cppc: advertise optional fast-channel doorbell (follow-up to autonomous mode) - #119
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@vlsunil FYI |
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The CPPC GET_FAST_CHANNEL_REGION service defines an optional doorbell (FLAGS[0] support, FLAGS[2:1] width, and the doorbell address plus write value in response words 6-8) that lets the application processor signal the platform microcontroller after updating its Perf Request fast-channel, instead of relying on polling. librpmi previously hardcoded these fields to zero, so a platform could never advertise a doorbell. Add an optional doorbell descriptor (struct rpmi_cppc_fastchan_doorbell) embedded in struct rpmi_cppc_regs, mirroring how the performance service group carries its doorbell in static platform data. When RPMI_CPPC_FST_CHN_DB_SUPP is set, GET_FAST_CHANNEL_REGION reports the doorbell; otherwise the response is unchanged. The create() signature is not modified. librpmi only advertises the doorbell; raising the doorbell interrupt and invoking rpmi_context_process_group_events() from the handler remains a platform responsibility. Add tests for doorbell advertisement in passive and autonomous mode, and S-mode access to GET_FAST_CHANNEL_REGION. Signed-off-by: Ivo Costa <ivo.costa@sifive.com>
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This is a follow-up to the previous PR that added CPPC autonomous mode. While wiring up
GET_FAST_CHANNEL_REGIONfor autonomous mode, one commit was forgotten. The optional fast-channel doorbell that the same service advertise, this PR fills that gap.Until now librpmi hardcoded these fields to zero, so even with the rest of the fast-channel path in place a platform had no way to advertise a doorbell.
The doorbell lets the application processor signal the platform microcontroller
after updating its Perf Request fast-channel, instead of relying on polling. It
is described by:
librpmi was still hardcoding these fields to zero, so a platform could never advertise a doorbell even though the rest of the fast-channel path was in place.
Tests
Added test coverage for:
FLAGS[4:3]+ doorbell bits)GET_FAST_CHANNEL_REGION