Date:   Tue, 23 Aug 2022 13:28:56 +0100
From:   James Clark <james.clark@....com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     suzuki.poulose@....com, coresight@...ts.linaro.org,
        mike.leach@...aro.org, leo.yan@...aro.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/4] coresight: Simplify sysfs accessors by using
 csdev_access abstraction



On 22/08/2022 18:37, Mathieu Poirier wrote:
> Hi James,
> 
> On Mon, Jul 25, 2022 at 03:52:19PM +0100, James Clark wrote:
>> The coresight_device struct is available in the sysfs accessor, and this
>> contains a csdev_access struct which can be used to access registers.
>> Use this instead of passing in the type of each drvdata so that a common
>> function can be shared between all the cs drivers.
>>
>> No functional changes.
>>
>> Signed-off-by: James Clark <james.clark@....com>
>> ---
>>  drivers/hwtracing/coresight/coresight-catu.c  | 18 +++++-----
>>  drivers/hwtracing/coresight/coresight-etb10.c | 19 +++++------
>>  .../coresight/coresight-etm3x-sysfs.c         | 23 ++++++-------
>>  drivers/hwtracing/coresight/coresight-priv.h  | 14 ++++----
>>  .../coresight/coresight-replicator.c          |  7 ++--
>>  drivers/hwtracing/coresight/coresight-stm.c   | 27 +++++++--------
>>  .../hwtracing/coresight/coresight-tmc-core.c  | 33 ++++++++-----------
>>  include/linux/coresight.h                     | 18 ++++++++++
>>  8 files changed, 79 insertions(+), 80 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-catu.c b/drivers/hwtracing/coresight/coresight-catu.c
>> index e0740c6dbd54..9d89c4054046 100644
>> --- a/drivers/hwtracing/coresight/coresight-catu.c
>> +++ b/drivers/hwtracing/coresight/coresight-catu.c
>> @@ -365,16 +365,14 @@ static const struct etr_buf_operations etr_catu_buf_ops = {
>>  	.get_data = catu_get_data_etr_buf,
>>  };
>>  
>> -coresight_simple_reg32(struct catu_drvdata, devid, CORESIGHT_DEVID);
>> -coresight_simple_reg32(struct catu_drvdata, control, CATU_CONTROL);
>> -coresight_simple_reg32(struct catu_drvdata, status, CATU_STATUS);
>> -coresight_simple_reg32(struct catu_drvdata, mode, CATU_MODE);
>> -coresight_simple_reg32(struct catu_drvdata, axictrl, CATU_AXICTRL);
>> -coresight_simple_reg32(struct catu_drvdata, irqen, CATU_IRQEN);
>> -coresight_simple_reg64(struct catu_drvdata, sladdr,
>> -		       CATU_SLADDRLO, CATU_SLADDRHI);
>> -coresight_simple_reg64(struct catu_drvdata, inaddr,
>> -		       CATU_INADDRLO, CATU_INADDRHI);
>> +coresight_simple_reg32(devid, CORESIGHT_DEVID);
>> +coresight_simple_reg32(control, CATU_CONTROL);
>> +coresight_simple_reg32(status, CATU_STATUS);
>> +coresight_simple_reg32(mode, CATU_MODE);
>> +coresight_simple_reg32(axictrl, CATU_AXICTRL);
>> +coresight_simple_reg32(irqen, CATU_IRQEN);
>> +coresight_simple_reg64(sladdr, CATU_SLADDRLO, CATU_SLADDRHI);
>> +coresight_simple_reg64(inaddr, CATU_INADDRLO, CATU_INADDRHI);
>>  
>>  static struct attribute *catu_mgmt_attrs[] = {
>>  	&dev_attr_devid.attr,
>> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
>> index efa39820acec..405bb3355cb1 100644
>> --- a/drivers/hwtracing/coresight/coresight-etb10.c
>> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
>> @@ -655,17 +655,14 @@ static const struct file_operations etb_fops = {
>>  	.llseek		= no_llseek,
>>  };
>>  
>> -#define coresight_etb10_reg(name, offset)		\
>> -	coresight_simple_reg32(struct etb_drvdata, name, offset)
>> -
>> -coresight_etb10_reg(rdp, ETB_RAM_DEPTH_REG);
>> -coresight_etb10_reg(sts, ETB_STATUS_REG);
>> -coresight_etb10_reg(rrp, ETB_RAM_READ_POINTER);
>> -coresight_etb10_reg(rwp, ETB_RAM_WRITE_POINTER);
>> -coresight_etb10_reg(trg, ETB_TRG);
>> -coresight_etb10_reg(ctl, ETB_CTL_REG);
>> -coresight_etb10_reg(ffsr, ETB_FFSR);
>> -coresight_etb10_reg(ffcr, ETB_FFCR);
>> +coresight_simple_reg32(rdp, ETB_RAM_DEPTH_REG);
>> +coresight_simple_reg32(sts, ETB_STATUS_REG);
>> +coresight_simple_reg32(rrp, ETB_RAM_READ_POINTER);
>> +coresight_simple_reg32(rwp, ETB_RAM_WRITE_POINTER);
>> +coresight_simple_reg32(trg, ETB_TRG);
>> +coresight_simple_reg32(ctl, ETB_CTL_REG);
