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

[Igor Mammedov <imammedo@redhat.com>]

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?

> 
> 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);