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>

7 files changed, 559 insertions, 1 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 4183f2f..4d96f85 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1133,6 +1133,7 @@ F: hw/arm/stm32l4x5_soc.c
 F: hw/misc/stm32l4x5_exti.c
 F: hw/misc/stm32l4x5_syscfg.c
 F: hw/misc/stm32l4x5_rcc.c
+F: hw/gpio/stm32l4x5_gpio.c
 F: include/hw/*/stm32l4x5_*.h
 
 B-L475E-IOT01A IoT Node
diff --git a/docs/system/arm/b-l475e-iot01a.rst b/docs/system/arm/b-l475e-iot01a.rst
index b857a56..0afef8e 100644
--- a/docs/system/arm/b-l475e-iot01a.rst
+++ b/docs/system/arm/b-l475e-iot01a.rst
@@ -18,6 +18,7 @@ Currently B-L475E-IOT01A machine's only supports the following devices:
 - STM32L4x5 EXTI (Extended interrupts and events controller)
 - STM32L4x5 SYSCFG (System configuration controller)
 - STM32L4x5 RCC (Reset and clock control)
+- STM32L4x5 GPIOs (General-purpose I/Os)
 
 Missing devices
 """""""""""""""
@@ -25,7 +26,6 @@ Missing devices
 The B-L475E-IOT01A does *not* support the following devices:
 
 - Serial ports (UART)
-- General-purpose I/Os (GPIO)
 - Analog to Digital Converter (ADC)
 - SPI controller
 - Timer controller (TIMER)
diff --git a/hw/gpio/Kconfig b/hw/gpio/Kconfig
index d2cf3ac..712940b 100644
--- a/hw/gpio/Kconfig
+++ b/hw/gpio/Kconfig
@@ -16,3 +16,6 @@ config GPIO_PWR
 
 config SIFIVE_GPIO
     bool
+
+config STM32L4X5_GPIO
+    bool
diff --git a/hw/gpio/meson.build b/hw/gpio/meson.build
index 8a8d03d..3454b50 100644
--- a/hw/gpio/meson.build
+++ b/hw/gpio/meson.build
@@ -13,5 +13,6 @@ system_ss.add(when: 'CONFIG_RASPI', if_true: files(
     'bcm2835_gpio.c',
     'bcm2838_gpio.c'
 ))
+system_ss.add(when: 'CONFIG_STM32L4X5_SOC', if_true: files('stm32l4x5_gpio.c'))
 system_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: files('aspeed_gpio.c'))
 system_ss.add(when: 'CONFIG_SIFIVE_GPIO', if_true: files('sifive_gpio.c'))
diff --git a/hw/gpio/stm32l4x5_gpio.c b/hw/gpio/stm32l4x5_gpio.c
new file mode 100644
index 0000000..63b8763
--- /dev/null
+++ b/hw/gpio/stm32l4x5_gpio.c
@@ -0,0 +1,477 @@
+/*
+ * 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
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "hw/gpio/stm32l4x5_gpio.h"
+#include "hw/irq.h"
+#include "hw/qdev-clock.h"
+#include "hw/qdev-properties.h"
+#include "qapi/visitor.h"
+#include "qapi/error.h"
+#include "migration/vmstate.h"
+#include "trace.h"
+
+#define GPIO_MODER 0x00
+#define GPIO_OTYPER 0x04
+#define GPIO_OSPEEDR 0x08
+#define GPIO_PUPDR 0x0C
+#define GPIO_IDR 0x10
+#define GPIO_ODR 0x14
+#define GPIO_BSRR 0x18
+#define GPIO_LCKR 0x1C
+#define GPIO_AFRL 0x20
+#define GPIO_AFRH 0x24
+#define GPIO_BRR 0x28
+#define GPIO_ASCR 0x2C
+
+/* 0b11111111_11111111_00000000_00000000 */
+#define RESERVED_BITS_MASK 0xFFFF0000
+
+static void update_gpio_idr(Stm32l4x5GpioState *s);
+
+static bool is_pull_up(Stm32l4x5GpioState *s, unsigned pin)
+{
+    return extract32(s->pupdr, 2 * pin, 2) == 1;
+}
+
+static bool is_pull_down(Stm32l4x5GpioState *s, unsigned pin)
+{
+    return extract32(s->pupdr, 2 * pin, 2) == 2;
+}
+
+static bool is_output(Stm32l4x5GpioState *s, unsigned pin)
+{
+    return extract32(s->moder, 2 * pin, 2) == 1;
+}
+
+static bool is_open_drain(Stm32l4x5GpioState *s, unsigned pin)
+{
+    return extract32(s->otyper, pin, 1) == 1;
+}
+
+static bool is_push_pull(Stm32l4x5GpioState *s, unsigned pin)
+{
+    return extract32(s->otyper, pin, 1) == 0;
+}
+
+static void stm32l4x5_gpio_reset_hold(Object *obj)
+{
+    Stm32l4x5GpioState *s = STM32L4X5_GPIO(obj);
