1 files changed, 101 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index d942404779c1..864334b337a3 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -190,6 +190,8 @@ static int __initdata of_platform;
 
 static char __initdata prom_cmd_line[COMMAND_LINE_SIZE];
 
+static unsigned long __initdata prom_memory_limit;
+
 static unsigned long __initdata alloc_top;
 static unsigned long __initdata alloc_top_high;
 static unsigned long __initdata alloc_bottom;
@@ -484,6 +486,67 @@ static int __init prom_setprop(phandle node, const char *nodename,
         return call_prom("interpret", 1, 1, (u32)(unsigned long) cmd);
 }
 
+/* We can't use the standard versions because of RELOC headaches. */
+#define isxdigit(c)     (('0' <= (c) && (c) <= '9') \
+                         || ('a' <= (c) && (c) <= 'f') \
+                         || ('A' <= (c) && (c) <= 'F'))
+
+#define isdigit(c)      ('0' <= (c) && (c) <= '9')
+#define islower(c)      ('a' <= (c) && (c) <= 'z')
+#define toupper(c)      (islower(c) ? ((c) - 'a' + 'A') : (c))
+
+unsigned long prom_strtoul(const char *cp, const char **endp)
+{
+        unsigned long result = 0, base = 10, value;
+
+        if (*cp == '0') {
+                base = 8;
+                cp++;
+                if (toupper(*cp) == 'X') {
+                        cp++;
+                        base = 16;
+                }
+        }
+
+        while (isxdigit(*cp) &&
+               (value = isdigit(*cp) ? *cp - '0' : toupper(*cp) - 'A' + 10) < base) {
+                result = result * base + value;
+                cp++;
+        }
+
+        if (endp)
+                *endp = cp;
+
+        return result;
+}
+
+unsigned long prom_memparse(const char *ptr, const char **retptr)
+{
+        unsigned long ret = prom_strtoul(ptr, retptr);
+        int shift = 0;
+
+        /*
+         * We can't use a switch here because GCC *may* generate a
+         * jump table which won't work, because we're not running at
+         * the address we're linked at.
+         */
+        if ('G' == **retptr || 'g' == **retptr)
+                shift = 30;
+
+        if ('M' == **retptr || 'm' == **retptr)
+                shift = 20;
+
+        if ('K' == **retptr || 'k' == **retptr)
+                shift = 10;
+
+        if (shift) {
+                ret <<= shift;
+                (*retptr)++;
+        }
+
+        return ret;
+}
+
 /*
  * Early parsing of the command line passed to the kernel, used for
  * "mem=x" and the options that affect the iommu
@@ -491,9 +554,8 @@ static int __init prom_setprop(phandle node, const char *nodename,
 static void __init early_cmdline_parse(void)
 {
         struct prom_t *_prom = &RELOC(prom);
-#ifdef CONFIG_PPC64
         const char *opt;
-#endif
+
         char *p;
         int l = 0;
 
@@ -521,6 +583,15 @@ static void __init early_cmdline_parse(void)
                         RELOC(prom_iommu_force_on) = 1;
         }
 #endif
+        opt = strstr(RELOC(prom_cmd_line), RELOC("mem="));
+        if (opt) {
+                opt += 4;
+                RELOC(prom_memory_limit) = prom_memparse(opt, (const char **)&opt);
+#ifdef CONFIG_PPC64
+                /* Align to 16 MB == size of ppc64 large page */
+                RELOC(prom_memory_limit) = ALIGN(RELOC(prom_memory_limit), 0x1000000);
+#endif
+        }
 }
 
 #ifdef CONFIG_PPC_PSERIES
@@ -1027,6 +1098,29 @@ static void __init prom_init_mem(void)
         }
 
         /*
+         * If prom_memory_limit is set we reduce the upper limits *except* for
+         * alloc_top_high. This must be the real top of RAM so we can put
+         * TCE's up there.
+         */
+
+        RELOC(alloc_top_high) = RELOC(ram_top);
+
+        if (RELOC(prom_memory_limit)) {
+                if (RELOC(prom_memory_limit) <= RELOC(alloc_bottom)) {
+                        prom_printf("Ignoring mem=%x <= alloc_bottom.\n",
+                                RELOC(prom_memory_limit));
+                        RELOC(prom_memory_limit) = 0;
+                } else if (RELOC(prom_memory_limit) >= RELOC(ram_top)) {
+                        prom_printf("Ignoring mem=%x >= ram_top.\n",
+                                RELOC(prom_memory_limit));
+                        RELOC(prom_memory_limit) = 0;
+                } else {
+                        RELOC(ram_top) = RELOC(prom_memory_limit);
+                        RELOC(rmo_top) = min(RELOC(rmo_top), RELOC(prom_memory_limit));
+                }
+        }
+
+        /*
          * Setup our top alloc point, that is top of RMO or top of
          * segment 0 when running non-LPAR.
          * Some RS64 machines have buggy firmware where claims up at
@@ -1041,6 +1135,7 @@ static void __init prom_init_mem(void)
         RELOC(alloc_top_high) = RELOC(ram_top);
 
         prom_printf("memory layout at init:\n");
+        prom_printf("  memory_limit : %x (16 MB aligned)\n", RELOC(prom_memory_limit));
         prom_printf("  alloc_bottom : %x\n", RELOC(alloc_bottom));
         prom_printf("  alloc_top    : %x\n", RELOC(alloc_top));
         prom_printf("  alloc_top_hi : %x\n", RELOC(alloc_top_high));
@@ -2395,6 +2490,10 @@ unsigned long __init prom_init(unsigned long r3, unsigned long r4,
         /*
          * Fill in some infos for use by the kernel later on
          */
+        if (RELOC(prom_memory_limit))
+                prom_setprop(_prom->chosen, "/chosen", "linux,memory-limit",
+                             &RELOC(prom_memory_limit),
+                             sizeof(prom_memory_limit));
 #ifdef CONFIG_PPC64
         if (RELOC(prom_iommu_off))
                 prom_setprop(_prom->chosen, "/chosen", "linux,iommu-off",