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Date: Mon, 22 Feb 2021 14:02:09 -0800
From: Ben Widawsky <ben.widawsky@intel.com>
To: Vishal Verma <vishal.l.verma@intel.com>
Subject: Re: [ndctl PATCH v2 04/13] libcxl: add support for the 'Identify
 Device' command
Message-ID: <20210222220209.62pvejo6mxhcqqth@intel.com>
References: <20210219020331.725687-1-vishal.l.verma@intel.com>
 <20210219020331.725687-5-vishal.l.verma@intel.com>
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On 21-02-18 19:03:22, Vishal Verma wrote:
> Add APIs to allocate and send an 'Identify Device' command, and
> accessors to retrieve some of the fields from the resulting data.
> 
> Only add a handful accessor functions; more can be added as the need
> arises. The fields added are fw_revision, partition_align, and
> lsa_size.
> 

How do we feel about for each command the ability to return n bytes as an opaque
object? That way, if some client application wants more of the identify data
they can get it without needing library API to do it.

/**
 * cxl_cmd_identify_get_payload() - Return output payload
 * @cmd: Identify command.
 * @n: Max number of bytes to return.
 * @out: Buffer to copy to.
 *
 * Returns actual number of bytes copied out.
 *
 * Returns up to n bytes in (CXL native format) of data from the output payload
 * of the identify command.
 */
CXL_EXPORT unsigned int
cxl_cmd_identify_get_payload(struct cxl_cmd *cmd, unsigned int n, void *out)
{
}

I recall discussing this briefly, but I don't recall what we had decided.

