| /* |
| * (C) Copyright 2004 |
| * Wolfgang Denk, DENX Software Engineering, wd@denx.de. |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| */ |
| |
| #include <common.h> |
| |
| DECLARE_GLOBAL_DATA_PTR; |
| |
| #ifdef __PPC__ |
| /* |
| * At least on G2 PowerPC cores, sequential accesses to non-existent |
| * memory must be synchronized. |
| */ |
| # include <asm/io.h> /* for sync() */ |
| #else |
| # define sync() /* nothing */ |
| #endif |
| |
| /* |
| * Check memory range for valid RAM. A simple memory test determines |
| * the actually available RAM size between addresses `base' and |
| * `base + maxsize'. |
| */ |
| long get_ram_size(long *base, long maxsize) |
| { |
| volatile long *addr; |
| long save[31]; |
| long save_base; |
| long cnt; |
| long val; |
| long size; |
| int i = 0; |
| |
| for (cnt = (maxsize / sizeof(long)) >> 1; cnt > 0; cnt >>= 1) { |
| addr = base + cnt; /* pointer arith! */ |
| sync(); |
| save[i++] = *addr; |
| sync(); |
| *addr = ~cnt; |
| } |
| |
| addr = base; |
| sync(); |
| save_base = *addr; |
| sync(); |
| *addr = 0; |
| |
| sync(); |
| if ((val = *addr) != 0) { |
| /* Restore the original data before leaving the function. */ |
| sync(); |
| *base = save_base; |
| for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) { |
| addr = base + cnt; |
| sync(); |
| *addr = save[--i]; |
| } |
| return (0); |
| } |
| |
| for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) { |
| addr = base + cnt; /* pointer arith! */ |
| val = *addr; |
| *addr = save[--i]; |
| if (val != ~cnt) { |
| size = cnt * sizeof(long); |
| /* |
| * Restore the original data |
| * before leaving the function. |
| */ |
| for (cnt <<= 1; |
| cnt < maxsize / sizeof(long); |
| cnt <<= 1) { |
| addr = base + cnt; |
| *addr = save[--i]; |
| } |
| return (size); |
| } |
| } |
| |
| return (maxsize); |
| } |
| |
| phys_size_t __weak get_effective_memsize(void) |
| { |
| #ifndef CONFIG_VERY_BIG_RAM |
| return gd->ram_size; |
| #else |
| /* limit stack to what we can reasonable map */ |
| return ((gd->ram_size > CONFIG_MAX_MEM_MAPPED) ? |
| CONFIG_MAX_MEM_MAPPED : gd->ram_size); |
| #endif |
| } |