mfd: rt5033: Fix chip revision readout

After reading the data from the DEVICE_ID register, mask 0x0f needs to be
applied to extract the revision of the chip [1].

The other part of the DEVICE_ID register, mask 0xf0, is a vendor identification
code. That's how it is set up at similar products of Richtek, e.g. RT9455 [2]
page 21 top.

[1] https://github.com/msm8916-mainline/linux-downstream/blob/GT-I9195I/drivers/mfd/rt5033_core.c#L484
[2] https://www.richtek.com/assets/product_file/RT9455/DS9455-00.pdfSigned-off-by: Jakob Hauser <jahau@rocketmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/9a98521ffdf76851d5d344afa6ce65f692ecc024.1684182964.git.jahau@rocketmail.com

drivers/mfd/rt5033.c

@@ -55,7 +55,7 @@ static const struct regmap_config rt5033_regmap_config = {
 static int rt5033_i2c_probe(struct i2c_client *i2c)
 {
 	struct rt5033_dev *rt5033;
-	unsigned int dev_id;
+	unsigned int dev_id, chip_rev;
 	int ret;
 
 	rt5033 = devm_kzalloc(&i2c->dev, sizeof(*rt5033), GFP_KERNEL);
@@ -78,7 +78,8 @@ static int rt5033_i2c_probe(struct i2c_client *i2c)
 		dev_err(&i2c->dev, "Device not found\n");
 		return -ENODEV;
 	}
-	dev_info(&i2c->dev, "Device found Device ID: %04x\n", dev_id);
+	chip_rev = dev_id & RT5033_CHIP_REV_MASK;
+	dev_info(&i2c->dev, "Device found (rev. %d)\n", chip_rev);
 
 	ret = regmap_add_irq_chip(rt5033->regmap, rt5033->irq,
 			IRQF_TRIGGER_FALLING | IRQF_ONESHOT,

include/linux/mfd/rt5033-private.h

@@ -71,6 +71,10 @@ enum rt5033_reg {
 /* RT5033 CHGCTRL2 register */
 #define RT5033_CHGCTRL2_CV_MASK		0xfc
 
+/* RT5033 DEVICE_ID register */
+#define RT5033_VENDOR_ID_MASK		0xf0
+#define RT5033_CHIP_REV_MASK		0x0f
+
 /* RT5033 CHGCTRL3 register */
 #define RT5033_CHGCTRL3_CFO_EN_MASK	0x40
 #define RT5033_CHGCTRL3_TIMER_MASK	0x38