The LTR values follow PCIE LTR encoding format and can be decoded as per https://pcisig.com/sites/default/files/specification_documents/ECN_LatencyTolnReporting_14Aug08.pdf
This adds support to translate the raw LTR values as read from the PMC to meaningful values in nanosecond units of time. Signed-off-by: Rajneesh Bhardwaj <[email protected]> --- drivers/platform/x86/intel_pmc_core.c | 62 ++++++++++++++++++++++++++- drivers/platform/x86/intel_pmc_core.h | 14 ++++++ 2 files changed, 74 insertions(+), 2 deletions(-) diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c index c1330a03523d..ffa912a8a5f5 100644 --- a/drivers/platform/x86/intel_pmc_core.c +++ b/drivers/platform/x86/intel_pmc_core.c @@ -651,16 +651,74 @@ static int pmc_core_slps0_dbg_show(struct seq_file *s, void *unused) } DEFINE_SHOW_ATTRIBUTE(pmc_core_slps0_dbg); +static void get_ltr_scale(u32 *val) +{ + /* + * As per PCIE specification supprting document + * ECN_LatencyTolnReporting_14Aug08.pdf the Latency + * Tolerance Reporting data payload is encoded in a + * 3 bit scale and 10 bit value fields. Values are + * multiplied by the indicated scale to yield an absolute time + * value, expressible in a range from 1 nanosecond to + * 2^25*(2^10-1) = 34,326,183,936 nanoseconds. + * + * scale encoding is as follows: + * + * ---------------------------------------------- + * |scale factor | Multiplier (ns) | + * ---------------------------------------------- + * | 0 | 1 | + * | 1 | 32 | + * | 2 | 1024 | + * | 3 | 32768 | + * | 4 | 1048576 | + * | 5 | 33554432 | + * | 6 | Invalid | + * | 7 | Invalid | + * ---------------------------------------------- + */ + if (*val > 5) { + *val = 0; + pr_warn("Invalid LTR scale factor.\n"); + } else { + *val = 1U << (5 * (*val)); + } +} + static int pmc_core_ltr_show(struct seq_file *s, void *unused) { struct pmc_dev *pmcdev = s->private; const struct pmc_bit_map *map = pmcdev->map->ltr_show_sts; + u64 decoded_snoop_ltr = 0, decoded_non_snoop_ltr = 0; + union ltr_payload ltr_data; + u32 scale = 0; int index; for (index = 0; map[index].name ; index++) { - seq_printf(s, "%-32s\tRAW LTR: 0x%x\n", + ltr_data.raw_data = pmc_core_reg_read(pmcdev, + map[index].bit_mask); + + if (ltr_data.bits.non_snoop_req) { + scale = ltr_data.bits.non_snoop_scale; + get_ltr_scale(&scale); + decoded_non_snoop_ltr = + ltr_data.bits.non_snoop_val * scale; + } + + if (ltr_data.bits.snoop_req) { + scale = ltr_data.bits.snoop_scale; + get_ltr_scale(&scale); + decoded_snoop_ltr = + ltr_data.bits.snoop_val * scale; + } + + seq_printf(s, "%-24s\tRaw LTR: 0x%-16x\t Non-Snoop LTR (ns): %-16llu\t Snoop LTR (ns): %-16llu\n", map[index].name, - pmc_core_reg_read(pmcdev, map[index].bit_mask)); + ltr_data.raw_data, + decoded_non_snoop_ltr, + decoded_snoop_ltr); + + decoded_snoop_ltr = decoded_non_snoop_ltr = 0; } return 0; } diff --git a/drivers/platform/x86/intel_pmc_core.h b/drivers/platform/x86/intel_pmc_core.h index 12663c58f122..bbf9a2790548 100644 --- a/drivers/platform/x86/intel_pmc_core.h +++ b/drivers/platform/x86/intel_pmc_core.h @@ -243,4 +243,18 @@ struct pmc_dev { struct mutex lock; /* generic mutex lock for PMC Core */ }; +union ltr_payload { + u32 raw_data; + struct { + u32 snoop_val : 10; + u32 snoop_scale : 3; + u32 snoop_res : 2; + u32 snoop_req : 1; + u32 non_snoop_val : 10; + u32 non_snoop_scale : 3; + u32 non_snoop_res : 2; + u32 non_snoop_req : 1; + } bits; +}; + #endif /* PMC_CORE_H */ -- 2.17.1
