Re: [PATCH v6 03/22] of/platform: Point to struct device from device node

[Rafael J. Wysocki]

On Monday, September 21, 2015 04:02:43 PM Tomeu Vizoso wrote:
> When adding platform and AMBA devices, set the device node's device
> member to point to it.
> 
> This speeds lookups considerably and is safe because we only create one
> of these devices for any given device node.
> 
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> ---
> 
> Changes in v5:
> - Set the pointer to struct device also for AMBA devices
> - Unset the pointer to struct device when the platform device is about
>   to be unregistered
> - Increase the reference count of the device before returning from
>   of_find_device_by_node()
> 
>  drivers/of/platform.c | 19 ++++++++++---------
>  include/linux/of.h    |  1 +
>  2 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 1001efaedcb8..408d89f1d124 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -32,11 +32,6 @@ const struct of_device_id of_default_bus_match_table[] = {
>  	{} /* Empty terminated list */
>  };
>  
> -static int of_dev_node_match(struct device *dev, void *data)
> -{
> -	return dev->of_node == data;
> -}
> -
>  /**
>   * of_find_device_by_node - Find the platform_device associated with a node
>   * @np: Pointer to device tree node
> @@ -45,10 +40,10 @@ static int of_dev_node_match(struct device *dev, void *data)
>   */
>  struct platform_device *of_find_device_by_node(struct device_node *np)
>  {
> -	struct device *dev;
> -
> -	dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match);
> -	return dev ? to_platform_device(dev) : NULL;
> +	if (np->device && np->device->bus == &platform_bus_type &&
> +	    get_device(np->device))
> +		return to_platform_device(np->device);
> +	return NULL;
>  }
>  EXPORT_SYMBOL(of_find_device_by_node);
>  
> @@ -192,6 +187,8 @@ static struct platform_device *of_platform_device_create_pdata(
>  		goto err_clear_flag;
>  	}
>  
> +	np->device = &dev->dev;
> +
>  	return dev;
>  
>  err_clear_flag:
> @@ -272,6 +269,8 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>  		goto err_free;
>  	}
>  
> +	node->device = &dev->dev;
> +
>  	return dev;
>  
>  err_free:
> @@ -476,6 +475,8 @@ static int of_platform_device_destroy(struct device *dev, void *data)
>  	if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS))
>  		device_for_each_child(dev, NULL, of_platform_device_destroy);
>  
> +	dev->of_node->device = NULL;
> +
>  	if (dev->bus == &platform_bus_type)
>  		platform_device_unregister(to_platform_device(dev));
>  #ifdef CONFIG_ARM_AMBA
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 2194b8ca41f9..eb091be0f8ee 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -52,6 +52,7 @@ struct device_node {
>  	phandle phandle;
>  	const char *full_name;
>  	struct fwnode_handle fwnode;
> +	struct device *device;

There are cases in which multiple device objects point to the same device_node,
so is the single struct device pointer here really sufficient?

>  
>  	struct	property *properties;
>  	struct	property *deadprops;	/* removed properties */
> 

Thanks,
Rafael

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