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hw/char/pl011: Warn when using disabled transmitter

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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 <philmd@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240719181041.49545-9-philmd@linaro.org>
This commit is contained in:
Philippe Mathieu-Daudé 2024-07-18 17:23:42 +02:00
parent dee8284b6f
commit 51b61dd4d5
1 changed files with 10 additions and 1 deletions
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11
hw/char/pl011.c
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@ -85,7 +85,9 @@ DeviceState *pl011_create(hwaddr addr, qemu_irq irq, Chardev *chr)
#define CR_OUT1 (1 << 12) #define CR_OUT1 (1 << 12)
#define CR_RTS (1 << 11) #define CR_RTS (1 << 11)
#define CR_DTR (1 << 10) #define CR_DTR (1 << 10)
#define CR_TXE (1 << 8)
#define CR_LBE (1 << 7) #define CR_LBE (1 << 7)
#define CR_UARTEN (1 << 0)
/* Integer Baud Rate Divider, UARTIBRD */ /* Integer Baud Rate Divider, UARTIBRD */
#define IBRD_MASK 0x3f #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) 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 * XXX this blocks entire thread. Rewrite to use