[U-Boot] [PATCH v4 7/7] MIPS: bootm: Add support for compatibility with redboot

[Gregory CLEMENT <gregory.clement@bootlin.com>]

The kernels built to be launch by redboot (such as the Vcore III) have
different expectation in the way the data were passed.

Unlike with yamon, the command line is expected to be a single string
passed in argv[1]. An other expectation is that the arguments are located
in the cached address space.

However, like yamon, they expect that rd_start and rd_size was passed by
the bootloader in the command line of the kernel.

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
---
 arch/mips/Kconfig     |  4 +++
 arch/mips/lib/bootm.c | 76 +++++++++++++++++++++++++++++++------------
 2 files changed, 60 insertions(+), 20 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index bfe9c11069..eae5cb0f99 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -63,6 +63,7 @@ config ARCH_MSCC
 	bool "Support MSCC VCore-III"
 	select OF_CONTROL
 	select DM
+	select MIPS_BOOT_CMDLINE_SINGLESTRING
 
 config ARCH_BMIPS
 	bool "Support BMIPS SoCs"
@@ -466,6 +467,9 @@ config MIPS_BOOT_CONFIG_WORD1
 	help
 	  Value which is inserted as boot config word 1.
 
+config MIPS_BOOT_CMDLINE_SINGLESTRING
+	bool
+
 endif
 
 endmenu
diff --git a/arch/mips/lib/bootm.c b/arch/mips/lib/bootm.c
index deca5189e3..38243cfa92 100644
--- a/arch/mips/lib/bootm.c
+++ b/arch/mips/lib/bootm.c
@@ -15,6 +15,11 @@ DECLARE_GLOBAL_DATA_PTR;
 #define	LINUX_MAX_ENVS		256
 #define	LINUX_MAX_ARGS		256
 
+enum legacy_boot_type {
+	LEGACY_BOOT_YAML,
+	LEGACY_BOOT_CMDLINE_SINGLESTRING,
+};
+
 static int linux_argc;
 static char **linux_argv;
 static char *linux_argp;
@@ -44,22 +49,47 @@ void arch_lmb_reserve(struct lmb *lmb)
 	lmb_reserve(lmb, sp, gd->ram_top - sp);
 }
 
-static void linux_cmdline_init(void)
+static void linux_cmdline_init(enum legacy_boot_type boot_type)
 {
+	switch (boot_type) {
+		/*
+		 * Vcore III linux kernels expect arguments in the cached
+		 * address space. They also expect the command line being a
+		 * single string in the first argument
+		 */
+	case LEGACY_BOOT_CMDLINE_SINGLESTRING:
+		linux_argv = (char **)(gd->bd->bi_boot_params);
+		linux_argp = (char *)(linux_argv + LINUX_MAX_ARGS);
+		linux_argv[1] = linux_argp;
+		break;
+	case LEGACY_BOOT_YAML:
+		/* fall-through */
+	default:
+		linux_argv = (char **)UNCACHED_SDRAM(gd->bd->bi_boot_params);
+		linux_argp = (char *)(linux_argv + LINUX_MAX_ARGS);
+	}
 	linux_argc = 1;
-	linux_argv = (char **)UNCACHED_SDRAM(gd->bd->bi_boot_params);
 	linux_argv[0] = 0;
-	linux_argp = (char *)(linux_argv + LINUX_MAX_ARGS);
 }
 
