net: dsa: sja1105: don't keep a persistent reference to the reset GPIO

The driver only needs the reset GPIO for a very brief period, so instead
of using devres and keeping the descriptor pointer inside priv, just use
that descriptor inside the sja1105_hw_reset function and then let go of
it.

Also use gpiod_get_optional while at it, and error out on real errors
(bad flags etc).
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/sja1105/sja1105.h

@@ -231,7 +231,6 @@ struct sja1105_private {
 	unsigned long bcast_egress_floods;
 	const struct sja1105_info *info;
 	size_t max_xfer_len;
-	struct gpio_desc *reset_gpio;
 	struct spi_device *spidev;
 	struct dsa_switch *ds;
 	u16 bridge_pvid[SJA1105_MAX_NUM_PORTS];

drivers/net/dsa/sja1105/sja1105_main.c

@@ -27,15 +27,29 @@
 
 #define SJA1105_UNKNOWN_MULTICAST	0x010000000000ull
 
-static void sja1105_hw_reset(struct gpio_desc *gpio, unsigned int pulse_len,
-			     unsigned int startup_delay)
+/* Configure the optional reset pin and bring up switch */
+static int sja1105_hw_reset(struct device *dev, unsigned int pulse_len,
+			    unsigned int startup_delay)
 {
+	struct gpio_desc *gpio;
+
+	gpio = gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+
+	if (!gpio)
+		return 0;
+
 	gpiod_set_value_cansleep(gpio, 1);
 	/* Wait for minimum reset pulse length */
 	msleep(pulse_len);
 	gpiod_set_value_cansleep(gpio, 0);
 	/* Wait until chip is ready after reset */
 	msleep(startup_delay);
+
+	gpiod_put(gpio);
+
+	return 0;
 }
 
 static void
@@ -3228,17 +3242,14 @@ static int sja1105_probe(struct spi_device *spi)
 		return -EINVAL;
 	}
 
+	rc = sja1105_hw_reset(dev, 1, 1);
+	if (rc)
+		return rc;
+
 	priv = devm_kzalloc(dev, sizeof(struct sja1105_private), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
-	/* Configure the optional reset pin and bring up switch */
-	priv->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
-	if (IS_ERR(priv->reset_gpio))
-		dev_dbg(dev, "reset-gpios not defined, ignoring\n");
-	else
-		sja1105_hw_reset(priv->reset_gpio, 1, 1);
-
 	/* Populate our driver private structure (priv) based on
 	 * the device tree node that was probed (spi)
 	 */