ARM: 6116/1: kdump: reserve memory for crashkernel

Implemented ARM support for command line option
"crashkernel=size@start" which allows user to reserve some memory
for a dump capture kernel.
Signed-off-by: NMika Westerberg <ext-mika.1.westerberg@nokia.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/setup.c

@@ -19,6 +19,7 @@
 #include <linux/seq_file.h>
 #include <linux/screen_info.h>
 #include <linux/init.h>
+#include <linux/kexec.h>
 #include <linux/root_dev.h>
 #include <linux/cpu.h>
 #include <linux/interrupt.h>
@@ -680,6 +681,55 @@ static int __init customize_machine(void)
 }
 arch_initcall(customize_machine);
 
+#ifdef CONFIG_KEXEC
+static inline unsigned long long get_total_mem(void)
+{
+	unsigned long total;
+
+	total = max_low_pfn - min_low_pfn;
+	return total << PAGE_SHIFT;
+}
+
+/**
+ * reserve_crashkernel() - reserves memory are for crash kernel
+ *
+ * This function reserves memory area given in "crashkernel=" kernel command
+ * line parameter. The memory reserved is used by a dump capture kernel when
+ * primary kernel is crashing.
+ */
+static void __init reserve_crashkernel(void)
+{
+	unsigned long long crash_size, crash_base;
+	unsigned long long total_mem;
+	int ret;
+
+	total_mem = get_total_mem();
+	ret = parse_crashkernel(boot_command_line, total_mem,
+				&crash_size, &crash_base);
+	if (ret)
+		return;
+
+	ret = reserve_bootmem(crash_base, crash_size, BOOTMEM_EXCLUSIVE);
+	if (ret < 0) {
+		printk(KERN_WARNING "crashkernel reservation failed - "
+		       "memory is in use (0x%lx)\n", (unsigned long)crash_base);
+		return;
+	}
+
+	printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "
+	       "for crashkernel (System RAM: %ldMB)\n",
+	       (unsigned long)(crash_size >> 20),
+	       (unsigned long)(crash_base >> 20),
+	       (unsigned long)(total_mem >> 20));
+
+	crashk_res.start = crash_base;
+	crashk_res.end = crash_base + crash_size - 1;
+	insert_resource(&iomem_resource, &crashk_res);
+}
+#else
+static inline void reserve_crashkernel(void) {}
+#endif /* CONFIG_KEXEC */
+
 void __init setup_arch(char **cmdline_p)
 {
 	struct tag *tags = (struct tag *)&init_tags;
@@ -739,6 +789,7 @@ void __init setup_arch(char **cmdline_p)
 #ifdef CONFIG_SMP
 	smp_init_cpus();
 #endif
+	reserve_crashkernel();
 
 	cpu_init();
 	tcm_init();