MIPS: of: Introduce helper function to get DTB

Selection of the DTB to be used was burried in more or less readable
code in head.S. Move this code into a inline helper function and
use it.

Signed-off-by: Thomas Bogendoerfer <[e-mail]>
Acked-by: Florian Fainelli <[e-mail]>

arch/mips/ath79/setup.c

···
 
 void __init plat_mem_setup(void)
 {
-	unsigned long fdt_start;
+	void *dtb;
 
 	set_io_port_base(KSEG1);
 
 	/* Get the position of the FDT passed by the bootloader */
-	fdt_start = fw_getenvl("fdt_start");
-	if (fdt_start)
-		__dt_setup_arch((void *)KSEG0ADDR(fdt_start));
-	else if (fw_passed_dtb)
-		__dt_setup_arch((void *)KSEG0ADDR(fw_passed_dtb));
+	dtb = (void *)fw_getenvl("fdt_start");
+	if (dtb == NULL)
+		dtb = get_fdt();
+
+	if (dtb)
+		__dt_setup_arch((void *)KSEG0ADDR(dtb));
 
 	ath79_reset_base = ioremap(AR71XX_RESET_BASE,
 					   AR71XX_RESET_SIZE);

arch/mips/bmips/setup.c

···
 	/* intended to somewhat resemble ARM; see Documentation/arm/booting.rst */
 	if (fw_arg0 == 0 && fw_arg1 == 0xffffffff)
 		dtb = phys_to_virt(fw_arg2);
-	else if (fw_passed_dtb) /* UHI interface or appended dtb */
-		dtb = (void *)fw_passed_dtb;
-	else if (&__dtb_start != &__dtb_end)
-		dtb = (void *)__dtb_start;
 	else
+		dtb = get_fdt();
+
+	if (!dtb)
 		panic("no dtb found");
 
 	__dt_setup_arch(dtb);

arch/mips/generic/init.c

···
 		/* Already set up */
 		return (void *)fdt;
 
-	if (fw_passed_dtb && !fdt_check_header((void *)fw_passed_dtb)) {
+	fdt = (void *)get_fdt();
+	if (fdt && !fdt_check_header(fdt)) {
 		/*
 		 * We have been provided with the appropriate device tree for
 		 * the board. Make use of it & search for any machine struct
 		 * based upon the root compatible string.
 		 */
-		fdt = (void *)fw_passed_dtb;
-
 		for_each_mips_machine(check_mach) {
 			match = mips_machine_is_compatible(check_mach, fdt);
 			if (match) {

arch/mips/include/asm/bootinfo.h

···
 extern unsigned long fw_arg0, fw_arg1, fw_arg2, fw_arg3;
 
 #ifdef CONFIG_USE_OF
-extern unsigned long fw_passed_dtb;
+#include <linux/libfdt.h>
+#include <linux/of_fdt.h>
+
+extern char __appended_dtb[];
+
+static inline void *get_fdt(void)
+{
+	if (IS_ENABLED(CONFIG_MIPS_RAW_APPENDED_DTB) ||
+	    IS_ENABLED(CONFIG_MIPS_ELF_APPENDED_DTB))
+		if (fdt_magic(&__appended_dtb) == FDT_MAGIC)
+			return &__appended_dtb;
+
+	if (fw_arg0 == -2) /* UHI interface */
+		return (void *)fw_arg1;
+
+	if (IS_ENABLED(CONFIG_BUILTIN_DTB))
+		if (&__dtb_start != &__dtb_end)
+			return &__dtb_start;
+
+	return NULL;
+}
 #endif
 
 /*

arch/mips/include/asm/octeon/octeon.h

···
 extern void octeon_check_cpu_bist(void);
 
 int octeon_prune_device_tree(void);
-extern const char __appended_dtb;
 extern const char __dtb_octeon_3xxx_begin;
 extern const char __dtb_octeon_68xx_begin;
 

arch/mips/kernel/head.S

···
 	jr	t0
 0:
 