+
+    s->moder = s->moder_reset;
+    s->otyper = 0x00000000;
+    s->ospeedr = s->ospeedr_reset;
+    s->pupdr = s->pupdr_reset;
+    s->idr = 0x00000000;
+    s->odr = 0x00000000;
+    s->lckr = 0x00000000;
+    s->afrl = 0x00000000;
+    s->afrh = 0x00000000;
+    s->ascr = 0x00000000;
+
+    s->disconnected_pins = 0xFFFF;
+    s->pins_connected_high = 0x0000;
+    update_gpio_idr(s);
+}
+
+static void stm32l4x5_gpio_set(void *opaque, int line, int level)
+{
+    Stm32l4x5GpioState *s = opaque;
+    /*
+     * The pin isn't set if line is configured in output mode
+     * except if level is 0 and the output is open-drain.
+     * This way there will be no short-circuit prone situations.
+     */
+    if (is_output(s, line) && !(is_open_drain(s, line) && (level == 0))) {
+        qemu_log_mask(LOG_GUEST_ERROR, "Line %d can't be driven externally\n",
+                      line);
+        return;
+    }
+
+    s->disconnected_pins &= ~(1 << line);
+    if (level) {
+        s->pins_connected_high |= (1 << line);
+    } else {
+        s->pins_connected_high &= ~(1 << line);
+    }
+    trace_stm32l4x5_gpio_pins(s->name, s->disconnected_pins,
+                              s->pins_connected_high);
+    update_gpio_idr(s);
+}
+
+
+static void update_gpio_idr(Stm32l4x5GpioState *s)
+{
+    uint32_t new_idr_mask = 0;
+    uint32_t new_idr = s->odr;
+    uint32_t old_idr = s->idr;
+    int new_pin_state, old_pin_state;
+
+    for (int i = 0; i < GPIO_NUM_PINS; i++) {
+        if (is_output(s, i)) {
+            if (is_push_pull(s, i)) {
+                new_idr_mask |= (1 << i);
+            } else if (!(s->odr & (1 << i))) {
+                /* open-drain ODR 0 */
+                new_idr_mask |= (1 << i);
+            /* open-drain ODR 1 */
+            } else if (!(s->disconnected_pins & (1 << i)) &&
+                       !(s->pins_connected_high & (1 << i))) {
+                /* open-drain ODR 1 with pin connected low */
+                new_idr_mask |= (1 << i);
+                new_idr &= ~(1 << i);
+            /* open-drain ODR 1 with unactive pin */
+            } else if (is_pull_up(s, i)) {
+                new_idr_mask |= (1 << i);
+            } else if (is_pull_down(s, i)) {
+                new_idr_mask |= (1 << i);
+                new_idr &= ~(1 << i);
+            }
+            /*
+             * The only case left is for open-drain ODR 1
+             * with unactive pin without pull-up or pull-down :
+             * the value is floating.
+             */
+        /* input or analog mode with connected pin */
+        } else if (!(s->disconnected_pins & (1 << i))) {
+            if (s->pins_connected_high & (1 << i)) {
+                /* pin high */
+                new_idr_mask |= (1 << i);
+                new_idr |= (1 << i);
+            } else {
+                /* pin low */
+                new_idr_mask |= (1 << i);
+                new_idr &= ~(1 << i);
+            }
+        /* input or analog mode with disconnected pin */
+        } else {
+            if (is_pull_up(s, i)) {
+                /* pull-up */
+                new_idr_mask |= (1 << i);
+                new_idr |= (1 << i);
+            } else if (is_pull_down(s, i)) {
+                /* pull-down */
+                new_idr_mask |= (1 << i);
+                new_idr &= ~(1 << i);
+            }
+            /*
+             * The only case left is for a disconnected pin
+             * without pull-up or pull-down :
+             * the value is floating.
