arm: apple: Add initial support for Apple's M1 SoC

Add support for Apple's M1 SoC that is used in "Apple Silicon"
Macs.  This builds a basic U-Boot that can be used as a payload
for the m1n1 boot loader being developed by the Asahi Linux
project.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Add MAINTAINERS entry]

include/configs/apple.h

@@ -0,0 +1,36 @@
+#ifndef __CONFIG_H
+#define __CONFIG_H
+
+#include <linux/sizes.h>
+
+#define CONFIG_SYS_SDRAM_BASE	0x880000000
+
+#define CONFIG_LNX_KRNL_IMG_TEXT_OFFSET_BASE	CONFIG_SYS_TEXT_BASE
+
+/* Environment */
+#define ENV_DEVICE_SETTINGS \
+	"stdin=serial,usbkbd\0" \
+	"stdout=serial,vidconsole\0" \
+	"stderr=serial,vidconsole\0"
+
+#define ENV_MEM_LAYOUT_SETTINGS \
+	"fdt_addr_r=0x960100000\0" \
+	"kernel_addr_r=0x960200000\0"
+
+#if CONFIG_IS_ENABLED(CMD_USB)
+	#define BOOT_TARGET_USB(func) func(USB, usb, 0)
+#else
+	#define BOOT_TARGET_USB(func)
+#endif
+
+#define BOOT_TARGET_DEVICES(func) \
+	BOOT_TARGET_USB(func)
+
+#include <config_distro_bootcmd.h>
+
+#define CONFIG_EXTRA_ENV_SETTINGS \
+	ENV_DEVICE_SETTINGS \
+	ENV_MEM_LAYOUT_SETTINGS \
+	BOOTENV
+
+#endif