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>

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index dfe5809..0417ce3 100644 (file)
--- 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 a01b8b3..8fd1707 100644 (file)
--- 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);