Re: [Qemu-arm] [PATCH v4 2/3] utils: Add helper to read arm MIDR_EL1 register

[Vijay Kilari]

On Thu, Oct 27, 2016 at 9:33 PM, Peter Maydell <address@hidden> wrote:
> On 25 October 2016 at 13:12,  <address@hidden> wrote:
>> From: Vijaya Kumar K <address@hidden>
>>
>> Add helper API to read MIDR_EL1 registers to fetch
>> cpu identification information. This helps in
>> adding errata's and architecture specific features.
>>
>> This is implemented only for arm architecture.
>>
>> Signed-off-by: Vijaya Kumar K <address@hidden>
>> ---
>>  include/qemu/aarch64-cpuid.h | 29 +++++++++++++++++++++
>>  util/Makefile.objs           |  1 +
>>  util/aarch64-cpuid.c         | 61 
>> ++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 91 insertions(+)
>>
>> diff --git a/include/qemu/aarch64-cpuid.h b/include/qemu/aarch64-cpuid.h
>> new file mode 100644
>> index 0000000..8f776e8
>> --- /dev/null
>> +++ b/include/qemu/aarch64-cpuid.h
>> @@ -0,0 +1,29 @@
>> +#ifndef QEMU_AARCH64_CPUID_H
>> +#define QEMU_AARCH64_CPUID_H
>> +
>> +#if defined(__aarch64__)
>> +#define MIDR_IMPLEMENTER_SHIFT  24
>> +#define MIDR_IMPLEMENTER_MASK   (0xffULL << MIDR_IMPLEMENTER_SHIFT)
>> +#define MIDR_ARCHITECTURE_SHIFT 16
>> +#define MIDR_ARCHITECTURE_MASK  (0xf << MIDR_ARCHITECTURE_SHIFT)
>> +#define MIDR_PARTNUM_SHIFT      4
>> +#define MIDR_PARTNUM_MASK       (0xfff << MIDR_PARTNUM_SHIFT)
>> +
>> +#define MIDR_CPU_PART(imp, partnum) \
>> +        (((imp)                 << MIDR_IMPLEMENTER_SHIFT)  | \
>> +        (0xf                    << MIDR_ARCHITECTURE_SHIFT) | \
>> +        ((partnum)              << MIDR_PARTNUM_SHIFT))
>> +
>> +#define ARM_CPU_IMP_CAVIUM        0x43
>> +#define CAVIUM_CPU_PART_THUNDERX  0x0A1
>> +
>> +#define MIDR_THUNDERX_PASS2  \
>> +               MIDR_CPU_PART(ARM_CPU_IMP_CAVIUM, CAVIUM_CPU_PART_THUNDERX)
>> +#define CPU_MODEL_MASK  (MIDR_IMPLEMENTER_MASK | MIDR_ARCHITECTURE_MASK | \
>> +                         MIDR_PARTNUM_MASK)
>> +
>> +uint64_t get_aarch64_cpu_id(void);
>> +bool is_thunderx_pass2_cpu(void);
>> +#endif
>> +
>> +#endif
>> diff --git a/util/Makefile.objs b/util/Makefile.objs
>> index 36c7dcc..d14a455 100644
>> --- a/util/Makefile.objs
>> +++ b/util/Makefile.objs
>> @@ -37,3 +37,4 @@ util-obj-y += log.o
>>  util-obj-y += qdist.o
>>  util-obj-y += qht.o
>>  util-obj-y += range.o
>> +util-obj-y += aarch64-cpuid.o
>> diff --git a/util/aarch64-cpuid.c b/util/aarch64-cpuid.c
>> new file mode 100644
>> index 0000000..536ece1
>> --- /dev/null
>> +++ b/util/aarch64-cpuid.c
>> @@ -0,0 +1,61 @@
>> +/*
>> + * Dealing with arm cpu identification information.
>> + *
>> + * Copyright (C) 2016 Cavium, Inc.
>> + *
>> + * Authors:
>> + *  Vijaya Kumar K <address@hidden>
>> + *
>> + * This work is licensed under the terms of the GNU LGPL, version 2.1
>> + * or later.  See the COPYING.LIB file in the top-level directory.
>> + */
>> +
>> +#include <math.h>
>> +#include "qemu/osdep.h"
>
> osdep.h must always be the first #include, before anything else.
>
> What do we need math.h for anyway?
>
>> +#include "qemu-common.h"
>
> What do we need qemu-common.h for ?
>
>> +#include "qemu/cutils.h"
>> +#include "qemu/aarch64-cpuid.h"
>> +
>> +#if defined(__aarch64__)
>> +static uint64_t qemu_read_aarch64_midr_el1(void)
>> +{
>> +#ifdef CONFIG_LINUX
>
> When will CONFIG_LINUX not be defined but __aarch64__ is?
  The contents of this file is compiled only for aarch64 and hence
all the contents are under this __aarch64__.
Also the code is only for linux, have added CONFIG_LINUX.