-static void linux_cmdline_set(const char *value, size_t len)
+static void linux_cmdline_set(const char *value, size_t len,
+			      enum legacy_boot_type boot_type)
 {
-	linux_argv[linux_argc] = linux_argp;
 	memcpy(linux_argp, value, len);
-	linux_argp[len] = 0;
-
+	switch (boot_type) {
+	case LEGACY_BOOT_CMDLINE_SINGLESTRING:
+		linux_argv[linux_argc] = linux_argp;
+		linux_argp[len] = 0;
+		linux_argc++;
+		break;
+	case LEGACY_BOOT_YAML:
+		/* fall-through */
+	default:
+		linux_argp[len] = ' ';
+		linux_argp[len + 1] = 0;
+		linux_argc = 2;
+	}
 	linux_argp += len + 1;
-	linux_argc++;
 }
 
 static void linux_cmdline_dump(void)
@@ -73,12 +103,11 @@ static void linux_cmdline_dump(void)
 		debug("   arg %03d: %s\n", i, linux_argv[i]);
 }
 
-static void linux_cmdline_legacy(bootm_headers_t *images)
+static void linux_cmdline_legacy(bootm_headers_t *images,
+				 enum legacy_boot_type boot_type)
 {
 	const char *bootargs, *next, *quote;
-
-	linux_cmdline_init();
-
+	linux_cmdline_init(boot_type);
 	bootargs = env_get("bootargs");
 	if (!bootargs)
 		return;
@@ -104,7 +133,7 @@ static void linux_cmdline_legacy(bootm_headers_t *images)
 		if (!next)
 			next = bootargs + strlen(bootargs);
 
-		linux_cmdline_set(bootargs, next - bootargs);
+		linux_cmdline_set(bootargs, next - bootargs, boot_type);
 
 		if (*next)
 			next++;
@@ -113,7 +142,8 @@ static void linux_cmdline_legacy(bootm_headers_t *images)
 	}
 }
 
-static void linux_cmdline_append(bootm_headers_t *images)
+static void linux_cmdline_append(bootm_headers_t *images,
+				 enum legacy_boot_type boot_type)
 {
 	char buf[24];
 	ulong mem, rd_start, rd_size;
@@ -121,7 +151,7 @@ static void linux_cmdline_append(bootm_headers_t *images)
 	/* append mem */
 	mem = gd->ram_size >> 20;
 	sprintf(buf, "mem=%luM", mem);
-	linux_cmdline_set(buf, strlen(buf));
+	linux_cmdline_set(buf, strlen(buf), boot_type);
 
 	/* append rd_start and rd_size */
 	rd_start = images->initrd_start;
@@ -129,9 +159,9 @@ static void linux_cmdline_append(bootm_headers_t *images)
 
 	if (rd_size) {
 		sprintf(buf, "rd_start=0x%08lX", rd_start);
-		linux_cmdline_set(buf, strlen(buf));
+		linux_cmdline_set(buf, strlen(buf), boot_type);
 		sprintf(buf, "rd_size=0x%lX", rd_size);
-		linux_cmdline_set(buf, strlen(buf));
+		linux_cmdline_set(buf, strlen(buf), boot_type);
 	}
 }
 
@@ -276,11 +306,17 @@ static void boot_prep_linux(bootm_headers_t *images)
 		boot_reloc_fdt(images);
 		boot_setup_fdt(images);
 	} else {
-		if (CONFIG_IS_ENABLED(MIPS_BOOT_CMDLINE_LEGACY)) {
-			linux_cmdline_legacy(images);
+		if (CONFIG_IS_ENABLED(MIPS_BOOT_CMDLINE_SINGLESTRING)) {
+			linux_cmdline_legacy(images,
+					     LEGACY_BOOT_CMDLINE_SINGLESTRING);
+			linux_cmdline_append(images,
+					     LEGACY_BOOT_CMDLINE_SINGLESTRING);
+			linux_cmdline_dump();
+		} else if (CONFIG_IS_ENABLED(MIPS_BOOT_CMDLINE_LEGACY)) {
+			linux_cmdline_legacy(images, 0);
 
 			if (!CONFIG_IS_ENABLED(MIPS_BOOT_ENV_LEGACY))
-				linux_cmdline_append(images);
+				linux_cmdline_append(images, LEGACY_BOOT_YAML);
 
 			linux_cmdline_dump();
 		}
-- 
2.19.2