+             */
+        }
+    }
+
+    s->idr = (old_idr & ~new_idr_mask) | (new_idr & new_idr_mask);
+    trace_stm32l4x5_gpio_update_idr(s->name, old_idr, s->idr);
+
+    for (int i = 0; i < GPIO_NUM_PINS; i++) {
+        if (new_idr_mask & (1 << i)) {
+            new_pin_state = (new_idr & (1 << i)) > 0;
+            old_pin_state = (old_idr & (1 << i)) > 0;
+            if (new_pin_state > old_pin_state) {
+                qemu_irq_raise(s->pin[i]);
+            } else if (new_pin_state < old_pin_state) {
+                qemu_irq_lower(s->pin[i]);
+            }
+        }
+    }
+}
+
+/*
+ * Return mask of pins that are both configured in output
+ * mode and externally driven (except pins in open-drain
+ * mode externally set to 0).
+ */
+static uint32_t get_gpio_pinmask_to_disconnect(Stm32l4x5GpioState *s)
+{
+    uint32_t pins_to_disconnect = 0;
+    for (int i = 0; i < GPIO_NUM_PINS; i++) {
+        /* for each connected pin in output mode */
+        if (!(s->disconnected_pins & (1 << i)) && is_output(s, i)) {
+            /* if either push-pull or high level */
+            if (is_push_pull(s, i) || s->pins_connected_high & (1 << i)) {
+                pins_to_disconnect |= (1 << i);
+                qemu_log_mask(LOG_GUEST_ERROR,
+                              "Line %d can't be driven externally\n",
+                              i);
+            }
+        }
+    }
+    return pins_to_disconnect;
+}
+
+/*
+ * Set field `disconnected_pins` and call `update_gpio_idr()`
+ */
+static void disconnect_gpio_pins(Stm32l4x5GpioState *s, uint16_t lines)
+{
+    s->disconnected_pins |= lines;
+    trace_stm32l4x5_gpio_pins(s->name, s->disconnected_pins,
+                              s->pins_connected_high);
+    update_gpio_idr(s);
+}
+
+static void disconnected_pins_set(Object *obj, Visitor *v,
+    const char *name, void *opaque, Error **errp)
+{
+    Stm32l4x5GpioState *s = STM32L4X5_GPIO(obj);
+    uint16_t value;
+    if (!visit_type_uint16(v, name, &value, errp)) {
+        return;
+    }
+    disconnect_gpio_pins(s, value);
+}
+
+static void disconnected_pins_get(Object *obj, Visitor *v,
+    const char *name, void *opaque, Error **errp)
+{
+    visit_type_uint16(v, name, (uint16_t *)opaque, errp);
+}
+
+static void clock_freq_get(Object *obj, Visitor *v,
+    const char *name, void *opaque, Error **errp)
+{
+    Stm32l4x5GpioState *s = STM32L4X5_GPIO(obj);
+    uint32_t clock_freq_hz = clock_get_hz(s->clk);
+    visit_type_uint32(v, name, &clock_freq_hz, errp);
+}
+
+static void stm32l4x5_gpio_write(void *opaque, hwaddr addr,
+                                 uint64_t val64, unsigned int size)
+{
+    Stm32l4x5GpioState *s = opaque;
+
+    uint32_t value = val64;
+    trace_stm32l4x5_gpio_write(s->name, addr, val64);
+
+    switch (addr) {
+    case GPIO_MODER:
+        s->moder = value;
+        disconnect_gpio_pins(s, get_gpio_pinmask_to_disconnect(s));
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: Analog and AF modes aren't supported\n\
+                       Analog and AF mode behave like input mode\n",
+                      __func__);
+        return;
+    case GPIO_OTYPER:
+        s->otyper = value & ~RESERVED_BITS_MASK;
+        disconnect_gpio_pins(s, get_gpio_pinmask_to_disconnect(s));
+        return;
+    case GPIO_OSPEEDR:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: Changing I/O output speed isn't supported\n\
+                       I/O speed is already maximal\n",
+                      __func__);
