Messages in this thread | | | From | Michael Ellerman <> | Subject | Re: [PATCH v4 3/3] powerpc/powernv: Parse device tree, population of SPR support | Date | Tue, 17 Mar 2020 14:13:31 +1100 |
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Pratik Rajesh Sampat <psampat@linux.ibm.com> writes: > Parse the device tree for nodes self-save, self-restore and populate > support for the preferred SPRs based what was advertised by the device > tree.
These should be documented in: Documentation/devicetree/bindings/powerpc/opal/power-mgt.txt
> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c > index 97aeb45e897b..27dfadf609e8 100644 > --- a/arch/powerpc/platforms/powernv/idle.c > +++ b/arch/powerpc/platforms/powernv/idle.c > @@ -1436,6 +1436,85 @@ static void __init pnv_probe_idle_states(void) > supported_cpuidle_states |= pnv_idle_states[i].flags; > } > > +/* > + * Extracts and populates the self save or restore capabilities > + * passed from the device tree node > + */ > +static int extract_save_restore_state_dt(struct device_node *np, int type) > +{ > + int nr_sprns = 0, i, bitmask_index; > + int rc = 0; > + u64 *temp_u64; > + u64 bit_pos; > + > + nr_sprns = of_property_count_u64_elems(np, "sprn-bitmask"); > + if (nr_sprns <= 0) > + return rc;
Using <= 0 means zero SPRs is treated by success as the caller, is that intended? If so a comment would be appropriate.
> + temp_u64 = kcalloc(nr_sprns, sizeof(u64), GFP_KERNEL); > + if (of_property_read_u64_array(np, "sprn-bitmask", > + temp_u64, nr_sprns)) { > + pr_warn("cpuidle-powernv: failed to find registers in DT\n"); > + kfree(temp_u64); > + return -EINVAL; > + } > + /* > + * Populate acknowledgment of support for the sprs in the global vector > + * gotten by the registers supplied by the firmware. > + * The registers are in a bitmask, bit index within > + * that specifies the SPR > + */ > + for (i = 0; i < nr_preferred_sprs; i++) { > + bitmask_index = preferred_sprs[i].spr / 64; > + bit_pos = preferred_sprs[i].spr % 64;
This is basically a hand coded bitmap, see eg. BIT_WORD(), BIT_MASK() etc.
I don't think there's an easy way to convert temp_u64 into a proper bitmap, so it's probably not worth doing that. But at least use the macros.
> + if ((temp_u64[bitmask_index] & (1UL << bit_pos)) == 0) { > + if (type == SELF_RESTORE_TYPE) > + preferred_sprs[i].supported_mode &= > + ~SELF_RESTORE_STRICT; > + else > + preferred_sprs[i].supported_mode &= > + ~SELF_SAVE_STRICT; > + continue; > + } > + if (type == SELF_RESTORE_TYPE) { > + preferred_sprs[i].supported_mode |= > + SELF_RESTORE_STRICT; > + } else { > + preferred_sprs[i].supported_mode |= > + SELF_SAVE_STRICT; > + } > + } > + > + kfree(temp_u64); > + return rc; > +} > + > +static int pnv_parse_deepstate_dt(void) > +{ > + struct device_node *sr_np, *ss_np;
You never use these concurrently AFAICS, so you could just have a single *np.
> + int rc = 0, i; > + > + /* Self restore register population */ > + sr_np = of_find_node_by_path("/ibm,opal/power-mgt/self-restore");
I know the existing idle code uses of_find_node_by_path(), but that's because it's old and crufty. Please don't add new searches by path. You should be searching by compatible.
> + if (!sr_np) { > + pr_warn("opal: self restore Node not found");
This warning and the others below will fire on all existing firmware versions, which is not OK.
> + } else { > + rc = extract_save_restore_state_dt(sr_np, SELF_RESTORE_TYPE); > + if (rc != 0) > + return rc; > + } > + /* Self save register population */ > + ss_np = of_find_node_by_path("/ibm,opal/power-mgt/self-save"); > + if (!ss_np) { > + pr_warn("opal: self save Node not found"); > + pr_warn("Legacy firmware. Assuming default self-restore support"); > + for (i = 0; i < nr_preferred_sprs; i++) > + preferred_sprs[i].supported_mode &= ~SELF_SAVE_STRICT; > + } else { > + rc = extract_save_restore_state_dt(ss_np, SELF_SAVE_TYPE); > + } > + return rc;
You're leaking references on all the device_nodes in here, you need of_node_put() before exiting.
> +}
cheers
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