3 files changed, 225 insertions, 0 deletions
diff --git a/drivers/soc/samsung/Kconfig b/drivers/soc/samsung/Kconfig
index c7a2003687c7..264185664594 100644
--- a/drivers/soc/samsung/Kconfig
+++ b/drivers/soc/samsung/Kconfig
@@ -37,4 +37,7 @@ config EXYNOS_PM_DOMAINS
 	bool "Exynos PM domains" if COMPILE_TEST
 	depends on PM_GENERIC_DOMAINS || COMPILE_TEST
 
+config EXYNOS_REGULATOR_COUPLER
+	bool "Exynos SoC Regulator Coupler" if COMPILE_TEST
+	depends on ARCH_EXYNOS || COMPILE_TEST
 endif
diff --git a/drivers/soc/samsung/Makefile b/drivers/soc/samsung/Makefile
index edd1d6ea064d..ecc3a32f6406 100644
--- a/drivers/soc/samsung/Makefile
+++ b/drivers/soc/samsung/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_EXYNOS_PMU)	+= exynos-pmu.o
 obj-$(CONFIG_EXYNOS_PMU_ARM_DRIVERS)	+= exynos3250-pmu.o exynos4-pmu.o \
 					exynos5250-pmu.o exynos5420-pmu.o
 obj-$(CONFIG_EXYNOS_PM_DOMAINS) += pm_domains.o
+obj-$(CONFIG_EXYNOS_REGULATOR_COUPLER) += exynos-regulator-coupler.o
diff --git a/drivers/soc/samsung/exynos-regulator-coupler.c b/drivers/soc/samsung/exynos-regulator-coupler.c
new file mode 100644
index 000000000000..61a156b44a48
--- /dev/null
+++ b/drivers/soc/samsung/exynos-regulator-coupler.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020 Samsung Electronics Co., Ltd.
+ *	      http://www.samsung.com/
+ * Author: Marek Szyprowski <m.szyprowski@samsung.com>
+ *
+ * Simplified generic voltage coupler from regulator core.c
+ * The main difference is that it keeps current regulator voltage
+ * if consumers didn't apply their constraints yet.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/regulator/coupler.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+
+static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
+					 int *current_uV,
+					 int *min_uV, int *max_uV,
+					 suspend_state_t state)
+{
+	struct coupling_desc *c_desc = &rdev->coupling_desc;
+	struct regulator_dev **c_rdevs = c_desc->coupled_rdevs;
+	struct regulation_constraints *constraints = rdev->constraints;
+	int desired_min_uV = 0, desired_max_uV = INT_MAX;
+	int max_current_uV = 0, min_current_uV = INT_MAX;
+	int highest_min_uV = 0, target_uV, possible_uV;
+	int i, ret, max_spread, n_coupled = c_desc->n_coupled;
+	bool done;
+
+	*current_uV = -1;
+
+	/* Find highest min desired voltage */
+	for (i = 0; i < n_coupled; i++) {
+		int tmp_min = 0;
+		int tmp_max = INT_MAX;
+
+		lockdep_assert_held_once(&c_rdevs[i]->mutex.base);
+
+		ret = regulator_check_consumers(c_rdevs[i],
+						&tmp_min,
+						&tmp_max, state);
+		if (ret < 0)
+			return ret;
+
+		if (tmp_min == 0) {
+			ret = regulator_get_voltage_rdev(c_rdevs[i]);
+			if (ret < 0)
+				return ret;
+			tmp_min = ret;
+		}
+
+		/* apply constraints */
+		ret = regulator_check_voltage(c_rdevs[i], &tmp_min, &tmp_max);
+		if (ret < 0)
+			return ret;
+
+		highest_min_uV = max(highest_min_uV, tmp_min);
+
+		if (i == 0) {
+			desired_min_uV = tmp_min;
+			desired_max_uV = tmp_max;
+		}
+	}
+
+	max_spread = constraints->max_spread[0];
+
+	/*
+	 * Let target_uV be equal to the desired one if possible.
+	 * If not, set it to minimum voltage, allowed by other coupled
+	 * regulators.
+	 */
+	target_uV = max(desired_min_uV, highest_min_uV - max_spread);
+
+	/*
+	 * Find min and max voltages, which currently aren't violating
+	 * max_spread.
