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>

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>
Mark Brown
1 parent c86845dc7b
Showing 2 changed files with 48 additions and 13 deletions Side-by-side Diff
drivers/base/regmap/regmap.c
include/linux/regmap.h
@@ -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;
  
  
  
@@ -594,15 +585,56 @@
 	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)
 {
@@ -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);
...	...	@@ -569,18 +569,9 @@
569	569	}
570	570	EXPORT_SYMBOL_GPL(regmap_bulk_read);
571	571
572		-/**
573		- * regmap_update_bits: Perform a read/modify/write cycle on the register map
574		- *
575		- * @map: Register map to update
576		- * @reg: Register to update
577		- * @mask: Bitmask to change
578		- * @val: New value for bitmask
579		- *
580		- * Returns zero for success, a negative number on error.
581		- */
582		-int regmap_update_bits(struct regmap *map, unsigned int reg,
583		- unsigned int mask, unsigned int val)
	572	+static int _regmap_update_bits(struct regmap *map, unsigned int reg,
	573	+ unsigned int mask, unsigned int val,
	574	+ bool *change)
584	575	{
585	576	int ret;
586	577	unsigned int tmp, orig;
587	578
588	579
589	580
...	...	@@ -594,15 +585,56 @@
594	585	tmp = orig & ~mask;
595	586	tmp \|= val & mask;
596	587
597		- if (tmp != orig)
	588	+ if (tmp != orig) {
598	589	ret = _regmap_write(map, reg, tmp);
	590	+ *change = true;
	591	+ } else {
	592	+ *change = false;
	593	+ }
599	594
600	595	out:
601	596	mutex_unlock(&map->lock);
602	597
603	598	return ret;
604	599	}
	600	+
	601	+/**
	602	+ * regmap_update_bits: Perform a read/modify/write cycle on the register map
	603	+ *
	604	+ * @map: Register map to update
	605	+ * @reg: Register to update
	606	+ * @mask: Bitmask to change
	607	+ * @val: New value for bitmask
	608	+ *
	609	+ * Returns zero for success, a negative number on error.
	610	+ */
	611	+int regmap_update_bits(struct regmap *map, unsigned int reg,
	612	+ unsigned int mask, unsigned int val)
	613	+{
	614	+ bool change;
	615	+ return _regmap_update_bits(map, reg, mask, val, &change);
	616	+}
605	617	EXPORT_SYMBOL_GPL(regmap_update_bits);
	618	+
	619	+/**
	620	+ * regmap_update_bits_check: Perform a read/modify/write cycle on the
	621	+ * register map and report if updated
	622	+ *
	623	+ * @map: Register map to update
	624	+ * @reg: Register to update
	625	+ * @mask: Bitmask to change
	626	+ * @val: New value for bitmask
	627	+ * @change: Boolean indicating if a write was done
	628	+ *
	629	+ * Returns zero for success, a negative number on error.
	630	+ */
	631	+int regmap_update_bits_check(struct regmap *map, unsigned int reg,
	632	+ unsigned int mask, unsigned int val,
	633	+ bool *change)
	634	+{
	635	+ return _regmap_update_bits(map, reg, mask, val, change);
	636	+}
	637	+EXPORT_SYMBOL_GPL(regmap_update_bits_check);
606	638
607	639	static int __init regmap_initcall(void)
608	640	{
...	...	@@ -138,6 +138,9 @@
138	138	size_t val_count);
139	139	int regmap_update_bits(struct regmap *map, unsigned int reg,
140	140	unsigned int mask, unsigned int val);
	141	+int regmap_update_bits_check(struct regmap *map, unsigned int reg,
	142	+ unsigned int mask, unsigned int val,
	143	+ bool *change);
141	144
142	145	int regcache_sync(struct regmap *map);
143	146	void regcache_cache_only(struct regmap *map, bool enable);