mfd: da9052: Avoid multiwrite mode due to silicon errata

DA9053 (up to revision bc) can corrupt internal registers when multi-write
mode is enabled and power is removed or during shutdown.

Signed-off-by: David Jander <david@protonic.nl>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/da9052-i2c.c

@@ -86,7 +86,11 @@ static int da9052_i2c_fix(struct da9052 *da9052, unsigned char reg)
 	return 0;
 }
 
-static int da9052_i2c_enable_multiwrite(struct da9052 *da9052)
+/*
+ * According to errata item 24, multiwrite mode should be avoided
+ * in order to prevent register data corruption after power-down.
+ */
+static int da9052_i2c_disable_multiwrite(struct da9052 *da9052)
 {
 	int reg_val, ret;
 
@@ -94,8 +98,8 @@ static int da9052_i2c_enable_multiwrite(struct da9052 *da9052)
 	if (ret < 0)
 		return ret;
 
-	if (reg_val & DA9052_CONTROL_B_WRITEMODE) {
-		reg_val &= ~DA9052_CONTROL_B_WRITEMODE;
+	if (!(reg_val & DA9052_CONTROL_B_WRITEMODE)) {
+		reg_val |= DA9052_CONTROL_B_WRITEMODE;
 		ret = regmap_write(da9052->regmap, DA9052_CONTROL_B_REG,
 				   reg_val);
 		if (ret < 0)
@@ -154,7 +158,7 @@ static int da9052_i2c_probe(struct i2c_client *client,
 		return ret;
 	}
 
-	ret = da9052_i2c_enable_multiwrite(da9052);
+	ret = da9052_i2c_disable_multiwrite(da9052);
 	if (ret < 0)
 		return ret;
 

include/linux/mfd/da9052/da9052.h

@@ -148,10 +148,15 @@ static inline int da9052_group_read(struct da9052 *da9052, unsigned char reg,
 				     unsigned reg_cnt, unsigned char *val)
 {
 	int ret;
+	unsigned int tmp;
+	int i;
 
-	ret = regmap_bulk_read(da9052->regmap, reg, val, reg_cnt);
-	if (ret < 0)
-		return ret;
+	for (i = 0; i < reg_cnt; i++) {
+		ret = regmap_read(da9052->regmap, reg + i, &tmp);
+		val[i] = (unsigned char)tmp;
+		if (ret < 0)
+			return ret;
+	}
 
 	if (da9052->fix_io) {
 		ret = da9052->fix_io(da9052, reg);
@@ -166,10 +171,13 @@ static inline int da9052_group_write(struct da9052 *da9052, unsigned char reg,
 				      unsigned reg_cnt, unsigned char *val)
 {
 	int ret;
+	int i;
 
-	ret = regmap_raw_write(da9052->regmap, reg, val, reg_cnt);
-	if (ret < 0)
-		return ret;
+	for (i = 0; i < reg_cnt; i++) {
+		ret = regmap_write(da9052->regmap, reg + i, val[i]);
+		if (ret < 0)
+			return ret;
+	}
 
 	if (da9052->fix_io) {
 		ret = da9052->fix_io(da9052, reg);