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

[Grant Likely]

On Tue, 13 May 2014 17:24:54 +0100, Pawel Moll <pawel.moll at 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).

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

Acked-by: Grant Likely <grant.likely at linaro.org>

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

> 
> Signed-off-by: Pawel Moll <pawel.moll at arm.com>
> ---
> 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
>