bmips: add new target

This target has full device tree support, thus reducing the number of
patches needed for bcm63xx, in which there's a patch for every board.

The intention is to start with a minimal amount of downstream patches and
start upstreaming all of them.

Current status:
 - Enabling EHCI/OHCI on BCM6358 causes a kernel panic.
 - BCM63268 lacks Timer Clocks/Reset support.
 - No PCI/PCIe drivers.
 - No ethernet drivers.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Acked-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/bmips/image/lzma-loader/src/loader.c

@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * LZMA compressed kernel loader for Atheros AR7XXX/AR9XXX based boards
+ *
+ * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
+ *
+ * Some parts of this code was based on the OpenWrt specific lzma-loader
+ * for the BCM47xx and ADM5120 based boards:
+ *	Copyright (C) 2004 Manuel Novoa III (mjn3@codepoet.org)
+ *	Copyright (C) 2005 Mineharu Takahara <mtakahar@yahoo.com>
+ *	Copyright (C) 2005 by Oleg I. Vdovikin <oleg@cs.msu.su>
+ *
+ * The image_header structure has been taken from the U-Boot project.
+ *	(C) Copyright 2008 Semihalf
+ *	(C) Copyright 2000-2005
+ *	Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "config.h"
+#include "cache.h"
+#include "printf.h"
+#include "LzmaDecode.h"
+
+#define KSEG0			0x80000000
+#define KSEG1			0xa0000000
+
+#define KSEG1ADDR(a)		((((unsigned)(a)) & 0x1fffffffU) | KSEG1)
+
+#undef LZMA_DEBUG
+
+#ifdef LZMA_DEBUG
+#  define DBG(f, a...)	printf(f, ## a)
+#else
+#  define DBG(f, a...)	do {} while (0)
+#endif
+
+/* beyond the image end, size not known in advance */
+extern unsigned char workspace[];
+
+
+static CLzmaDecoderState lzma_state;
+static unsigned char *lzma_data;
+static unsigned long lzma_datasize;
+static unsigned long lzma_outsize;
+static unsigned long kernel_la;
+
+static void halt(void)
+{
+	printf("\nSystem halted!\n");
+	for(;;);
+}
+
+static __inline__ unsigned char lzma_get_byte(void)
+{
+	unsigned char c;
+
+	lzma_datasize--;
+	c = *lzma_data++;
+
+	return c;
+}
+
+static int lzma_init_props(void)
+{
+	unsigned char props[LZMA_PROPERTIES_SIZE];
+	int res;
+	int i;
+
+	/* read lzma properties */
+	for (i = 0; i < LZMA_PROPERTIES_SIZE; i++)
+		props[i] = lzma_get_byte();
+
+	/* read the lower half of uncompressed size in the header */
+	lzma_outsize = ((SizeT) lzma_get_byte()) +
+		       ((SizeT) lzma_get_byte() << 8) +
+		       ((SizeT) lzma_get_byte() << 16) +
+		       ((SizeT) lzma_get_byte() << 24);
+
+	/* skip rest of the header (upper half of uncompressed size) */
+	for (i = 0; i < 4; i++)
+		lzma_get_byte();
+
+	res = LzmaDecodeProperties(&lzma_state.Properties, props,
+					LZMA_PROPERTIES_SIZE);
+	return res;
+}
+
+static int lzma_decompress(unsigned char *outStream)
+{
+	SizeT ip, op;
+	int ret;
+
+	lzma_state.Probs = (CProb *) workspace;
+
+	ret = LzmaDecode(&lzma_state, lzma_data, lzma_datasize, &ip, outStream,
+			 lzma_outsize, &op);
+
+	if (ret != LZMA_RESULT_OK) {
+		int i;
+
+		DBG("LzmaDecode error %d at %08x, osize:%d ip:%d op:%d\n",
+		    ret, lzma_data + ip, lzma_outsize, ip, op);
+
+		for (i = 0; i < 16; i++)
+			DBG("%02x ", lzma_data[ip + i]);
+
+		DBG("\n");
+	}
+
+	return ret;
+}
+
+static void lzma_init_data(void)
+{
+	extern unsigned char _lzma_data_start[];
+	extern unsigned char _lzma_data_end[];
+
+	kernel_la = LOADADDR;
+	lzma_data = _lzma_data_start;
+	lzma_datasize = _lzma_data_end - _lzma_data_start;
+}
+
+void loader_main(unsigned long reg_a0, unsigned long reg_a1,
+		 unsigned long reg_a2, unsigned long reg_a3)
+{
+	void (*kernel_entry) (unsigned long, unsigned long, unsigned long,
+			      unsigned long);
+	int res;
+
+	printf("\n\nOpenWrt kernel loader for BMIPS\n");
+	printf("Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>\n");
+	printf("Copyright (C) 2014 Jonas Gorski <jogo@openwrt.org>\n");
+	printf("Copyright (C) 2020 Alvaro Fernandez Rojas <noltari@gmail.com>\n");
+
+	lzma_init_data();
+
+	res = lzma_init_props();
+	if (res != LZMA_RESULT_OK) {
+		printf("Incorrect LZMA stream properties!\n");
+		halt();
+	}
+
+	printf("Decompressing kernel... ");
+
+	res = lzma_decompress((unsigned char *) kernel_la);
+	if (res != LZMA_RESULT_OK) {
+		printf("failed, ");
+		switch (res) {
+		case LZMA_RESULT_DATA_ERROR:
+			printf("data error!\n");
+			break;
+		default:
+			printf("unknown error %d!\n", res);
+		}
+		halt();
+	} else {
+		printf("done!\n");
+	}
+
+	flush_cache(kernel_la, lzma_outsize);
+
+	printf("Starting kernel at %08x...\n\n", kernel_la);
+
+	kernel_entry = (void *) kernel_la;
+	kernel_entry(reg_a0, reg_a1, reg_a2, reg_a3);
+}