> Cc: Ben Widawsky <ben.widawsky@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
>  cxl/lib/private.h  | 19 ++++++++++++++++++
>  cxl/lib/libcxl.c   | 49 ++++++++++++++++++++++++++++++++++++++++++++++
>  cxl/libcxl.h       |  4 ++++
>  cxl/lib/libcxl.sym |  4 ++++
>  4 files changed, 76 insertions(+)
> 
> diff --git a/cxl/lib/private.h b/cxl/lib/private.h
> index 87ca17e..3273f21 100644
> --- a/cxl/lib/private.h
> +++ b/cxl/lib/private.h
> @@ -54,6 +54,25 @@ struct cxl_cmd {
>  	int status;
>  };
>  
> +#define CXL_CMD_IDENTIFY_FW_REV_LENGTH 0x10
> +
> +struct cxl_cmd_identify {
> +	char fw_revision[CXL_CMD_IDENTIFY_FW_REV_LENGTH];
> +	le64 total_capacity;
> +	le64 volatile_capacity;
> +	le64 persistent_capacity;
> +	le64 partition_align;
> +	le16 info_event_log_size;
> +	le16 warning_event_log_size;
> +	le16 failure_event_log_size;
> +	le16 fatal_event_log_size;
> +	le32 lsa_size;
> +	u8 poison_list_max_mer[3];
> +	le16 inject_poison_limit;
> +	u8 poison_caps;
> +	u8 qos_telemetry_caps;
> +} __attribute__((packed));
> +
>  static inline int check_kmod(struct kmod_ctx *kmod_ctx)
>  {
>  	return kmod_ctx ? 0 : -ENXIO;
> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> index f1155a1..4751cba 100644
> --- a/cxl/lib/libcxl.c
> +++ b/cxl/lib/libcxl.c
> @@ -13,7 +13,10 @@
>  #include <sys/sysmacros.h>
>  #include <uuid/uuid.h>
>  #include <ccan/list/list.h>
> +#include <ccan/endian/endian.h>
> +#include <ccan/minmax/minmax.h>
>  #include <ccan/array_size/array_size.h>
> +#include <ccan/short_types/short_types.h>
>  
>  #include <util/log.h>
>  #include <util/sysfs.h>
> @@ -675,6 +678,52 @@ CXL_EXPORT const char *cxl_cmd_get_devname(struct cxl_cmd *cmd)
>  	return cxl_memdev_get_devname(cmd->memdev);
>  }
>  
> +CXL_EXPORT struct cxl_cmd *cxl_cmd_new_identify(struct cxl_memdev *memdev)
> +{
> +	return cxl_cmd_new_generic(memdev, CXL_MEM_COMMAND_ID_IDENTIFY);
> +}
> +
> +CXL_EXPORT int cxl_cmd_identify_get_fw_rev(struct cxl_cmd *cmd, char *fw_rev,
> +		int fw_len)
> +{
> +	struct cxl_cmd_identify *id = (void *)cmd->send_cmd->out.payload;
> +
> +	if (cmd->send_cmd->id != CXL_MEM_COMMAND_ID_IDENTIFY)
> +		return -EINVAL;
> +	if (cmd->status < 0)
> +		return cmd->status;
> +
> +	if (fw_len > 0)
> +		memcpy(fw_rev, id->fw_revision,
> +			min(fw_len, CXL_CMD_IDENTIFY_FW_REV_LENGTH));
> +	return 0;
> +}
> +
> +CXL_EXPORT unsigned long long cxl_cmd_identify_get_partition_align(
> +		struct cxl_cmd *cmd)
> +{
> +	struct cxl_cmd_identify *id = (void *)cmd->send_cmd->out.payload;
> +
> +	if (cmd->send_cmd->id != CXL_MEM_COMMAND_ID_IDENTIFY)
> +		return -EINVAL;
> +	if (cmd->status < 0)
> +		return cmd->status;
> +
> +	return le64_to_cpu(id->partition_align);
> +}
> +
> +CXL_EXPORT unsigned int cxl_cmd_identify_get_lsa_size(struct cxl_cmd *cmd)
> +{
> +	struct cxl_cmd_identify *id = (void *)cmd->send_cmd->out.payload;
> +
> +	if (cmd->send_cmd->id != CXL_MEM_COMMAND_ID_IDENTIFY)
> +		return -EINVAL;
> +	if (cmd->status < 0)
> +		return cmd->status;
> +
> +	return le32_to_cpu(id->lsa_size);
> +}
> +
>  CXL_EXPORT struct cxl_cmd *cxl_cmd_new_raw(struct cxl_memdev *memdev,
>  		int opcode)
>  {
> diff --git a/cxl/libcxl.h b/cxl/libcxl.h
> index 6e87b80..9ed8c83 100644
> --- a/cxl/libcxl.h
> +++ b/cxl/libcxl.h
> @@ -58,6 +58,10 @@ void cxl_cmd_unref(struct cxl_cmd *cmd);
>  int cxl_cmd_submit(struct cxl_cmd *cmd);
>  int cxl_cmd_get_mbox_status(struct cxl_cmd *cmd);
>  int cxl_cmd_get_out_size(struct cxl_cmd *cmd);
> +struct cxl_cmd *cxl_cmd_new_identify(struct cxl_memdev *memdev);
> +int cxl_cmd_identify_get_fw_rev(struct cxl_cmd *cmd, char *fw_rev, int fw_len);
> +unsigned long long cxl_cmd_identify_get_partition_align(struct cxl_cmd *cmd);
> +unsigned int cxl_cmd_identify_get_lsa_size(struct cxl_cmd *cmd);
>  
>  #ifdef __cplusplus
>  } /* extern "C" */
> diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
> index 493429c..d6aa0b2 100644
> --- a/cxl/lib/libcxl.sym
> +++ b/cxl/lib/libcxl.sym
> @@ -39,4 +39,8 @@ global:
>  	cxl_cmd_submit;
>  	cxl_cmd_get_mbox_status;
>  	cxl_cmd_get_out_size;
> +	cxl_cmd_new_identify;
> +	cxl_cmd_identify_get_fw_rev;
> +	cxl_cmd_identify_get_partition_align;
> +	cxl_cmd_identify_get_lsa_size;
>  } LIBCXL_2;
> -- 
> 2.29.2
> 
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