[Skiboot] [PATCH V2] doc/opal-api : Document opal-api's related to errorlog

[Mukesh Ojha]

Hi Vasant,

Thanks for the review.
All the comments has been taken care in the V3 of this patch.

Regards,
Mukesh

On Wednesday 13 July 2016 12:30 PM, Vasant Hegde wrote:
> On 07/08/2016 02:30 PM, Mukesh Ojha wrote:
>> It documents opal-api's related to errorlog.
>> 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>
>>
>> ---
>> 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.txt | 119 
>> ++++++++++++++++++++++++++++++
>>   1 file changed, 119 insertions(+)
>>   create mode 100644 doc/opal-api/opal-elog-71-72-73-74-75.txt
>>
>> diff --git a/doc/opal-api/opal-elog-71-72-73-74-75.txt 
>> b/doc/opal-api/opal-elog-71-72-73-74-75.txt
>> new file mode 100644
>> index 0000000..f6f501b
>> --- /dev/null
>> +++ b/doc/opal-api/opal-elog-71-72-73-74-75.txt
>> @@ -0,0 +1,119 @@
>> +Error logging on FSP based machine:
>> +----------------------------------
>> +
>> +There are five OPAL calls for errorlog on FSP based machine:
>
> These are generic API's , not specific to FSP.  Presently only FSP 
> based machine is using these API's.
> Hence we don't need to mention FSP here.
>
>
>> +
>> +#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 register callbacks with the above tokens.
>
> There is no registration in host.. All these API's are called by 
> kernel. We can check given API is supported or not before calling.
>
>> +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);
>> +    OPAL_CALL(opal_write_elog,        OPAL_ELOG_WRITE);
>
> I think we can remove above line as we are not using this API now .. I 
> doubt we will use it anytime soon.
>
>> +
>> +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 corressponding interface(fsp_opal_elog_read) in the OPAL.
>
> s/corressponding/corresponding/
>
>> +
>> +e.g.
>> +
>> +Below is the example of one of the call from the host kernel.
>> +<Snippet>:
>> +    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 errorlog 
>> content to
>
> Better "error log"
>
>> +the passed buffer with the passed elog id and elog size from the 
>> host kernel.
>> +
>> +OPAL_ELOG_READ accepts 3 parameters:
>> +- elog buffer
>> +- elog size
>> +- 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 
>> errorlog 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.
>> +
>> +It returns OPAL_SUCCESS on successfully copying the errorlog 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 FSP and move the
>
> s/acknowledgement/acknowledgment/
>
> Also s/FSP/service processor/   -OR- just say ...to error log source.
>
>
>> +acknowledge elog id from processed list to the read free list.
>> +
>> +OPAL_ELOG_ACK accepts 1 parameter::
>> +- ack id
>> +
>> +In case of opal errorlogs, 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 acknowledement to the FSP and OPAL_SUCCESS on success.
>> +
>> +
>> +OPAL_ELOG_RESEND
>> +----------------
>> +
>> +This token is used to register a call which will resend all the 
>> elogs again to
>
> error log
>
>> +new kexec kernel.
>
> We can resend all the error log anytime, not just new kexec kernel. 
> Today we make this call from
> 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
>> +errorlog like id, size and type.
>> +
>> +OPAL_ELOG_SIZE accepts 3 parameters:
>> +- elog ID
>> +- elog size
>> +- elog type
>> +
>
>
> We have type field so that these API"s can support multiple error log 
> format. today its PEL format.
>
> Hence document type field here.
>
>
> -Vasant
>