+        s->ospeedr = value;
+        return;
+    case GPIO_PUPDR:
+        s->pupdr = value;
+        update_gpio_idr(s);
+        return;
+    case GPIO_IDR:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: GPIO->IDR is read-only\n",
+                      __func__);
+        return;
+    case GPIO_ODR:
+        s->odr = value & ~RESERVED_BITS_MASK;
+        update_gpio_idr(s);
+        return;
+    case GPIO_BSRR: {
+        uint32_t bits_to_reset = (value & RESERVED_BITS_MASK) >> GPIO_NUM_PINS;
+        uint32_t bits_to_set = value & ~RESERVED_BITS_MASK;
+        /* If both BSx and BRx are set, BSx has priority.*/
+        s->odr &= ~bits_to_reset;
+        s->odr |= bits_to_set;
+        update_gpio_idr(s);
+        return;
+    }
+    case GPIO_LCKR:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: Locking port bits configuration isn't supported\n",
+                      __func__);
+        s->lckr = value & ~RESERVED_BITS_MASK;
+        return;
+    case GPIO_AFRL:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: Alternate functions aren't supported\n",
+                      __func__);
+        s->afrl = value;
+        return;
+    case GPIO_AFRH:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: Alternate functions aren't supported\n",
+                      __func__);
+        s->afrh = value;
+        return;
+    case GPIO_BRR: {
+        uint32_t bits_to_reset = value & ~RESERVED_BITS_MASK;
+        s->odr &= ~bits_to_reset;
+        update_gpio_idr(s);
+        return;
+    }
+    case GPIO_ASCR:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: ADC function isn't supported\n",
+                      __func__);
+        s->ascr = value & ~RESERVED_BITS_MASK;
+        return;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, addr);
+    }
+}
+
+static uint64_t stm32l4x5_gpio_read(void *opaque, hwaddr addr,
+                                    unsigned int size)
+{
+    Stm32l4x5GpioState *s = opaque;
+
+    trace_stm32l4x5_gpio_read(s->name, addr);
+
+    switch (addr) {
+    case GPIO_MODER:
+        return s->moder;
+    case GPIO_OTYPER:
+        return s->otyper;
+    case GPIO_OSPEEDR:
+        return s->ospeedr;
+    case GPIO_PUPDR:
+        return s->pupdr;
+    case GPIO_IDR:
+        return s->idr;
+    case GPIO_ODR:
+        return s->odr;
+    case GPIO_BSRR:
+        return 0;
+    case GPIO_LCKR:
+        return s->lckr;
+    case GPIO_AFRL:
+        return s->afrl;
+    case GPIO_AFRH:
+        return s->afrh;
+    case GPIO_BRR:
+        return 0;
+    case GPIO_ASCR:
+        return s->ascr;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Bad offset 0x%" HWADDR_PRIx "\n", __func__, addr);
+        return 0;
+    }
+}
+
+static const MemoryRegionOps stm32l4x5_gpio_ops = {
+    .read = stm32l4x5_gpio_read,
+    .write = stm32l4x5_gpio_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+        .unaligned = false,
+    },
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+        .unaligned = false,
+    },
+};
+
+static void stm32l4x5_gpio_init(Object *obj)
+{
+    Stm32l4x5GpioState *s = STM32L4X5_GPIO(obj);
+
+    memory_region_init_io(&s->mmio, obj, &stm32l4x5_gpio_ops, s,
+                          TYPE_STM32L4X5_GPIO, 0x400);
+
+    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
+
+    qdev_init_gpio_out(DEVICE(obj), s->pin, GPIO_NUM_PINS);
+    qdev_init_gpio_in(DEVICE(obj), stm32l4x5_gpio_set, GPIO_NUM_PINS);
+
+    s->clk = qdev_init_clock_in(DEVICE(s), "clk", NULL, s, 0);
+
