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);
+}