hw/gpio: Implement STM32L4x5 GPIO

Features supported :
- the 8 STM32L4x5 GPIOs are initialized with their reset values
    (except IDR, see below)
- input mode : setting a pin in input mode "externally" (using input
    irqs) results in an out irq (transmitted to SYSCFG)
- output mode : setting a bit in ODR sets the corresponding out irq
    (if this line is configured in output mode)
- pull-up, pull-down
- push-pull, open-drain

Difference with the real GPIOs :
- Alternate Function and Analog mode aren't implemented :
    pins in AF/Analog behave like pins in input mode
- floating pins stay at their last value
- register IDR reset values differ from the real one :
    values are coherent with the other registers reset values
    and the fact that AF/Analog modes aren't implemented
- setting I/O output speed isn't supported
- locking port bits isn't supported
- ADC function isn't supported
- GPIOH has 16 pins instead of 2 pins
- writing to registers LCKR, AFRL, AFRH and ASCR is ineffective

Signed-off-by: Arnaud Minier <arnaud.minier@telecom-paris.fr>
Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20240305210444.310665-2-ines.varhol@telecom-paris.fr
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

include/hw/gpio/stm32l4x5_gpio.h

@@ -0,0 +1,70 @@
+/*
+ * STM32L4x5 GPIO (General Purpose Input/Ouput)
+ *
+ * Copyright (c) 2024 Arnaud Minier <arnaud.minier@telecom-paris.fr>
+ * Copyright (c) 2024 Inès Varhol <ines.varhol@telecom-paris.fr>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+/*
+ * The reference used is the STMicroElectronics RM0351 Reference manual
+ * for STM32L4x5 and STM32L4x6 advanced Arm ® -based 32-bit MCUs.
+ * https://www.st.com/en/microcontrollers-microprocessors/stm32l4x5/documentation.html
+ */
+
+#ifndef HW_STM32L4X5_GPIO_H
+#define HW_STM32L4X5_GPIO_H
+
+#include "hw/sysbus.h"
+#include "qom/object.h"
+
+#define TYPE_STM32L4X5_GPIO "stm32l4x5-gpio"
+OBJECT_DECLARE_SIMPLE_TYPE(Stm32l4x5GpioState, STM32L4X5_GPIO)
+
+#define GPIO_NUM_PINS 16
+
+struct Stm32l4x5GpioState {
+    SysBusDevice parent_obj;
+
+    MemoryRegion mmio;
+
+    /* GPIO registers */
+    uint32_t moder;
+    uint32_t otyper;
+    uint32_t ospeedr;
+    uint32_t pupdr;
+    uint32_t idr;
+    uint32_t odr;
+    uint32_t lckr;
+    uint32_t afrl;
+    uint32_t afrh;
+    uint32_t ascr;
+
+    /* GPIO registers reset values */
+    uint32_t moder_reset;
+    uint32_t ospeedr_reset;
+    uint32_t pupdr_reset;
+
+    /*
+     * External driving of pins.
+     * The pins can be set externally through the device
+     * anonymous input GPIOs lines under certain conditions.
+     * The pin must not be in push-pull output mode,
+     * and can't be set high in open-drain mode.
+     * Pins driven externally and configured to
+     * output mode will in general be "disconnected"
+     * (see `get_gpio_pinmask_to_disconnect()`)
+     */
+    uint16_t disconnected_pins;
+    uint16_t pins_connected_high;
+
+    char *name;
+    Clock *clk;
+    qemu_irq pin[GPIO_NUM_PINS];
+};
+
+#endif