[Skiboot] [PATCH v3] occ: Poll OCC throttle status and queue OCC events to host

[Preeti U Murthy]

Hi Shilpa,

On 05/21/2015 03:50 PM, Shilpasri G Bhat wrote:
> Add a new class of message definition OPAL_MSG_OCC to
> opal_message_type to notify the following OCC events to host:
> 1) OCC Reset
> 2) OCC Load
> 3) OCC Throttle Status Change
> 
> Add an opal poller to periodically read throttle status updated by OCC
> for each chip and notify any change in throttle status to host. The
> throttle status indicates the reason why OCC may have limited the max
> Pstate of the chip.
> 
> Signed-off-by: Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com>
> ---
> Changes from V2:
> - Added documentation of OPAL_MSG_OCC to doc/opal-api/opal-messages.txt
> - Moved macros OCC_RESET, OCC_LOAD, OCC_THROTTLE to opal-api.h
> - Added a structure opal_occ_msg.
> 
> Changes from V1:
> - Initialize prev_throttle to 0 instead of 0xF
> - Add pr_log when opal_queue_msg() fails on OCC reset and load.
> - Do not update occ_reset and prev_throttle if opal_queue_msg fails in
>   occ_throttle_poll() 
> - Do not queue if throttle reason is greater than 5.
> 
>  doc/opal-api/opal-messages.txt | 37 ++++++++++++++++++
>  hw/occ.c                       | 89 ++++++++++++++++++++++++++++++++++++++++++
>  include/chip.h                 |  1 +
>  include/opal-api.h             | 24 ++++++++++++
>  4 files changed, 151 insertions(+)
> 
> diff --git a/doc/opal-api/opal-messages.txt b/doc/opal-api/opal-messages.txt
> index fdde247..451b217 100644
> --- a/doc/opal-api/opal-messages.txt
> +++ b/doc/opal-api/opal-messages.txt
> @@ -158,3 +158,40 @@ struct opal_prd_msg:
> 
>  Responses from the kernel use the same message format, but are passed
>  through the opal_prd_msg call.
> +
> +OPAL_MSG_OCC
> +------------
> +
> +This is used by OPAL to inform host about OCC events like OCC reset,
> +OCC load and throttle status change by OCC which can indicate the
> +host the reason for frequency throttling/unthrottling.
> +
> +#define OCC_RESET	0
> +#define OCC_LOAD 	1
> +#define OCC_THROTTLE 	2
> +
> +/*
> + * struct opal_occ_msg:
> + * type: OCC_RESET, OCC_LOAD, OCC_THROTTLE
> + * chip: chip id
> + * throttle status: Indicates the reason why OCC may have limited
> + * the max Pstate of the chip.
> + * 0x00 = No throttle
> + * 0x01 = Power Cap
> + * 0x02 = Processor Over Temperature
> + * 0x03 = Power Supply Failure (currently not used)
> + * 0x04 = Over current (currently not used)
> + * 0x05 = OCC Reset (not reliable as some failures will not allow for
> + * OCC to update throttle status)
> + */
> +struct opal_occ_msg {
> +	__be64 type;
> +	__be64 chip;
> +	__be64 throttle_status;
> +};
> +
> +Host should read opal_occ_msg.chip and opal_occ_msg.throttle_status
> +only when opal_occ_msg.type = OCC_THROTTLE.
> +If opal_occ_msg.type > 2 then host should ignore the message for now,
> +new events can be defined for opal_occ_msg.type in the future
> +versions of OPAL.
> diff --git a/hw/occ.c b/hw/occ.c
> index fe513cb..7d11c4f 100644
> --- a/hw/occ.c
> +++ b/hw/occ.c
> @@ -24,6 +24,8 @@
>  #include <timebase.h>
>  #include <hostservices.h>
>  #include <errorlog.h>
> +#include <opal-api.h>
> +#include <opal-msg.h>
> 
>  /* OCC Communication Area for PStates */
> 
> @@ -31,6 +33,13 @@
> 
>  #define MAX_PSTATES 256
> 
> +struct opal_occ_msg occ_msg;
> +#define chip_occ_data(chip) \
> +		((struct occ_pstate_table *)(chip->homer_base + \
> +				P8_HOMER_SAPPHIRE_DATA_OFFSET))
> +
> +static bool occ_reset;
> +
>  struct occ_pstate_entry {
>  	s8 id;
>  	u8 flags;
> @@ -302,6 +311,54 @@ static bool cpu_pstates_prepare_core(struct proc_chip *chip, struct cpu_thread *
>  	return true;
>  }
> 
> +static void occ_throttle_poll(void *data __unused)
> +{
> +	struct proc_chip *chip;
> +	struct occ_pstate_table *occ_data;
> +	int rc;
> +
> +	if (occ_reset) {
> +		int inactive = 0;
> +
> +		for_each_chip(chip) {
> +			occ_data = chip_occ_data(chip);
> +			if (occ_data->valid != 1) {
> +				inactive = 1;
> +				break;
> +			}
> +		}
> +		if (!inactive) {
> +			/*
> +			 * Queue OCC_THROTTLE with throttle status as 0 to
> +			 * indicate all OCCs are active after a reset.
> +			 */
> +			occ_msg.type = OCC_THROTTLE;
> +			occ_msg.chip = 0;
> +			occ_msg.throttle_status = 0;
> +			rc = _opal_queue_msg(OPAL_MSG_OCC, NULL, NULL, 3,
> +					     (uint64_t *)&occ_msg);

Note that the corresponding patch in the kernel is expecting three
parameters, while now we are passing just one.

Regards
Preeti U Murthy