>> +coresight_simple_reg32(ffsr, ETB_FFSR);
>> +coresight_simple_reg32(ffcr, ETB_FFCR);
>>  
>>  static struct attribute *coresight_etb_mgmt_attrs[] = {
>>  	&dev_attr_rdp.attr,
>> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>> index 68fcbf4ce7a8..12f8e8176c7e 100644
>> --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>> +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
>> @@ -1252,19 +1252,16 @@ static struct attribute *coresight_etm_attrs[] = {
>>  	NULL,
>>  };
>>  
>> -#define coresight_etm3x_reg(name, offset)			\
>> -	coresight_simple_reg32(struct etm_drvdata, name, offset)
>> -
>> -coresight_etm3x_reg(etmccr, ETMCCR);
>> -coresight_etm3x_reg(etmccer, ETMCCER);
>> -coresight_etm3x_reg(etmscr, ETMSCR);
>> -coresight_etm3x_reg(etmidr, ETMIDR);
>> -coresight_etm3x_reg(etmcr, ETMCR);
>> -coresight_etm3x_reg(etmtraceidr, ETMTRACEIDR);
>> -coresight_etm3x_reg(etmteevr, ETMTEEVR);
>> -coresight_etm3x_reg(etmtssvr, ETMTSSCR);
>> -coresight_etm3x_reg(etmtecr1, ETMTECR1);
>> -coresight_etm3x_reg(etmtecr2, ETMTECR2);
>> +coresight_simple_reg32(etmccr, ETMCCR);
>> +coresight_simple_reg32(etmccer, ETMCCER);
>> +coresight_simple_reg32(etmscr, ETMSCR);
>> +coresight_simple_reg32(etmidr, ETMIDR);
>> +coresight_simple_reg32(etmcr, ETMCR);
>> +coresight_simple_reg32(etmtraceidr, ETMTRACEIDR);
>> +coresight_simple_reg32(etmteevr, ETMTEEVR);
>> +coresight_simple_reg32(etmtssvr, ETMTSSCR);
>> +coresight_simple_reg32(etmtecr1, ETMTECR1);
>> +coresight_simple_reg32(etmtecr2, ETMTECR2);
>>  
>>  static struct attribute *coresight_etm_mgmt_attrs[] = {
>>  	&dev_attr_etmccr.attr,
>> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
>> index f2458b794ef3..cf8ae768106e 100644
>> --- a/drivers/hwtracing/coresight/coresight-priv.h
>> +++ b/drivers/hwtracing/coresight/coresight-priv.h
>> @@ -40,23 +40,23 @@
>>  #define ETM_MODE_EXCL_KERN	BIT(30)
>>  #define ETM_MODE_EXCL_USER	BIT(31)
>>  
>> -#define __coresight_simple_show(type, name, lo_off, hi_off)		\
>> +#define __coresight_simple_show(name, lo_off, hi_off)		\
>>  static ssize_t name##_show(struct device *_dev,				\
>>  			   struct device_attribute *attr, char *buf)	\
>>  {									\
>> -	type *drvdata = dev_get_drvdata(_dev->parent);			\
>> +	struct coresight_device *csdev = container_of(_dev, struct coresight_device, dev); \
>>  	u64 val;							\
>>  	pm_runtime_get_sync(_dev->parent);				\
>> -	val = coresight_read_reg_pair(drvdata->base, lo_off, hi_off);	\
>> +	val = csdev_access_relaxed_read_pair(&csdev->access, lo_off, hi_off);	\
>>  	pm_runtime_put_sync(_dev->parent);				\
>>  	return scnprintf(buf, PAGE_SIZE, "0x%llx\n", val);		\
>>  }									\
>>  static DEVICE_ATTR_RO(name)
>>  
>> -#define coresight_simple_reg32(type, name, offset)			\
>> -	__coresight_simple_show(type, name, offset, -1)
>> -#define coresight_simple_reg64(type, name, lo_off, hi_off)		\
>> -	__coresight_simple_show(type, name, lo_off, hi_off)
>> +#define coresight_simple_reg32(name, offset)			\
>> +	__coresight_simple_show(name, offset, -1)
>> +#define coresight_simple_reg64(name, lo_off, hi_off)		\
>> +	__coresight_simple_show(name, lo_off, hi_off)
>>  
>>  extern const u32 coresight_barrier_pkt[4];
>>  #define CORESIGHT_BARRIER_PKT_SIZE (sizeof(coresight_barrier_pkt))
>> diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
>> index b86acbc74cf0..7cffcbb2ec42 100644
>> --- a/drivers/hwtracing/coresight/coresight-replicator.c
>> +++ b/drivers/hwtracing/coresight/coresight-replicator.c
>> @@ -196,11 +196,8 @@ static const struct coresight_ops replicator_cs_ops = {
>>  	.link_ops	= &replicator_link_ops,
>>  };
>>  
>> -#define coresight_replicator_reg(name, offset) \
>> -	coresight_simple_reg32(struct replicator_drvdata, name, offset)
>> -
>> -coresight_replicator_reg(idfilter0, REPLICATOR_IDFILTER0);
>> -coresight_replicator_reg(idfilter1, REPLICATOR_IDFILTER1);
>> +coresight_simple_reg32(idfilter0, REPLICATOR_IDFILTER0);
>> +coresight_simple_reg32(idfilter1, REPLICATOR_IDFILTER1);
>>  
>>  static struct attribute *replicator_mgmt_attrs[] = {
