[PATCH] mfd: tps65219: Implement LOCK register handling for TPS65214

[Kory Maincent <kory.maincent@bootlin.com>]

From: "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.

Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
---
 drivers/mfd/tps65219.c       | 53 +++++++++++++++++++++++++++++++++++-
 include/linux/mfd/tps65219.h |  3 ++
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/tps65219.c b/drivers/mfd/tps65219.c
index 65a952555218d..1d8a06afb1048 100644
--- a/drivers/mfd/tps65219.c
+++ b/drivers/mfd/tps65219.c
@@ -473,6 +473,55 @@ static const struct tps65219_chip_data chip_info_table[] = {
 	},
 };
 
+static int tps65219_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);
+	if (tps->chip_id == TPS65214) {
+		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;
+
+	if (tps->chip_id == TPS65214)
+		return i2c_smbus_write_byte_data(i2c, TPS65214_REG_LOCK, 0);
+
+	return 0;
+}
+
+static int tps65219_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 tps65219_regmap_bus = {
+	.reg_write = tps65219_reg_write,
+	.reg_read = tps65219_reg_read,
+};
+
 static int tps65219_probe(struct i2c_client *client)
 {
 	struct tps65219 *tps;
@@ -490,8 +539,10 @@ static int tps65219_probe(struct i2c_client *client)
 	tps->dev = &client->dev;
 	chip_id = (uintptr_t)i2c_get_match_data(client);
 	pmic = &chip_info_table[chip_id];
+	tps->chip_id = chip_id;
 
-	tps->regmap = devm_regmap_init_i2c(client, &tps65219_regmap_config);
+	tps->regmap = devm_regmap_init(&client->dev, &tps65219_regmap_bus, 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..53e53cbc5c76f 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)
@@ -444,6 +446,7 @@ struct tps65219 {
 	struct regmap *regmap;
 
 	struct regmap_irq_chip_data *irq_data;
+	enum pmic_id chip_id;
 };
 
 #endif /* MFD_TPS65219_H */
-- 
2.43.0