regmap: Support raw reads from cached registers

Fall back to a register by register read to do so; most likely we'll be
cache only so the overhead will be low.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 22 insertions, 6 deletions

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 73a8111aea93..ef7022d45744 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -604,16 +604,32 @@ EXPORT_SYMBOL_GPL(regmap_read);
 int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
                     size_t val_len)
 {
-        size_t val_count = val_len / map->format.val_bytes;
-        int ret;
-
-        WARN_ON(!regmap_volatile_range(map, reg, val_count) &&
-                map->cache_type != REGCACHE_NONE);
+        size_t val_bytes = map->format.val_bytes;
+        size_t val_count = val_len / val_bytes;
+        unsigned int v;
+        int ret, i;
 
         mutex_lock(&map->lock);
 
-        ret = _regmap_raw_read(map, reg, val, val_len);
+        if (regmap_volatile_range(map, reg, val_count) || map->cache_bypass ||
+            map->cache_type == REGCACHE_NONE) {
+                /* Physical block read if there's no cache involved */
+                ret = _regmap_raw_read(map, reg, val, val_len);
+
+        } else {
+                /* Otherwise go word by word for the cache; should be low
+                 * cost as we expect to hit the cache.
+                 */
+                for (i = 0; i < val_count; i++) {
+                        ret = _regmap_read(map, reg + i, &v);
+                        if (ret != 0)
+                                goto out;
+
+                        map->format.format_val(val + (i * val_bytes), v);
+                }
+        }
 
+ out:
         mutex_unlock(&map->lock);
 
         return ret;