>>  	&dev_attr_idfilter0.attr,
>> diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
>> index bb14a3a8a921..4a31905604fe 100644
>> --- a/drivers/hwtracing/coresight/coresight-stm.c
>> +++ b/drivers/hwtracing/coresight/coresight-stm.c
>> @@ -634,21 +634,18 @@ static ssize_t traceid_store(struct device *dev,
>>  }
>>  static DEVICE_ATTR_RW(traceid);
>>  
>> -#define coresight_stm_reg(name, offset)	\
>> -	coresight_simple_reg32(struct stm_drvdata, name, offset)
>> -
>> -coresight_stm_reg(tcsr, STMTCSR);
>> -coresight_stm_reg(tsfreqr, STMTSFREQR);
>> -coresight_stm_reg(syncr, STMSYNCR);
>> -coresight_stm_reg(sper, STMSPER);
>> -coresight_stm_reg(spter, STMSPTER);
>> -coresight_stm_reg(privmaskr, STMPRIVMASKR);
>> -coresight_stm_reg(spscr, STMSPSCR);
>> -coresight_stm_reg(spmscr, STMSPMSCR);
>> -coresight_stm_reg(spfeat1r, STMSPFEAT1R);
>> -coresight_stm_reg(spfeat2r, STMSPFEAT2R);
>> -coresight_stm_reg(spfeat3r, STMSPFEAT3R);
>> -coresight_stm_reg(devid, CORESIGHT_DEVID);
>> +coresight_simple_reg32(tcsr, STMTCSR);
>> +coresight_simple_reg32(tsfreqr, STMTSFREQR);
>> +coresight_simple_reg32(syncr, STMSYNCR);
>> +coresight_simple_reg32(sper, STMSPER);
>> +coresight_simple_reg32(spter, STMSPTER);
>> +coresight_simple_reg32(privmaskr, STMPRIVMASKR);
>> +coresight_simple_reg32(spscr, STMSPSCR);
>> +coresight_simple_reg32(spmscr, STMSPMSCR);
>> +coresight_simple_reg32(spfeat1r, STMSPFEAT1R);
>> +coresight_simple_reg32(spfeat2r, STMSPFEAT2R);
>> +coresight_simple_reg32(spfeat3r, STMSPFEAT3R);
>> +coresight_simple_reg32(devid, CORESIGHT_DEVID);
>>  
>>  static struct attribute *coresight_stm_attrs[] = {
>>  	&dev_attr_hwevent_enable.attr,
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
>> index d0276af82494..781d213526b7 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
>> @@ -251,25 +251,20 @@ static enum tmc_mem_intf_width tmc_get_memwidth(u32 devid)
>>  	return memwidth;
>>  }
>>  
>> -#define coresight_tmc_reg(name, offset)			\
>> -	coresight_simple_reg32(struct tmc_drvdata, name, offset)
>> -#define coresight_tmc_reg64(name, lo_off, hi_off)	\
>> -	coresight_simple_reg64(struct tmc_drvdata, name, lo_off, hi_off)
>> -
>> -coresight_tmc_reg(rsz, TMC_RSZ);
>> -coresight_tmc_reg(sts, TMC_STS);
>> -coresight_tmc_reg(trg, TMC_TRG);
>> -coresight_tmc_reg(ctl, TMC_CTL);
>> -coresight_tmc_reg(ffsr, TMC_FFSR);
>> -coresight_tmc_reg(ffcr, TMC_FFCR);
>> -coresight_tmc_reg(mode, TMC_MODE);
>> -coresight_tmc_reg(pscr, TMC_PSCR);
>> -coresight_tmc_reg(axictl, TMC_AXICTL);
>> -coresight_tmc_reg(authstatus, TMC_AUTHSTATUS);
>> -coresight_tmc_reg(devid, CORESIGHT_DEVID);
>> -coresight_tmc_reg64(rrp, TMC_RRP, TMC_RRPHI);
>> -coresight_tmc_reg64(rwp, TMC_RWP, TMC_RWPHI);
>> -coresight_tmc_reg64(dba, TMC_DBALO, TMC_DBAHI);
>> +coresight_simple_reg32(rsz, TMC_RSZ);
>> +coresight_simple_reg32(sts, TMC_STS);
>> +coresight_simple_reg32(trg, TMC_TRG);
>> +coresight_simple_reg32(ctl, TMC_CTL);
>> +coresight_simple_reg32(ffsr, TMC_FFSR);
>> +coresight_simple_reg32(ffcr, TMC_FFCR);
>> +coresight_simple_reg32(mode, TMC_MODE);
>> +coresight_simple_reg32(pscr, TMC_PSCR);
>> +coresight_simple_reg32(axictl, TMC_AXICTL);
>> +coresight_simple_reg32(authstatus, TMC_AUTHSTATUS);
>> +coresight_simple_reg32(devid, CORESIGHT_DEVID);
>> +coresight_simple_reg64(rrp, TMC_RRP, TMC_RRPHI);
>> +coresight_simple_reg64(rwp, TMC_RWP, TMC_RWPHI);
>> +coresight_simple_reg64(dba, TMC_DBALO, TMC_DBAHI);
>>  
>>  static struct attribute *coresight_tmc_mgmt_attrs[] = {
>>  	&dev_attr_rsz.attr,
>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>> index 9f445f09fcfe..c1bb93c7c1de 100644
>> --- a/include/linux/coresight.h
>> +++ b/include/linux/coresight.h
>> @@ -372,6 +372,24 @@ static inline u32 csdev_access_relaxed_read32(struct csdev_access *csa,
>>  	return csa->read(offset, true, false);
>>  }
>>  
>> +static inline u64 csdev_access_relaxed_read_pair(struct csdev_access *csa,
>> +						 u32 lo_offset, u32 hi_offset)
> 
> Parameters lo_offset and hi_offset are s32 in coresight_read_reg_pair()...