-#ifdef CONFIG_USE_OF
-#if defined(CONFIG_MIPS_RAW_APPENDED_DTB) || \
-	defined(CONFIG_MIPS_ELF_APPENDED_DTB)
-
-	PTR_LA		t2, __appended_dtb
-
-#ifdef CONFIG_CPU_BIG_ENDIAN
-	li		t1, 0xd00dfeed
-#else  /* !CONFIG_CPU_BIG_ENDIAN */
-	li		t1, 0xedfe0dd0
-#endif /* !CONFIG_CPU_BIG_ENDIAN */
-	lw		t0, (t2)
-	beq		t0, t1, dtb_found
-#endif /* CONFIG_MIPS_RAW_APPENDED_DTB || CONFIG_MIPS_ELF_APPENDED_DTB */
-	li		t1, -2
-	move		t2, a1
-	beq		a0, t1, dtb_found
-
-#ifdef CONFIG_BUILTIN_DTB
-	PTR_LA	t2, __dtb_start
-	PTR_LA	t1, __dtb_end
-	bne		t1, t2, dtb_found
-#endif /* CONFIG_BUILTIN_DTB */
-
-	li		t2, 0
-dtb_found:
-#endif /* CONFIG_USE_OF */
 	PTR_LA		t0, __bss_start		# clear .bss
 	LONG_S		zero, (t0)
 	PTR_LA		t1, __bss_stop - LONGSIZE
···
 	LONG_S		a1, fw_arg1
 	LONG_S		a2, fw_arg2
 	LONG_S		a3, fw_arg3
-
-#ifdef CONFIG_USE_OF
-	LONG_S		t2, fw_passed_dtb
-#endif
 
 	MTC0		zero, CP0_CONTEXT	# clear context register
 #ifdef CONFIG_64BIT

arch/mips/kernel/setup.c

···
 unsigned long kernelsp[NR_CPUS];
 unsigned long fw_arg0, fw_arg1, fw_arg2, fw_arg3;
 
-#ifdef CONFIG_USE_OF
-unsigned long fw_passed_dtb;
-#endif
-
 #ifdef CONFIG_DEBUG_FS
 struct dentry *mips_debugfs_dir;
 static int __init debugfs_mips(void)

arch/mips/lantiq/prom.c

···
 
 	set_io_port_base((unsigned long) KSEG1);
 
-	if (fw_passed_dtb) /* UHI interface */
-		dtb = (void *)fw_passed_dtb;
-	else if (&__dtb_start != &__dtb_end)
-		dtb = (void *)__dtb_start;
-	else
+	dtb = get_fdt();
+	if (dtb == NULL)
 		panic("no dtb found");
 
 	/*

arch/mips/pic32/pic32mzda/init.c

···
 	return "PIC32MZDA";
 }
 
-static ulong get_fdtaddr(void)
-{
-	ulong ftaddr = 0;
-
-	if (fw_passed_dtb && !fw_arg2 && !fw_arg3)
-		return (ulong)fw_passed_dtb;
-
-	if (&__dtb_start < &__dtb_end)
-		ftaddr = (ulong)__dtb_start;
-
-	return ftaddr;
-}
-
 void __init plat_mem_setup(void)
 {
 	void *dtb;
 
-	dtb = (void *)get_fdtaddr();
+	dtb = get_fdt();
 	if (!dtb) {
 		pr_err("pic32: no DTB found.\n");
 		return;

arch/mips/ralink/of.c

···
 
 void __init plat_mem_setup(void)
 {
-	void *dtb = NULL;
+	void *dtb;
 
 	set_io_port_base(KSEG1);
 
 	/*
 	 * Load the builtin devicetree. This causes the chosen node to be
-	 * parsed resulting in our memory appearing. fw_passed_dtb is used
-	 * by CONFIG_MIPS_APPENDED_RAW_DTB as well.
+	 * parsed resulting in our memory appearing.
 	 */
-	if (fw_passed_dtb)
-		dtb = (void *)fw_passed_dtb;
-	else if (&__dtb_start != &__dtb_end)
-		dtb = (void *)__dtb_start;
-
+	dtb = get_fdt();
 	__dt_setup_arch(dtb);
 
 	of_scan_flat_dt(early_init_dt_find_memory, NULL);