1 files changed, 117 insertions, 0 deletions
diff --git a/arch/mips/dec/prom/memory.c b/arch/mips/dec/prom/memory.c
new file mode 100644
index 000000000..44490c30d
--- /dev/null
+++ b/arch/mips/dec/prom/memory.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * memory.c: memory initialisation code.
+ *
+ * Copyright (C) 1998 Harald Koerfgen, Frieder Streffer and Paul M. Antoine
+ * Copyright (C) 2000, 2002  Maciej W. Rozycki
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/memblock.h>
+#include <linux/types.h>
+
+#include <asm/addrspace.h>
+#include <asm/dec/machtype.h>
+#include <asm/dec/prom.h>
+#include <asm/page.h>
+#include <asm/sections.h>
+
+
+volatile unsigned long mem_err;		/* So we know an error occurred */
+
+/*
+ * Probe memory in 4MB chunks, waiting for an error to tell us we've fallen
+ * off the end of real memory.  Only suitable for the 2100/3100's (PMAX).
+ */
+
+#define CHUNK_SIZE 0x400000
+
+static __init void pmax_setup_memory_region(void)
+{
+	volatile unsigned char *memory_page, dummy;
+	char old_handler[0x80];
+	extern char genexcept_early;
+
+	/* Install exception handler */
+	memcpy(&old_handler, (void *)(CKSEG0 + 0x80), 0x80);
+	memcpy((void *)(CKSEG0 + 0x80), &genexcept_early, 0x80);
+
+	/* read unmapped and uncached (KSEG1)
+	 * DECstations have at least 4MB RAM
+	 * Assume less than 480MB of RAM, as this is max for 5000/2xx
+	 * FIXME this should be replaced by the first free page!
+	 */
+	for (memory_page = (unsigned char *)CKSEG1 + CHUNK_SIZE;
+	     mem_err == 0 && memory_page < (unsigned char *)CKSEG1 + 0x1e00000;
+	     memory_page += CHUNK_SIZE) {
+		dummy = *memory_page;
+	}
+	memcpy((void *)(CKSEG0 + 0x80), &old_handler, 0x80);
+
+	memblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE);
+}
+
+/*
+ * Use the REX prom calls to get hold of the memory bitmap, and thence
+ * determine memory size.
+ */
+static __init void rex_setup_memory_region(void)
+{
+	int i, bitmap_size;
+	unsigned long mem_start = 0, mem_size = 0;
+	memmap *bm;
+
+	/* some free 64k */
+	bm = (memmap *)CKSEG0ADDR(0x28000);
+
+	bitmap_size = rex_getbitmap(bm);
+
+	for (i = 0; i < bitmap_size; i++) {
+		/* FIXME: very simplistically only add full sets of pages */
+		if (bm->bitmap[i] == 0xff)
+			mem_size += (8 * bm->pagesize);
+		else if (!mem_size)
+			mem_start += (8 * bm->pagesize);
+		else {
+			memblock_add(mem_start, mem_size);
+			mem_start += mem_size + (8 * bm->pagesize);
+			mem_size = 0;
+		}
+	}
+	if (mem_size)
+		memblock_add(mem_start, mem_size);
+}
+
+void __init prom_meminit(u32 magic)
+{
+	if (!prom_is_rex(magic))
+		pmax_setup_memory_region();
+	else
+		rex_setup_memory_region();
+}
+
+void __init prom_free_prom_memory(void)
+{
+	unsigned long end;
+
+	/*
+	 * Free everything below the kernel itself but leave
+	 * the first page reserved for the exception handlers.
+	 */
+
+#if IS_ENABLED(CONFIG_DECLANCE)
+	/*
+	 * Leave 128 KB reserved for Lance memory for
+	 * IOASIC DECstations.
+	 *
+	 * XXX: save this address for use in dec_lance.c?
+	 */
+	if (IOASIC)
+		end = __pa(&_text) - 0x00020000;
+	else
+#endif
+		end = __pa(&_text);
+
+	free_init_pages("unused PROM memory", PAGE_SIZE, end);
+}