1 files changed, 101 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index d942404779c..864334b337a 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",