1*4882a593Smuzhiyun /* 2*4882a593Smuzhiyun * (C) Copyright 2004 3*4882a593Smuzhiyun * Wolfgang Denk, DENX Software Engineering, wd@denx.de. 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * SPDX-License-Identifier: GPL-2.0+ 6*4882a593Smuzhiyun */ 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun #include <common.h> 9*4882a593Smuzhiyun 10*4882a593Smuzhiyun DECLARE_GLOBAL_DATA_PTR; 11*4882a593Smuzhiyun 12*4882a593Smuzhiyun #ifdef __PPC__ 13*4882a593Smuzhiyun /* 14*4882a593Smuzhiyun * At least on G2 PowerPC cores, sequential accesses to non-existent 15*4882a593Smuzhiyun * memory must be synchronized. 16*4882a593Smuzhiyun */ 17*4882a593Smuzhiyun # include <asm/io.h> /* for sync() */ 18*4882a593Smuzhiyun #else 19*4882a593Smuzhiyun # define sync() /* nothing */ 20*4882a593Smuzhiyun #endif 21*4882a593Smuzhiyun 22*4882a593Smuzhiyun /* 23*4882a593Smuzhiyun * Check memory range for valid RAM. A simple memory test determines 24*4882a593Smuzhiyun * the actually available RAM size between addresses `base' and 25*4882a593Smuzhiyun * `base + maxsize'. 26*4882a593Smuzhiyun */ get_ram_size(long * base,long maxsize)27*4882a593Smuzhiyunlong get_ram_size(long *base, long maxsize) 28*4882a593Smuzhiyun { 29*4882a593Smuzhiyun volatile long *addr; 30*4882a593Smuzhiyun long save[32]; 31*4882a593Smuzhiyun long cnt; 32*4882a593Smuzhiyun long val; 33*4882a593Smuzhiyun long size; 34*4882a593Smuzhiyun int i = 0; 35*4882a593Smuzhiyun 36*4882a593Smuzhiyun for (cnt = (maxsize / sizeof(long)) >> 1; cnt > 0; cnt >>= 1) { 37*4882a593Smuzhiyun addr = base + cnt; /* pointer arith! */ 38*4882a593Smuzhiyun sync(); 39*4882a593Smuzhiyun save[i++] = *addr; 40*4882a593Smuzhiyun sync(); 41*4882a593Smuzhiyun *addr = ~cnt; 42*4882a593Smuzhiyun } 43*4882a593Smuzhiyun 44*4882a593Smuzhiyun addr = base; 45*4882a593Smuzhiyun sync(); 46*4882a593Smuzhiyun save[i] = *addr; 47*4882a593Smuzhiyun sync(); 48*4882a593Smuzhiyun *addr = 0; 49*4882a593Smuzhiyun 50*4882a593Smuzhiyun sync(); 51*4882a593Smuzhiyun if ((val = *addr) != 0) { 52*4882a593Smuzhiyun /* Restore the original data before leaving the function. */ 53*4882a593Smuzhiyun sync(); 54*4882a593Smuzhiyun *addr = save[i]; 55*4882a593Smuzhiyun for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) { 56*4882a593Smuzhiyun addr = base + cnt; 57*4882a593Smuzhiyun sync(); 58*4882a593Smuzhiyun *addr = save[--i]; 59*4882a593Smuzhiyun } 60*4882a593Smuzhiyun return (0); 61*4882a593Smuzhiyun } 62*4882a593Smuzhiyun 63*4882a593Smuzhiyun for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) { 64*4882a593Smuzhiyun addr = base + cnt; /* pointer arith! */ 65*4882a593Smuzhiyun val = *addr; 66*4882a593Smuzhiyun *addr = save[--i]; 67*4882a593Smuzhiyun if (val != ~cnt) { 68*4882a593Smuzhiyun size = cnt * sizeof(long); 69*4882a593Smuzhiyun /* 70*4882a593Smuzhiyun * Restore the original data 71*4882a593Smuzhiyun * before leaving the function. 72*4882a593Smuzhiyun */ 73*4882a593Smuzhiyun for (cnt <<= 1; 74*4882a593Smuzhiyun cnt < maxsize / sizeof(long); 75*4882a593Smuzhiyun cnt <<= 1) { 76*4882a593Smuzhiyun addr = base + cnt; 77*4882a593Smuzhiyun *addr = save[--i]; 78*4882a593Smuzhiyun } 79*4882a593Smuzhiyun return (size); 80*4882a593Smuzhiyun } 81*4882a593Smuzhiyun } 82*4882a593Smuzhiyun 83*4882a593Smuzhiyun return (maxsize); 84*4882a593Smuzhiyun } 85*4882a593Smuzhiyun get_effective_memsize(void)86*4882a593Smuzhiyunphys_size_t __weak get_effective_memsize(void) 87*4882a593Smuzhiyun { 88*4882a593Smuzhiyun #ifndef CONFIG_VERY_BIG_RAM 89*4882a593Smuzhiyun return gd->ram_size; 90*4882a593Smuzhiyun #else 91*4882a593Smuzhiyun /* limit stack to what we can reasonable map */ 92*4882a593Smuzhiyun return ((gd->ram_size > CONFIG_MAX_MEM_MAPPED) ? 93*4882a593Smuzhiyun CONFIG_MAX_MEM_MAPPED : gd->ram_size); 94*4882a593Smuzhiyun #endif 95*4882a593Smuzhiyun } 96