[PATCH net-next v4 05/27] net: pse-pd: tps23881: Use helpers to calculate bit offset for a channel

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

From: Kory Maincent (Dent Project) <kory.maincent@bootlin.com>

This driver frequently follows a pattern where two registers are read or
written in a single operation, followed by calculating the bit offset for
a specific channel.

Introduce helpers to streamline this process and reduce code redundancy,
making the codebase cleaner and more maintainable.

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
---

Thanks to Oleksij for the design of the helpers functions.

Change in v3:
- Small fix: use chan >= 4 instead of chan > 4;

Change in v2:
- New patch
---
 drivers/net/pse-pd/tps23881.c | 107 +++++++++++++++++++++++++++---------------
 1 file changed, 69 insertions(+), 38 deletions(-)

diff --git a/drivers/net/pse-pd/tps23881.c b/drivers/net/pse-pd/tps23881.c
index a3507520ff87..4a75206b2de6 100644
--- a/drivers/net/pse-pd/tps23881.c
+++ b/drivers/net/pse-pd/tps23881.c
@@ -53,6 +53,55 @@ static struct tps23881_priv *to_tps23881_priv(struct pse_controller_dev *pcdev)
 	return container_of(pcdev, struct tps23881_priv, pcdev);
 }
 
+/*
+ * Helper to extract a value from a u16 register value, which is made of two
+ * u8 registers. The function calculates the bit offset based on the channel
+ * and extracts the relevant bits using a provided field mask.
+ *
+ * @param reg_val: The u16 register value (composed of two u8 registers).
+ * @param chan: The channel number (0-7).
+ * @param field_offset: The base bit offset to apply (e.g., 0 or 4).
+ * @param field_mask: The mask to apply to extract the required bits.
+ * @return: The extracted value for the specific channel.
+ */
+static u16 tps23881_calc_val(u16 reg_val, u8 chan, u8 field_offset,
+			     u16 field_mask)
+{
+	if (chan >= 4)
+		reg_val >>= 8;
+
+	return (reg_val >> field_offset) & field_mask;
+}
+
+/*
+ * Helper to combine individual channel values into a u16 register value.
+ * The function sets the value for a specific channel in the appropriate
+ * position.
+ *
+ * @param reg_val: The current u16 register value.
+ * @param chan: The channel number (0-7).
+ * @param field_offset: The base bit offset to apply (e.g., 0 or 4).
+ * @param field_mask: The mask to apply for the field (e.g., 0x0F).
+ * @param field_val: The value to set for the specific channel (masked by
+ *                   field_mask).
+ * @return: The updated u16 register value with the channel value set.
+ */
+static u16 tps23881_set_val(u16 reg_val, u8 chan, u8 field_offset,
+			    u16 field_mask, u16 field_val)
+{
+	field_val &= field_mask;
+
+	if (chan < 4) {
+		reg_val &= ~(field_mask << field_offset);
+		reg_val |= (field_val << field_offset);
+	} else {
+		reg_val &= ~(field_mask << (field_offset + 8));
+		reg_val |= (field_val << (field_offset + 8));
+	}
+
+	return reg_val;
+}
+
 static int tps23881_pi_enable(struct pse_controller_dev *pcdev, int id)
 {
 	struct tps23881_priv *priv = to_tps23881_priv(pcdev);
@@ -64,17 +113,12 @@ static int tps23881_pi_enable(struct pse_controller_dev *pcdev, int id)
 		return -ERANGE;
 
 	chan = priv->port[id].chan[0];
-	if (chan < 4)
-		val = BIT(chan);
-	else
-		val = BIT(chan + 4);
+	val = tps23881_set_val(0, chan, 0, BIT(chan % 4), BIT(chan % 4));
 
 	if (priv->port[id].is_4p) {
 		chan = priv->port[id].chan[1];
-		if (chan < 4)
-			val |= BIT(chan);
-		else
-			val |= BIT(chan + 4);
+		val = tps23881_set_val(val, chan, 0, BIT(chan % 4),
+				       BIT(chan % 4));
 	}
 
