Add a trace event to track baudrate changes. Example when running the FreeRTOS acceptance test [1]:
$ qemu-system-avr -machine arduino-mega-2560-v3 -bios demo.elf -trace avr\* 2546@1597415281.399619:avr_usart_update_baudrate baudrate 0x0019 (38461 bauds) 2546@1597415281.400029:avr_usart_update_baudrate baudrate 0x0019 (38461 bauds) Which confirm the definition from the test [2]: #define mainCOM_TEST_BAUD_RATE ( ( unsigned long ) 38400 ) [1] tests/acceptance/machine_avr6.py [2] https://github.com/seharris/qemu-avr-tests/blob/9c0c24da1b1/free-rtos/Demo/AVR_ATMega2560_GCC/main.c#L80 Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org> --- hw/char/avr_usart.c | 13 +++++++++++++ hw/char/trace-events | 3 +++ 2 files changed, 16 insertions(+) diff --git a/hw/char/avr_usart.c b/hw/char/avr_usart.c index 4a43492082..176158a96b 100644 --- a/hw/char/avr_usart.c +++ b/hw/char/avr_usart.c @@ -25,6 +25,7 @@ #include "hw/irq.h" #include "hw/qdev-clock.h" #include "hw/qdev-properties.h" +#include "trace.h" /* Offsets of registers. */ #define USART_DR 0x06 @@ -56,6 +57,8 @@ #define USART_CSRC_CSZ1 (1 << 2) #define USART_CSRC_CSZ0 (1 << 1) +#define USART_CLOCK_DIVISOR 16 /* baudrate is input clock / 16 */ + static int avr_usart_can_receive(void *opaque) { AVRUsartState *usart = opaque; @@ -120,6 +123,14 @@ static void update_char_mask(AVRUsartState *usart) } } +static void avr_usart_update_baudrate(AVRUsartState *s) +{ + unsigned baudrate = (clock_get_hz(s->clkin) / USART_CLOCK_DIVISOR) + / (((s->brrh << 8) | s->brrl) + 1); + + trace_avr_usart_update_baudrate((s->brrh << 8) | s->brrl, baudrate); +} + static void avr_usart_reset(DeviceState *dev) { AVRUsartState *usart = AVR_USART(dev); @@ -269,9 +280,11 @@ static void avr_usart_write(void *opaque, hwaddr addr, uint64_t value, break; case USART_BRRL: usart->brrl = value; + avr_usart_update_baudrate(usart); break; case USART_BRRH: usart->brrh = value & 0b00001111; + avr_usart_update_baudrate(usart); break; default: qemu_log_mask( diff --git a/hw/char/trace-events b/hw/char/trace-events index d20eafd56f..b92cecbfaa 100644 --- a/hw/char/trace-events +++ b/hw/char/trace-events @@ -100,3 +100,6 @@ exynos_uart_rx_timeout(uint32_t channel, uint32_t stat, uint32_t intsp) "UART%d: # hw/char/cadence_uart.c cadence_uart_baudrate(unsigned baudrate) "baudrate %u" + +# avr_usart.c +avr_usart_update_baudrate(uint16_t regval, unsigned baudrate) "baudrate 0x%04x (%u bauds)" -- 2.21.3
