Re: [PATCH v8 4/9] qdev-clock: introduce an init array to ease the device construction

[Alistair Francis]

On Tue, Feb 25, 2020 at 5:56 AM Damien Hedde <address@hidden> wrote:
>
> Introduce a function and macro helpers to setup several clocks
> in a device from a static array description.
>
> An element of the array describes the clock (name and direction) as
> well as the related callback and an optional offset to store the
> created object pointer in the device state structure.
>
> The array must be terminated by a special element QDEV_CLOCK_END.
>
> This is based on the original work of Frederic Konrad.
>
> Signed-off-by: Damien Hedde <address@hidden>
> Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

Reviewed-by: Alistair Francis <address@hidden>

Alistair

> --
>
> v7:
>  + update ClockIn/Out types
>  + remove the QDEV_CLOCK_IN_NOFIELD macro
>  + remove leading underscores in macro arguments (Peter)
>  + updated some comments (Peter)
>  + removed trivial asserts (Peter)
> ---
>  include/hw/qdev-clock.h | 55 +++++++++++++++++++++++++++++++++++++++++
>  hw/core/qdev-clock.c    | 17 +++++++++++++
>  2 files changed, 72 insertions(+)
>
> diff --git a/include/hw/qdev-clock.h b/include/hw/qdev-clock.h
> index b3b3a3e021..a340f65ff9 100644
> --- a/include/hw/qdev-clock.h
> +++ b/include/hw/qdev-clock.h
> @@ -101,4 +101,59 @@ Clock *qdev_alias_clock(DeviceState *dev, const char 
> *name,
>   */
>  void qdev_finalize_clocklist(DeviceState *dev);
>
> +/**
> + * ClockPortInitElem:
> + * @name: name of the clock (can't be NULL)
> + * @output: indicates whether the clock is input or output
> + * @callback: for inputs, optional callback to be called on clock's update
> + * with device as opaque
> + * @offset: optional offset to store the ClockIn or ClockOut pointer in 
> device
> + * state structure (0 means unused)
> + */
> +struct ClockPortInitElem {
> +    const char *name;
> +    bool is_output;
> +    ClockCallback *callback;
> +    size_t offset;
> +};
> +
> +#define clock_offset_value(devstate, field) \
> +    (offsetof(devstate, field) + \
> +     type_check(Clock *, typeof_field(devstate, field)))
> +
> +#define QDEV_CLOCK(out_not_in, devstate, field, cb) { \
> +    .name = (stringify(field)), \
> +    .is_output = out_not_in, \
> +    .callback = cb, \
> +    .offset = clock_offset_value(devstate, field), \
> +}
> +
> +/**
> + * QDEV_CLOCK_(IN|OUT):
> + * @devstate: structure type. @dev argument of qdev_init_clocks below must be
> + * a pointer to that same type.
> + * @field: a field in @_devstate (must be Clock*)
> + * @callback: (for input only) callback (or NULL) to be called with the 
> device
> + * state as argument
> + *
> + * The name of the clock will be derived from @field
> + */
> +#define QDEV_CLOCK_IN(devstate, field, callback) \
> +    QDEV_CLOCK(false, devstate, field, callback)
> +
> +#define QDEV_CLOCK_OUT(devstate, field) \
> +    QDEV_CLOCK(true, devstate, field, NULL)
> +
> +#define QDEV_CLOCK_END { .name = NULL }
> +
> +typedef struct ClockPortInitElem ClockPortInitArray[];
> +
> +/**
> + * qdev_init_clocks:
> + * @dev: the device to add clocks to
> + * @clocks: a QDEV_CLOCK_END-terminated array which contains the
> + * clocks information.
> + */
> +void qdev_init_clocks(DeviceState *dev, const ClockPortInitArray clocks);
> +
>  #endif /* QDEV_CLOCK_H */
> diff --git a/hw/core/qdev-clock.c b/hw/core/qdev-clock.c
> index 62035aef83..a94cc44437 100644
> --- a/hw/core/qdev-clock.c
> +++ b/hw/core/qdev-clock.c
> @@ -116,6 +116,23 @@ Clock *qdev_init_clock_in(DeviceState *dev, const char 
> *name,
>      return ncl->clock;
>  }
>
> +void qdev_init_clocks(DeviceState *dev, const ClockPortInitArray clocks)
> +{
> +    const struct ClockPortInitElem *elem;
> +
> +    for (elem = &clocks[0]; elem->name != NULL; elem++) {
> +        Clock **clkp;
> +        /* offset cannot be inside the DeviceState part */
> +        assert(elem->offset > sizeof(DeviceState));
> +        clkp = (Clock **)(((void *) dev) + elem->offset);
> +        if (elem->is_output) {
> +            *clkp = qdev_init_clock_out(dev, elem->name);
> +        } else {
> +            *clkp = qdev_init_clock_in(dev, elem->name, elem->callback, dev);
> +        }
> +    }
> +}
> +
>  static NamedClockList *qdev_get_clocklist(DeviceState *dev, const char *name)
>  {
>      NamedClockList *ncl;
> --
> 2.25.1
>
>