hw/arm: Add minimal support for the B-L475E-IOT01A board

This commit adds a new B-L475E-IOT01A board using the STM32L475VG SoC
as well as a dedicated documentation file.
The implementation is derived from the Netduino Plus 2 machine.
There are no peripherals implemented yet, only memory regions.

Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-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>
Message-id: 20240108135849.351719-3-ines.varhol@telecom-paris.fr
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

MAINTAINERS

@@ -1130,6 +1130,13 @@ S: Maintained
 F: hw/arm/stm32l4x5_soc.c
 F: include/hw/arm/stm32l4x5_soc.h
 
+B-L475E-IOT01A IoT Node
+M: Arnaud Minier <arnaud.minier@telecom-paris.fr>
+M: Inès Varhol <ines.varhol@telecom-paris.fr>
+L: qemu-arm@nongnu.org
+S: Maintained
+F: hw/arm/b-l475e-iot01a.c
+
 SmartFusion2
 M: Subbaraya Sundeep <sundeep.lkml@gmail.com>
 M: Peter Maydell <peter.maydell@linaro.org>

configs/devices/arm-softmmu/default.mak

@@ -19,6 +19,7 @@ CONFIG_ARM_VIRT=y
 # CONFIG_NSERIES=n
 # CONFIG_STELLARIS=n
 # CONFIG_STM32VLDISCOVERY=n
+# CONFIG_B_L475E_IOT01A=n
 # CONFIG_REALVIEW=n
 # CONFIG_VERSATILE=n
 # CONFIG_VEXPRESS=n

docs/system/arm/b-l475e-iot01a.rst

@@ -0,0 +1,46 @@
+B-L475E-IOT01A IoT Node (``b-l475e-iot01a``)
+============================================
+
+The B-L475E-IOT01A IoT Node uses the STM32L475VG SoC which is based on
+ARM Cortex-M4F core. It is part of STMicroelectronics
+:doc:`STM32 boards </system/arm/stm32>` and more specifically the STM32L4
+ultra-low power series. The STM32L4x5 chip runs at up to 80 MHz and
+integrates 128 KiB of SRAM and up to 1MiB of Flash. The B-L475E-IOT01A board
+namely features 64 Mibit QSPI Flash, BT, WiFi and RF connectivity,
+USART, I2C, SPI, CAN and USB OTG, as well as a variety of sensors.
+
+Supported devices
+"""""""""""""""""
+
+Currently, B-L475E-IOT01A machine's implementation is minimal,
+it only supports the following device:
+
+- Cortex-M4F based STM32L4x5 SoC
+
+Missing devices
+"""""""""""""""
+
+The B-L475E-IOT01A does *not* support the following devices:
+
+- Extended interrupts and events controller (EXTI)
+- Reset and clock control (RCC)
+- Serial ports (UART)
+- System configuration controller (SYSCFG)
+- General-purpose I/Os (GPIO)
+- Analog to Digital Converter (ADC)
+- SPI controller
+- Timer controller (TIMER)
+
+See the complete list of unimplemented peripheral devices
+in the STM32L4x5 module : ``./hw/arm/stm32l4x5_soc.c``
+
+Boot options
+""""""""""""
+
+The B-L475E-IOT01A machine can be started using the ``-kernel``
+option to load a firmware. Example:
+
+.. code-block:: bash
+
+  $ qemu-system-arm -M b-l475e-iot01a -kernel firmware.bin
+

docs/system/arm/stm32.rst

@@ -16,11 +16,13 @@ based on this chip :
 
 - ``netduino2``         Netduino 2 board with STM32F205RFT6 microcontroller
 
-The STM32F4 series is based on ARM Cortex-M4F core. This series is pin-to-pin
-compatible with STM32F2 series. The following machines are based on this chip :
+The STM32F4 series is based on ARM Cortex-M4F core, as well as the STM32L4
+ultra-low-power series. The STM32F4 series is pin-to-pin compatible with STM32F2 series.
+The following machines are based on this ARM Cortex-M4F chip :
 
 - ``netduinoplus2``     Netduino Plus 2 board with STM32F405RGT6 microcontroller
 - ``olimex-stm32-h405`` Olimex STM32 H405 board with STM32F405RGT6 microcontroller
+- ``b-l475e-iot01a``     :doc:`B-L475E-IOT01A IoT Node </system/arm/b-l475e-iot01a>` board with STM32L475VG microcontroller
 
 There are many other STM32 series that are currently not supported by QEMU.
 

