->constraints->pw_budget_mW - rdev->pw_requested_mW);
+		regulator_notifier_call_chain(rdev,
+					      REGULATOR_EVENT_OVER_CURRENT_WARN,
+					      NULL);
+		ret = -ERANGE;
+		goto out;
+	}
+
+	rdev->pw_requested_mW = pw_tot_req;
+out:
+	regulator_unlock(rdev);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regulator_request_power_budget);
+
+/**
+ * regulator_free_power_budget - free power budget on a regulator
+ * @regulator: regulator source
+ * @pw: Power to be released.
+ *
+ * Return: Power budget of the regulator in mW.
+ */
+void regulator_free_power_budget(struct regulator *regulator,
+				 unsigned int pw)
+{
+	struct regulator_dev *rdev = regulator->rdev;
+	int pw_tot_req;
+
+	regulator_lock(rdev);
+	if (rdev->supply)
+		regulator_free_power_budget(rdev->supply, pw);
+
+	pw_tot_req = rdev->pw_requested_mW - pw;
+	if (pw_tot_req >= 0)
+		rdev->pw_requested_mW = pw_tot_req;
+	else
+		rdev_warn(rdev,
+			  "too much power freed %d mW (already requested %d mW)",
+			  pw, rdev->pw_requested_mW);
+
+	regulator_unlock(rdev);
+}
+EXPORT_SYMBOL_GPL(regulator_free_power_budget);
+
 /**
  * regulator_set_mode - set regulator operating mode
  * @regulator: regulator source
@@ -5239,6 +5347,8 @@ static struct attribute *regulator_dev_attrs[] = {
 	&dev_attr_suspend_standby_mode.attr,
 	&dev_attr_suspend_mem_mode.attr,
 	&dev_attr_suspend_disk_mode.attr,
+	&dev_attr_power_budget_milliwatt.attr,
+	&dev_attr_power_requested_milliwatt.attr,
 	NULL
 };
 
@@ -5320,6 +5430,10 @@ static umode_t regulator_attr_is_visible(struct kobject *kobj,
 	    attr == &dev_attr_suspend_disk_mode.attr)
 		return ops->set_suspend_mode ? mode : 0;
 
+	if (attr == &dev_attr_power_budget_milliwatt.attr ||
+	    attr == &dev_attr_power_requested_milliwatt.attr)
+		return rdev->constraints->pw_budget_mW != INT_MAX ? mode : 0;
+
 	return mode;
 }
 

drivers/regulator/of_regulator.c

@@ -125,6 +125,9 @@ static int of_get_regulation_constraints(struct device *dev,
 	if (constraints->min_uA != constraints->max_uA)
 		constraints->valid_ops_mask |= REGULATOR_CHANGE_CURRENT;
 
+	if (!of_property_read_u32(np, "regulator-power-budget-milliwatt", &pval))
+		constraints->pw_budget_mW = pval;
+
 	constraints->boot_on = of_property_read_bool(np, "regulator-boot-on");
 	constraints->always_on = of_property_read_bool(np, "regulator-always-on");
 	if (!constraints->always_on) /* status change should be possible. */

include/linux/regulator/consumer.h

@@ -258,6 +258,11 @@ int regulator_sync_voltage(struct regulator *regulator);
 int regulator_set_current_limit(struct regulator *regulator,
 			       int min_uA, int max_uA);
 int regulator_get_current_limit(struct regulator *regulator);
+int regulator_get_unclaimed_power_budget(struct regulator *regulator);
+int regulator_request_power_budget(struct regulator *regulator,
+				   unsigned int pw_req);
+void regulator_free_power_budget(struct regulator *regulator,
+				 unsigned int pw);
 
 int regulator_set_mode(struct regulator *regulator, unsigned int mode);
 unsigned int regulator_get_mode(struct regulator *regulator);
@@ -571,6 +576,22 @@ static inline int regulator_get_current_limit(struct regulator *regulator)
 	return 0;
 }
 
+static inline int regulator_get_unclaimed_power_budget(struct regulator *regulator)
+{
+	return INT_MAX;
+}
+
+static inline int regulator_request_power_budget(struct regulator *regulator,
+						 unsigned int pw_req)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void regulator_free_power_budget(struct regulator *regulator,
+					       unsigned int pw)
+{
+}
+
 static inline int regulator_set_mode(struct regulator *regulator,
 	unsigned int mode)
 {

include/linux/regulator/driver.h

@@ -656,6 +656,8 @@ struct regulator_dev {
 	int cached_err;
 	bool use_cached_err;
 	spinlock_t err_lock;
+
+	int pw_requested_mW;
 };
 
 /*

include/linux/regulator/machine.h

@@ -113,6 +113,7 @@ struct notification_limit {
  * @min_uA: Smallest current consumers may set.
  * @max_uA: Largest current consumers may set.
  * @ilim_uA: Maximum input current.
+ * @pw_budget_mW: Power budget for the regulator in mW.
  * @system_load: Load that isn't captured by any consumer requests.
  *
  * @over_curr_limits:		Limits for acting on over current.
@@ -185,6 +186,7 @@ struct regulation_constraints {
 	int max_uA;
 	int ilim_uA;
 
+	int pw_budget_mW;
 	int system_load;
 
 	/* used for coupled regulators */