mfd: twl-core: API to set the regcache bypass for a given regmap in twl

If the regcache is enabled on the regmap module drivers might need to access
to HW register(s) in certain cases in cache bypass mode.
As an example of this is the audio block's ANAMICL register. In normal
operation the content can be cached but during initialization one bit from
the register need to be monitored. With the twl_set_regcache_bypass() the
client driver can switch regcache bypass on and off when it is needed so
we can utilize the regcache for more registers.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: NMark Brown <broonie@kernel.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/twl-core.c

@@ -383,6 +383,27 @@ int twl_i2c_read(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
 }
 EXPORT_SYMBOL(twl_i2c_read);
 
+/**
+ * twl_regcache_bypass - Configure the regcache bypass for the regmap associated
+ *			 with the module
+ * @mod_no: module number
+ * @enable: Regcache bypass state
+ *
+ * Returns 0 else failure.
+ */
+int twl_set_regcache_bypass(u8 mod_no, bool enable)
+{
+	struct regmap *regmap = twl_get_regmap(mod_no);
+
+	if (!regmap)
+		return -EPERM;
+
+	regcache_cache_bypass(regmap, enable);
+
+	return 0;
+}
+EXPORT_SYMBOL(twl_set_regcache_bypass);
+
 /*----------------------------------------------------------------------*/
 
 /**

include/linux/i2c/twl.h

@@ -175,6 +175,9 @@ static inline int twl_class_is_ ##class(void)	\
 TWL_CLASS_IS(4030, TWL4030_CLASS_ID)
 TWL_CLASS_IS(6030, TWL6030_CLASS_ID)
 
+/* Set the regcache bypass for the regmap associated with the nodule */
+int twl_set_regcache_bypass(u8 mod_no, bool enable);
+
 /*
  * Read and write several 8-bit registers at once.
  */