2 files changed, 78 insertions, 10 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index da9782bd27d0..71d6adc4eeab 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -51,6 +51,7 @@
 static DEFINE_MUTEX(regulator_list_mutex);
 static LIST_HEAD(regulator_list);
 static LIST_HEAD(regulator_map_list);
+static LIST_HEAD(regulator_ena_gpio_list);
 static bool has_full_constraints;
 static bool board_wants_dummy_regulator;
 
@@ -69,6 +70,19 @@ struct regulator_map {
 };
 
 /*
+ * struct regulator_enable_gpio
+ *
+ * Management for shared enable GPIO pin
+ */
+struct regulator_enable_gpio {
+        struct list_head list;
+        int gpio;
+        u32 enable_count;       /* a number of enabled shared GPIO */
+        u32 request_count;      /* a number of requested shared GPIO */
+        unsigned int ena_gpio_invert:1;
+};
+
+/*
  * struct regulator
  *
  * One for each consumer device.
@@ -1456,6 +1470,65 @@ void devm_regulator_put(struct regulator *regulator)
 }
 EXPORT_SYMBOL_GPL(devm_regulator_put);
 
+/* Manage enable GPIO list. Same GPIO pin can be shared among regulators */
+static int regulator_ena_gpio_request(struct regulator_dev *rdev,
+                                const struct regulator_config *config)
+{
+        struct regulator_enable_gpio *pin;
+        int ret;
+
+        list_for_each_entry(pin, &regulator_ena_gpio_list, list) {
+                if (pin->gpio == config->ena_gpio) {
+                        rdev_dbg(rdev, "GPIO %d is already used\n",
+                                config->ena_gpio);
+                        goto update_ena_gpio_to_rdev;
+                }
+        }
+
+        ret = gpio_request_one(config->ena_gpio,
+                                GPIOF_DIR_OUT | config->ena_gpio_flags,
+                                rdev_get_name(rdev));
+        if (ret)
+                return ret;
+
+        pin = kzalloc(sizeof(struct regulator_enable_gpio), GFP_KERNEL);
+        if (pin == NULL) {
+                gpio_free(config->ena_gpio);
+                return -ENOMEM;
+        }
+
+        pin->gpio = config->ena_gpio;
+        pin->ena_gpio_invert = config->ena_gpio_invert;
+        list_add(&pin->list, &regulator_ena_gpio_list);
+
+update_ena_gpio_to_rdev:
+        pin->request_count++;
+        rdev->ena_pin = pin;
+        return 0;
+}
+
+static void regulator_ena_gpio_free(struct regulator_dev *rdev)
+{
+        struct regulator_enable_gpio *pin, *n;
+
+        if (!rdev->ena_pin)
+                return;
+
+        /* Free the GPIO only in case of no use */
+        list_for_each_entry_safe(pin, n, &regulator_ena_gpio_list, list) {
+                if (pin->gpio == rdev->ena_pin->gpio) {
+                        if (pin->request_count <= 1) {
+                                pin->request_count = 0;
+                                gpio_free(pin->gpio);
+                                list_del(&pin->list);
+                                kfree(pin);
+                        } else {
+                                pin->request_count--;
+                        }
+                }
+        }
+}
+
 static int _regulator_do_enable(struct regulator_dev *rdev)
 {
         int ret, delay;
@@ -3435,18 +3508,13 @@ regulator_register(const struct regulator_desc *regulator_desc,
         dev_set_drvdata(&rdev->dev, rdev);
 
         if (config->ena_gpio && gpio_is_valid(config->ena_gpio)) {
-                ret = gpio_request_one(config->ena_gpio,
-                                       GPIOF_DIR_OUT | config->ena_gpio_flags,
-                                       rdev_get_name(rdev));
+                ret = regulator_ena_gpio_request(rdev, config);
                 if (ret != 0) {
                         rdev_err(rdev, "Failed to request enable GPIO%d: %d\n",
                                  config->ena_gpio, ret);
                         goto wash;
                 }
 
-                rdev->ena_gpio = config->ena_gpio;
-                rdev->ena_gpio_invert = config->ena_gpio_invert;
-
                 if (config->ena_gpio_flags & GPIOF_OUT_INIT_HIGH)
                         rdev->ena_gpio_state = 1;
 
@@ -3522,8 +3590,7 @@ unset_supplies:
 scrub:
         if (rdev->supply)
                 _regulator_put(rdev->supply);
-        if (rdev->ena_gpio)
-                gpio_free(rdev->ena_gpio);
+        regulator_ena_gpio_free(rdev);
         kfree(rdev->constraints);
 wash:
         device_unregister(&rdev->dev);
@@ -3558,8 +3625,7 @@ void regulator_unregister(struct regulator_dev *rdev)
         unset_regulator_supplies(rdev);
         list_del(&rdev->list);
         kfree(rdev->constraints);
-        if (rdev->ena_gpio)
-                gpio_free(rdev->ena_gpio);
+        regulator_ena_gpio_free(rdev);
         device_unregister(&rdev->dev);
         mutex_unlock(&regulator_list_mutex);
 }
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 23070fd83872..a467d11dd67d 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -22,6 +22,7 @@
 struct regmap;
 struct regulator_dev;
 struct regulator_init_data;
+struct regulator_enable_gpio;
 
 enum regulator_status {
         REGULATOR_STATUS_OFF,
@@ -300,6 +301,7 @@ struct regulator_dev {
 
         struct dentry *debugfs;
 
+        struct regulator_enable_gpio *ena_pin;
         int ena_gpio;
         unsigned int ena_gpio_invert:1;
         unsigned int ena_gpio_state:1;