Re: [PATCH v4 04/15] cxl/mbox: Add GET_FEATURE mailbox command

[Dan Williams <dan.j.williams@intel.com>]

Dave Jiang wrote:
> From: Shiju Jose <shiju.jose@huawei.com>
> 
> Add support for GET_FEATURE mailbox command.
> 
> CXL spec r3.2 section 8.2.9.6 describes optional device specific features.
> The settings of a feature can be retrieved using Get Feature command.
> CXL spec r3.2 section 8.2.9.6.2 describes Get Feature command.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Li Ming <ming.li@zohomail.com>
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/cxl/core/features.c | 50 +++++++++++++++++++++++++++++++++++++
>  include/cxl/features.h      | 37 +++++++++++++++++++++++++++
>  2 files changed, 87 insertions(+)
> 
> diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
> index 77a0bf3a4916..262e4b1cb7fc 100644
> --- a/drivers/cxl/core/features.c
> +++ b/drivers/cxl/core/features.c
> @@ -177,3 +177,53 @@ int devm_cxl_setup_features(struct cxl_dev_state *cxlds)
>  	return 0;
>  }
>  EXPORT_SYMBOL_NS_GPL(devm_cxl_setup_features, "CXL");
> +
> +size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
> +		       enum cxl_get_feat_selection selection,
> +		       void *feat_out, size_t feat_out_size, u16 offset,
> +		       u16 *return_code)
> +{
> +	size_t data_to_rd_size, size_out;
> +	struct cxl_mbox_get_feat_in pi;
> +	struct cxl_mbox_cmd mbox_cmd;
> +	size_t data_rcvd_size = 0;
> +	int rc;
> +
> +	if (return_code)
> +		*return_code = CXL_MBOX_CMD_RC_INPUT;
> +
> +	if (!feat_out || !feat_out_size)
> +		return 0;
> +
> +	size_out = min(feat_out_size, cxl_mbox->payload_size);
> +	uuid_copy(&pi.uuid, feat_uuid);
> +	pi.selection = selection;
> +	do {
> +		data_to_rd_size = min(feat_out_size - data_rcvd_size,
> +				      cxl_mbox->payload_size);
> +		pi.offset = cpu_to_le16(offset + data_rcvd_size);
> +		pi.count = cpu_to_le16(data_to_rd_size);
> +
> +		mbox_cmd = (struct cxl_mbox_cmd) {
> +			.opcode = CXL_MBOX_OP_GET_FEATURE,
> +			.size_in = sizeof(pi),
> +			.payload_in = &pi,
> +			.size_out = size_out,
> +			.payload_out = feat_out + data_rcvd_size,
> +			.min_out = data_to_rd_size,
> +		};
> +		rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
> +		if (rc < 0 || !mbox_cmd.size_out) {
> +			if (return_code)
> +				*return_code = mbox_cmd.return_code;
> +			return 0;
> +		}
> +		data_rcvd_size += mbox_cmd.size_out;
> +	} while (data_rcvd_size < feat_out_size);
> +
> +	if (return_code)
> +		*return_code = CXL_MBOX_CMD_RC_SUCCESS;
> +
> +	return data_rcvd_size;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_get_feature, "CXL");

I don't think this needs to be exported. The only consumer in this
series is within drivers/cxl/core/features.c, and the EDAC consumer will
also be from within drivers/cxl/core/features.c with new exports for the
cxl_mem and cxl_region drivers to registers with EDAC.

> diff --git a/include/cxl/features.h b/include/cxl/features.h
> index e8861e690701..85036604fdba 100644
> --- a/include/cxl/features.h
> +++ b/include/cxl/features.h
> @@ -65,6 +65,29 @@ struct cxl_mbox_get_sup_feats_out {
>  	struct cxl_feat_entry ents[] __counted_by_le(num_entries);
>  } __packed;
>  
> +/*
> + * Get Feature CXL spec r3.2 Spec 8.2.9.6.2
> + */
> +
> +/*
> + * Get Feature input payload
> + * CXL spec r3.2 section 8.2.9.6.2 Table 8-99
> + */
> +struct cxl_mbox_get_feat_in {
> +	uuid_t uuid;
> +	__le16 offset;
> +	__le16 count;
> +	u8 selection;
> +}  __packed;
> +
> +/* Selection field for 'struct cxl_mbox_get_feat_in' */
> +enum cxl_get_feat_selection {
> +	CXL_GET_FEAT_SEL_CURRENT_VALUE,
> +	CXL_GET_FEAT_SEL_DEFAULT_VALUE,
> +	CXL_GET_FEAT_SEL_SAVED_VALUE,
> +	CXL_GET_FEAT_SEL_MAX
> +};
> +
>  /**
>   * struct cxl_features_state - The Features state for the device
>   * @cxlds: Pointer to CXL device state
> @@ -81,9 +104,14 @@ struct cxl_features_state {
>  	} *entries;
>  };
>  
> +struct cxl_mailbox;
>  #ifdef CONFIG_CXL_FEATURES
>  inline struct cxl_features_state *to_cxlfs(struct cxl_dev_state *cxlds);
>  int devm_cxl_setup_features(struct cxl_dev_state *cxlds);
> +size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox, const uuid_t *feat_uuid,
> +		       enum cxl_get_feat_selection selection,
> +		       void *feat_out, size_t feat_out_size, u16 offset,
> +		       u16 *return_code);
>  #else
>  static inline struct cxl_features_state *to_cxlfs(struct cxl_dev_state *cxlds)
>  {
> @@ -94,6 +122,15 @@ static inline int devm_cxl_setup_features(struct cxl_dev_state *cxlds)
>  {
>  	return -EOPNOTSUPP;
>  }
> +
> +static inline size_t cxl_get_feature(struct cxl_mailbox *cxl_mbox,
> +				     const uuid_t *feat_uuid,
> +				     enum cxl_get_feat_selection selection,
> +				     void *feat_out, size_t feat_out_size,
> +				     u16 offset, u16 *return_code)
> +{
> +	return 0;
> +}

With no callers external to drivers/cxl/core/features.c, this can also
go away.

I am fine if you just fix this up locally on applying.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>