2 files changed, 88 insertions, 7 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 01fbe48e8155..c130536e0ab0 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -77,6 +77,7 @@ struct regmap {
         unsigned int debugfs_tot_len;
 
         struct list_head debugfs_off_cache;
+        struct mutex cache_lock;
 #endif
 
         unsigned int max_register;
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 81d6f605c92e..23b701f5fd2f 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -88,16 +88,16 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
          * If we don't have a cache build one so we don't have to do a
          * linear scan each time.
          */
+        mutex_lock(&map->cache_lock);
+        i = base;
         if (list_empty(&map->debugfs_off_cache)) {
-                for (i = base; i <= map->max_register; i += map->reg_stride) {
+                for (; i <= map->max_register; i += map->reg_stride) {
                         /* Skip unprinted registers, closing off cache entry */
                         if (!regmap_readable(map, i) ||
                             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;
+                                        c->max_reg = i - map->reg_stride;
                                         list_add_tail(&c->list,
                                                       &map->debugfs_off_cache);
                                         c = NULL;
@@ -111,6 +111,7 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
                                 c = kzalloc(sizeof(*c), GFP_KERNEL);
                                 if (!c) {
                                         regmap_debugfs_free_dump_cache(map);
+                                        mutex_unlock(&map->cache_lock);
                                         return base;
                                 }
                                 c->min = p;
@@ -124,9 +125,7 @@ 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;
+                c->max_reg = i - map->reg_stride;
                 list_add_tail(&c->list,
                               &map->debugfs_off_cache);
         }
@@ -145,12 +144,14 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
                         fpos_offset = from - c->min;
                         reg_offset = fpos_offset / map->debugfs_tot_len;
                         *pos = c->min + (reg_offset * map->debugfs_tot_len);
+                        mutex_unlock(&map->cache_lock);
                         return c->base_reg + reg_offset;
                 }
 
                 *pos = c->max;
                 ret = c->max_reg;
         }
+        mutex_unlock(&map->cache_lock);
 
         return ret;
 }
@@ -311,6 +312,79 @@ static const struct file_operations regmap_range_fops = {
         .llseek = default_llseek,
 };
 
+static ssize_t regmap_reg_ranges_read_file(struct file *file,
+                                           char __user *user_buf, size_t count,
+                                           loff_t *ppos)
+{
+        struct regmap *map = file->private_data;
+        struct regmap_debugfs_off_cache *c;
+        loff_t p = 0;
+        size_t buf_pos = 0;
+        char *buf;
+        char *entry;
+        int ret;
+
+        if (*ppos < 0 || !count)
+                return -EINVAL;
+
+        buf = kmalloc(count, GFP_KERNEL);
+        if (!buf)
+                return -ENOMEM;
+
+        entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
+        if (!entry) {
+                kfree(buf);
+                return -ENOMEM;
+        }
+
+        /* While we are at it, build the register dump cache
+         * now so the read() operation on the `registers' file
+         * can benefit from using the cache.  We do not care
+         * about the file position information that is contained
+         * in the cache, just about the actual register blocks */
+        regmap_calc_tot_len(map, buf, count);
+        regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
+
+        /* Reset file pointer as the fixed-format of the `registers'
+         * file is not compatible with the `range' file */
+        p = 0;
+        mutex_lock(&map->cache_lock);
+        list_for_each_entry(c, &map->debugfs_off_cache, list) {
+                snprintf(entry, PAGE_SIZE, "%x-%x",
+                         c->base_reg, c->max_reg);
+                if (p >= *ppos) {
+                        if (buf_pos + 1 + strlen(entry) > count)
+                                break;
+                        snprintf(buf + buf_pos, count - buf_pos,
+                                 "%s", entry);
+                        buf_pos += strlen(entry);
+                        buf[buf_pos] = '\n';
+                        buf_pos++;
+                }
+                p += strlen(entry) + 1;
+        }
+        mutex_unlock(&map->cache_lock);
+
+        kfree(entry);
+        ret = buf_pos;
+
+        if (copy_to_user(user_buf, buf, buf_pos)) {
+                ret = -EFAULT;
+                goto out_buf;
+        }
+
+        *ppos += buf_pos;
+out_buf:
+        kfree(buf);
+        return ret;
+}
+
+static const struct file_operations regmap_reg_ranges_fops = {
+        .open = simple_open,
+        .read = regmap_reg_ranges_read_file,
+        .llseek = default_llseek,
+};
+
 static ssize_t regmap_access_read_file(struct file *file,
                                        char __user *user_buf, size_t count,
                                        loff_t *ppos)
@@ -385,6 +459,7 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
         struct regmap_range_node *range_node;
 
         INIT_LIST_HEAD(&map->debugfs_off_cache);
+        mutex_init(&map->cache_lock);
 
         if (name) {
                 map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
@@ -403,6 +478,9 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
         debugfs_create_file("name", 0400, map->debugfs,
                             map, &regmap_name_fops);
 
+        debugfs_create_file("range", 0400, map->debugfs,
+                            map, &regmap_reg_ranges_fops);
+
         if (map->max_register) {
                 debugfs_create_file("registers", 0400, map->debugfs,
                                     map, &regmap_map_fops);
@@ -435,7 +513,9 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
 void regmap_debugfs_exit(struct regmap *map)
 {
         debugfs_remove_recursive(map->debugfs);
+        mutex_lock(&map->cache_lock);
         regmap_debugfs_free_dump_cache(map);
+        mutex_unlock(&map->cache_lock);
         kfree(map->debugfs_name);
 }