[PATCH] of: reserved-mem: expose reserved-mem details via debugfs

[Martin Liu <liumartin@google.com>]

It's important to know reserved-mem information in mobile world
since reserved memory via device tree keeps increased in platform
(e.g., 45% in our platform). Therefore, it's crucial to know the
reserved memory sizes breakdown for the memory accounting.

This patch shows the reserved memory breakdown under debugfs to
make them visible.

Below is an example output:
cat $debugfs/reserved_mem/show
0x00000009fc400000..0x00000009ffffffff (   61440 KB )   map     reusable test1
0x00000009f9000000..0x00000009fc3fffff (   53248 KB )   map     reusable test2
0x00000000ffdf0000..0x00000000ffffffff (    2112 KB )   map non-reusable test3
0x00000009f6000000..0x00000009f8ffffff (   49152 KB )   map     reusable test4
...
0x00000000fd902000..0x00000000fd909fff (      32 KB ) nomap non-reusable test38
0x00000000fd90a000..0x00000000fd90bfff (       8 KB ) nomap non-reusable test39
Total 39 regions, 1446140 KB

Signed-off-by: Martin Liu <liumartin@google.com>
---
 drivers/of/of_reserved_mem.c | 39 ++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 65f3b02a0e4e..a73228e07c8c 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -23,6 +23,7 @@
 #include <linux/memblock.h>
 #include <linux/kmemleak.h>
 #include <linux/cma.h>
+#include <linux/debugfs.h>
 
 #include "of_private.h"
 
@@ -446,3 +447,41 @@ struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);
+
+#if defined(CONFIG_DEBUG_FS)
+static int of_reserved_mem_debug_show(struct seq_file *m, void *private)
+{
+	unsigned int i;
+	size_t sum = 0;
+
+	for (i = 0; i < reserved_mem_count; i++) {
+		const struct reserved_mem *rmem = &reserved_mem[i];
+		unsigned long node = rmem->fdt_node;
+		phys_addr_t end = rmem->base + rmem->size - 1;
+		bool nomap = (of_get_flat_dt_prop(node, "no-map", NULL)) != NULL;
+		bool reusable = (of_get_flat_dt_prop(node, "reusable", NULL)) != NULL;
+
+		sum += rmem->size;
+		seq_printf(m, "%pa..%pa ( %7lu KB ) %5s %12s %s\n", &rmem->base,
+			   &end, rmem->size / 1024,
+			   nomap ? "nomap" : "map",
+			   reusable ? "reusable" : "non-reusable",
+			   rmem->name ? rmem->name : "unknown");
+	}
+	seq_printf(m, "Total %d regions, %zu KB\n",
+		   reserved_mem_count,
+		   sum / 1024);
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(of_reserved_mem_debug);
+
+static int __init of_reserved_mem_init_debugfs(void)
+{
+	struct dentry *root = debugfs_create_dir("reserved_mem", NULL);
+
+	debugfs_create_file("show", 0444, root,
+			    NULL, &of_reserved_mem_debug_fops);
+	return 0;
+}
+device_initcall(of_reserved_mem_init_debugfs);
+#endif
-- 
2.39.1.519.gcb327c4b5f-goog