regulator: core: Provide a dummy regulator with full constraints

When a system has said that it has fully specified constraints for its
regulators it is still possible that some supplies may be missing,
especially if regulator support has been added to a driver after the
board was integrated. We can handle such situations more gracefully by
providing a dummy regulator.

Unless the caller has specifically indicated that the system design may
not include a given regulator by using regulator_get_optional() or that
it needs its interactions to have an effect using regulator_get_exclusive()
provide a dummy regulator if we can't locate a real one.

The kconfig option REGULATOR_DUMMY that provided similar behaviour for all
regulators has been removed, systems that need it should flag that they
have full constraints instead.

Signed-off-by: Mark Brown <broonie@linaro.org>

2 files changed, 19 insertions, 27 deletions

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index dfe58096b374..0417ce327cd8 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -28,16 +28,6 @@ config REGULATOR_DEBUG
         help
           Say yes here to enable debugging support.
 
-config REGULATOR_DUMMY
-        bool "Provide a dummy regulator if regulator lookups fail"
-        help
-          If this option is enabled then when a regulator lookup fails
-          and the board has not specified that it has provided full
-          constraints the regulator core will provide an always
-          enabled dummy regulator, allowing consumer drivers to continue.
-
-          A warning will be generated when this substitution is done.
-
 config REGULATOR_FIXED_VOLTAGE
         tristate "Fixed voltage regulator support"
         help
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index a01b8b3b70ca..8fd170788c3e 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1243,7 +1243,7 @@ static struct regulator_dev *regulator_dev_lookup(struct device *dev,
 
 /* Internal regulator request function */
 static struct regulator *_regulator_get(struct device *dev, const char *id,
-                                        bool exclusive)
+                                        bool exclusive, bool allow_dummy)
 {
         struct regulator_dev *rdev;
         struct regulator *regulator = ERR_PTR(-EPROBE_DEFER);
@@ -1268,30 +1268,32 @@ static struct regulator *_regulator_get(struct device *dev, const char *id,
          * If we have return value from dev_lookup fail, we do not expect to
          * succeed, so, quit with appropriate error value
          */
-        if (ret) {
+        if (ret && ret != -ENODEV) {
                 regulator = ERR_PTR(ret);
                 goto out;
         }
 
-        if (board_wants_dummy_regulator) {
-                rdev = dummy_regulator_rdev;
-                goto found;
-        }
-
-#ifdef CONFIG_REGULATOR_DUMMY
         if (!devname)
                 devname = "deviceless";
 
-        /* If the board didn't flag that it was fully constrained then
-         * substitute in a dummy regulator so consumers can continue.
+        /*
+         * Assume that a regulator is physically present and enabled
+         * even if it isn't hooked up and just provide a dummy.
          */
-        if (!has_full_constraints) {
-                pr_warn("%s supply %s not found, using dummy regulator\n",
-                        devname, id);
+        if (has_full_constraints && allow_dummy) {
+                /*
+                 * Log the substitution if regulator configuration is
+                 * not complete to help development.
+                 */
+                if (!has_full_constraints)
+                        pr_warn("%s supply %s not found, using dummy regulator\n",
+                                devname, id);
+
                 rdev = dummy_regulator_rdev;
                 goto found;
+        } else {
+                dev_err(dev, "dummy supplies not allowed\n");
         }
-#endif
 
         mutex_unlock(&regulator_list_mutex);
         return regulator;
@@ -1349,7 +1351,7 @@ out:
  */
 struct regulator *regulator_get(struct device *dev, const char *id)
 {
-        return _regulator_get(dev, id, false);
+        return _regulator_get(dev, id, false, true);
 }
 EXPORT_SYMBOL_GPL(regulator_get);
 
@@ -1410,7 +1412,7 @@ EXPORT_SYMBOL_GPL(devm_regulator_get);
  */
 struct regulator *regulator_get_exclusive(struct device *dev, const char *id)
 {
-        return _regulator_get(dev, id, true);
+        return _regulator_get(dev, id, true, false);
 }
 EXPORT_SYMBOL_GPL(regulator_get_exclusive);
 
@@ -1439,7 +1441,7 @@ EXPORT_SYMBOL_GPL(regulator_get_exclusive);
  */
 struct regulator *regulator_get_optional(struct device *dev, const char *id)
 {
-        return _regulator_get(dev, id, 0);
+        return _regulator_get(dev, id, false, false);
 }
 EXPORT_SYMBOL_GPL(regulator_get_optional);