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>

2 files changed, 22 insertions, 10 deletions

diff --git a/drivers/mfd/da9052-i2c.c b/drivers/mfd/da9052-i2c.c
index 6a9fec40d018..c319c4ef5d49 100644
--- a/drivers/mfd/da9052-i2c.c
+++ b/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;
 
diff --git a/include/linux/mfd/da9052/da9052.h b/include/linux/mfd/da9052/da9052.h
index 786d02eb79d2..21e21b81cc75 100644
--- a/include/linux/mfd/da9052/da9052.h
+++ b/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);