[POWERPC] pseries: phyp dump: Disable phyp-dump through boot-var

This adds a kernel command line option "phyp_dump", which takes a 0/1
value for disabling/ enabling phyp_dump at boot time.  Kdump can use
this on cmdline (phyp_dump=0) to disable phyp-dump during boot when
enabling itself.  This will ensure only one dumping mechanism is active
at any given time.

Signed-off-by: Manish Ahuja <mahuja@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom.c

@@ -1060,6 +1060,11 @@ static void __init phyp_dump_reserve_mem(void)
 		return;
 	}
 
+	if (!phyp_dump_info->phyp_dump_at_boot) {
+		printk(KERN_INFO "Phyp-dump disabled at boot time\n");
+		return;
+	}
+
 	if (phyp_dump_info->phyp_dump_is_active) {
 		/* Reserve *everything* above RMR.Area freed by userland tools*/
 		base = PHYP_DUMP_RMR_END;

arch/powerpc/platforms/pseries/phyp_dump.c

@@ -460,3 +460,21 @@ int __init early_init_dt_scan_phyp_dump(unsigned long node,
 						*((unsigned long *)&sizes[4]);
 	return 1;
 }
+
+/* Look for phyp_dump= cmdline option */
+static int __init early_phyp_dump_enabled(char *p)
+{
+	phyp_dump_info->phyp_dump_at_boot = 1;
+
+        if (!p)
+                return 0;
+
+        if (strncmp(p, "1", 1) == 0)
+		phyp_dump_info->phyp_dump_at_boot = 1;
+        else if (strncmp(p, "0", 1) == 0)
+		phyp_dump_info->phyp_dump_at_boot = 0;
+
+        return 0;
+}
+early_param("phyp_dump", early_phyp_dump_enabled);
+

include/asm-powerpc/phyp_dump.h

@@ -25,6 +25,7 @@ struct phyp_dump {
 	unsigned long init_reserve_start;
 	unsigned long init_reserve_size;
 	/* Check status during boot if dump supported, active & present*/
+	unsigned long phyp_dump_at_boot;
 	unsigned long phyp_dump_configured;
 	unsigned long phyp_dump_is_active;
 	/* store cpu & hpte size */