Re: [PATCH v3 1/3] fpga: dfl: add the match() ops for dfl driver

[Tom Rix <trix@redhat.com>]

On 12/16/20 9:44 PM, Xu Yilun wrote:
> The match ops allows dfl drivers have their own matching algorithem
> instead of the standard id_table matching.
>
> This is to support the DFL UIO driver. It intends to match any DFL
> device which could not be handled by other DFL drivers.
>
> Signed-off-by: Xu Yilun <yilun.xu@intel.com>

This looks fine.

Reviewed-by: Tom Rix <trix@redhat.com>

> ---
> v3: this patch is splited out from DFL UIO patch.
>     move the declarations of exported symbols from include/linux/dfl.h
>      to driver/fpga/dfl.h
>     fix some comments.
> ---
>  drivers/fpga/dfl.c  | 22 +++++++++++++++++-----
>  drivers/fpga/dfl.h  |  5 +++++
>  include/linux/dfl.h |  3 +++
>  3 files changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 511b20f..dd90111 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -256,12 +256,13 @@ dfl_match_one_device(const struct dfl_device_id *id, struct dfl_device *ddev)
>  	return NULL;
>  }
>  
> -static int dfl_bus_match(struct device *dev, struct device_driver *drv)
> +int dfl_match_device(struct dfl_device *ddev, struct dfl_driver *ddrv)
>  {
> -	struct dfl_device *ddev = to_dfl_dev(dev);
> -	struct dfl_driver *ddrv = to_dfl_drv(drv);
>  	const struct dfl_device_id *id_entry;
>  
> +	if (ddrv->match)
> +		return ddrv->match(ddev);
> +
>  	id_entry = ddrv->id_table;
>  	if (id_entry) {
>  		while (id_entry->feature_id) {
> @@ -275,6 +276,15 @@ static int dfl_bus_match(struct device *dev, struct device_driver *drv)
>  
>  	return 0;
>  }
> +EXPORT_SYMBOL_GPL(dfl_match_device);
> +
> +static int dfl_bus_match(struct device *dev, struct device_driver *drv)
> +{
> +	struct dfl_device *ddev = to_dfl_dev(dev);
> +	struct dfl_driver *ddrv = to_dfl_drv(drv);
> +
> +	return dfl_match_device(ddev, ddrv);
> +}
>  
>  static int dfl_bus_probe(struct device *dev)
>  {
> @@ -328,7 +338,7 @@ static struct attribute *dfl_dev_attrs[] = {
>  };
>  ATTRIBUTE_GROUPS(dfl_dev);
>  
> -static struct bus_type dfl_bus_type = {
> +struct bus_type dfl_bus_type = {
>  	.name		= "dfl",
>  	.match		= dfl_bus_match,
>  	.probe		= dfl_bus_probe,
> @@ -336,6 +346,7 @@ static struct bus_type dfl_bus_type = {
>  	.uevent		= dfl_bus_uevent,
>  	.dev_groups	= dfl_dev_groups,
>  };
> +EXPORT_SYMBOL_GPL(dfl_bus_type);
>  
>  static void release_dfl_dev(struct device *dev)
>  {
> @@ -469,7 +480,8 @@ static int dfl_devs_add(struct dfl_feature_platform_data *pdata)
>  
>  int __dfl_driver_register(struct dfl_driver *dfl_drv, struct module *owner)
>  {
> -	if (!dfl_drv || !dfl_drv->probe || !dfl_drv->id_table)
> +	if (!dfl_drv || !dfl_drv->probe ||
> +	    (!dfl_drv->id_table && !dfl_drv->match))
>  		return -EINVAL;
>  
>  	dfl_drv->drv.owner = owner;
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index 2b82c96..01c43d8 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -17,6 +17,7 @@
>  #include <linux/bitfield.h>
>  #include <linux/cdev.h>
>  #include <linux/delay.h>
> +#include <linux/dfl.h>
>  #include <linux/eventfd.h>
>  #include <linux/fs.h>
>  #include <linux/interrupt.h>
> @@ -517,4 +518,8 @@ long dfl_feature_ioctl_set_irq(struct platform_device *pdev,
>  			       struct dfl_feature *feature,
>  			       unsigned long arg);
>  
> +extern struct bus_type dfl_bus_type;
> +
> +int dfl_match_device(struct dfl_device *ddev, struct dfl_driver *ddrv);
> +
>  #endif /* __FPGA_DFL_H */
> diff --git a/include/linux/dfl.h b/include/linux/dfl.h
> index 6cc1098..cfd98a4 100644
> --- a/include/linux/dfl.h
> +++ b/include/linux/dfl.h
> @@ -51,6 +51,8 @@ struct dfl_device {
>   * @drv: driver model structure.
>   * @id_table: pointer to table of device IDs the driver is interested in.
>   *	      { } member terminated.
> + * @match: returns one if given device can be handled by the driver and zero
> + *	   otherwise. If NULL, matching is based on id_table.
>   * @probe: mandatory callback for device binding.
>   * @remove: callback for device unbinding.
>   */
> @@ -58,6 +60,7 @@ struct dfl_driver {
>  	struct device_driver drv;
>  	const struct dfl_device_id *id_table;
>  
> +	int (*match)(struct dfl_device *dfl_dev);
>  	int (*probe)(struct dfl_device *dfl_dev);
>  	void (*remove)(struct dfl_device *dfl_dev);
>  };