The Coresight SoC 600 TMC ETR supports save-restore feature, where the values of the RRP/RWP and STS.Full are retained when it leaves the Disabled state. Hence, we must program the RRP/RWP and STS.Full to a proper value. For now, set the RRP/RWP to the base address of the buffer and clear the STS.Full register. This can be later exploited for proper save-restore of ETR trace contexts (e.g, perf).
Cc: Mathieu Poirier <[email protected]> Signed-off-by: Suzuki K Poulose <[email protected]> --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 13 ++++++++++++- drivers/hwtracing/coresight/coresight-tmc.h | 8 ++++++++ 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index ff11b92..7294fb7 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -22,7 +22,7 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata) { - u32 axictl; + u32 axictl, sts; /* Zero out the memory to help with debug */ memset(drvdata->vaddr, 0, drvdata->size); @@ -45,6 +45,17 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata) TMC_AXICTL_PROT_CTL_B1; writel_relaxed(axictl, drvdata->base + TMC_AXICTL); tmc_write_dba(drvdata, drvdata->paddr); + /* + * If the TMC pointers must be programmed before the session, + * we have to set it properly (i.e, RRP/RWP to base address and + * STS to "not full"). + */ + if (tmc_has_cap(drvdata, TMC_CAP_ETR_SAVE_RESTORE)) { + tmc_write_rrp(drvdata, drvdata->paddr); + tmc_write_rwp(drvdata, drvdata->paddr); + sts = readl_relaxed(drvdata->base + TMC_STS) & ~TMC_STS_FULL; + writel_relaxed(sts, drvdata->base + TMC_STS); + } writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI | TMC_FFCR_FON_FLIN | TMC_FFCR_FON_TRIG_EVT | diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h index 87e4561..d5ef51e 100644 --- a/drivers/hwtracing/coresight/coresight-tmc.h +++ b/drivers/hwtracing/coresight/coresight-tmc.h @@ -90,6 +90,14 @@ enum tmc_mem_intf_width { }; #define TMC_CAP_ETR_SG_UNIT (1U << 0) +/* + * TMC_CAP_ETR_SAVE_RESTORE - Values of RRP/RWP/STS.Full are + * retained when TMC leaves Disabled state, allowing us to continue + * the tracing from a point where we stopped. This also implies that + * the RRP/RWP/STS.Full should always be programmed to the correct + * value. + */ +#define TMC_CAP_ETR_SAVE_RESTORE (1U << 1) /** * struct tmc_cap - Describes the capabilities of the TMC. -- 2.7.5
