On Wed, Oct 22, 2025 at 12:45:20AM +0100, Mike Leach wrote:
[...]
+/*
- Reading CLIAMSET returns a bitfield representing the number of claim tags
- implemented from bit 0 to bit nTag-1, valid bits set to 1.
- Claim protocol requires 2 bits so test for highest bit required,
- bit 1 - CORESIGHT_CLAIM_SELF_HOSTED_BIT
- return true if sufficient claim tags implemented for protocol
- */
+static bool coresight_claim_tags_implemented_unlocked(struct csdev_access *csa) +{
- u32 claim_bits_impl = FIELD_GET(CORESIGHT_CLAIM_BITS_MAX_MASK,
csdev_access_relaxed_read32(csa, CORESIGHT_CLAIMSET));- return ((claim_bits_impl & CORESIGHT_CLAIM_SELF_HOSTED_BIT) != 0);
+}
The logic looks good to me.
Can we improve a bit with a cached flag to avoid every time checking the CLAIMSET, we can read it only once at init time instead.
- We can add a new flag ("bool claim_impl" in the struct csdev_access), by default the field will be zero.
- The drivers support claim tags call coresight_clear_self_claim_tag() in probe (see __catu_probe() as an example), we can call a new function coresight_init_claim_tag() to replace it, this function sets "claim_impl" properly and clear the tag if supported.
- Afterwards, simply check the "claim_impl" flag.
[...]
+/*
- Coresight specification defines a maximum of 8 claim tag bits.
- The precise number is implementation defined, and may be obtained by
- reading the CLAIMSET register.
- */
+#define CORESIGHT_CLAIM_BITS_MAX_MASK GENMASK(7, 0) +#define CORESIGHT_CLAIM_SELF_HOSTED_BIT BIT(1)
Now we only care about the self-host bit. Can reuse existed macros ?
CORESIGHT_CLAIM_MASK CORESIGHT_CLAIM_SELF_HOSTED
I don't mind if extend CORESIGHT_CLAIM_MASK to 8 bits and even remove CORESIGHT_CLAIM_INVALID (as it cannot cover other invalid values). Or we can defer the extension as needed later.
Thanks, Leo