Hi James,
When reviewing another patch set I spotted that there is a FIELD_GET macro already defined for the kernel in include/linux/bitfield.h
Advantage of this is that you only need to define a shifted mask for each field and the macro handles the extraction and shifting automatically. It also ensures does a bunch of compile time sanity checks to ensure that the masks are in range for the type.
i.e. - define the mask _with_ the shift #define TRCIDR0_INSTP0_MASK GENMASK(2, 1)
then drvdata->instrp0 = !!(FIELD_GET(TRCIDR0_INSTP0_MASK, etmidr0) == 0b11);
which means all the shift #defines can be dropped
Should we use this and drop the REG_VAL or whatever?
Regards
Mike
On Tue, 8 Feb 2022 at 15:04, Suzuki K Poulose suzuki.poulose@arm.com wrote:
On 07/02/2022 05:44, Anshuman Khandual wrote:
Hi James,
These are all ETM4X specific changes. Something like this might be cleaner and also more compact. Also would suggest to follow the same for subsequent patches as well.
coresight: etm4x: Cleanup TRCIDR0 register accesses
Consistency with sysreg.h could be mentioned in the commit message itself.
On 2/3/22 5:35 PM, James Clark wrote:
This is a no-op change for style and consistency and has no effect on the binary produced by gcc-11.
This patch adds register definitions, helper macros as well. Please expand the commit message to add more details. This is too short, for the change it creates. BTW why is it necessary to mention GCC version number here.
Signed-off-by: James Clark james.clark@arm.com
.../coresight/coresight-etm4x-core.c | 36 +++++-------------- drivers/hwtracing/coresight/coresight-etm4x.h | 17 +++++++++ drivers/hwtracing/coresight/coresight-priv.h | 5 +++ 3 files changed, 30 insertions(+), 28 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index e2eebd865241..107e81948f76 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -1091,41 +1091,21 @@ static void etm4_init_arch_data(void *info) etmidr0 = etm4x_relaxed_read32(csa, TRCIDR0);
/* INSTP0, bits[2:1] P0 tracing support field */
- if (BMVAL(etmidr0, 1, 2) == 0b11)
drvdata->instrp0 = true;- else
drvdata->instrp0 = false;
- drvdata->instrp0 = !!(REG_VAL(etmidr0, TRCIDR0_INSTP0) == 0b11); /* TRCBB, bit[5] Branch broadcast tracing support bit */
- if (BMVAL(etmidr0, 5, 5))
drvdata->trcbb = true;- else
drvdata->trcbb = false;
- drvdata->trcbb = !!(etmidr0 & TRCIDR0_TRCBB); /* TRCCOND, bit[6] Conditional instruction tracing support bit */
- if (BMVAL(etmidr0, 6, 6))
drvdata->trccond = true;- else
drvdata->trccond = false;
- drvdata->trccond = !!(etmidr0 & TRCIDR0_TRCCOND); /* TRCCCI, bit[7] Cycle counting instruction bit */
- if (BMVAL(etmidr0, 7, 7))
drvdata->trccci = true;- else
drvdata->trccci = false;
- drvdata->trccci = !!(etmidr0 & TRCIDR0_TRCCCI); /* RETSTACK, bit[9] Return stack bit */
- if (BMVAL(etmidr0, 9, 9))
drvdata->retstack = true;- else
drvdata->retstack = false;
- drvdata->retstack = !!(etmidr0 & TRCIDR0_RETSTACK); /* NUMEVENT, bits[11:10] Number of events field */
- drvdata->nr_event = BMVAL(etmidr0, 10, 11);
- drvdata->nr_event = REG_VAL(etmidr0, TRCIDR0_NUMEVENT); /* QSUPP, bits[16:15] Q element support field */
- drvdata->q_support = BMVAL(etmidr0, 15, 16);
- drvdata->q_support = REG_VAL(etmidr0, TRCIDR0_QSUPP); /* TSSIZE, bits[28:24] Global timestamp size field */
- drvdata->ts_size = BMVAL(etmidr0, 24, 28);
drvdata->ts_size = REG_VAL(etmidr0, TRCIDR0_TSSIZE);
/* maximum size of resources */ etmidr2 = etm4x_relaxed_read32(csa, TRCIDR2);
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h index 3c4d69b096ca..2bd8ad953b8e 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.h +++ b/drivers/hwtracing/coresight/coresight-etm4x.h @@ -130,6 +130,23 @@
#define TRCRSR_TA BIT(12)
+/*
- Bit positions of registers that are defined above, in the sysreg.h style
- of _MASK, _SHIFT and BIT().
- */
^^^ not really necessary. Instead the format requirement for below mentioned CORESIGHT_REG_VAL() macro might be relevant and should be mentioned.
+#define TRCIDR0_INSTP0_SHIFT 1 +#define TRCIDR0_INSTP0_MASK GENMASK(1, 0) +#define TRCIDR0_TRCBB BIT(5) +#define TRCIDR0_TRCCOND BIT(6) +#define TRCIDR0_TRCCCI BIT(7) +#define TRCIDR0_RETSTACK BIT(9) +#define TRCIDR0_NUMEVENT_SHIFT 10 +#define TRCIDR0_NUMEVENT_MASK GENMASK(1, 0) +#define TRCIDR0_QSUPP_SHIFT 15 +#define TRCIDR0_QSUPP_MASK GENMASK(1, 0) +#define TRCIDR0_TSSIZE_SHIFT 24 +#define TRCIDR0_TSSIZE_MASK GENMASK(4, 0)
- /*
- System instructions to access ETM registers.
- See ETMv4.4 spec ARM IHI0064F section 4.3.6 System instructions
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index ff1dd2092ac5..1452c6038421 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -36,6 +36,11 @@
#define TIMEOUT_US 100 #define BMVAL(val, lsb, msb) ((val & GENMASK(msb, lsb)) >> lsb) +/*
- Extract a field from a register where field is #defined in the form
- <register_name>_<field_name>_MASK and <register_name>_<field_name>_SHIFT
- */
Looking at the usage, <register_name> is already embedded in <filed_name>. So it requires <field_name>_SHIFT and <field_name>_MASK instead. Unless register name should be passed as separate argument (which actually might be better).
REG_VAL(etmidr0, TRCIDR0_TSSIZE) ----> REG_VAL(etmidr0, TRCIDR0, TSSIZE)
I don't see much difference here. So I am fine either way.
with some restructuring in the comment ..
/*
- Extract a field from a coresight register
- Required fields are defined as macros like the following
- <register_name>_<field_name>_MASK and <register_name>_<field_name>_SHIFT
*/
+#define REG_VAL(val, field) ((val & (field##_MASK << field##_SHIFT)) >> field##_SHIFT)
This is too generic to be in a coresight header or it should just be named CORESIGHT_REG_VAL() instead, making it more specific for here.
The build should fail in case any required macro definition is absent. I guess no more fortification is required in case macros are missing.
However CORESIGHT_REG_VAL() is better placed in <coresight-etm4x.h> just before all the dependent SHIFT/MASK register field definition starts.
Not necessarily. CORESIGHT_REG_VAL() is a generic function and doesn't have anything specific to do with etm4x. We could reuse that for cleaning up other drivers in CoreSight.
Cheers Suzuki