+    object_property_add(obj, "disconnected-pins", "uint16",
+                        disconnected_pins_get, disconnected_pins_set,
+                        NULL, &s->disconnected_pins);
+    object_property_add(obj, "clock-freq-hz", "uint32",
+                        clock_freq_get, NULL, NULL, NULL);
+}
+
+static void stm32l4x5_gpio_realize(DeviceState *dev, Error **errp)
+{
+    Stm32l4x5GpioState *s = STM32L4X5_GPIO(dev);
+    if (!clock_has_source(s->clk)) {
+        error_setg(errp, "GPIO: clk input must be connected");
+        return;
+    }
+}
+
+static const VMStateDescription vmstate_stm32l4x5_gpio = {
+    .name = TYPE_STM32L4X5_GPIO,
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]){
+        VMSTATE_UINT32(moder, Stm32l4x5GpioState),
+        VMSTATE_UINT32(otyper, Stm32l4x5GpioState),
+        VMSTATE_UINT32(ospeedr, Stm32l4x5GpioState),
+        VMSTATE_UINT32(pupdr, Stm32l4x5GpioState),
+        VMSTATE_UINT32(idr, Stm32l4x5GpioState),
+        VMSTATE_UINT32(odr, Stm32l4x5GpioState),
+        VMSTATE_UINT32(lckr, Stm32l4x5GpioState),
+        VMSTATE_UINT32(afrl, Stm32l4x5GpioState),
+        VMSTATE_UINT32(afrh, Stm32l4x5GpioState),
+        VMSTATE_UINT32(ascr, Stm32l4x5GpioState),
+        VMSTATE_UINT16(disconnected_pins, Stm32l4x5GpioState),
+        VMSTATE_UINT16(pins_connected_high, Stm32l4x5GpioState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static Property stm32l4x5_gpio_properties[] = {
+    DEFINE_PROP_STRING("name", Stm32l4x5GpioState, name),
+    DEFINE_PROP_UINT32("mode-reset", Stm32l4x5GpioState, moder_reset, 0),
+    DEFINE_PROP_UINT32("ospeed-reset", Stm32l4x5GpioState, ospeedr_reset, 0),
+    DEFINE_PROP_UINT32("pupd-reset", Stm32l4x5GpioState, pupdr_reset, 0),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void stm32l4x5_gpio_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    ResettableClass *rc = RESETTABLE_CLASS(klass);
+
+    device_class_set_props(dc, stm32l4x5_gpio_properties);
+    dc->vmsd = &vmstate_stm32l4x5_gpio;
+    dc->realize = stm32l4x5_gpio_realize;
+    rc->phases.hold = stm32l4x5_gpio_reset_hold;
+}
+
+static const TypeInfo stm32l4x5_gpio_types[] = {
+    {
+        .name = TYPE_STM32L4X5_GPIO,
+        .parent = TYPE_SYS_BUS_DEVICE,
+        .instance_size = sizeof(Stm32l4x5GpioState),
+        .instance_init = stm32l4x5_gpio_init,
+        .class_init = stm32l4x5_gpio_class_init,
+    },
+};
+
+DEFINE_TYPES(stm32l4x5_gpio_types)
diff --git a/hw/gpio/trace-events b/hw/gpio/trace-events
index 9736b36..9331f42 100644
--- a/hw/gpio/trace-events
+++ b/hw/gpio/trace-events
@@ -31,3 +31,9 @@ sifive_gpio_update_output_irq(int64_t line, int64_t value) "line %" PRIi64 " val
 # aspeed_gpio.c
 aspeed_gpio_read(uint64_t offset, uint64_t value) "offset: 0x%" PRIx64 " value 0x%" PRIx64
 aspeed_gpio_write(uint64_t offset, uint64_t value) "offset: 0x%" PRIx64 " value 0x%" PRIx64
+
+# stm32l4x5_gpio.c
+stm32l4x5_gpio_read(char *gpio, uint64_t addr) "GPIO%s addr: 0x%" PRIx64 " "
+stm32l4x5_gpio_write(char *gpio, uint64_t addr, uint64_t data) "GPIO%s addr: 0x%" PRIx64 " val: 0x%" PRIx64 ""
+stm32l4x5_gpio_update_idr(char *gpio, uint32_t old_idr, uint32_t new_idr) "GPIO%s from: 0x%x to: 0x%x"
+stm32l4x5_gpio_pins(char *gpio, uint16_t disconnected, uint16_t high) "GPIO%s disconnected pins: 0x%x levels: 0x%x"
diff --git a/include/hw/gpio/stm32l4x5_gpio.h b/include/hw/gpio/stm32l4x5_gpio.h
new file mode 100644
index 0000000..0d361f3
--- /dev/null
+++ b/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