From 51b61dd4d56f20cc58d038440e3d9a8c03482953 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Thu, 18 Jul 2024 17:23:42 +0200 Subject: [PATCH] hw/char/pl011: Warn when using disabled transmitter MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We shouldn't transmit characters when the full UART or its transmitter is disabled. However we don't want to break the possibly incomplete "my first bare metal assembly program"s, so we choose to simply display a warning when this occurs. Signed-off-by: Philippe Mathieu-Daudé Reviewed-by: Alex Bennée Reviewed-by: Richard Henderson Message-Id: <20240719181041.49545-9-philmd@linaro.org> --- hw/char/pl011.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/hw/char/pl011.c b/hw/char/pl011.c index 0f9a5cd16d..f0df58f7a9 100644 --- a/hw/char/pl011.c +++ b/hw/char/pl011.c @@ -85,7 +85,9 @@ DeviceState *pl011_create(hwaddr addr, qemu_irq irq, Chardev *chr) #define CR_OUT1 (1 << 12) #define CR_RTS (1 << 11) #define CR_DTR (1 << 10) +#define CR_TXE (1 << 8) #define CR_LBE (1 << 7) +#define CR_UARTEN (1 << 0) /* Integer Baud Rate Divider, UARTIBRD */ #define IBRD_MASK 0x3f @@ -223,7 +225,14 @@ static void pl011_loopback_tx(PL011State *s, uint32_t value) static void pl011_write_txdata(PL011State *s, uint8_t data) { - /* ??? Check if transmitter is enabled. */ + if (!(s->cr & CR_UARTEN)) { + qemu_log_mask(LOG_GUEST_ERROR, + "PL011 data written to disabled UART\n"); + } + if (!(s->cr & CR_TXE)) { + qemu_log_mask(LOG_GUEST_ERROR, + "PL011 data written to disabled TX UART\n"); + } /* * XXX this blocks entire thread. Rewrite to use