eeprom: at24: refactor at24_probe()

The code in at24_probe() is pretty mangled. It can be cleaned up a bit
by doing things one by one.

Let's group the code by logic: parse and verify pdata, initialize the
regmap, allocate and fill the fields of at24_data, allocate dummy i2c
devices, initialize pm & register with nvmem.
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/eeprom/at24.c

@@ -566,6 +566,7 @@ static int at24_probe(struct i2c_client *client)
 	struct device *dev = &client->dev;
 	unsigned int i, num_addresses;
 	struct at24_data *at24;
+	struct regmap *regmap;
 	size_t at24_size;
 	bool writable;
 	u8 test_byte;
@@ -575,6 +576,11 @@ static int at24_probe(struct i2c_client *client)
 	if (err)
 		return err;
 
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
+	    !i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WRITE_I2C_BLOCK))
+		pdata.page_size = 1;
+
 	if (!pdata.page_size) {
 		dev_err(dev, "page_size must not be 0!\n");
 		return -EINVAL;
@@ -582,21 +588,26 @@ static int at24_probe(struct i2c_client *client)
 	if (!is_power_of_2(pdata.page_size))
 		dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
 
-	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
-	    !i2c_check_functionality(client->adapter,
-				     I2C_FUNC_SMBUS_WRITE_I2C_BLOCK))
-		pdata.page_size = 1;
-
 	if (pdata.flags & AT24_FLAG_TAKE8ADDR)
 		num_addresses = 8;
 	else
 		num_addresses =	DIV_ROUND_UP(pdata.byte_len,
 			(pdata.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
 
+	if ((pdata.flags & AT24_FLAG_SERIAL) && (pdata.flags & AT24_FLAG_MAC)) {
+		dev_err(dev,
+			"invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
+		return -EINVAL;
+	}
+
 	regmap_config.val_bits = 8;
 	regmap_config.reg_bits = (pdata.flags & AT24_FLAG_ADDR16) ? 16 : 8;
 	regmap_config.disable_locking = true;
 
+	regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
 	at24_size = sizeof(*at24) + num_addresses * sizeof(struct at24_client);
 	at24 = devm_kzalloc(dev, at24_size, GFP_KERNEL);
 	if (!at24)
@@ -608,22 +619,13 @@ static int at24_probe(struct i2c_client *client)
 	at24->flags = pdata.flags;
 	at24->num_addresses = num_addresses;
 	at24->offset_adj = at24_get_offset_adj(pdata.flags, pdata.byte_len);
+	at24->client[0].client = client;
+	at24->client[0].regmap = regmap;
 
 	at24->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_HIGH);
 	if (IS_ERR(at24->wp_gpio))
 		return PTR_ERR(at24->wp_gpio);
 
-	at24->client[0].client = client;
-	at24->client[0].regmap = devm_regmap_init_i2c(client, &regmap_config);
-	if (IS_ERR(at24->client[0].regmap))
-		return PTR_ERR(at24->client[0].regmap);
-
-	if ((pdata.flags & AT24_FLAG_SERIAL) && (pdata.flags & AT24_FLAG_MAC)) {
-		dev_err(dev,
-			"invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
-		return -EINVAL;
-	}
-
 	writable = !(pdata.flags & AT24_FLAG_READONLY);
 	if (writable) {
 		at24->write_max = min_t(unsigned int,