TRCSTALLCTLR register is only implemented if

   TRCIDR3.STALLCTL == 0b1

Make sure the driver touches the register only it is implemented.

Cc: [email protected]
Cc: Mathieu Poirier <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mike Leach <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
---
Changes since v1:
  - No change to the patch, fixed the stable email address and
    added usual reviewers.
---
 drivers/hwtracing/coresight/coresight-etm4x-core.c  | 9 ++++++---
 drivers/hwtracing/coresight/coresight-etm4x-sysfs.c | 3 +++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c 
b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index b40e3c2bf818..814b49dae0c7 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -367,7 +367,8 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
        etm4x_relaxed_write32(csa, 0x0, TRCAUXCTLR);
        etm4x_relaxed_write32(csa, config->eventctrl0, TRCEVENTCTL0R);
        etm4x_relaxed_write32(csa, config->eventctrl1, TRCEVENTCTL1R);
-       etm4x_relaxed_write32(csa, config->stall_ctrl, TRCSTALLCTLR);
+       if (drvdata->stallctl)
+               etm4x_relaxed_write32(csa, config->stall_ctrl, TRCSTALLCTLR);
        etm4x_relaxed_write32(csa, config->ts_ctrl, TRCTSCTLR);
        etm4x_relaxed_write32(csa, config->syncfreq, TRCSYNCPR);
        etm4x_relaxed_write32(csa, config->ccctlr, TRCCCCTLR);
@@ -1545,7 +1546,8 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata)
        state->trcauxctlr = etm4x_read32(csa, TRCAUXCTLR);
        state->trceventctl0r = etm4x_read32(csa, TRCEVENTCTL0R);
        state->trceventctl1r = etm4x_read32(csa, TRCEVENTCTL1R);
-       state->trcstallctlr = etm4x_read32(csa, TRCSTALLCTLR);
+       if (drvdata->stallctl)
+               state->trcstallctlr = etm4x_read32(csa, TRCSTALLCTLR);
        state->trctsctlr = etm4x_read32(csa, TRCTSCTLR);
        state->trcsyncpr = etm4x_read32(csa, TRCSYNCPR);
        state->trcccctlr = etm4x_read32(csa, TRCCCCTLR);
@@ -1657,7 +1659,8 @@ static void etm4_cpu_restore(struct etmv4_drvdata 
*drvdata)
        etm4x_relaxed_write32(csa, state->trcauxctlr, TRCAUXCTLR);
        etm4x_relaxed_write32(csa, state->trceventctl0r, TRCEVENTCTL0R);
        etm4x_relaxed_write32(csa, state->trceventctl1r, TRCEVENTCTL1R);
-       etm4x_relaxed_write32(csa, state->trcstallctlr, TRCSTALLCTLR);
+       if (drvdata->stallctl)
+               etm4x_relaxed_write32(csa, state->trcstallctlr, TRCSTALLCTLR);
        etm4x_relaxed_write32(csa, state->trctsctlr, TRCTSCTLR);
        etm4x_relaxed_write32(csa, state->trcsyncpr, TRCSYNCPR);
        etm4x_relaxed_write32(csa, state->trcccctlr, TRCCCCTLR);
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c 
b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
index 1c490bcef3ad..cd9249fbf913 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
@@ -296,6 +296,9 @@ static ssize_t mode_store(struct device *dev,
        if (kstrtoul(buf, 16, &val))
                return -EINVAL;
 
+       if ((val & ETM_MODE_ISTALL_EN) && !drvdata->stallctl)
+               return -EINVAL;
+
        spin_lock(&drvdata->spinlock);
        config->mode = val & ETMv4_MODE_ALL;
 
-- 
2.24.1

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