[PATCH] arm64: print cpu frequency in /proc/cpuinfo

[Rob Herring]

On Fri, Dec 13, 2013 at 4:36 AM, Will Deacon <will.deacon at arm.com> wrote:
> On Fri, Dec 13, 2013 at 08:43:42AM +0000, Vinayak Kale wrote:
>> Print the cpu frequency field in /proc/cpuinfo.
>
> Why? ["x86 does this" isn't a valid answer :)].

People want to know this stuff. How about making lscpu work and print
useful things. Here is what you get on x66. You get a lot less on ARM
IIRC. lscpu uses on cpuinfo and sysfs data. The cache info is based on
sysfs cache data which I believe someone is working on for ARM.

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 37
Stepping:              5
CPU MHz:               2393.881
BogoMIPS:              4787.76
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3


>> Signed-off-by: Vinayak Kale <vkale at apm.com>
>> ---
>>  arch/arm64/kernel/setup.c |   15 +++++++++++++++
>>  1 files changed, 15 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index bd9bbd0..bca982b 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -41,6 +41,7 @@
>>  #include <linux/memblock.h>
>>  #include <linux/of_fdt.h>
>>  #include <linux/of_platform.h>
>> +#include <linux/cpufreq.h>
>>
>>  #include <asm/cputype.h>
>>  #include <asm/elf.h>
>> @@ -278,9 +279,19 @@ static const char *hwcap_str[] = {
>>       NULL
>>  };
>>
>> +static unsigned int get_cpufreq_khz(unsigned int cpu)
>> +{
>> +#ifdef CONFIG_CPU_FREQ
>> +     return cpufreq_quick_get(cpu);
>> +#else
>> +     return 0;
>> +#endif
>> +}
>
> That's going to be hilarious fun when cpufreq isn't compiled in.
> Just use the existing sysfs interfaces exposed by the cpufreq governers if
> you need to know this stuff.

We should be able to get the frequency independently from cpufreq
being enabled. This should come from DT cpu clock-frequency property
if cpufreq is not enabled.

Rob