Re: [PATCH] spmi-pmic-arb: add irq tracepoints to the pmic-arb driver

["Ankit Gupta" <ankgupta@codeaurora.org>]

> On Tue, 26 May 2015 17:39:15 -0600
> Ankit Gupta <ankgupta@codeaurora.org> wrote:
>
>> The spmi-pmic-arb is also an interrupt controller. It gets a
>> single aggregate irq and disseminates it to individual
>> pmic-peripheral drivers. Each pmic-peripheral has a unique apid
>> number, and can have multiple interrupt capable functions.
>> The registered apid range shows the lowest and highest apid
>> numbers of pmic-peripheral drivers which request irqs. Pid is
>> the base address of that peripheral. For performance measurement,
>> tracepoints are added at the beginning of the aggregate irq and
>> at the end of the individual pmic-peripheral irqs.
>>
>> Following is a list showing the new tracepoint events:
>>
>> spmi_pmic_arb_aggregate_irq_start: aggregate irq number and registered
>> 				   apid range.
>>
>> spmi_pmic_arb_apid_irq_end: apid, irq, func_num, sid and pid.
>>
>> SPMI Interrupts tracepoints can be enabled like:
>>
>> echo 1 >/sys/kernel/debug/tracing/events/spmi-pmic-arb/enable
>>
>> and will dump messages that can be viewed in
>> /sys/kernel/debug/tracing/trace that look like:
>> ... spmi_pmic_arb_aggregate_irq_start: irq=150 registered apid
>> range=(3,189)
>> ... spmi_pmic_arb_apid_irq_end: apid=3 irq=1 func_num=0 sid=0 pid=0x8
>>
>> Suggested-by: Sagar Dharia <sdharia@codeaurora.org>
>> Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>
>> Signed-off-by: Ankit Gupta <ankgupta@codeaurora.org>
>> ---
>>  drivers/spmi/spmi-pmic-arb.c         | 15 ++++++---
>>  include/trace/events/spmi-pmic-arb.h | 62
>> ++++++++++++++++++++++++++++++++++++
>>  2 files changed, 72 insertions(+), 5 deletions(-)
>>  create mode 100644 include/trace/events/spmi-pmic-arb.h
>>
>> diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c
>> index 20559ab..342a71d 100644
>> --- a/drivers/spmi/spmi-pmic-arb.c
>> +++ b/drivers/spmi/spmi-pmic-arb.c
>> @@ -23,6 +23,9 @@
>>  #include <linux/slab.h>
>>  #include <linux/spmi.h>
>>
>> +#define CREATE_TRACE_POINTS
>> +#include <trace/events/spmi-pmic-arb.h>
>> +
>>  /* PMIC Arbiter configuration registers */
>>  #define PMIC_ARB_VERSION		0x0000
>>  #define PMIC_ARB_INT_EN			0x0004
>> @@ -375,16 +378,17 @@ static void periph_interrupt(struct
>> spmi_pmic_arb_dev *pa, u8 apid)
>>  	unsigned int irq;
>>  	u32 status;
>>  	int id;
>> +	u16 ppid = pa->apid_to_ppid[apid];
>> +	u8 sid = (ppid >> 8) & 0x0F;
>> +	u8 pid = ppid & 0xFF;
>>
>>  	status = readl_relaxed(pa->intr + SPMI_PIC_IRQ_STATUS(apid));
>>  	while (status) {
>>  		id = ffs(status) - 1;
>>  		status &= ~(1 << id);
>> -		irq = irq_find_mapping(pa->domain,
>> -				       pa->apid_to_ppid[apid] << 16
>> -				     | id << 8
>> -				     | apid);
>> +		irq = irq_find_mapping(pa->domain, ppid << 16 | id << 8 | apid);
>>  		generic_handle_irq(irq);
>> +		trace_spmi_pmic_arb_apid_irq_end(apid, irq, id, sid, pid);
>
> It looks like sid is only used for the tracepoint processing. Instead
> of doing the work up above "(ppid >> 8) & 0x0F" that would only be used
> in the unlikely event that you happen to be tracing, what about moving
> the work below into the tracepoint, by passing in ppid, and having:
>
> 	__entry->sid = (ppid >> 8) & 0x0F;
>
> That way you would save some CPU cycles when not tracing.
>
> -- Steve
Will do it.
>
>>  	}
>>  }
>>
>> @@ -399,7 +403,8 @@ static void pmic_arb_chained_irq(unsigned int irq,
>> struct irq_desc *desc)
>>  	int i, id;
>>
>>  	chained_irq_enter(chip, desc);
>> -
>> +	trace_spmi_pmic_arb_aggregate_irq_start(irq, pa->min_apid,
>> +						pa->max_apid);
>>  	for (i = first; i <= last; ++i) {
>>  		status = readl_relaxed(intr +
>>  				       SPMI_PIC_OWNER_ACC_STATUS(pa->ee, i));
>> diff --git a/include/trace/events/spmi-pmic-arb.h
>> b/include/trace/events/spmi-pmic-arb.h
>> new file mode 100644
>> index 0000000..6c4dbca
>> --- /dev/null
>> +++ b/include/trace/events/spmi-pmic-arb.h
>> @@ -0,0 +1,62 @@
>> +#undef TRACE_SYSTEM
>> +#define TRACE_SYSTEM spmi-pmic-arb
>> +
>> +#if !defined(_TRACE_SPMI_PMIC_ARB_H) ||
>> defined(TRACE_HEADER_MULTI_READ)
>> +#define _TRACE_SPMI_PMIC_ARB_H
>> +
>> +#include <linux/spmi.h>
>> +#include <linux/tracepoint.h>
>> +
>> +/*
>> + * drivers/spmi/spmi-pmic-arb.c
>> + */
>> +
>> +TRACE_EVENT(spmi_pmic_arb_aggregate_irq_start,
>> +	TP_PROTO(unsigned int irq, int first, int last),
>> +	TP_ARGS(irq, first, last),
>> +
>> +	TP_STRUCT__entry(
>> +		__field		( unsigned int,   irq   )
>> +		__field		( int,            first )
>> +		__field		( int,            last  )
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->irq    = irq;
>> +		__entry->first  = first;
>> +		__entry->last   = last;
>> +	),
>> +
>> +	TP_printk("irq=%d registered apid range=(%d,%d)",
>> +		  (int)__entry->irq, __entry->first, __entry->last)
>> +);
>> +
>> +TRACE_EVENT(spmi_pmic_arb_apid_irq_end,
>> +	TP_PROTO(u8 apid, unsigned int irq, int func_num, u8 sid, u8 pid),
>> +	TP_ARGS(apid, irq, func_num, sid, pid),
>> +
>> +	TP_STRUCT__entry(
>> +		__field		( u8,           apid     )
>> +		__field		( unsigned int, irq      )
>> +		__field		( int,          func_num )
>> +		__field		( u8,           sid      )
>> +		__field		( u8,           pid      )
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->apid     = apid;
>> +		__entry->irq      = irq;
>> +		__entry->func_num = func_num;
>> +		__entry->sid      = sid;
>> +		__entry->pid      = pid;
>> +	),
>> +
>> +	TP_printk("apid=%d irq=%d func_num=%d sid=%d pid=0x%d",
>> +		  (int)__entry->apid, (int)__entry->irq, (int)__entry->func_num,
>> +		  (int)__entry->sid, (int)__entry->pid)
>> +);
>> +
>> +#endif /* _TRACE_SPMI_PMIC_ARB_H */
>> +
>> +/* This part must be outside protection */
>> +#include <trace/define_trace.h>
>
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