 	return i2c_smbus_write_word_data(client, TPS23881_REG_PW_EN, val);
@@ -91,17 +135,12 @@ static int tps23881_pi_disable(struct pse_controller_dev *pcdev, int id)
 		return -ERANGE;
 
 	chan = priv->port[id].chan[0];
-	if (chan < 4)
-		val = BIT(chan + 4);
-	else
-		val = BIT(chan + 8);
+	val = tps23881_set_val(0, chan, 4, BIT(chan % 4), BIT(chan % 4));
 
 	if (priv->port[id].is_4p) {
 		chan = priv->port[id].chan[1];
-		if (chan < 4)
-			val |= BIT(chan + 4);
-		else
-			val |= BIT(chan + 8);
+		val = tps23881_set_val(val, chan, 4, BIT(chan % 4),
+				       BIT(chan % 4));
 	}
 
 	return i2c_smbus_write_word_data(client, TPS23881_REG_PW_EN, val);
@@ -113,6 +152,7 @@ static int tps23881_pi_is_enabled(struct pse_controller_dev *pcdev, int id)
 	struct i2c_client *client = priv->client;
 	bool enabled;
 	u8 chan;
+	u16 val;
 	int ret;
 
 	ret = i2c_smbus_read_word_data(client, TPS23881_REG_PW_STATUS);
@@ -120,17 +160,13 @@ static int tps23881_pi_is_enabled(struct pse_controller_dev *pcdev, int id)
 		return ret;
 
 	chan = priv->port[id].chan[0];
-	if (chan < 4)
-		enabled = ret & BIT(chan);
-	else
-		enabled = ret & BIT(chan + 4);
+	val = tps23881_calc_val(ret, chan, 0, BIT(chan % 4));
+	enabled = !!(val);
 
 	if (priv->port[id].is_4p) {
 		chan = priv->port[id].chan[1];
-		if (chan < 4)
-			enabled &= !!(ret & BIT(chan));
-		else
-			enabled &= !!(ret & BIT(chan + 4));
+		val = tps23881_calc_val(ret, chan, 0, BIT(chan % 4));
+		enabled &= !!(val);
 	}
 
 	/* Return enabled status only if both channel are on this state */
@@ -146,6 +182,7 @@ static int tps23881_ethtool_get_status(struct pse_controller_dev *pcdev,
 	struct i2c_client *client = priv->client;
 	bool enabled, delivering;
 	u8 chan;
+	u16 val;
 	int ret;
 
 	ret = i2c_smbus_read_word_data(client, TPS23881_REG_PW_STATUS);
@@ -153,23 +190,17 @@ static int tps23881_ethtool_get_status(struct pse_controller_dev *pcdev,
 		return ret;
 
 	chan = priv->port[id].chan[0];
-	if (chan < 4) {
-		enabled = ret & BIT(chan);
-		delivering = ret & BIT(chan + 4);
-	} else {
-		enabled = ret & BIT(chan + 4);
-		delivering = ret & BIT(chan + 8);
-	}
+	val = tps23881_calc_val(ret, chan, 0, BIT(chan % 4));
+	enabled = !!(val);
+	val = tps23881_calc_val(ret, chan, 4, BIT(chan % 4));
+	delivering = !!(val);
 
 	if (priv->port[id].is_4p) {
 		chan = priv->port[id].chan[1];
-		if (chan < 4) {
-			enabled &= !!(ret & BIT(chan));
-			delivering &= !!(ret & BIT(chan + 4));
-		} else {
-			enabled &= !!(ret & BIT(chan + 4));
-			delivering &= !!(ret & BIT(chan + 8));
-		}
+		val = tps23881_calc_val(ret, chan, 0, BIT(chan % 4));
+		enabled &= !!(val);
+		val = tps23881_calc_val(ret, chan, 4, BIT(chan % 4));
+		delivering &= !!(val);
 	}
 
 	/* Return delivering status only if both channel are on this state */

-- 
2.34.1