Hi Mathieu,

I probably should have mentioned this in the commit message. You're
right that the previous version used signed values, but the csdev
accessors in include/linux/coresight.h all use u32 and I had to add a
new one in there for 'csdev_access_relaxed_read_pair()' which would have
looked very out of place if it was the only one to used signed values.

Because of this I also changed the 'not set' test for hi_offset from '<
-1' to '== -1' which would also work with unsigned values. So although
it looks different, it is still working the same way as before.

I can think of some possible options to make it better:

  * Have csdev_access_relaxed_read_pair() be the only csdev_access_
    function to take signed values

  * Keep the unsigned type but change the unset value of -1 to be
    UINT_MAX

  * Split the accessors into ones that are 64 bit pairs, and ones that
    are a single read. It's always known when it's defined whether it's
    a 'pair' or not, so technically this if statement with the 'not set'
    value isn't actually needed, you just use a different accessor type

I was tempted to do the 3rd one during the refactor, but I wanted to
keep it more like the original than not. I'm not a fan of the first
option, I think that would be confusing to read the code and would look
like a mistake. So I'm more in favour of 2 or 3. What are your thoughts?

> 
>> +{
>> +	u64 val;
>> +
>> +	if (likely(csa->io_mem)) {
>> +		val = readl_relaxed(csa->base + lo_offset);
>> +		val |= (hi_offset == -1) ? 0 :
>> +		       (u64)readl_relaxed(csa->base + hi_offset) << 32;
>> +		return val;
>> +	}
>> +
>> +	val = csa->read(lo_offset, true, false);
>> +	val |= (hi_offset == -1) ? 0 :
> 
> ... and hi_offset can't take on a negative value.

This is just shorthand for UINT_MAX. I could change it to be more
explicit (option 2 above)?

> 
>> +	       (u64)csa->read(hi_offset, true, false) << 32;
>> +	return val;
>> +}
>> +
>>  static inline u32 csdev_access_read32(struct csdev_access *csa, u32 offset)
>>  {
>>  	if (likely(csa->io_mem))
>> -- 
>> 2.28.0
>>

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