mfd: mfd-core: Add mechanism for removal of a subset of children

Currently, the only way to remove MFD children is with a call to
mfd_remove_devices, which will remove all the children. Under
some circumstances it is useful to remove only a subset of the
child devices. For example if some additional clean up is required
between removal of certain child devices.

To accomplish this a level field is added to mfd_cell, the normal
mfd_remove_devices is modified to not remove devices that are set
to a higher level and a corresponding mfd_remove_devices_late
function is added to remove those children.

See further discussion at:
https://lore.kernel.org/lkml/20200616075834.GF2608702@dell/

Suggested-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index b201842f82ad6329f645b09ed5a158b7d09acae2..c3651f06684fa81b2912b7924eaa02b0f35fa824 100644 (file)
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -356,6 +356,7 @@ static int mfd_remove_devices_fn(struct device *dev, void *data)
 {
        struct platform_device *pdev;
        const struct mfd_cell *cell;
+       int *level = data;
 
        if (dev->type != &mfd_dev_type)
                return 0;
@@ -363,6 +364,9 @@ static int mfd_remove_devices_fn(struct device *dev, void *data)
        pdev = to_platform_device(dev);
        cell = mfd_get_cell(pdev);
 
+       if (level && cell->level > *level)
+               return 0;
+
        regulator_bulk_unregister_supply_alias(dev, cell->parent_supplies,
                                               cell->num_parent_supplies);
 
@@ -372,9 +376,19 @@ static int mfd_remove_devices_fn(struct device *dev, void *data)
        return 0;
 }
 
+void mfd_remove_devices_late(struct device *parent)
+{
+       int level = MFD_DEP_LEVEL_HIGH;
+
+       device_for_each_child_reverse(parent, &level, mfd_remove_devices_fn);
+}
+EXPORT_SYMBOL(mfd_remove_devices_late);
+
 void mfd_remove_devices(struct device *parent)
 {
-       device_for_each_child_reverse(parent, NULL, mfd_remove_devices_fn);
+       int level = MFD_DEP_LEVEL_NORMAL;
+
+       device_for_each_child_reverse(parent, &level, mfd_remove_devices_fn);
 }
 EXPORT_SYMBOL(mfd_remove_devices);
 

diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
index 6d68f44a26a1c9606fe91c071b44ac1b53d16aa7..4b35baa14d308c229eca570daafbab461b917fd2 100644 (file)
--- a/include/linux/mfd/core.h
+++ b/include/linux/mfd/core.h
@@ -46,6 +46,9 @@
 #define MFD_CELL_NAME(_name) \
        MFD_CELL_ALL(_name, NULL, NULL, 0, 0, NULL, 0, false, NULL)
 
+#define MFD_DEP_LEVEL_NORMAL 0
+#define MFD_DEP_LEVEL_HIGH 1
+
 struct irq_domain;
 struct property_entry;
 
@@ -63,6 +66,7 @@ struct mfd_cell_acpi_match {
 struct mfd_cell {
        const char              *name;
        int                     id;
+       int                     level;
 
        int                     (*enable)(struct platform_device *dev);
        int                     (*disable)(struct platform_device *dev);
@@ -150,6 +154,7 @@ static inline int mfd_add_hotplug_devices(struct device *parent,
 }
 
 extern void mfd_remove_devices(struct device *parent);
+extern void mfd_remove_devices_late(struct device *parent);
 
 extern int devm_mfd_add_devices(struct device *dev, int id,
                                const struct mfd_cell *cells, int n_devs,