mfd: Allow mapping regulator supplies to MFD device from children

Occasionally, it is useful to map supplies from a child device onto the
MFD device. A typical usecase for this would be if the MFD device is
represented as a single node in device tree. All supplies will be
defined in device tree as existing on the MFD device. When a child
depends on frameworks which might have no knowledge of MFD to lookup
supplies on its behalf the supply will not be found.

This patch adds a list of supplies that should be looked up on the
parent rather than the child as part of the mfd_cell structure.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/mfd/mfd-core.c

@@ -20,6 +20,7 @@
 #include <linux/module.h>
 #include <linux/irqdomain.h>
 #include <linux/of.h>
+#include <linux/regulator/consumer.h>
 
 static struct device_type mfd_dev_type = {
 	.name	= "mfd_device",
@@ -99,6 +100,13 @@ static int mfd_add_device(struct device *parent, int id,
 	pdev->dev.dma_mask = parent->dma_mask;
 	pdev->dev.dma_parms = parent->dma_parms;
 
+	ret = devm_regulator_bulk_register_supply_alias(
+			&pdev->dev, cell->parent_supplies,
+			parent, cell->parent_supplies,
+			cell->num_parent_supplies);
+	if (ret < 0)
+		goto fail_res;
+
 	if (parent->of_node && cell->of_compatible) {
 		for_each_child_of_node(parent->of_node, np) {
 			if (of_device_is_compatible(np, cell->of_compatible)) {
@@ -112,12 +120,12 @@ static int mfd_add_device(struct device *parent, int id,
 		ret = platform_device_add_data(pdev,
 					cell->platform_data, cell->pdata_size);
 		if (ret)
-			goto fail_res;
+			goto fail_alias;
 	}
 
 	ret = mfd_platform_add_cell(pdev, cell);
 	if (ret)
-		goto fail_res;
+		goto fail_alias;
 
 	for (r = 0; r < cell->num_resources; r++) {
 		res[r].name = cell->resources[r].name;
@@ -152,17 +160,17 @@ static int mfd_add_device(struct device *parent, int id,
 		if (!cell->ignore_resource_conflicts) {
 			ret = acpi_check_resource_conflict(&res[r]);
 			if (ret)
-				goto fail_res;
+				goto fail_alias;
 		}
 	}
 
 	ret = platform_device_add_resources(pdev, res, cell->num_resources);
 	if (ret)
-		goto fail_res;
+		goto fail_alias;
 
 	ret = platform_device_add(pdev);
 	if (ret)
-		goto fail_res;
+		goto fail_alias;
 
 	if (cell->pm_runtime_no_callbacks)
 		pm_runtime_no_callbacks(&pdev->dev);
@@ -171,6 +179,10 @@ static int mfd_add_device(struct device *parent, int id,
 
 	return 0;
 
+fail_alias:
+	devm_regulator_bulk_unregister_supply_alias(&pdev->dev,
+						    cell->parent_supplies,
+						    cell->num_parent_supplies);
 fail_res:
 	kfree(res);
 fail_device:

include/linux/mfd/core.h

@@ -59,6 +59,12 @@ struct mfd_cell {
 	 * pm_runtime_no_callbacks().
 	 */
 	bool			pm_runtime_no_callbacks;
+
+	/* A list of regulator supplies that should be mapped to the MFD
+	 * device rather than the child device when requested
+	 */
+	const char		**parent_supplies;
+	int			num_parent_supplies;
 };
 
 /*