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 <rajneesh.bhardwaj@xxxxxxxxxxxxxxx> --- Changes in v2: * Get rid of union and bitfields to decode LTR and use FIELD_GET macro * Change get_ltr_scale to convert_ltr_scale. * Other style fixes and misc. improvements suggested by Andy for v1. drivers/platform/x86/intel_pmc_core.c | 64 +++++++++++++++++++++++++-- drivers/platform/x86/intel_pmc_core.h | 5 +++ 2 files changed, 66 insertions(+), 3 deletions(-) diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c index c616cfedf2be..fbcab53456f3 100644 --- a/drivers/platform/x86/intel_pmc_core.c +++ b/drivers/platform/x86/intel_pmc_core.c @@ -21,6 +21,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/acpi.h> +#include <linux/bitfield.h> #include <linux/debugfs.h> #include <linux/delay.h> #include <linux/io.h> @@ -650,16 +651,73 @@ static int pmc_core_slps0_dbg_show(struct seq_file *s, void *unused) } DEFINE_SHOW_ATTRIBUTE(pmc_core_slps0_dbg); +static u32 convert_ltr_scale(u32 val) +{ + u32 scale = 0; + /* + * As per PCIE specification supporting 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) + pr_warn("Invalid LTR scale factor.\n"); + else + scale = 1U << (5 * (val)); + + return scale; +} + 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, decoded_non_snoop_ltr; + u32 ltr_raw_data, scale, val; + u16 snoop_ltr, nonsnoop_ltr; int index; for (index = 0; map[index].name ; index++) { - seq_printf(s, "IP %-2d :%-32s\tRAW LTR: 0x%x\n", index, - map[index].name, - pmc_core_reg_read(pmcdev, map[index].bit_mask)); + decoded_snoop_ltr = decoded_non_snoop_ltr = 0; + ltr_raw_data = pmc_core_reg_read(pmcdev, + map[index].bit_mask); + snoop_ltr = ltr_raw_data & ~MTPMC_MASK; + nonsnoop_ltr = (ltr_raw_data >> 0x10) & ~MTPMC_MASK; + + if (FIELD_GET(LTR_REQ_NONSNOOP, ltr_raw_data)) { + scale = FIELD_GET(LTR_DECODED_SCALE, nonsnoop_ltr); + val = FIELD_GET(LTR_DECODED_VAL, nonsnoop_ltr); + decoded_non_snoop_ltr = val * convert_ltr_scale(scale); + } + + if (FIELD_GET(LTR_REQ_SNOOP, ltr_raw_data)) { + scale = FIELD_GET(LTR_DECODED_SCALE, snoop_ltr); + val = FIELD_GET(LTR_DECODED_VAL, snoop_ltr); + decoded_snoop_ltr = val * convert_ltr_scale(scale); + } + + seq_printf(s, "IP %-2d :%-24s\tRaw LTR: 0x%-16x\t Non-Snoop LTR (ns): %-16llu\t Snoop LTR (ns): %-16llu\n", + index, map[index].name, ltr_raw_data, + decoded_non_snoop_ltr, + decoded_snoop_ltr); } return 0; } diff --git a/drivers/platform/x86/intel_pmc_core.h b/drivers/platform/x86/intel_pmc_core.h index 7f8181057ec8..cc49cd4c86e9 100644 --- a/drivers/platform/x86/intel_pmc_core.h +++ b/drivers/platform/x86/intel_pmc_core.h @@ -177,6 +177,11 @@ enum ppfear_regs { #define CNP_PMC_LTR_EMMC 0x1BF4 #define CNP_PMC_LTR_UFSX2 0x1BF8 +#define LTR_REQ_NONSNOOP BIT(31) +#define LTR_REQ_SNOOP BIT(15) +#define LTR_DECODED_VAL GENMASK(9, 0) +#define LTR_DECODED_SCALE GENMASK(12, 10) + struct pmc_bit_map { const char *name; u32 bit_mask; -- 2.17.1
