[PATCH v2 1/2] mfd: tps65219: Implement LOCK register handling for TPS65214

["Kory Maincent (TI.com)" <kory.maincent@bootlin.com>]

The TPS65214 PMIC variant has a LOCK_REG register that prevents writes to
nearly all registers.

Implement custom regmap operations that automatically unlock before writes
and re-lock afterwards for TPS65214, while leaving other chip variants
unaffected.

The implementation follows the regmap-i2c design pattern.

Cc: <stable@vger.kernel.org>
Fixes: 7947219ab1a2d ("mfd: tps65219: Add support for TI TPS65214 PMIC")
Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
---

Changes in v2:
- Setup a custom regmap_bus only for the TPS65214 instead of checking
  the chip_id every time reg_write is called.
---
 drivers/mfd/tps65219.c       | 51 +++++++++++++++++++++++++++++++++++++++++++-
 include/linux/mfd/tps65219.h |  2 ++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/tps65219.c b/drivers/mfd/tps65219.c
index 65a952555218d..7e916a9ce2335 100644
--- a/drivers/mfd/tps65219.c
+++ b/drivers/mfd/tps65219.c
@@ -473,6 +473,50 @@ static const struct tps65219_chip_data chip_info_table[] = {
 	},
 };
 
+static int tps65214_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct i2c_client *i2c = context;
+	struct tps65219 *tps;
+	int ret;
+
+	if (val > 0xff || reg > 0xff)
+		return -EINVAL;
+
+	tps = i2c_get_clientdata(i2c);
+	ret = i2c_smbus_write_byte_data(i2c, TPS65214_REG_LOCK,
+					TPS65214_LOCK_ACCESS_CMD);
+	if (ret)
+		return ret;
+
+	ret = i2c_smbus_write_byte_data(i2c, reg, val);
+	if (ret)
+		return ret;
+
+	return i2c_smbus_write_byte_data(i2c, TPS65214_REG_LOCK, 0);
+}
+
+static int tps65214_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct i2c_client *i2c = context;
+	int ret;
+
+	if (reg > 0xff)
+		return -EINVAL;
+
+	ret = i2c_smbus_read_byte_data(i2c, reg);
+	if (ret < 0)
+		return ret;
+
+	*val = ret;
+
+	return 0;
+}
+
+static const struct regmap_bus tps65214_regmap_bus = {
+	.reg_write = tps65214_reg_write,
+	.reg_read = tps65214_reg_read,
+};
+
 static int tps65219_probe(struct i2c_client *client)
 {
 	struct tps65219 *tps;
@@ -491,7 +535,12 @@ static int tps65219_probe(struct i2c_client *client)
 	chip_id = (uintptr_t)i2c_get_match_data(client);
 	pmic = &chip_info_table[chip_id];
 
-	tps->regmap = devm_regmap_init_i2c(client, &tps65219_regmap_config);
+	if (chip_id == TPS65214)
+		tps->regmap = devm_regmap_init(&client->dev,
+					       &tps65214_regmap_bus, client,
+					       &tps65219_regmap_config);
+	else
+		tps->regmap = devm_regmap_init_i2c(client, &tps65219_regmap_config);
 	if (IS_ERR(tps->regmap)) {
 		ret = PTR_ERR(tps->regmap);
 		dev_err(tps->dev, "Failed to allocate register map: %d\n", ret);
diff --git a/include/linux/mfd/tps65219.h b/include/linux/mfd/tps65219.h
index 55234e771ba73..198ee319dd1db 100644
--- a/include/linux/mfd/tps65219.h
+++ b/include/linux/mfd/tps65219.h
@@ -149,6 +149,8 @@ enum pmic_id {
 #define TPS65215_ENABLE_LDO2_EN_MASK                    BIT(5)
 #define TPS65214_ENABLE_LDO1_EN_MASK			BIT(5)
 #define TPS65219_ENABLE_LDO4_EN_MASK			BIT(6)
+/* Register Lock */
+#define TPS65214_LOCK_ACCESS_CMD			0x5a
 /* power ON-OFF sequence slot */
 #define TPS65219_BUCKS_LDOS_SEQUENCE_OFF_SLOT_MASK	GENMASK(3, 0)
 #define TPS65219_BUCKS_LDOS_SEQUENCE_ON_SLOT_MASK	GENMASK(7, 4)

-- 
2.43.0