[PATCH v5 08/15] coresight: trbe: Allow driver to choose a different alignment

Suzuki K Poulose
2021-10-14T22:31:59Z

The TRBE hardware mandates a minimum alignment for the TRBPTR_EL1,
advertised via the TRBIDR_EL1. This is used by the driver to
align the buffer write head. This patch allows the driver to
choose a different alignment from that of the hardware, by
decoupling the alignment tracking. This will be useful for
working around errata.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
drivers/hwtracing/coresight/coresight-trbe.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 58796ff425a4..f8c04c428780 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -67,8 +67,18 @@ struct trbe_buf {
struct trbe_cpudata *cpudata;
};

+/*
+ * struct trbe_cpudata: TRBE instance specific data
+ * @trbe_flag - TRBE dirty/access flag support
+ * @trbe_hw_align - Actual TRBE alignment required for TRBPTR_EL1.
+ * @trbe_align - Software alignment used for the TRBPTR_EL1,
+ * @cpu - CPU this TRBE belongs to.
+ * @mode - Mode of current operation. (perf/disabled)
+ * @drvdata - TRBE specific drvdata
+ */
struct trbe_cpudata {
bool trbe_flag;
+ u64 trbe_hw_align;
u64 trbe_align;
int cpu;
enum cs_mode mode;
@@ -875,7 +885,7 @@ static ssize_t align_show(struct device *dev, struct device_attribute *attr, cha
{
struct trbe_cpudata *cpudata = dev_get_drvdata(dev);

- return sprintf(buf, "%llx\n", cpudata->trbe_align);
+ return sprintf(buf, "%llx\n", cpudata->trbe_hw_align);
}
static DEVICE_ATTR_RO(align);

@@ -963,11 +973,13 @@ static void arm_trbe_probe_cpu(void *info)
goto cpu_clear;
}

- cpudata->trbe_align = 1ULL << get_trbe_address_align(trbidr);
- if (cpudata->trbe_align > SZ_2K) {
+ cpudata->trbe_hw_align = 1ULL << get_trbe_address_align(trbidr);
+ if (cpudata->trbe_hw_align > SZ_2K) {
pr_err("Unsupported alignment on cpu %d\n", cpu);
goto cpu_clear;
}
+
+ cpudata->trbe_align = cpudata->trbe_hw_align;
cpudata->trbe_flag = get_trbe_flag_update(trbidr);
cpudata->cpu = cpu;
cpudata->drvdata = drvdata;
--
2.25.4