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Mon, 09 Dec 2024 20:48:25 -0800 (PST) Received: from sholland-0826.internal.sifive.com ([147.124.94.167]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-3a9c9da809dsm17022405ab.4.2024.12.09.20.48.25 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 09 Dec 2024 20:48:25 -0800 (PST) From: Samuel Holland To: kvm@vger.kernel.org Cc: Samuel Holland Subject: [kvm-unit-tests PATCH 2/3] riscv: Rate limit UART output to avoid FIFO overflows Date: Mon, 9 Dec 2024 22:44:41 -0600 Message-Id: <20241210044442.91736-3-samuel.holland@sifive.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20241210044442.91736-1-samuel.holland@sifive.com> References: <20241210044442.91736-1-samuel.holland@sifive.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This is necessary when running tests on bare metal. Signed-off-by: Samuel Holland --- lib/riscv/io.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/lib/riscv/io.c b/lib/riscv/io.c index b3f587bb..8d684ccd 100644 --- a/lib/riscv/io.c +++ b/lib/riscv/io.c @@ -13,6 +13,9 @@ #include #include +#define UART_LSR_OFFSET 5 +#define UART_LSR_THRE 0x20 + /* * Use this guess for the uart base in order to make an attempt at * having earlier printf support. We'll overwrite it with the real @@ -76,8 +79,11 @@ void io_init(void) void puts(const char *s) { spin_lock(&uart_lock); - while (*s) + while (*s) { + while (!(readb(uart0_base + UART_LSR_OFFSET) & UART_LSR_THRE)) + ; writeb(*s++, uart0_base); + } spin_unlock(&uart_lock); }