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Subject[PATCH v4 5/7] regulator: core: Resolve coupled regulators
Date
On Odroid XU3/4 and other Exynos5422 based boards there is a case, that
different devices on the board are supplied by different regulators
with non-fixed voltages. If one of these devices temporarily requires
higher voltage, there might occur a situation that the spread between
two devices' voltages is so high, that there is a risk of changing
'high' and 'low' states on the interconnection between devices powered
by those regulators.

Fill coupling descriptor with data obtained from DTS using previously
defined of_functions. Fail to register a regulator, if some data
inconsistency occurs. If some coupled regulators are not yet registered,
don't fail to register, but try to resolve them in late init call.

Signed-off-by: Maciej Purski <m.purski@samsung.com>
---
drivers/regulator/core.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 1118527..3628949 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -3945,6 +3945,88 @@ static int regulator_register_resolve_supply(struct device *dev, void *data)
return 0;
}

+static int regulator_fill_coupling_array(struct regulator_dev *rdev)
+{
+ struct coupling_desc *c_desc = &rdev->coupling_desc;
+ int n_coupled = c_desc->n_coupled;
+ struct regulator_dev *c_rdev;
+ int i;
+
+ for (i = 1; i < n_coupled; i++) {
+ /* already resolved */
+ if (c_desc->coupled_rdevs[i])
+ continue;
+
+ c_rdev = of_parse_coupled_regulator(rdev, i - 1);
+
+ if (c_rdev) {
+ c_desc->coupled_rdevs[i] = c_rdev;
+ c_desc->n_resolved++;
+ }
+ }
+
+ if (rdev->coupling_desc.n_resolved < n_coupled)
+ return -1;
+ else
+ return 0;
+}
+
+static int regulator_register_fill_coupling_array(struct device *dev,
+ void *data)
+{
+ struct regulator_dev *rdev = dev_to_rdev(dev);
+
+ if (regulator_fill_coupling_array(rdev))
+ rdev_dbg(rdev, "unable to resolve coupling\n");
+
+ return 0;
+}
+
+static int regulator_resolve_coupling(struct regulator_dev *rdev)
+{
+ int n_phandles = of_get_n_coupled(rdev);
+
+ if (n_phandles + 1 > MAX_COUPLED) {
+ rdev_err(rdev, "too many regulators coupled\n");
+ return -EPERM;
+ }
+
+ /*
+ * Every regulator should always have coupling descriptor filled with
+ * at least pointer to itself.
+ */
+ rdev->coupling_desc.coupled_rdevs[0] = rdev;
+ rdev->coupling_desc.n_coupled = n_phandles + 1;
+ rdev->coupling_desc.n_resolved++;
+
+ /* regulator isn't coupled */
+ if (n_phandles == 0)
+ return 0;
+
+ /* regulator, which can't change its voltage, can't be coupled */
+ if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_VOLTAGE)) {
+ rdev_err(rdev, "voltage operation not allowed\n");
+ return -EPERM;
+ }
+
+ if (rdev->constraints->max_spread <= 0) {
+ rdev_err(rdev, "wrong max_spread value\n");
+ return -EPERM;
+ }
+
+ if (!of_check_coupling_data(rdev))
+ return -EPERM;
+
+ /*
+ * After everything has been checked, try to fill rdevs array
+ * with pointers to regulators parsed from device tree. If some
+ * regulators are not registered yet, retry in late init call
+ */
+ regulator_fill_coupling_array(rdev);
+
+ return 0;
+}
+
/**
* regulator_register - register regulator
* @regulator_desc: regulator to register
@@ -4077,6 +4159,13 @@ regulator_register(const struct regulator_desc *regulator_desc,
if (ret < 0)
goto wash;

+ mutex_lock(&regulator_list_mutex);
+ ret = regulator_resolve_coupling(rdev);
+ mutex_unlock(&regulator_list_mutex);
+
+ if (ret != 0)
+ goto wash;
+
/* add consumers devices */
if (init_data) {
mutex_lock(&regulator_list_mutex);
@@ -4565,6 +4654,9 @@ static int __init regulator_init_complete(void)
class_for_each_device(&regulator_class, NULL, NULL,
regulator_late_cleanup);

+ class_for_each_device(&regulator_class, NULL, NULL,
+ regulator_register_fill_coupling_array);
+
return 0;
}
late_initcall_sync(regulator_init_complete);
--
2.7.4
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