[PATCH v4] LoongArch: Make CONFIG_CMDLINE work with CONFIG_CMDLINE_EXTEND and CONFIG_CMDLINE_BOOTLOADER

[Dong Zhihong]

Make CONFIG_CMDLINE work with CONFIG_CMDLINE_EXTEND and
CONFIG_CMDLINE_BOOTLOADER. The touched function is bootcmdline_init()`.
There's already code handling CONFIG_CMDLINE_FORCE, which replaces
`boot_command_line` with CONFIG_CMDLINE and immediately`goto out`. It'd be
similar way to handle CONFIG_CMDLINE_EXTEND and CONFIG_CMDLINE_BOOTLOADER,
so some code is added after OF_FLATTREE part to handle them.

Signed-off-by: Dong Zhihong <donmor3000@xxxxxxxxxxx>
---

v4 -> v3: Make CONFIG_CMDLINE appended to the end of command line (Huacai);
	Removed unnecessary #ifdef since CONFIG_CMDLINE is always a string on
	loongarch
v3 -> v2: Reworded the commit message again to make it imperative (Ruoyao)
v2 -> v1: Reworded the commit message so it's more imperative (Markus);
	Added `goto out` to FDT part (Huacai)

 arch/loongarch/kernel/setup.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 78a00359bde3..3cafda1a409e 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -332,7 +332,24 @@ static void __init bootcmdline_init(char **cmdline_p)
 			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
 
 		strlcat(boot_command_line, init_command_line, COMMAND_LINE_SIZE);
+		goto out;
+	}
+#endif
+
+#ifdef CONFIG_CMDLINE
+	/*
+	 * If CONFIG_CMDLINE_BOOTLOADER is enabled then we use thei built-in
+	 * command line if no command line given, or we append given command
+	 * line to the built-in one if CONFIG_CMDLINE_EXTEND is enabled.
+	 */
+	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND)) {
+		strscpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+		strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+		strlcat(boot_command_line, init_command_line, COMMAND_LINE_SIZE);
 	}
+
+	if (IS_ENABLED(CONFIG_CMDLINE_BOOTLOADER) && !boot_command_line[0])
+		strscpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 #endif
 
 out:
-- 
2.25.1