[Skiboot] [PATCH RESEND V5] doc/opal-api : Document opal-api's related to error log

[Vasant Hegde]

On 08/05/2016 04:01 PM, Mukesh Ojha wrote:
> It documents opal-api's related to error log.
> OPAL_ELOG_READ          71
> OPAL_ELOG_WRITE         72(UNUSED)
> OPAL_ELOG_ACK           73
> OPAL_ELOG_RESEND        74
> OPAL_ELOG_SIZE          75
>
> Signed-off-by: Mukesh Ojha <mukesh02 at linux.vnet.ibm.com>

Looks good.

Reviewed-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>

-Vasant

> ---
> Changes in V5:
>   - Changes file extension from .txt file to .rst and adheres to sphinx
>     documentation.
>   - Replaces all 'errorlog' words occurance with 'error log'.
>   - Replaces 'FSP' word to 'error log creator' to make more sense.
>   - Error log type description changes as per Vasant's comment.
>   - Adds data types to the parameters.
>
> Changes in V4:
>   - Adds little detail about error log type format.
>   - Changes related Vasant's review.
>
> Changes in V3:
>   - It takes care of the comment made by Vasant.
>
> Changes in V2:
>   - As per the discussion with Stewart offline, This patch adds examples
>     and the usage of the api's from the host kernel.
>
>   doc/opal-api/opal-elog-71-72-73-74-75.rst | 126 ++++++++++++++++++++++++++++++
>   1 file changed, 126 insertions(+)
>   create mode 100644 doc/opal-api/opal-elog-71-72-73-74-75.rst
>
> diff --git a/doc/opal-api/opal-elog-71-72-73-74-75.rst b/doc/opal-api/opal-elog-71-72-73-74-75.rst
> new file mode 100644
> index 0000000..3543ba4
> --- /dev/null
> +++ b/doc/opal-api/opal-elog-71-72-73-74-75.rst
> @@ -0,0 +1,126 @@
> +Error logging API's description:
> +================================
> +
> +There are five OPAL calls from host to OPAL on error log: ::
> +
> +	#define OPAL_ELOG_READ         71
> +	#define OPAL_ELOG_WRITE        72
> +	#define OPAL_ELOG_ACK          73
> +	#define OPAL_ELOG_RESEND       74
> +	#define OPAL_ELOG_SIZE         75
> +
> +Note: ``OPAL_ELOG_WRITE`` (72) Unused for now, can be used in future.
> +
> +Host kernel define macros for the call with the above tokens.
> +e.g. ::
> +
> +	OPAL_CALL(opal_read_elog,		OPAL_ELOG_READ);
> +	OPAL_CALL(opal_send_ack_elog,		OPAL_ELOG_ACK);
> +	OPAL_CALL(opal_get_elog_size,		OPAL_ELOG_SIZE);
> +	OPAL_CALL(opal_resend_pending_logs,	OPAL_ELOG_RESEND);
> +
> +And OPAL also register interfaces for the above tokens.
> +e.g. ::
> +
> +	opal_register(OPAL_ELOG_READ, fsp_opal_elog_read, 3);
> +	opal_register(OPAL_ELOG_ACK, fsp_opal_elog_ack, 1);
> +	opal_register(OPAL_ELOG_RESEND, fsp_opal_resend_pending_logs, 0);
> +	opal_register(OPAL_ELOG_SIZE, fsp_opal_elog_info, 3);
> +
> +Numbers in the above example are the number of parameter(e.g. 3) the callback
> +(e.g. ``fsp_opal_elog_read``) accepts.
> +
> +So, a call to any of the above api's(``opal_read_elog``) in the host kernel will
> +call the corresponding interface(``fsp_opal_elog_read``) in the OPAL.
> +
> +e.g. Below is the example of one of the call from the host kernel. ::
> +
> +	elog->id = id;
> +	elog->size = size;
> +	elog->type = type;
> +	elog->buffer = kzalloc(elog->size, GFP_KERNEL);
> +
> +	if (elog->buffer) {
> +		rc = opal_read_elog(__pa(elog->buffer),
> +				elog->size, elog->id);
> +		if (rc != OPAL_SUCCESS) {
> +			pr_err("ELOG: log read failed for log-id=%llx\n",
> +					elog->id);
> +			kfree(elog->buffer);
> +			elog->buffer = NULL;
> +		}
> +	}
> +
> +
> +OPAL_ELOG_READ
> +--------------
> +
> +This token is used to register a call which will copy the error log content to
> +the passed buffer with the passed ``elog id`` and ``elog size`` from the host
> +kernel.
> +
> +``OPAL_ELOG_READ`` accepts 3 parameters: ::
> +
> +	uint64_t elog buffer
> +	uint64_t elog size
> +	uint64_t elog id
> +
> +The call registered with this token returns ``OPAL_WRONG_STATE``, when read
> +state of state machine is not in ``ELOG_STATE_FETCHED_DATA`` or error log read
> +pending list is empty.
> +
> +It returns ``OPAL_PARAMETER``, when passed log id is not the same as log id of the
> +top node in the elog_read_pending list and ``OPAL_SUCCESS`` on successfully copying
> +the error log data to the passed buffer.
> +
> +
> +OPAL_ELOG_ACK
> +-------------
> +
> +This token is used to register a call which acknowledges the passed ``ack_id``
> +(elog_id) which in turn sends a acknowledgement to the error log source and
> +move the acknowledge elog id from processed list to the read free list.
> +
> +``OPAL_ELOG_ACK`` accepts 1 parameter: ::
> +
> +	uint64_t ack id
> +
> +In case of OPAL error logs, for the passed ``ack_id`` the corresponding node is
> +returned to the pool of free object.
> +
> +The call registered with this token returns ``OPAL_INTERNAL_ERROR`` on failure to
> +send acknowledgement to the error log creator and ``OPAL_SUCCESS`` on success.
> +
> +
> +OPAL_ELOG_RESEND
> +----------------
> +
> +This token is used to register a call which will resend all the error logs
> +again to newly loaded kernel.
> +
> +The call registered with this token accepts no parameter and returns type is
> +void.
> +
> +
> +OPAL_ELOG_SIZE
> +--------------
> +
> +This token is used to register a call which will fill information about the
> +error log like id, size and type.
> +
> +Here, ``type`` specifies error log format. Supported types are : ::
> +
> +	 0 -> Platform Error Log
> +
> +``OPAL_ELOG_SIZE`` accepts 3 parameters: ::
> +
> +	uint64_t elog ID
> +	uint64_t elog size
> +	uint64_t type
> +
> +The call registered with this token returns ``OPAL_WRONG_STATE``, when read
> +state of state machine is not in ``ELOG_STATE_FETCHED_DATA`` or error log read
> +pending list is empty.
> +
> +It returns ``OPAL_SUCCESS`` on successfully filling up the error log information
> +in passed parameters.
>