[Skiboot] [PATCH] Add in new OPAL call to flush the L2 and L3 caches.

[Alistair Popple]

Hi Rashmica,

> > +	}
> > +	start_time = tb_to_msecs(mftb());
> > +	while ((val & L2_PRD_PURGE_CMD_REG_BUSY) && !(timeout =
> > time_expired(start_time))) {
> Can we please not have '=' in a condition?

...

> ... and ditch this check. And the time_expired() helper (which does not
> seem to help much anyway). And the local @timeout variable. And '=' in
> the condition :)

Take a look at the tb_compare() function (and perhaps how others use it). I 
think that probably does what you want.

- Alistair

> > +
> > +	/* We have to clear the trigger bit ourselves */
> > +	val &= ~L2_PRD_PURGE_CMD_TRIGGER;
> > +	rc = xscom_write(chip_id, addr, val);
> > +	if (rc)
> > +		prlog(PR_ERR, "FLUSH L2 on core 0x%x: XSCOM write failed %i\n",
> > core_id, rc); +	return 0;
> 
> Why not return rc?
> 
> > +
> > +}
> > +
> > +static int flush_l3_caches(uint32_t chip_id, uint32_t core_id)
> > +{
> > +	int rc, timeout = 0;
> > +	unsigned long start_time;
> > +	uint64_t val = L3_PRD_PURGE_REQ;
> > +	uint64_t addr = XSCOM_ADDR_P9_EX(core_id, L3_PRD_PURGE_REG);
> > +
> > +	rc = xscom_write_mask(chip_id, addr, L3_PRD_PURGE_REQ,
> > L3_PRD_PURGE_REQ);
> 
> Similar to L2CAC_FLUSH question here:
> 
>  putspy pu.ex EXP.L3.L3_MISC.L3CERRS.L3_PRD_PURGE_TTYPE FULL_PURGE -all
> 
>  putspy pu.ex EXP.L3.L3_MISC.L3CERRS.L3_PRD_PURGE_REQ ON -all
> 
> 
> There is L3_PRD_PURGE_REQ but no FULL_PURGE.
> 
> > +	if (rc) {
> > +		prlog(PR_ERR, "FLUSH L3 on core 0x%x: XSCOM write_mask failed %i
\n",
> > core_id, rc);
> return rc?
> 
> > +	}
> > +
> > +	/* Trigger bit is automatically set to zero when flushing is done*/
> > +	start_time = tb_to_msecs(mftb());
> > +	while ((val & L3_PRD_PURGE_REQ) && !(timeout = 
time_expired(start_time)
> > )) { +		rc = xscom_read(chip_id, addr, &val);
> > +		if (rc) {
> > +			prlog(PR_ERR, "FLUSH L3 on core 0x%x: XSCOM read failed %i\n",
> > core_id, rc); +			break;
> > +		}
> > +	}
> > +	if (timeout) {
> > +		prlog(PR_ERR, "FLUSH L3 on core 0x%x timed out %i\n", core_id, 
rc);
> > +		return OPAL_BUSY;
> > +	}
> > +
> > +	return 0;
> 
> return rc?
> 
> > +}
> > +
> > +int flush_caches(void)
> 
> OPAL calls return int64_t. And the handlers are static so there is no
> reason to export the symbol via include/cpu.h below.
> 
> > +{
> > +	int rc = 0;
> > +	struct cpu_thread *t;
> > +	uint64_t chip_id, core_id, prev_core_id = 0xdeadbeef;
> > +
> > +	if ((mfspr(SPR_PVR) & PVR_TYPE_P9) != PVR_TYPE_P9)
> > +		return OPAL_UNSUPPORTED;
> > +
> > +	for_each_cpu(t) {
> > +		/* Only need to do it once per core chiplet */
> > +		core_id = pir_to_core_id(t->pir);
> > +		if (prev_core_id == core_id)
> > +			continue;
> > +		prev_core_id = core_id;
> > +		chip_id = t->chip_id;
> 
> The chip_id local variable seems pretty useless, could just use t->chip_id.
> 
> > +
> > +		rc |= flush_l2_caches(chip_id, core_id);
> > +		rc |= flush_l3_caches(chip_id, core_id);
> > +	}
> > +
> > +	return rc;
> > +}
> > +
> > +
> 
> Extra empty line?
> 
> > +opal_call(OPAL_CLEAR_CACHE, flush_caches, 0);
> > diff --git a/include/cpu.h b/include/cpu.h
> > index 2fe47982..04c862c5 100644
> > --- a/include/cpu.h
> > +++ b/include/cpu.h
> > @@ -329,4 +329,6 @@ int dctl_set_special_wakeup(struct cpu_thread *t);
> > 
> >  int dctl_clear_special_wakeup(struct cpu_thread *t);
> >  int dctl_core_is_gated(struct cpu_thread *t);
> > 
> > +extern int flush_caches(void);
> > +
> > 
> >  #endif /* __CPU_H */
> > 
> > diff --git a/include/opal-api.h b/include/opal-api.h
> > index 5f397c8e..c24838d2 100644
> > --- a/include/opal-api.h
> > +++ b/include/opal-api.h
> > @@ -226,7 +226,8 @@
> > 
> >  #define OPAL_NX_COPROC_INIT			167
> >  #define OPAL_NPU_SET_RELAXED_ORDER		168
> >  #define OPAL_NPU_GET_RELAXED_ORDER		169
> > 
> > -#define OPAL_LAST				169
> > +#define OPAL_CLEAR_CACHE			170
> 
> s/clear/purge/. The scoms calls it "purge", let's stick to this name.
> 
> > +#define OPAL_LAST				170
> > 
> >  #define QUIESCE_HOLD			1 /* Spin all calls at entry */
> >  #define QUIESCE_REJECT			2 /* Fail all calls with OPAL_BUSY */