docs/system/target-arm.rst

@@ -84,6 +84,7 @@ undocumented; you can get a complete list by running
    arm/vexpress
    arm/aspeed
    arm/bananapi_m2u.rst
+   arm/b-l475e-iot01a.rst
    arm/sabrelite
    arm/digic
    arm/cubieboard

hw/arm/Kconfig

@@ -449,6 +449,12 @@ config STM32F405_SOC
     select STM32F4XX_SYSCFG
     select STM32F4XX_EXTI
 
+config B_L475E_IOT01A
+    bool
+    default y
+    depends on TCG && ARM
+    select STM32L4X5_SOC
+
 config STM32L4X5_SOC
     bool
     select ARM_V7M

hw/arm/b-l475e-iot01a.c

@@ -0,0 +1,72 @@
+/*
+ * B-L475E-IOT01A Discovery Kit machine
+ * (B-L475E-IOT01A IoT Node)
+ *
+ * Copyright (c) 2023 Arnaud Minier <arnaud.minier@telecom-paris.fr>
+ * Copyright (c) 2023 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.
+ *
+ * This work is heavily inspired by the netduinoplus2 by Alistair Francis.
+ * Original code is licensed under the MIT License:
+ *
+ * Copyright (c) 2014 Alistair Francis <alistair@alistair23.me>
+ */
+
+/*
+ * The reference used is the STMicroElectronics UM2153 User manual
+ * Discovery kit for IoT node, multi-channel communication with STM32L4.
+ * https://www.st.com/en/evaluation-tools/b-l475e-iot01a.html#documentation
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/boards.h"
+#include "hw/qdev-properties.h"
+#include "hw/qdev-clock.h"
+#include "qemu/error-report.h"
+#include "hw/arm/stm32l4x5_soc.h"
+#include "hw/arm/boot.h"
+
+/* Main SYSCLK frequency in Hz (80MHz) */
+#define MAIN_SYSCLK_FREQ_HZ 80000000ULL
+
+static void b_l475e_iot01a_init(MachineState *machine)
+{
+    const Stm32l4x5SocClass *sc;
+    DeviceState *dev;
+    Clock *sysclk;
+
+    /* This clock doesn't need migration because it is fixed-frequency */
+    sysclk = clock_new(OBJECT(machine), "SYSCLK");
+    clock_set_hz(sysclk, MAIN_SYSCLK_FREQ_HZ);
+
+    dev = qdev_new(TYPE_STM32L4X5XG_SOC);
+    object_property_add_child(OBJECT(machine), "soc", OBJECT(dev));
+    qdev_connect_clock_in(dev, "sysclk", sysclk);
+    sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
+
+    sc = STM32L4X5_SOC_GET_CLASS(dev);
+    armv7m_load_kernel(ARM_CPU(first_cpu),
+                       machine->kernel_filename,
+                       0, sc->flash_size);
+}
+
+static void b_l475e_iot01a_machine_init(MachineClass *mc)
+{
+    static const char *machine_valid_cpu_types[] = {
+        ARM_CPU_TYPE_NAME("cortex-m4"),
+        NULL
+    };
+    mc->desc = "B-L475E-IOT01A Discovery Kit (Cortex-M4)";
+    mc->init = b_l475e_iot01a_init;
+    mc->valid_cpu_types = machine_valid_cpu_types;
+
+    /* SRAM pre-allocated as part of the SoC instantiation */
+    mc->default_ram_size = 0;
+}
+
+DEFINE_MACHINE("b-l475e-iot01a", b_l475e_iot01a_machine_init)

hw/arm/meson.build

@@ -42,6 +42,7 @@ arm_ss.add(when: 'CONFIG_RASPI', if_true: files('bcm2836.c', 'raspi.c'))
 arm_ss.add(when: 'CONFIG_STM32F100_SOC', if_true: files('stm32f100_soc.c'))
 arm_ss.add(when: 'CONFIG_STM32F205_SOC', if_true: files('stm32f205_soc.c'))
 arm_ss.add(when: 'CONFIG_STM32F405_SOC', if_true: files('stm32f405_soc.c'))
+arm_ss.add(when: 'CONFIG_B_L475E_IOT01A', if_true: files('b-l475e-iot01a.c'))
 arm_ss.add(when: 'CONFIG_STM32L4X5_SOC', if_true: files('stm32l4x5_soc.c'))
 arm_ss.add(when: 'CONFIG_XLNX_ZYNQMP_ARM', if_true: files('xlnx-zynqmp.c', 'xlnx-zcu102.c'))
 arm_ss.add(when: 'CONFIG_XLNX_VERSAL', if_true: files('xlnx-versal.c', 'xlnx-versal-virt.c'))