Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
To:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Huacai Chen <chenhc@lemote.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xuefeng Li <lixuefeng@loongson.cn>
Subject: [PATCH] MIPS: Loongson: Add support for serial console
Date:   Sat, 16 May 2020 15:03:08 +0800
Message-Id: <1589612588-29196-1-git-send-email-yangtiezhu@loongson.cn>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

After commit 87fcfa7b7fe6 ("MIPS: Loongson64: Add generic dts"),
there already exists the node and property of Loongson CPU UART0
in loongson3-package.dtsi:

cpu_uart0: serial@1fe001e0 {
        compatible = "ns16550a";
        reg = <0 0x1fe001e0 0x8>;
        clock-frequency = <33000000>;
        interrupt-parent = <&liointc>;
        interrupts = <10 IRQ_TYPE_LEVEL_HIGH>;
        no-loopback-test;
};

In order to support for serial console on the Loongson platform,
add CONFIG_SERIAL_OF_PLATFORM=y to loongson3_defconfig.

With this patch, we can see the following boot message:

[    1.877745] printk: console [ttyS0] disabled
[    1.881979] 1fe001e0.serial: ttyS0 at MMIO 0x1fe001e0 (irq = 16, base_baud = 2062500) is a 16550A
[    1.890838] printk: console [ttyS0] enabled

And also, we can login normally from the serial console.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---

Hi Jiaxun,

Thank you very much for your suggestion.

 arch/mips/configs/loongson3_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/mips/configs/loongson3_defconfig b/arch/mips/configs/loongson3_defconfig
index 6768c16..cd95f08 100644
--- a/arch/mips/configs/loongson3_defconfig
+++ b/arch/mips/configs/loongson3_defconfig
@@ -217,6 +217,7 @@ CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_MANY_PORTS=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
 CONFIG_SERIAL_8250_RSA=y
+CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_HW_RANDOM=y
 CONFIG_RAW_DRIVER=m
 CONFIG_I2C_CHARDEV=y
-- 
2.1.0