Re: [PATCH 01/16] hw/core/cpu: Let CPU object have a clock source - Philippe Mathieu-Daudé

From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: Igor Mammedov <imammedo@redhat.com>
Cc: "Damien Hedde" <damien.hedde@greensocs.com>,
	"Huacai Chen" <zltjiangshi@gmail.com>,
	"Aleksandar Rikalo" <aleksandar.rikalo@syrmia.com>,
	"qemu-riscv@nongnu.org" <qemu-riscv@nongnu.org>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Paul Burton" <paulburton@kernel.org>,
	qemu-ppc <qemu-ppc@nongnu.org>,
	qemu-devel@nongnu.org,
	"Wainer dos Santos Moschetta" <wainersm@redhat.com>,
	"Aleksandar Markovic" <aleksandar.qemu.devel@gmail.com>,
	qemu-arm <qemu-arm@nongnu.org>,
	"Hervé Poussineau" <hpoussin@reactos.org>,
	"Cleber Rosa" <crosa@redhat.com>,
	"Huacai Chen" <chenhc@lemote.com>,
	"Edgar E . Iglesias" <edgar.iglesias@gmail.com>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>,
	"Aurelien Jarno" <aurelien@aurel32.net>,
	"Richard Henderson" <rth@twiddle.net>
Subject: Re: [PATCH 01/16] hw/core/cpu: Let CPU object have a clock source
Date: Wed, 30 Sep 2020 12:16:53 +0200	[thread overview]
Message-ID: <da7248f7-5098-188b-d274-e122c87bb498@amsat.org> (raw)
In-Reply-To: <20200930094313.1120a040@redhat.com>

+arm/ppc/riscv folks

On 9/30/20 9:43 AM, Igor Mammedov wrote:
> On Mon, 28 Sep 2020 19:15:24 +0200
> Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> 
>> Let CPUState have a clock source (named 'clk') and CPUClass
>> have a clock_update() callback. The clock can be optionally
>> set Using qdev_connect_clock_in() from the Clock API.
>> If the clock changes, the optional clock_update() will be
>> called.
> 
> the sole user of it is mips cpu, so question is why
> you are making it part of generic CPUm instead of
> MIPSCPUClass/MIPSCPU?

This is a feature of the CPU, regardless its architecture.

I expect the other archs to start using it soon.

> 
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>  include/hw/core/cpu.h |  5 +++++
>>  hw/core/cpu.c         | 12 ++++++++++++
>>  2 files changed, 17 insertions(+)
>>
>> diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
>> index 6c34798c8b3..6989d90c193 100644
>> --- a/include/hw/core/cpu.h
>> +++ b/include/hw/core/cpu.h
>> @@ -31,6 +31,7 @@
>>  #include "qemu/thread.h"
>>  #include "qemu/plugin.h"
>>  #include "qom/object.h"
>> +#include "hw/clock.h"
>>  
>>  typedef int (*WriteCoreDumpFunction)(const void *buf, size_t size,
>>                                       void *opaque);
>> @@ -155,6 +156,7 @@ struct TranslationBlock;
>>   * @disas_set_info: Setup architecture specific components of disassembly info
>>   * @adjust_watchpoint_address: Perform a target-specific adjustment to an
>>   * address before attempting to match it against watchpoints.
>> + * @clock_update: Callback for input clock changes
>>   *
>>   * Represents a CPU family or model.
>>   */
>> @@ -176,6 +178,7 @@ struct CPUClass {
>>                                    unsigned size, MMUAccessType access_type,
>>                                    int mmu_idx, MemTxAttrs attrs,
>>                                    MemTxResult response, uintptr_t retaddr);
>> +    void (*clock_update)(CPUState *cpu);
>>      bool (*virtio_is_big_endian)(CPUState *cpu);
>>      int (*memory_rw_debug)(CPUState *cpu, vaddr addr,
>>                             uint8_t *buf, int len, bool is_write);
>> @@ -316,6 +319,7 @@ struct qemu_work_item;
>>   *   QOM parent.
>>   * @nr_cores: Number of cores within this CPU package.
>>   * @nr_threads: Number of threads within this CPU.
>> + * @clock: this CPU source clock (an output clock of another device)
>>   * @running: #true if CPU is currently running (lockless).
>>   * @has_waiter: #true if a CPU is currently waiting for the cpu_exec_end;
>>   * valid under cpu_list_lock.
>> @@ -400,6 +404,7 @@ struct CPUState {
>>      int num_ases;
>>      AddressSpace *as;
>>      MemoryRegion *memory;
>> +    Clock *clock;
>>  
>>      void *env_ptr; /* CPUArchState */
>>      IcountDecr *icount_decr_ptr;
>> diff --git a/hw/core/cpu.c b/hw/core/cpu.c
>> index c55c09f734c..37fcff3ec64 100644
>> --- a/hw/core/cpu.c
>> +++ b/hw/core/cpu.c
>> @@ -30,6 +30,7 @@
>>  #include "qemu/qemu-print.h"
>>  #include "sysemu/tcg.h"
>>  #include "hw/boards.h"
>> +#include "hw/qdev-clock.h"
>>  #include "hw/qdev-properties.h"
>>  #include "trace/trace-root.h"
>>  #include "qemu/plugin.h"
>> @@ -247,6 +248,16 @@ void cpu_reset(CPUState *cpu)
>>      trace_guest_cpu_reset(cpu);
>>  }
>>  
>> +static void cpu_clk_update(void *opaque)
>> +{
>> +    CPUState *cpu = opaque;
>> +    CPUClass *cc = CPU_GET_CLASS(cpu);
>> +
>> +    if (cc->clock_update) {
>> +        cc->clock_update(cpu);
>> +    }
>> +}
>> +
>>  static void cpu_common_reset(DeviceState *dev)
>>  {
>>      CPUState *cpu = CPU(dev);
>> @@ -367,6 +378,7 @@ static void cpu_common_initfn(Object *obj)
>>      /* the default value is changed by qemu_init_vcpu() for softmmu */
>>      cpu->nr_cores = 1;
>>      cpu->nr_threads = 1;
>> +    cpu->clock = qdev_init_clock_in(DEVICE(obj), "clk", cpu_clk_update, cpu);
>>  
>>      qemu_mutex_init(&cpu->work_mutex);
>>      QSIMPLEQ_INIT(&cpu->work_list);
> 