1 files changed, 64 insertions, 25 deletions

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 07aad786f817..78d5f20c5f5b 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -56,6 +56,19 @@ static const struct file_operations regmap_name_fops = {
 	.llseek = default_llseek,
 };
 
+static void regmap_debugfs_free_dump_cache(struct regmap *map)
+{
+	struct regmap_debugfs_off_cache *c;
+
+	while (!list_empty(&map->debugfs_off_cache)) {
+		c = list_first_entry(&map->debugfs_off_cache,
+				     struct regmap_debugfs_off_cache,
+				     list);
+		list_del(&c->list);
+		kfree(c);
+	}
+}
+
 /*
  * Work out where the start offset maps into register numbers, bearing
  * in mind that we suppress hidden registers.
@@ -68,6 +81,8 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 	struct regmap_debugfs_off_cache *c = NULL;
 	loff_t p = 0;
 	unsigned int i, ret;
+	unsigned int fpos_offset;
+	unsigned int reg_offset;
 
 	/*
 	 * If we don't have a cache build one so we don't have to do a
@@ -80,6 +95,9 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 			    regmap_precious(map, i)) {
 				if (c) {
 					c->max = p - 1;
+					fpos_offset = c->max - c->min;
+					reg_offset = fpos_offset / map->debugfs_tot_len;
+					c->max_reg = c->base_reg + reg_offset;
 					list_add_tail(&c->list,
 						      &map->debugfs_off_cache);
 					c = NULL;
@@ -91,8 +109,10 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 			/* No cache entry?  Start a new one */
 			if (!c) {
 				c = kzalloc(sizeof(*c), GFP_KERNEL);
-				if (!c)
-					break;
+				if (!c) {
+					regmap_debugfs_free_dump_cache(map);
+					return base;
+				}
 				c->min = p;
 				c->base_reg = i;
 			}
@@ -101,19 +121,53 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 		}
 	}
 
-	/* Find the relevant block */
+	/* Close the last entry off if we didn't scan beyond it */
+	if (c) {
+		c->max = p - 1;
+		fpos_offset = c->max - c->min;
+		reg_offset = fpos_offset / map->debugfs_tot_len;
+		c->max_reg = c->base_reg + reg_offset;
+		list_add_tail(&c->list,
+			      &map->debugfs_off_cache);
+	}
+
+	/*
+	 * This should never happen; we return above if we fail to
+	 * allocate and we should never be in this code if there are
+	 * no registers at all.
+	 */
+	WARN_ON(list_empty(&map->debugfs_off_cache));
+	ret = base;
+
+	/* Find the relevant block:offset */
 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
-		if (*pos >= c->min && *pos <= c->max) {
-			*pos = c->min;
-			return c->base_reg;
+		if (from >= c->min && from <= c->max) {
+			fpos_offset = from - c->min;
+			reg_offset = fpos_offset / map->debugfs_tot_len;
+			*pos = c->min + (reg_offset * map->debugfs_tot_len);
+			return c->base_reg + reg_offset;
 		}
 
-		ret = c->max;
+		*pos = c->max;
+		ret = c->max_reg;
 	}
 
 	return ret;
 }
 
+static inline void regmap_calc_tot_len(struct regmap *map,
+				       void *buf, size_t count)
+{
+	/* Calculate the length of a fixed format  */
+	if (!map->debugfs_tot_len) {
+		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register,
+							   buf, count);
+		map->debugfs_val_len = 2 * map->format.val_bytes;
+		map->debugfs_tot_len = map->debugfs_reg_len +
+			map->debugfs_val_len + 3;      /* : \n */
+	}
+}
+
 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 				   unsigned int to, char __user *user_buf,
 				   size_t count, loff_t *ppos)
@@ -132,14 +186,7 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 	if (!buf)
 		return -ENOMEM;
 
-	/* Calculate the length of a fixed format  */
-	if (!map->debugfs_tot_len) {
-		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register,
-							   buf, count);
-		map->debugfs_val_len = 2 * map->format.val_bytes;
-		map->debugfs_tot_len = map->debugfs_reg_len +
-			map->debugfs_val_len + 3;      /* : \n */
-	}
+	regmap_calc_tot_len(map, buf, count);
 
 	/* Work out which register we're starting at */
 	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
@@ -154,7 +201,7 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 		/* If we're in the region the user is trying to read */
 		if (p >= *ppos) {
 			/* ...but not beyond it */
-			if (buf_pos + 1 + map->debugfs_tot_len >= count)
+			if (buf_pos + map->debugfs_tot_len > count)
 				break;
 
 			/* Format the register */
@@ -387,16 +434,8 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
 
 void regmap_debugfs_exit(struct regmap *map)
 {
-	struct regmap_debugfs_off_cache *c;
-
 	debugfs_remove_recursive(map->debugfs);
-	while (!list_empty(&map->debugfs_off_cache)) {
-		c = list_first_entry(&map->debugfs_off_cache,
-				     struct regmap_debugfs_off_cache,
-				     list);
-		list_del(&c->list);
-		kfree(c);
-	}
+	regmap_debugfs_free_dump_cache(map);
 	kfree(map->debugfs_name);
 }