[PATCH] of: Add of_platform_depopulate() helper

[PATCH] of: Add of_platform_depopulate() helper

[Pawel Moll]

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-5wv7dgnIgG8@public.gmane.org>
---
 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;
+	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 */
-- 
1.9.1

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Re: [PATCH] of: Add of_platform_depopulate() helper

[Rob Herring]

On Tue, May 13, 2014 at 6:50 AM, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org> 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-5wv7dgnIgG8@public.gmane.org>
> ---
>  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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Re: [PATCH] of: Add of_platform_depopulate() helper

[Pawel Moll]

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-5wv7dgnIgG8@public.gmane.org> 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-5wv7dgnIgG8@public.gmane.org>
> > ---
> >  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.

Paweł

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[PATCH v2] of/platform: Add of_platform_depopulate() helper

[Pawel Moll]

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-5wv7dgnIgG8@public.gmane.org>
---
Changes since v1:

- using bool rather than int to signal remaining children
- recursing using of_platform_depopulate() itself

 drivers/of/platform.c       | 50 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_platform.h |  5 +++++
 2 files changed, 55 insertions(+)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 236f47e..3b51e04 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -495,4 +495,54 @@ 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)
+{
+	bool *children_left = data;
+
+	/* Do not touch devices not populated from the device tree */
+	if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) {
+		*children_left = true;
+		return 0;
+	}
+
+	/* Recurse, but don't touch this device if it has any children left */
+	if (of_platform_depopulate(dev) != 0) {
+		*children_left = true;
+		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
+		*children_left = true;
+
+	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)
+{
+	bool children_left = false;
+
+	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 */
-- 
1.9.1

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Re: [PATCH v2] of/platform: Add of_platform_depopulate() helper

[Grant Likely]

On Tue, 13 May 2014 17:24:54 +0100, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org> 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).

Nit: What's with the 50-column word wrap? 72 is the norm for commit
text.

Acked-by: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

If you like you can merge this with your other series since it is
dependent.

> 
> Signed-off-by: Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>
> ---
> Changes since v1:
> 
> - using bool rather than int to signal remaining children
> - recursing using of_platform_depopulate() itself
> 
>  drivers/of/platform.c       | 50 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of_platform.h |  5 +++++
>  2 files changed, 55 insertions(+)
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 236f47e..3b51e04 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -495,4 +495,54 @@ 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)
> +{
> +	bool *children_left = data;
> +
> +	/* Do not touch devices not populated from the device tree */
> +	if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) {
> +		*children_left = true;
> +		return 0;
> +	}
> +
> +	/* Recurse, but don't touch this device if it has any children left */
> +	if (of_platform_depopulate(dev) != 0) {
> +		*children_left = true;
> +		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
> +		*children_left = true;
> +
> +	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)
> +{
> +	bool children_left = false;
> +
> +	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 */
> -- 
> 1.9.1
> 

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