xtensa: use CONFIG_USE_OF instead of CONFIG_OF

CONFIG_OF can be set by a randconfig or by a user -- without setting the
early flattree option (OF_EARLY_FLATTREE).  This causes build errors.
However, if randconfig or a user sets USE_OF in the Xtensa config,
the right kconfig symbols are set to fix the build.

Fixes these build errors:

../arch/xtensa/kernel/setup.c:67:19: error: ‘__dtb_start’ undeclared here (not in a function); did you mean ‘dtb_start’?
   67 | void *dtb_start = __dtb_start;
      |                   ^~~~~~~~~~~
../arch/xtensa/kernel/setup.c: In function 'xtensa_dt_io_area':
../arch/xtensa/kernel/setup.c:201:14: error: implicit declaration of function 'of_flat_dt_is_compatible'; did you mean 'of_machine_is_compatible'? [-Werror=implicit-function-declaration]
  201 |         if (!of_flat_dt_is_compatible(node, "simple-bus"))
../arch/xtensa/kernel/setup.c:204:18: error: implicit declaration of function 'of_get_flat_dt_prop' [-Werror=implicit-function-declaration]
  204 |         ranges = of_get_flat_dt_prop(node, "ranges", &len);
../arch/xtensa/kernel/setup.c:204:16: error: assignment to 'const __be32 *' {aka 'const unsigned int *'} from 'int' makes pointer from integer without a cast [-Werror=int-conversion]
  204 |         ranges = of_get_flat_dt_prop(node, "ranges", &len);
      |                ^
../arch/xtensa/kernel/setup.c: In function 'early_init_devtree':
../arch/xtensa/kernel/setup.c:228:9: error: implicit declaration of function 'early_init_dt_scan'; did you mean 'early_init_devtree'? [-Werror=implicit-function-declaration]
  228 |         early_init_dt_scan(params);
../arch/xtensa/kernel/setup.c:229:9: error: implicit declaration of function 'of_scan_flat_dt' [-Werror=implicit-function-declaration]
  229 |         of_scan_flat_dt(xtensa_dt_io_area, NULL);

xtensa-elf-ld: arch/xtensa/mm/mmu.o:(.text+0x0): undefined reference to `xtensa_kio_paddr'

Fixes: da844a81 ("xtensa: add device trees support")
Fixes: 6cb97111 ("xtensa: remap io area defined in device tree")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/kmem_layout.h

@@ -78,7 +78,7 @@
 #endif
 #define XCHAL_KIO_SIZE			0x10000000
 
-#if (!XCHAL_HAVE_PTP_MMU || XCHAL_HAVE_SPANNING_WAY) && defined(CONFIG_OF)
+#if (!XCHAL_HAVE_PTP_MMU || XCHAL_HAVE_SPANNING_WAY) && defined(CONFIG_USE_OF)
 #define XCHAL_KIO_PADDR			xtensa_get_kio_paddr()
 #ifndef __ASSEMBLY__
 extern unsigned long xtensa_kio_paddr;

arch/xtensa/kernel/setup.c

@@ -63,7 +63,7 @@ extern unsigned long initrd_end;
 extern int initrd_below_start_ok;
 #endif
 
-#ifdef CONFIG_OF
+#ifdef CONFIG_USE_OF
 void *dtb_start = __dtb_start;
 #endif
 
@@ -125,7 +125,7 @@ __tagtable(BP_TAG_INITRD, parse_tag_initrd);
 
 #endif /* CONFIG_BLK_DEV_INITRD */
 
-#ifdef CONFIG_OF
+#ifdef CONFIG_USE_OF
 
 static int __init parse_tag_fdt(const bp_tag_t *tag)
 {
@@ -135,7 +135,7 @@ static int __init parse_tag_fdt(const bp_tag_t *tag)
 
 __tagtable(BP_TAG_FDT, parse_tag_fdt);
 
-#endif /* CONFIG_OF */
+#endif /* CONFIG_USE_OF */
 
 static int __init parse_tag_cmdline(const bp_tag_t* tag)
 {
@@ -183,7 +183,7 @@ static int __init parse_bootparam(const bp_tag_t *tag)
 }
 #endif
 
-#ifdef CONFIG_OF
+#ifdef CONFIG_USE_OF
 
 #if !XCHAL_HAVE_PTP_MMU || XCHAL_HAVE_SPANNING_WAY
 unsigned long xtensa_kio_paddr = XCHAL_KIO_DEFAULT_PADDR;
@@ -232,7 +232,7 @@ void __init early_init_devtree(void *params)
 		strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 }
 
-#endif /* CONFIG_OF */
+#endif /* CONFIG_USE_OF */
 
 /*
  * Initialize architecture. (Early stage)
@@ -253,7 +253,7 @@ void __init init_arch(bp_tag_t *bp_start)
 	if (bp_start)
 		parse_bootparam(bp_start);
 
-#ifdef CONFIG_OF
+#ifdef CONFIG_USE_OF
 	early_init_devtree(dtb_start);
 #endif
 

arch/xtensa/mm/mmu.c

@@ -101,7 +101,7 @@ void init_mmu(void)
 
 void init_kio(void)
 {
-#if XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY && defined(CONFIG_OF)
+#if XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY && defined(CONFIG_USE_OF)
 	/*
 	 * Update the IO area mapping in case xtensa_kio_paddr has changed
 	 */