[PATCH v6 26/26] coresight: Add support for v8.4 SelfHosted tracing

[Suzuki K Poulose]

From: Jonathan Zhou <jonathan.zhou...@huawei.com>

v8.4 tracing extensions added support for trace filtering controlled
by TRFCR_ELx. This must be programmed to allow tracing at EL1/EL2 and
EL0. The timestamp used is the virtual time. Also enable CONTEXIDR_EL2
tracing if we are running the kernel at EL2.

Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
Cc: Mike Leach <mike.le...@linaro.org>
Cc: Will Deacon <w...@kernel.org>
Signed-off-by: Jonathan Zhou <jonathan.zhou...@huawei.com>
[ Move the trace filtering setup etm_init_arch_data() and
 clean ups]
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
 .../coresight/coresight-etm4x-core.c          | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c 
b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 34a6cdff75e7..6d96f4226bca 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -859,6 +859,30 @@ static bool etm4_init_csdev_access(struct etmv4_drvdata 
*drvdata,
        return false;
 }
 
+static void cpu_enable_tracing(void)
+{
+       u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
+       u64 trfcr;
+
+       if (!cpuid_feature_extract_unsigned_field(dfr0, 
ID_AA64DFR0_TRACE_FILT_SHIFT))
+               return;
+
+       /*
+        * If the CPU supports v8.4 SelfHosted Tracing, enable
+        * tracing at the kernel EL and EL0, forcing to use the
+        * virtual time as the timestamp.
+        */
+       trfcr = (TRFCR_ELx_TS_VIRTUAL |
+                TRFCR_ELx_ExTRE |
+                TRFCR_ELx_E0TRE);
+
+       /* If we are running at EL2, allow tracing the CONTEXTIDR_EL2. */
+       if (is_kernel_in_hyp_mode())
+               trfcr |= TRFCR_EL2_CX;
+
+       write_sysreg_s(trfcr, SYS_TRFCR_EL1);
+}
+
 static void etm4_init_arch_data(void *info)
 {
        u32 etmidr0;
@@ -1044,6 +1068,7 @@ static void etm4_init_arch_data(void *info)
        /* NUMCNTR, bits[30:28] number of counters available for tracing */
        drvdata->nr_cntr = BMVAL(etmidr5, 28, 30);
        etm4_cs_lock(drvdata, csa);
+       cpu_enable_tracing();
 }
 
 static inline u32 etm4_get_victlr_access_type(struct etmv4_config *config)
-- 
2.24.1