RE: [PATCH 05/22] NTB: Alter Scratchpads NTB API to support multi-ports interface

[Allen Hubbe]

From: Serge Semin 
> Even though there is no any real NTB hardware, which would have both more
> than two ports and Scratchpad registers, it is logically correct to have
> Scratchpad API accepting a peer port index as well. Intel/AMD drivers used
> to utilize Primary and Secondary topology to split Scratchpad between
> connected root devices. Since port-index API replaced Primary and Secondary
> topology, Intel/AMD NTB hadrware drivers can use device port to determine
> which Scratchpad registers actually belong to local and peer devices.
> The same approach can be used if some potential hardware in future will be
> multi-port and have some set of Scratchpads.
> 

I agree with addition of the peer port index, but I don't think s/idx/sidx/ for scratchpad index is necessary.

> Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx>
> 
> ---
>  include/linux/ntb.h | 46 ++++++++++++++++++++++++++--------------------
>  1 file changed, 26 insertions(+), 20 deletions(-)
> 
> diff --git a/include/linux/ntb.h b/include/linux/ntb.h
> index 59de1f6..fc9d034 100644
> --- a/include/linux/ntb.h
> +++ b/include/linux/ntb.h
> @@ -268,13 +268,14 @@ struct ntb_dev_ops {
>  	int (*spad_is_unsafe)(struct ntb_dev *ntb);
>  	int (*spad_count)(struct ntb_dev *ntb);
> 
> -	u32 (*spad_read)(struct ntb_dev *ntb, int idx);
> -	int (*spad_write)(struct ntb_dev *ntb, int idx, u32 val);
> +	u32 (*spad_read)(struct ntb_dev *ntb, int sidx);
> +	int (*spad_write)(struct ntb_dev *ntb, int sidx, u32 val);
> 
> -	int (*peer_spad_addr)(struct ntb_dev *ntb, int idx,
> +	int (*peer_spad_addr)(struct ntb_dev *ntb, int pidx, int sidx,
>  			      phys_addr_t *spad_addr);
> -	u32 (*peer_spad_read)(struct ntb_dev *ntb, int idx);
> -	int (*peer_spad_write)(struct ntb_dev *ntb, int idx, u32 val);
> +	u32 (*peer_spad_read)(struct ntb_dev *ntb, int pidx, int sidx);
> +	int (*peer_spad_write)(struct ntb_dev *ntb, int pidx, int sidx,
> +			       u32 val);
> 
>  	int (*msg_count)(struct ntb_dev *ntb);
>  	u64 (*msg_inbits)(struct ntb_dev *ntb);
> @@ -1201,6 +1202,7 @@ static inline int ntb_spad_is_unsafe(struct ntb_dev *ntb)
>   * @ntb:	NTB device context.
>   *
>   * Hardware and topology may support a different number of scratchpads.
> + * Although it must be the same for all ports per NTB device.
>   *
>   * Return: the number of scratchpads.
>   */
> @@ -1215,42 +1217,43 @@ static inline int ntb_spad_count(struct ntb_dev *ntb)
>  /**
>   * ntb_spad_read() - read the local scratchpad register
>   * @ntb:	NTB device context.
> - * @idx:	Scratchpad index.
> + * @sidx:	Scratchpad index.
>   *
>   * Read the local scratchpad register, and return the value.
>   *
>   * Return: The value of the local scratchpad register.
>   */
> -static inline u32 ntb_spad_read(struct ntb_dev *ntb, int idx)
> +static inline u32 ntb_spad_read(struct ntb_dev *ntb, int sidx)
>  {
>  	if (!ntb->ops->spad_read)
>  		return ~(u32)0;
> 
> -	return ntb->ops->spad_read(ntb, idx);
> +	return ntb->ops->spad_read(ntb, sidx);
>  }
> 
>  /**
>   * ntb_spad_write() - write the local scratchpad register
>   * @ntb:	NTB device context.
> - * @idx:	Scratchpad index.
> + * @sidx:	Scratchpad index.
>   * @val:	Scratchpad value.
>   *
>   * Write the value to the local scratchpad register.
>   *
>   * Return: Zero on success, otherwise an error number.
>   */
> -static inline int ntb_spad_write(struct ntb_dev *ntb, int idx, u32 val)
> +static inline int ntb_spad_write(struct ntb_dev *ntb, int sidx, u32 val)
>  {
>  	if (!ntb->ops->spad_write)
>  		return -EINVAL;
> 
> -	return ntb->ops->spad_write(ntb, idx, val);
> +	return ntb->ops->spad_write(ntb, sidx, val);
>  }
> 
>  /**
>   * ntb_peer_spad_addr() - address of the peer scratchpad register
>   * @ntb:	NTB device context.
> - * @idx:	Scratchpad index.
> + * @pidx:	Port index of peer device.
> + * @sidx:	Scratchpad index.
>   * @spad_addr:	OUT - The address of the peer scratchpad register.
>   *
>   * Return the address of the peer doorbell register.  This may be used, for
> @@ -1258,48 +1261,51 @@ static inline int ntb_spad_write(struct ntb_dev *ntb, int idx, u32
> val)
>   *
>   * Return: Zero on success, otherwise an error number.
>   */
> -static inline int ntb_peer_spad_addr(struct ntb_dev *ntb, int idx,
> +static inline int ntb_peer_spad_addr(struct ntb_dev *ntb, int pidx, int sidx,
>  				     phys_addr_t *spad_addr)
>  {
>  	if (!ntb->ops->peer_spad_addr)
>  		return -EINVAL;
> 
> -	return ntb->ops->peer_spad_addr(ntb, idx, spad_addr);
> +	return ntb->ops->peer_spad_addr(ntb, pidx, sidx, spad_addr);
>  }
> 
>  /**
>   * ntb_peer_spad_read() - read the peer scratchpad register
>   * @ntb:	NTB device context.
> - * @idx:	Scratchpad index.
> + * @pidx:	Port index of peer device.
> + * @sidx:	Scratchpad index.
>   *
>   * Read the peer scratchpad register, and return the value.
>   *
>   * Return: The value of the local scratchpad register.
>   */
> -static inline u32 ntb_peer_spad_read(struct ntb_dev *ntb, int idx)
> +static inline u32 ntb_peer_spad_read(struct ntb_dev *ntb, int pidx, int sidx)
>  {
>  	if (!ntb->ops->peer_spad_read)
>  		return ~(u32)0;
> 
> -	return ntb->ops->peer_spad_read(ntb, idx);
> +	return ntb->ops->peer_spad_read(ntb, pidx, sidx);
>  }
> 
>  /**
>   * ntb_peer_spad_write() - write the peer scratchpad register
>   * @ntb:	NTB device context.
> - * @idx:	Scratchpad index.
> + * @pidx:	Port index of peer device.
> + * @sidx:	Scratchpad index.
>   * @val:	Scratchpad value.
>   *
>   * Write the value to the peer scratchpad register.
>   *
>   * Return: Zero on success, otherwise an error number.
>   */
> -static inline int ntb_peer_spad_write(struct ntb_dev *ntb, int idx, u32 val)
> +static inline int ntb_peer_spad_write(struct ntb_dev *ntb, int pidx, int sidx,
> +				      u32 val)
>  {
>  	if (!ntb->ops->peer_spad_write)
>  		return -EINVAL;
> 
> -	return ntb->ops->peer_spad_write(ntb, idx, val);
> +	return ntb->ops->peer_spad_write(ntb, pidx, sidx, val);
>  }
> 
>  /**
> --
> 2.6.6