regmap: Add support for discarding parts of the register cache

Allow drivers to discard parts of the register cache, for example if part
of the hardware has been reset.

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

4 files changed, 70 insertions, 0 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index c130536e0ab0..b33a4ff67adf 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -148,6 +148,7 @@ struct regcache_ops {
         int (*read)(struct regmap *map, unsigned int reg, unsigned int *value);
         int (*write)(struct regmap *map, unsigned int reg, unsigned int value);
         int (*sync)(struct regmap *map, unsigned int min, unsigned int max);
+        int (*drop)(struct regmap *map, unsigned int min, unsigned int max);
 };
 
 bool regmap_writeable(struct regmap *map, unsigned int reg);
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 75923f2396bd..8a0ab5fa75f5 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -359,6 +359,43 @@ out:
 EXPORT_SYMBOL_GPL(regcache_sync_region);
 
 /**
+ * regcache_drop_region: Discard part of the register cache
+ *
+ * @map: map to operate on
+ * @min: first register to discard
+ * @max: last register to discard
+ *
+ * Discard part of the register cache.
+ *
+ * Return a negative value on failure, 0 on success.
+ */
+int regcache_drop_region(struct regmap *map, unsigned int min,
+                         unsigned int max)
+{
+        unsigned int reg;
+        int ret = 0;
+
+        if (!map->cache_present && !(map->cache_ops && map->cache_ops->drop))
+                return -EINVAL;
+
+        map->lock(map);
+
+        trace_regcache_drop_region(map->dev, min, max);
+
+        if (map->cache_present)
+                for (reg = min; reg < max + 1; reg++)
+                        clear_bit(reg, map->cache_present);
+
+        if (map->cache_ops && map->cache_ops->drop)
+                ret = map->cache_ops->drop(map, min, max);
+
+        map->unlock(map);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(regcache_drop_region);
+
+/**
  * regcache_cache_only: Put a register map into cache only mode
  *
  * @map: map to configure
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 02d84e24b7c2..5067ee94eb92 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -394,6 +394,8 @@ bool regmap_can_raw_write(struct regmap *map);
 int regcache_sync(struct regmap *map);
 int regcache_sync_region(struct regmap *map, unsigned int min,
                          unsigned int max);
+int regcache_drop_region(struct regmap *map, unsigned int min,
+                         unsigned int max);
 void regcache_cache_only(struct regmap *map, bool enable);
 void regcache_cache_bypass(struct regmap *map, bool enable);
 void regcache_mark_dirty(struct regmap *map);
@@ -562,6 +564,13 @@ static inline int regcache_sync_region(struct regmap *map, unsigned int min,
         return -EINVAL;
 }
 
+static inline int regcache_drop_region(struct regmap *map, unsigned int min,
+                                       unsigned int max)
+{
+        WARN_ONCE(1, "regmap API is disabled");
+        return -EINVAL;
+}
+
 static inline void regcache_cache_only(struct regmap *map, bool enable)
 {
         WARN_ONCE(1, "regmap API is disabled");
diff --git a/include/trace/events/regmap.h b/include/trace/events/regmap.h
index a43a2f67bd8e..23d561512f64 100644
--- a/include/trace/events/regmap.h
+++ b/include/trace/events/regmap.h
@@ -223,6 +223,29 @@ DEFINE_EVENT(regmap_async, regmap_async_complete_done,
 
 );
 
+TRACE_EVENT(regcache_drop_region,
+
+        TP_PROTO(struct device *dev, unsigned int from,
+                 unsigned int to),
+
+        TP_ARGS(dev, from, to),
+
+        TP_STRUCT__entry(
+                __string(       name,           dev_name(dev)   )
+                __field(        unsigned int,   from            )
+                __field(        unsigned int,   to              )
+        ),
+
+        TP_fast_assign(
+                __assign_str(name, dev_name(dev));
+                __entry->from = from;
+                __entry->to = to;
+        ),
+
+        TP_printk("%s %u-%u", __get_str(name), (unsigned int)__entry->from,
+                  (unsigned int)__entry->to)
+);
+
 #endif /* _TRACE_REGMAP_H */
 
 /* This part must be outside protection */