of: Add of_platform_depopulate() helper

Message ID 1399981836-24837-1-git-send-email-pawel.moll@arm.com
State New
Headers show

Commit Message

Pawel Moll May 13, 2014, 11:50 a.m.
Drivers can us of_platform_populate() to create
platform devices for children of the device
main node (this can particularly happen in case
of MFD devices). Unfortunately, there was no
standard way of removing such sub-devices when
the main one is being removed.

This patch adds of_platform_depopulate() as
a complementary operation for the _populate()
one. It removes all platform and amba devices
that have been created from the Device Tree,
but leaves all other ones untouched (returning
-EBUSY in such case).

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
---
 drivers/of/platform.c       | 52 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_platform.h |  5 +++++
 2 files changed, 57 insertions(+)

Comments

Rob Herring May 13, 2014, 1:19 p.m. | #1
On Tue, May 13, 2014 at 6:50 AM, Pawel Moll <pawel.moll@arm.com> wrote:
> Drivers can us of_platform_populate() to create
> platform devices for children of the device
> main node (this can particularly happen in case
> of MFD devices). Unfortunately, there was no
> standard way of removing such sub-devices when
> the main one is being removed.
>
> This patch adds of_platform_depopulate() as
> a complementary operation for the _populate()
> one. It removes all platform and amba devices
> that have been created from the Device Tree,
> but leaves all other ones untouched (returning
> -EBUSY in such case).
>
> Signed-off-by: Pawel Moll <pawel.moll@arm.com>
> ---
>  drivers/of/platform.c       | 52 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of_platform.h |  5 +++++
>  2 files changed, 57 insertions(+)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 2d0c8b7..b5c49c3 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -495,4 +495,56 @@ int of_platform_populate(struct device_node *root,
>         return rc;
>  }
>  EXPORT_SYMBOL_GPL(of_platform_populate);
> +
> +static int of_platform_device_destroy(struct device *dev, void *data)
> +{
> +       int *parents_children_left = data;

You are not really tracking how many children are left, so this can
just be a bool.

> +       int my_children_left = 0;
> +
> +       /* Do not touch devices not populated from the device tree */
> +       if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) {
> +               (*parents_children_left)++;
> +               return 0;
> +       }
> +
> +       device_for_each_child(dev, &my_children_left,
> +                       of_platform_device_destroy);

Can't you call of_platform_depopulate here?

> +       if (my_children_left) {
> +               (*parents_children_left)++;
> +               return 0;
> +       }
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Pawel Moll May 13, 2014, 4:08 p.m. | #2
On Tue, 2014-05-13 at 14:19 +0100, Rob Herring wrote:
> On Tue, May 13, 2014 at 6:50 AM, Pawel Moll <pawel.moll@arm.com> wrote:
> > Drivers can us of_platform_populate() to create
> > platform devices for children of the device
> > main node (this can particularly happen in case
> > of MFD devices). Unfortunately, there was no
> > standard way of removing such sub-devices when
> > the main one is being removed.
> >
> > This patch adds of_platform_depopulate() as
> > a complementary operation for the _populate()
> > one. It removes all platform and amba devices
> > that have been created from the Device Tree,
> > but leaves all other ones untouched (returning
> > -EBUSY in such case).
> >
> > Signed-off-by: Pawel Moll <pawel.moll@arm.com>
> > ---
> >  drivers/of/platform.c       | 52 +++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/of_platform.h |  5 +++++
> >  2 files changed, 57 insertions(+)
> >
> > diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> > index 2d0c8b7..b5c49c3 100644
> > --- a/drivers/of/platform.c
> > +++ b/drivers/of/platform.c
> > @@ -495,4 +495,56 @@ int of_platform_populate(struct device_node *root,
> >         return rc;
> >  }
> >  EXPORT_SYMBOL_GPL(of_platform_populate);
> > +
> > +static int of_platform_device_destroy(struct device *dev, void *data)
> > +{
> > +       int *parents_children_left = data;
> 
> You are not really tracking how many children are left, so this can
> just be a bool.

That's true.

> > +       int my_children_left = 0;
> > +
> > +       /* Do not touch devices not populated from the device tree */
> > +       if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) {
> > +               (*parents_children_left)++;
> > +               return 0;
> > +       }
> > +
> > +       device_for_each_child(dev, &my_children_left,
> > +                       of_platform_device_destroy);
> 
> Can't you call of_platform_depopulate here?

... and check its result instead of ? I guess I could. Will have a look
how it looks like.

PaweĊ‚

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Patch

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 2d0c8b7..b5c49c3 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -495,4 +495,56 @@  int of_platform_populate(struct device_node *root,
 	return rc;
 }
 EXPORT_SYMBOL_GPL(of_platform_populate);
+
+static int of_platform_device_destroy(struct device *dev, void *data)
+{
+	int *parents_children_left = data;
+	int my_children_left = 0;
+
+	/* Do not touch devices not populated from the device tree */
+	if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) {
+		(*parents_children_left)++;
+		return 0;
+	}
+
+	device_for_each_child(dev, &my_children_left,
+			of_platform_device_destroy);
+	if (my_children_left) {
+		(*parents_children_left)++;
+		return 0;
+	}
+
+	if (dev->bus == &platform_bus_type)
+		platform_device_unregister(to_platform_device(dev));
+	else if (dev->bus == &amba_bustype)
+		amba_device_unregister(to_amba_device(dev));
+	else
+		(*parents_children_left)++;
+
+	return 0;
+}
+
+/**
+ * of_platform_depopulate() - Remove devices populated from device tree
+ * @parent: device which childred will be removed
+ *
+ * Complementary to of_platform_populate(), this function removes children
+ * of the given device (and, recurrently, their children) that have been
+ * created from their respective device tree nodes (and only those,
+ * leaving others - eg. manually created - unharmed).
+ *
+ * Returns 0 when all children devices have been removed or
+ * -EBUSY when some children remained.
+ */
+int of_platform_depopulate(struct device *parent)
+{
+	int children_left = 0;
+
+	device_for_each_child(parent, &children_left,
+			of_platform_device_destroy);
+
+	return children_left ? -EBUSY : 0;
+}
+EXPORT_SYMBOL_GPL(of_platform_depopulate);
+
 #endif /* CONFIG_OF_ADDRESS */
diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
index 05cb4a9..b1010ee 100644
--- a/include/linux/of_platform.h
+++ b/include/linux/of_platform.h
@@ -72,6 +72,7 @@  extern int of_platform_populate(struct device_node *root,
 				const struct of_device_id *matches,
 				const struct of_dev_auxdata *lookup,
 				struct device *parent);
+extern int of_platform_depopulate(struct device *parent);
 #else
 static inline int of_platform_populate(struct device_node *root,
 					const struct of_device_id *matches,
@@ -80,6 +81,10 @@  static inline int of_platform_populate(struct device_node *root,
 {
 	return -ENODEV;
 }
+static inline int of_platform_depopulate(struct device *parent)
+{
+	return -ENODEV;
+}
 #endif
 
 #endif	/* _LINUX_OF_PLATFORM_H */