+	 */
+	for (i = 1; i < n_coupled; i++) {
+		int tmp_act;
+
+		tmp_act = regulator_get_voltage_rdev(c_rdevs[i]);
+		if (tmp_act < 0)
+			return tmp_act;
+
+		min_current_uV = min(tmp_act, min_current_uV);
+		max_current_uV = max(tmp_act, max_current_uV);
+	}
+
+	/*
+	 * Correct target voltage, so as it currently isn't
+	 * violating max_spread
+	 */
+	possible_uV = max(target_uV, max_current_uV - max_spread);
+	possible_uV = min(possible_uV, min_current_uV + max_spread);
+
+	if (possible_uV > desired_max_uV)
+		return -EINVAL;
+
+	done = (possible_uV == target_uV);
+	desired_min_uV = possible_uV;
+
+	/* Set current_uV if wasn't done earlier in the code and if necessary */
+	if (*current_uV == -1) {
+		ret = regulator_get_voltage_rdev(rdev);
+		if (ret < 0)
+			return ret;
+		*current_uV = ret;
+	}
+
+	*min_uV = desired_min_uV;
+	*max_uV = desired_max_uV;
+
+	return done;
+}
+
+static int exynos_coupler_balance_voltage(struct regulator_coupler *coupler,
+					  struct regulator_dev *rdev,
+					  suspend_state_t state)
+{
+	struct regulator_dev **c_rdevs;
+	struct regulator_dev *best_rdev;
+	struct coupling_desc *c_desc = &rdev->coupling_desc;
+	int i, ret, n_coupled, best_min_uV, best_max_uV, best_c_rdev;
+	unsigned int delta, best_delta;
+	unsigned long c_rdev_done = 0;
+	bool best_c_rdev_done;
+
+	c_rdevs = c_desc->coupled_rdevs;
+	n_coupled = c_desc->n_coupled;
+
+	/*
+	 * Find the best possible voltage change on each loop. Leave the loop
+	 * if there isn't any possible change.
+	 */
+	do {
+		best_c_rdev_done = false;
+		best_delta = 0;
+		best_min_uV = 0;
+		best_max_uV = 0;
+		best_c_rdev = 0;
+		best_rdev = NULL;
+
+		/*
+		 * Find highest difference between optimal voltage
+		 * and current voltage.
+		 */
+		for (i = 0; i < n_coupled; i++) {
+			/*
+			 * optimal_uV is the best voltage that can be set for
+			 * i-th regulator at the moment without violating
+			 * max_spread constraint in order to balance
+			 * the coupled voltages.
+			 */
+			int optimal_uV = 0, optimal_max_uV = 0, current_uV = 0;
+
+			if (test_bit(i, &c_rdev_done))
+				continue;
+
+			ret = regulator_get_optimal_voltage(c_rdevs[i],
+							    &current_uV,
+							    &optimal_uV,
+							    &optimal_max_uV,
+							    state);
+			if (ret < 0)
+				goto out;
+
+			delta = abs(optimal_uV - current_uV);
+
+			if (delta && best_delta <= delta) {
+				best_c_rdev_done = ret;
+				best_delta = delta;
+				best_rdev = c_rdevs[i];
+				best_min_uV = optimal_uV;
+				best_max_uV = optimal_max_uV;
+				best_c_rdev = i;
+			}
+		}
+
+		/* Nothing to change, return successfully */
+		if (!best_rdev) {
+			ret = 0;
+			goto out;
+		}
+
+		ret = regulator_set_voltage_rdev(best_rdev, best_min_uV,
+						 best_max_uV, state);
+
+		if (ret < 0)
+			goto out;
+
+		if (best_c_rdev_done)
+			set_bit(best_c_rdev, &c_rdev_done);
+
+	} while (n_coupled > 1);
+
+out:
+	return ret;
+}
+
+static int exynos_coupler_attach(struct regulator_coupler *coupler,
+				 struct regulator_dev *rdev)
+{
+	return 0;
+}
+
+static struct regulator_coupler exynos_coupler = {
+	.attach_regulator = exynos_coupler_attach,
+	.balance_voltage  = exynos_coupler_balance_voltage,
+};
+
+static int __init exynos_coupler_init(void)
+{
+	if (!of_machine_is_compatible("samsung,exynos5800"))
+		return 0;
+
+	return regulator_coupler_register(&exynos_coupler);
+}
+arch_initcall(exynos_coupler_init);