Pcode

Xe PCODE is the component responsible for interfacing with the PCODE firmware. It shall provide a very simple ABI to other Xe components, but be the single and consolidated place that will communicate with PCODE. All read and write operations to PCODE will be internal and private to this component.

What’s next: - PCODE hw metrics - PCODE for display operations

Internal API

int xe_pcode_request(struct xe_tile *tile, u32 mbox, u32 request, u32 reply_mask, u32 reply, int timeout_base_ms)

send PCODE request until acknowledgment

Parameters

struct xe_tile *tile

tile

u32 mbox

PCODE mailbox ID the request is targeted for

u32 request

request ID

u32 reply_mask

mask used to check for request acknowledgment

u32 reply

value used to check for request acknowledgment

int timeout_base_ms

timeout for polling with preemption enabled

Description

Keep resending the request to mbox until PCODE acknowledges it, PCODE reports an error or an overall timeout of timeout_base_ms**+50 ms expires. The request is acknowledged once the PCODE reply dword equals **reply after applying reply_mask. Polling is first attempted with preemption enabled for timeout_base_ms and if this times out for another 50 ms with preemption disabled.

Returns 0 on success, -ETIMEDOUT in case of a timeout, <0 in case of some other error as reported by PCODE.

int xe_pcode_init_min_freq_table(struct xe_tile *tile, u32 min_gt_freq, u32 max_gt_freq)

Initialize PCODE’s QOS frequency table

Parameters

struct xe_tile *tile

tile instance

u32 min_gt_freq

Minimal (RPn) GT frequency in units of 50MHz.

u32 max_gt_freq

Maximal (RP0) GT frequency in units of 50MHz.

Description

This function initialize PCODE’s QOS frequency table for a proper minimal frequency/power steering decision, depending on the current requested GT frequency. For older platforms this was a more complete table including the IA freq. However for the latest platforms this table become a simple 1-1 Ring vs GT frequency. Even though, without setting it, PCODE might not take the right decisions for some memory frequencies and affect latency.

It returns 0 on success, and -ERROR number on failure, -EINVAL if max frequency is higher then the minimal, and other errors directly translated from the PCODE Error returs: - -ENXIO: “Illegal Command” - -ETIMEDOUT: “Timed out” - -EINVAL: “Illegal Data” - -ENXIO, “Illegal Subcommand” - -EBUSY: “PCODE Locked” - -EOVERFLOW, “GT ratio out of range” - -EACCES, “PCODE Rejected” - -EPROTO, “Unknown”

int xe_pcode_ready(struct xe_device *xe, bool locked)

Ensure PCODE is initialized

Parameters

struct xe_device *xe

xe instance

bool locked

true if lock held, false otherwise

Description

PCODE init mailbox is polled only on root gt of root tile as the root tile provides the initialization is complete only after all the tiles have completed the initialization. Called only on early probe without locks and with locks in resume path.

Returns 0 on success, and -error number on failure.

void xe_pcode_init(struct xe_tile *tile)

initialize components of PCODE

Parameters

struct xe_tile *tile

tile instance

Description

This function initializes the xe_pcode component. To be called once only during probe.

int xe_pcode_probe_early(struct xe_device *xe)

initializes PCODE

Parameters

struct xe_device *xe

xe instance

Description

This function checks the initialization status of PCODE To be called once only during early probe without locks.

Returns 0 on success, error code otherwise