16782: drivers/mfrc522: add new driver r=benpicco a=HendrikVE
### Contribution description
This PR adds support for the MFRC522. It is quite common in the Arduino world and it is quite cheap. The driver connects to the MFRC522 via SPI and is heavily based on the Arduino driver available [here](https://github.com/miguelbalboa/rfid). Basically it was ported, but with several improvements in readability and documentation.
### Testing procedure
The given (manual) test provides single commands for some driver functions.
19201: cpu/gd32v: add periph_i2c support r=benpicco a=gschorcht
### Contribution description
This PR provides the `periph_i2c` support and is one of a bunch of PRs that complete the peripheral drivers for GD32VF103.
The driver is a modified version of the driver for STM32F1 with some changes that were necessary to get it working on GD32V. As for STM32F1, the driver is using polling instead of interrupts for now. It will be implemented interrupt-driven later.
### Testing procedure
`tests/periph_i2c` as well as a test with any I2C sensor should work. The driver was tested with `tests/driver_l3gxxxx` and `tests/driver_bmp180`.
### Issues/PRs references
Co-authored-by: Hendrik van Essen <hendrik.ve@fu-berlin.de>
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
When a timer is set, any pending interrupts must be cleared before the interrupt is enabled for the channel. Otherwise the interrupt would be triggered immediately when the timer is set.
19185: cpu/gd32v: add periph_gpio_irq support r=gschorcht a=gschorcht
### Contribution description
This PR provides the `periph_gpio_irq` support and is one of a bunch of follow up PRs that complete the peripheral drivers for GD32VF103.
### Testing procedure
Use a GD32VF103 board and flash `tests/periph_gpio`. Note: The Sipeed Longan Nano works also with `seeedstudio-gd32` board defintion and could be used for testing.
```
BOARD=seeedstudio-gd32 make -C tests/periph_gpio flash (until PR #19170 is merged only `seeedstudio
```
With the GPIO PB8 and PB9 connected, the following test sequence should work:
```
> init_out 1 8
> init_int 1 9 2 0
GPIO_PIN(1, 9) successfully initialized as ext int
> set 1 8
INT: external interrupt from pin 9
> clear 1 8
INT: external interrupt from pin 9
```
### Issues/PRs references
19187: cpu/gd32v: add pm_layered support in periph_pm r=gschorcht a=gschorcht
### Contribution description
This PR provides the `pm_layered` support and is one of a bunch of follow up PRs that complete the peripheral drivers for GD32VF103.
Since the configuration of the deep sleep and the standby mode require the access CSR (control and status registers) of the MCU, the Nuclei-SDK NMSIS is added as package which provides a low-level interface for Nuclei-based RISC-V MCUs.
### Testing procedure
The best way to test it is to rebase this PR onto PR #19186 and to flash `tests/periph_pm` to any GD32VF103 board. Note: The Sipeed Longan Nano works also with `seeedstudio-gd32` board definition and could be used for testing.
```
BOARD=seeedstudio-gd32 make -C tests/periph_pm flash
```
The test output should be:
```
main(): This is RIOT! (Version: 2023.04-devel-174-g7dc91-cpu/gd32v/periph_pm_test)
...
mode 0 blockers: 1
mode 1 blockers: 2
mode 2 blockers: 0
Lowest allowed mode: 2
```
Using command the `set_rtc 1 5` command should let the MCU deep sleep for 5 seconds
```
> set_rtc 1 5
Setting power mode 1 for 5 seconds.
␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀␀>
```
while command `set_rtc 1 5` should set the MCU into the standby mode which is left with restart.
```
> set_rtc 0 5
Setting power mode 0 for 5 seconds.
main(): This is RIOT! (Version: 2023.04-devel-174-g7dc91-cpu/gd32v/periph_pm_test)
...
mode 0 blockers: 1
mode 1 blockers: 2
mode 2 blockers: 0
Lowest allowed mode: 2
>
```
The garbage on UART interface after deep sleep is caused by the clock synchronisation that becomes necessary after deep sleep and is the same as for other boards.
### Issues/PRs references
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
The configuration whether a HXTAL is present and what its clock frequency is will be added to Kconfig. Since it is the only GD32V board at the moment, the configuration is added to the Kconfig of the board, but should be moved to a common Kconfig later when more GD32V boards are added.
`CONFIG_BOARD_HAS_HXTAL` is used to indicate that the board has an HXTAL connected. If the HXTAL is present, it is used as PLL clock source. But if the HXTAL is not present, the half IRC8M clock should be used as PLL clock source and must not be disabled at the end of clock settings. Using IRC8M clock as PLL clock source also requires another PLL multiplication factor.
`CLOCK_HXTAL` is a value and not a flag, so that shifting to the left changes anything in the register but does not set the PLLSEL bit. `RCU_CFG0_PLLSEL_Msk` has to be used instead to set the PLLSEL bit.
Setting the `RCU_CTL` register just to the IRC8M bit also removes the IRC8M calibration and trim adjust value in this register. Therefore IRC8M calibration and trim adjust value have to be preserved and the IRC8M has to be set.
This adds support for the gd32v class devices from Gigadevice. The
gd32vf103 contains an 108 MHz RISC-V core with similar peripherals as
the stm32f1 devices
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>
