regmap: Allow regmap_update_bits() users to detect changes
Some users of regmap_update_bits() would like to be able to tell their
users if they actually did an update so provide a variant which also
returns a flag indicating if an update took place. We could return a
tristate in the return value of regmap_update_bits() but this makes the
API more cumbersome to use and doesn't fit with the general zero for
success idiom we have.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index a862090..add5da6 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -569,18 +569,9 @@
}
EXPORT_SYMBOL_GPL(regmap_bulk_read);
-/**
- * regmap_update_bits: Perform a read/modify/write cycle on the register map
- *
- * @map: Register map to update
- * @reg: Register to update
- * @mask: Bitmask to change
- * @val: New value for bitmask
- *
- * Returns zero for success, a negative number on error.
- */
-int regmap_update_bits(struct regmap *map, unsigned int reg,
- unsigned int mask, unsigned int val)
+static int _regmap_update_bits(struct regmap *map, unsigned int reg,
+ unsigned int mask, unsigned int val,
+ bool *change)
{
int ret;
unsigned int tmp, orig;
@@ -594,16 +585,57 @@
tmp = orig & ~mask;
tmp |= val & mask;
- if (tmp != orig)
+ if (tmp != orig) {
ret = _regmap_write(map, reg, tmp);
+ *change = true;
+ } else {
+ *change = false;
+ }
out:
mutex_unlock(&map->lock);
return ret;
}
+
+/**
+ * regmap_update_bits: Perform a read/modify/write cycle on the register map
+ *
+ * @map: Register map to update
+ * @reg: Register to update
+ * @mask: Bitmask to change
+ * @val: New value for bitmask
+ *
+ * Returns zero for success, a negative number on error.
+ */
+int regmap_update_bits(struct regmap *map, unsigned int reg,
+ unsigned int mask, unsigned int val)
+{
+ bool change;
+ return _regmap_update_bits(map, reg, mask, val, &change);
+}
EXPORT_SYMBOL_GPL(regmap_update_bits);
+/**
+ * regmap_update_bits_check: Perform a read/modify/write cycle on the
+ * register map and report if updated
+ *
+ * @map: Register map to update
+ * @reg: Register to update
+ * @mask: Bitmask to change
+ * @val: New value for bitmask
+ * @change: Boolean indicating if a write was done
+ *
+ * Returns zero for success, a negative number on error.
+ */
+int regmap_update_bits_check(struct regmap *map, unsigned int reg,
+ unsigned int mask, unsigned int val,
+ bool *change)
+{
+ return _regmap_update_bits(map, reg, mask, val, change);
+}
+EXPORT_SYMBOL_GPL(regmap_update_bits_check);
+
static int __init regmap_initcall(void)
{
regmap_debugfs_initcall();
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 81dfe0a..a83e4a0 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -138,6 +138,9 @@
size_t val_count);
int regmap_update_bits(struct regmap *map, unsigned int reg,
unsigned int mask, unsigned int val);
+int regmap_update_bits_check(struct regmap *map, unsigned int reg,
+ unsigned int mask, unsigned int val,
+ bool *change);
int regcache_sync(struct regmap *map);
void regcache_cache_only(struct regmap *map, bool enable);