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coresight tmc: Support for save-restore in ETR 

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 <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zero-colors
Suzuki K Poulose 2017-08-02 10:22:16 -06:00 committed by Greg Kroah-Hartman
parent ebab6a7db2
commit f2e931a2de
2 changed files with 21 additions and 1 deletions
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13
drivers/hwtracing/coresight/coresight-tmc-etr.c
View File

@ -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);
@ -47,6 +47,17 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
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_etr_has_cap(drvdata, TMC_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 |

9
drivers/hwtracing/coresight/coresight-tmc.h
View File

@ -119,6 +119,15 @@ enum tmc_mem_intf_width {
#define TMC_ETR_SG (0x1U << 0)
/* ETR has separate read/write cache encodings */
#define TMC_ETR_AXI_ARCACHE (0x1U << 1)
/*
* TMC_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. Unfortunately this is not advertised by the hardware,
* so we have to rely on PID of the IP to detect the functionality.
*/
#define TMC_ETR_SAVE_RESTORE (0x1U << 2)
/**
* struct tmc_drvdata - specifics associated to an TMC component