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lib: serial: fix RX path in litex-uart

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When used to read characters from the terminal (e.g., when the SBI
console is used via ecall from linux with `console=hvc0`), we must
acknowledge receipt of each character to "pop" it off the LiteUART
hardware queue, and allow the next character to be made available.

Fixes: 52af6e4b ("lib: utils: Add LiteX UART support")
Suggested-by: Dolu1990 <charles.papon.90@gmail.com>
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Gabriel Somlo
2024-06-07 14:23:42 -04:00
committed by Anup Patel
parent 62e178a0a7
commit 7830e98785
1 changed files with 8 additions and 2 deletions
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10
lib/utils/serial/litex-uart.c
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@@ -20,6 +20,8 @@
#define UART_REG_EV_PENDING 4
#define UART_REG_EV_ENABLE 5
#define UART_EV_RX 0x2
/* clang-format on */
static volatile u32 *uart_base;
@@ -42,10 +44,14 @@ static void litex_uart_putc(char ch)
static int litex_uart_getc(void)
{
int ret;
if (get_reg(UART_REG_RXEMPTY))
return -1;
else
return get_reg(UART_REG_RXTX);
ret = get_reg(UART_REG_RXTX);
set_reg(UART_REG_EV_PENDING, UART_EV_RX); /* ack. char read */
return ret;
}
static struct sbi_console_device litex_console = {