The USART devices were previously connecting their outbound IRQs
directly to the CPU because the EXTI wasn't handling direct lines
interrupts.
Now the USART connects to the EXTI inbound GPIOs, and the EXTI connects
its IRQs to the CPU.
The existing QTest for the USART (tests/qtest/stm32l4x5_usart-test.c)
checks that USART1_IRQ in the CPU is pending when expected so it
confirms that the connection through the EXTI still works.

Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/arm/stm32l4x5_soc.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/hw/arm/stm32l4x5_soc.c b/hw/arm/stm32l4x5_soc.c
index 38f7a2d5d9..fac83d349c 100644
--- a/hw/arm/stm32l4x5_soc.c
+++ b/hw/arm/stm32l4x5_soc.c
@@ -81,6 +81,10 @@ static const int exti_irq[NUM_EXTI_IRQ] = {
 #define RCC_BASE_ADDRESS 0x40021000
 #define RCC_IRQ 5
 
+#define EXTI_USART1_IRQ 26
+#define EXTI_UART4_IRQ 29
+#define EXTI_LPUART1_IRQ 31
+
 static const int exti_or_gates_out[NUM_EXTI_OR_GATES] = {
     23, 40, 63, 1,
 };
@@ -129,10 +133,6 @@ static const hwaddr uart_addr[] = {
 
 #define LPUART_BASE_ADDRESS 0x40008000
 
-static const int usart_irq[] = { 37, 38, 39 };
-static const int uart_irq[] = { 52, 53 };
-#define LPUART_IRQ 70
-
 static void stm32l4x5_soc_initfn(Object *obj)
 {
     Stm32l4x5SocState *s = STM32L4X5_SOC(obj);
@@ -297,6 +297,7 @@ static void stm32l4x5_soc_realize(DeviceState *dev_soc, Error **errp)
         }
     }
 
+    /* Connect SYSCFG to EXTI */
     for (unsigned i = 0; i < GPIO_NUM_PINS; i++) {
         qdev_connect_gpio_out(DEVICE(&s->syscfg), i,
                               qdev_get_gpio_in(DEVICE(&s->exti), i));
@@ -322,15 +323,10 @@ static void stm32l4x5_soc_realize(DeviceState *dev_soc, Error **errp)
             return;
         }
         sysbus_mmio_map(busdev, 0, usart_addr[i]);
-        sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(armv7m, usart_irq[i]));
+        sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(DEVICE(&s->exti),
+                                                       EXTI_USART1_IRQ + i));
     }
 
-    /*
-     * TODO: Connect the USARTs, UARTs and LPUART to the EXTI once the EXTI
-     * can handle other gpio-in than the gpios. (e.g. Direct Lines for the
-     * usarts)
-     */
-
     /* UART devices */
     for (int i = 0; i < STM_NUM_UARTS; i++) {
         g_autofree char *name = g_strdup_printf("uart%d-out", STM_NUM_USARTS + i + 1);
@@ -343,7 +339,8 @@ static void stm32l4x5_soc_realize(DeviceState *dev_soc, Error **errp)
             return;
         }
         sysbus_mmio_map(busdev, 0, uart_addr[i]);
-        sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(armv7m, uart_irq[i]));
+        sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(DEVICE(&s->exti),
+                                                       EXTI_UART4_IRQ + i));
     }
 
     /* LPUART device*/
@@ -356,7 +353,8 @@ static void stm32l4x5_soc_realize(DeviceState *dev_soc, Error **errp)
         return;
     }
     sysbus_mmio_map(busdev, 0, LPUART_BASE_ADDRESS);
-    sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(armv7m, LPUART_IRQ));
+    sysbus_connect_irq(busdev, 0, qdev_get_gpio_in(DEVICE(&s->exti),
+                                                   EXTI_LPUART1_IRQ));
 
     /* APB1 BUS */
     create_unimplemented_device("TIM2",      0x40000000, 0x400);
-- 
2.43.2