2 files changed, 33 insertions, 18 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 202518641779..2cad787fa548 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -26,6 +26,7 @@ struct regmap_debugfs_off_cache {
         off_t min;
         off_t max;
         unsigned int base_reg;
+        unsigned int max_reg;
 };
 
 struct regmap_format {
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index d9a6c94ce423..78d5f20c5f5b 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -81,6 +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
@@ -93,6 +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;
@@ -119,6 +124,9 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
         /* 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);
         }
@@ -128,25 +136,38 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
          * allocate and we should never be in this code if there are
          * no registers at all.
          */
-        if (list_empty(&map->debugfs_off_cache)) {
-                WARN_ON(list_empty(&map->debugfs_off_cache));
-                return base;
-        }
+        WARN_ON(list_empty(&map->debugfs_off_cache));
+        ret = base;
 
-        /* Find the relevant block */
+        /* Find the relevant block:offset */
         list_for_each_entry(c, &map->debugfs_off_cache, list) {
                 if (from >= c->min && from <= c->max) {
-                        *pos = c->min;
-                        return c->base_reg;
+                        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;
                 }
 
-                *pos = c->min;
-                ret = c->base_reg;
+                *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)
@@ -165,14 +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);
@@ -187,7 +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 */