Re: [Qemu-devel] [PATCH V3 12/13] hw/sd.c: introduce SD card "device-id" property

[Markus Armbruster]

Igor Mitsyanko <address@hidden> writes:

> Setting "device-id" SD card property ties SD card with BlockDriverState of the
> same name. This property can be set dynamically, allowing for SD card 
> hot-insert.
>
> With "device-id" property we no longer need SDClass::init method, all work is
> done in property setter.
>
> Signed-off-by: Igor Mitsyanko <address@hidden>
> ---
>  hw/sd.c |   83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
>  hw/sd.h |    6 +++-
>  2 files changed, 79 insertions(+), 10 deletions(-)
>
> diff --git a/hw/sd.c b/hw/sd.c
> index 744c338..d067ffb 100644
> --- a/hw/sd.c
> +++ b/hw/sd.c
> @@ -491,16 +491,21 @@ static const VMStateDescription sd_vmstate = {
>     whether card should be in SSI or MMC/SD mode.  It is also up to the
>     board to ensure that ssi transfers only occur when the chip select
>     is asserted.  */
> -static void sd_init_card(SDState *sd, BlockDriverState *bs)
> +static void sd_init_card(SDState *sd, BlockDriverState *bdrv, Error **errp)
>  {
> -    sd->buf = qemu_blockalign(bs, 512);
> +    if (bdrv_attach_dev(bdrv, sd) < 0) {
> +        error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bdrv));
> +        return;
> +    }
> +
> +    bdrv_set_dev_ops(bdrv, &sd_block_ops, sd);
> +    sd->buf = qemu_blockalign(bdrv, 512);
>      sd->enable = true;
> -    sd_reset(sd, bs);
> -    if (sd->bdrv) {
> -        bdrv_attach_dev_nofail(sd->bdrv, sd);
> -        bdrv_set_dev_ops(sd->bdrv, &sd_block_ops, sd);
> +    sd_reset(sd, bdrv);
> +    qemu_set_irq(sd->inserted_cb, bdrv_is_inserted(sd->bdrv));
> +    if (bdrv_is_inserted(sd->bdrv)) {
> +        qemu_set_irq(sd->readonly_cb, sd->wp_switch);
>      }
> -    vmstate_register(NULL, -1, &sd_vmstate, sd);
>  }
>  
>  static void sd_set_callbacks(SDState *sd, qemu_irq readonly, qemu_irq insert)
> @@ -1756,7 +1761,6 @@ static void sd_class_init(ObjectClass *klass, void 
> *data)
>  {
>      SDClass *k = SD_CLASS(klass);
>  
> -    k->init = sd_init_card;
>      k->set_cb = sd_set_callbacks;
>      k->do_command = sd_send_command;
>      k->data_ready = sd_is_data_ready;
> @@ -1785,6 +1789,67 @@ static void sd_set_spimode(Object *obj, Visitor *v, 
> void *opaque,
>      }
>  }
>  
> +static char *sd_devid_get(Object *obj, Error **errp)
> +{
> +    SDState *sd = SD_CARD(obj);
> +    char *ret = NULL;
> +
> +    if (sd->bdrv) {
> +        ret = g_strndup(bdrv_get_device_name(sd->bdrv), 32);
> +    } else {
> +        error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, "SD card");
> +    }
> +
> +    return ret;
> +}
> +
> +static void sd_devid_set(Object *obj, const char *value, Error **errp)
> +{
> +    SDState *sd = SD_CARD(obj);
> +    BlockDriverState *bdrv = bdrv_find(value);
> +
> +    if (!bdrv) {
> +        error_set(errp, QERR_DEVICE_NOT_FOUND, value);
> +        return;
> +    }
> +
> +    if (sd->bdrv) {
> +        if (!strncmp(bdrv_get_device_name(sd->bdrv), value, 32)) {
> +            return;
> +        }
> +
> +        if (bdrv_in_use(sd->bdrv)) {
> +            error_set(errp, QERR_DEVICE_IN_USE, 
> bdrv_get_device_name(sd->bdrv));
> +            return;
> +        }
> +
> +        if (bdrv_get_attached_dev(bdrv)) {
> +            error_set(errp, QERR_DEVICE_IN_USE, value);
> +            return;
> +        }
> +
> +        bdrv_close(sd->bdrv);
> +        sd->enable = false;
> +        bdrv_detach_dev(sd->bdrv, sd);
> +        if (sd->buf) {
> +            qemu_vfree(sd->buf);
> +            sd->buf = NULL;
> +        }
> +        sd_reset(sd, NULL);
> +
> +        sd_init_card(sd, bdrv, errp);
> +        if (error_is_set(errp)) {
> +            vmstate_unregister(NULL, &sd_vmstate, sd);
> +        }
> +    } else {
> +        sd_init_card(sd, bdrv, errp);
> +        if (error_is_set(errp)) {
> +            return;
> +        }
> +        vmstate_register(NULL, -1, &sd_vmstate, sd);
> +    }
> +}
> +
>  static void sd_initfn(Object *obj)
>  {
>      SDState *sd = SD_CARD(obj);
> @@ -1792,6 +1857,8 @@ static void sd_initfn(Object *obj)
>      sd->spi = false;
>      object_property_add(obj, "spi", "boolean", sd_is_spi, sd_set_spimode,
>              NULL, NULL, NULL);
> +    object_property_add_str(OBJECT(sd), "device-id", sd_devid_get, 
> sd_devid_set,
> +            NULL);
>  }
>  
>  static const TypeInfo sd_type_info = {
> diff --git a/hw/sd.h b/hw/sd.h
> index c78eaa1..9042e87 100644
> --- a/hw/sd.h
> +++ b/hw/sd.h
> @@ -74,7 +74,6 @@ typedef struct SDState SDState;
>  typedef struct SDClass {
>      ObjectClass parent_class;
>  
> -    void (*init)(SDState *sd, BlockDriverState *bdrv);
>      int (*do_command)(SDState *sd, SDRequest *req, uint8_t *response);
>      void (*write_data)(SDState *sd, uint8_t value);
>      uint8_t (*read_data)(SDState *sd);
> @@ -96,8 +95,11 @@ static inline SDState *sd_init(BlockDriverState *bs, bool 
> is_spi)
>      SDState *sd = SD_CARD(object_new(TYPE_SD_CARD));
>      Error *errp = NULL;
>      object_property_set_bool(OBJECT(sd), is_spi, "spi", &errp);
> +    if (bs) {
> +        object_property_set_str(OBJECT(sd), bdrv_get_device_name(bs),
> +                "device-id", &errp);
> +    }
>      assert_no_error(errp);
> -    SD_GET_CLASS(sd)->init(sd, bs);
>      return sd;
>  }

The other block device models use a property "drive" for connecting to a
block backend, usually via DEFINE_BLOCK_PROPERTIES().  Why is it
necessary for sd.c to be different?