Re: [PATCH QEMU v2 4/5] ARM: PL061: Add gpiodev support

[Philippe Mathieu-Daudé <f4bug@xxxxxxxxx>]

On 4/23/20 11:33 AM, Philippe Mathieu-Daudé wrote:
> On 4/23/20 11:01 AM, Geert Uytterhoeven wrote:
>> Make the PL061 GPIO controller user-creatable, and allow the user to tie
>> a newly created instance to a gpiochip on the host.
>>
>> To create a new GPIO controller, the QEMU command line must be augmented
>> with:
>>
>>     -device pl061,host=<gpiochip>
>>
>> with <gpiochip> the name or label of the gpiochip on the host.
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>> ---
>> v2:
>>   - New.
>> ---
>>  hw/gpio/pl061.c | 35 +++++++++++++++++++++++++++++++++++
>>  qemu-options.hx |  9 +++++++++
>>  2 files changed, 44 insertions(+)
>>
>> diff --git a/hw/gpio/pl061.c b/hw/gpio/pl061.c
>> index 74ba733a8a5e8ca5..98204f9a586ae8c8 100644
>> --- a/hw/gpio/pl061.c
>> +++ b/hw/gpio/pl061.c
>> @@ -12,11 +12,14 @@
>>  #include "hw/arm/fdt.h"
>>  #include "hw/gpio/pl061.h"
>>  #include "hw/irq.h"
>> +#include "hw/qdev-properties.h"
>>  #include "hw/sysbus.h"
>>  #include "migration/vmstate.h"
>> +#include "qapi/error.h"
>>  #include "qemu/log.h"
>>  #include "qemu/module.h"
>>  #include "sysemu/device_tree.h"
>> +#include "sysemu/gpiodev.h"
>>  
>>  //#define DEBUG_PL061 1
>>  
>> @@ -41,6 +44,9 @@ static const uint8_t pl061_id_luminary[12] =
>>  typedef struct PL061State {
>>      SysBusDevice parent_obj;
>>  
>> +#ifdef CONFIG_GPIODEV
>> +    char *host;
>> +#endif
>>      MemoryRegion iomem;
>>      uint32_t locked;
>>      uint32_t data;
>> @@ -370,10 +376,39 @@ static void pl061_init(Object *obj)
>>      qdev_init_gpio_out(dev, s->out, 8);
> 
> Not related to this patch, but we should replace this 8 magic value by a
> proper definition...
> 
>>  }
>>  
>> +#ifdef CONFIG_GPIODEV
>> +static Property pl061_properties[] = {
>> +    DEFINE_PROP_STRING("host", PL061State, host),
>> +    DEFINE_PROP_END_OF_LIST(),
>> +};
>> +
>> +static void pl061_realize(DeviceState *dev, Error **errp)
>> +{
>> +    PL061State *s = PL061(dev);
>> +
>> +    if (!dev->opts) {
>> +        /* Not created by user */
>> +        return;
>> +    }
>> +
>> +    if (!s->host) {
>> +        error_setg(errp, "'host' property is required");
>> +        return;
>> +    }
>> +
>> +    qemu_gpiodev_add(dev, s->host, 8, errp);
>> +}
>> +#endif /* CONFIG_GPIODEV */
>> +
>>  static void pl061_class_init(ObjectClass *klass, void *data)
>>  {
>>      DeviceClass *dc = DEVICE_CLASS(klass);
>>  
>> +#ifdef CONFIG_GPIODEV
>> +    device_class_set_props(dc, pl061_properties);
>> +    dc->realize = pl061_realize;
>> +    dc->user_creatable = true;
>> +#endif
>>      dc->vmsd = &vmstate_pl061;
>>      dc->reset = &pl061_reset;
>>  }
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 292d4e7c0cef6097..182de7fb63923b38 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -875,6 +875,15 @@ SRST
>>  ``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
>>      Like the KCS interface, but defines a BT interface. The default port
>>      is 0xe4 and the default interrupt is 5.
>> +
>> +#ifdef CONFIG_GPIODEV
>> +``-device pl061,host=gpiochip``
>> +    Add a PL061 GPIO controller, and map its virtual GPIO lines to a GPIO
>> +    controller on the host.
>> +
>> +    ``host=gpiochip``
>> +        The name or label of the GPIO controller on the host.
>> +#endif
>>  ERST
>>  
>>  DEF("name", HAS_ARG, QEMU_OPTION_name,
>>
> 
> Instead of restricting this to the pl061, it would be cleaner you add a
> GPIO_PLUGGABLE_INTERFACE (or GPIO_BINDABLE_INTERFACE or better name),
> and have TYPE_PL061 implement it.

IOW your backend should consume devices implementing this generic interface.