Re: [PATCH V3 5/5] virtio: Bind virtio device to device-tree node

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 26/07/2021 14:51, Viresh Kumar wrote:
> Bind the virtio devices with their of_node. This will help users of the
> virtio devices to mention their dependencies on the device in the DT
> itself. Like GPIO pin users can use the phandle of the device node, or
> the node may contain more subnodes to add i2c or spi eeproms and other
> users.
> 
> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  drivers/virtio/virtio.c | 57 ++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 54 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index 4b15c00c0a0a..d001e84a5b23 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -4,6 +4,7 @@
>  #include <linux/virtio_config.h>
>  #include <linux/module.h>
>  #include <linux/idr.h>
> +#include <linux/of.h>
>  #include <uapi/linux/virtio_ids.h>
>  
>  /* Unique numbering for virtio devices. */
> @@ -292,6 +293,9 @@ static int virtio_dev_remove(struct device *_d)
>  
>  	/* Acknowledge the device's existence again. */
>  	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
> +
> +	of_node_put(dev->dev.of_node);
> +
>  	return 0;
>  }
>  
> @@ -319,6 +323,43 @@ void unregister_virtio_driver(struct virtio_driver *driver)
>  }
>  EXPORT_SYMBOL_GPL(unregister_virtio_driver);
>  
> +static int virtio_device_of_init(struct virtio_device *dev)
> +{
> +	struct device_node *np, *pnode = dev_of_node(dev->dev.parent);
> +	char compat[] = "virtio,XXXXXXXX"; /* Reserve enough space 32-bit id */
> +	int ret, count;
> +
> +	if (!pnode)
> +		return 0;
> +
> +	count = of_get_available_child_count(pnode);
> +	if (!count)
> +		return 0;
> +
> +	/* There can be only 1 child node */
> +	if (WARN_ON(count > 1))
> +		return -EINVAL;
> +
> +	np = of_get_next_available_child(pnode, NULL);
> +	if (WARN_ON(!np))
> +		return -ENODEV;
> +
> +	BUG_ON(snprintf(compat, sizeof(compat), "virtio,%x", dev->id.device) >=
> +	       sizeof(compat));
> +
> +	if (!of_device_is_compatible(np, compat)) {


This broke powerpc/pseries as there these virtio devices are PCI so
there is no "compat" - PCI vendor id/device ids play role of "compat".
Thanks,




> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	dev->dev.of_node = np;
> +	return 0;
> +
> +out:
> +	of_node_put(np);
> +	return ret;
> +}
> +
>  /**
>   * register_virtio_device - register virtio device
>   * @dev        : virtio device to be registered
> @@ -343,6 +384,10 @@ int register_virtio_device(struct virtio_device *dev)
>  	dev->index = err;
>  	dev_set_name(&dev->dev, "virtio%u", dev->index);
>  
> +	err = virtio_device_of_init(dev);
> +	if (err)
> +		goto out_ida_remove;
> +
>  	spin_lock_init(&dev->config_lock);
>  	dev->config_enabled = false;
>  	dev->config_change_pending = false;
> @@ -362,10 +407,16 @@ int register_virtio_device(struct virtio_device *dev)
>  	 */
>  	err = device_add(&dev->dev);
>  	if (err)
> -		ida_simple_remove(&virtio_index_ida, dev->index);
> +		goto out_of_node_put;
> +
> +	return 0;
> +
> +out_of_node_put:
> +	of_node_put(dev->dev.of_node);
> +out_ida_remove:
> +	ida_simple_remove(&virtio_index_ida, dev->index);
>  out:
> -	if (err)
> -		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> +	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
>  	return err;
>  }
>  EXPORT_SYMBOL_GPL(register_virtio_device);
> 

-- 
Alexey