Re: [PATCH v8 2/3] hw/arm: Connect STM32L4x5 EXTI to STM32L4x5 SoC

[Philippe Mathieu-Daudé]

Hi Inès,

(this is now commit 52671f69f7).

On 9/1/24 17:06, Inès Varhol wrote:
> Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> Signed-off-by: Arnaud Minier <arnaud.minier@telecom-paris.fr>
> Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
> ---
>   hw/arm/Kconfig                 |  1 +
>   hw/arm/stm32l4x5_soc.c         | 52 +++++++++++++++++++++++++++++++++-
>   include/hw/arm/stm32l4x5_soc.h |  3 ++
>   3 files changed, 55 insertions(+), 1 deletion(-)


> +#define NUM_EXTI_IRQ 40
> +/* Match exti line connections with their CPU IRQ number */
> +/* See Vector Table (Reference Manual p.396) */
> +static const int exti_irq[NUM_EXTI_IRQ] = {
> +    6,                      /* GPIO[0]                 */
> +    7,                      /* GPIO[1]                 */
> +    8,                      /* GPIO[2]                 */
> +    9,                      /* GPIO[3]                 */
> +    10,                     /* GPIO[4]                 */
> +    23, 23, 23, 23, 23,     /* GPIO[5..9]              */
> +    40, 40, 40, 40, 40, 40, /* GPIO[10..15]            */

I'm sorry because I missed that earlier, and I'm surprised
you aren't chasing weird bugs. Due to how QEMU IRQs are
implemented, we can not wire multiple input lines to the same
output without using an intermediate "OR gate". We model it
as TYPE_OR_IRQ. See the comment in "hw/qdev-core.h" added in
commit cd07d7f9f5 ("qdev: Document GPIO related functions"):

 * It is not valid to try to connect one outbound GPIO to multiple
 * qemu_irqs at once, or to connect multiple outbound GPIOs to the
 * same qemu_irq. (Warning: there is no assertion or other guard to
 * catch this error: the model will just not do the right thing.)
 * Instead, for fan-out you can use the TYPE_SPLIT_IRQ device: connect
 * a device's outbound GPIO to the splitter's input, and connect each
 * of the splitter's outputs to a different device.  For fan-in you
 * can use the TYPE_OR_IRQ device, which is a model of a logical OR
 * gate with multiple inputs and one output.

So for example for the GPIO[10..15] you need to create a 6-line
OR gate as (totally untested):

  /* 6-line OR IRQ gate */
  Object *orgate40 = object_new(TYPE_OR_IRQ);
  object_property_set_int(orgate40, "num-lines", 6, &error_fatal);
  qdev_realize(DEVICE(orgate), NULL, &error_fatal);

  /* OR gate -> IRQ #40 */
  qdev_connect_gpio_out(DEVICE(orgate40), 0,
                        qdev_get_gpio_in(armv7m, 40));

  /* EXTI GPIO[10..15] -> OR gate */
  for (unsigned i = 0; i < 6; i++) {
      sysbus_connect_irq(SYS_BUS_DEVICE(&s->exti), 10 + i,
                         qdev_get_gpio_in(DEVICE(orgate40), i));
  }

> +    1,                      /* PVD                     */
> +    67,                     /* OTG_FS_WKUP, Direct     */
> +    41,                     /* RTC_ALARM               */
> +    2,                      /* RTC_TAMP_STAMP2/CSS_LSE */
> +    3,                      /* RTC wakeup timer        */
> +    63,                     /* COMP1                   */
> +    63,                     /* COMP2                   */
> +    31,                     /* I2C1 wakeup, Direct     */
> +    33,                     /* I2C2 wakeup, Direct     */
> +    72,                     /* I2C3 wakeup, Direct     */
> +    37,                     /* USART1 wakeup, Direct   */
> +    38,                     /* USART2 wakeup, Direct   */
> +    39,                     /* USART3 wakeup, Direct   */
> +    52,                     /* UART4 wakeup, Direct    */
> +    53,                     /* UART4 wakeup, Direct    */
> +    70,                     /* LPUART1 wakeup, Direct  */
> +    65,                     /* LPTIM1, Direct          */
> +    66,                     /* LPTIM2, Direct          */
> +    76,                     /* SWPMI1 wakeup, Direct   */
> +    1,                      /* PVM1 wakeup             */
> +    1,                      /* PVM2 wakeup             */
> +    1,                      /* PVM3 wakeup             */
> +    1,                      /* PVM4 wakeup             */
> +    78                      /* LCD wakeup, Direct      */
> +};

> +    busdev = SYS_BUS_DEVICE(&s->exti);
> +    if (!sysbus_realize(busdev, errp)) {
> +        return;
> +    }
> +    sysbus_mmio_map(busdev, 0, EXTI_ADDR);
> +    for (unsigned i = 0; i < NUM_EXTI_IRQ; i++) {
> +        sysbus_connect_irq(busdev, i, qdev_get_gpio_in(armv7m, exti_irq[i]));

                                                              ^^^^^^^^^^
> +    }
Regards,

Phil.