[PATCH] iio: adc: fsl-imx25-gcq: initialize regulators as needed

From: Alexandru Ardelean <aardelean@deviqon.com>
To: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: jic23@kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de,
	Alexandru Ardelean <aardelean@deviqon.com>
Subject: [PATCH] iio: adc: fsl-imx25-gcq: initialize regulators as needed
Date: Fri, 25 Jun 2021 10:43:25 +0300	[thread overview]
Message-ID: <20210625074325.9237-1-aardelean@deviqon.com> (raw)

The driver tries to initialize all possible regulators from the DT, then
match the external regulators with each channel and then release all unused
regulators.

We can change the logic a bit to initialize regulators only when at least
one channel needs them.

This change creates a mx25_gcq_ext_regulator_setup() function that is
called only for the external regulators. If there's already a reference to
an external regulator, the function will just exit early with no error.

This way, the driver doesn't need to keep any track of these regulators
during init.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
---
 drivers/iio/adc/fsl-imx25-gcq.c | 57 ++++++++++++++++-----------------
 1 file changed, 28 insertions(+), 29 deletions(-)

diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c
index ab5139e911c3..31776f80f847 100644
--- a/drivers/iio/adc/fsl-imx25-gcq.c
+++ b/drivers/iio/adc/fsl-imx25-gcq.c
@@ -172,13 +172,37 @@ static const struct regmap_config mx25_gcq_regconfig = {
 	.reg_stride = 4,
 };
 
+static int mx25_gcq_ext_regulator_setup(struct device *dev,
+					struct mx25_gcq_priv *priv, u32 refp)
+{
+	char reg_name[12];
+	int ret;
+
+	if (priv->vref[refp])
+		return 0;
+
+	ret = snprintf(reg_name, sizeof(reg_name), "vref-%s",
+		       mx25_gcq_refp_names[refp]);
+	if (ret < 0)
+		return ret;
+
+	priv->vref[refp] = devm_regulator_get_optional(dev, reg_name);
+	if (IS_ERR(priv->vref[refp])) {
+		dev_err(dev,
+			"Error, trying to use external voltage reference without a %s regulator.",
+			reg_name);
+		return PTR_ERR(priv->vref[refp]);
+	}
+
+	return 0;
+}
+
 static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
 			       struct mx25_gcq_priv *priv)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct device_node *child;
 	struct device *dev = &pdev->dev;
-	unsigned int refp_used[4] = {};
 	int ret, i;
 
 	/*
@@ -194,19 +218,6 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
 			     MX25_ADCQ_CFG_IN(i) |
 			     MX25_ADCQ_CFG_REFN_NGND2);
 
-	/*
-	 * First get all regulators to store them in channel_vref_mv if
-	 * necessary. Later we use that information for proper IIO scale
-	 * information.
-	 */
-	priv->vref[MX25_ADC_REFP_INT] = NULL;
-	priv->vref[MX25_ADC_REFP_EXT] =
-		devm_regulator_get_optional(&pdev->dev, "vref-ext");
-	priv->vref[MX25_ADC_REFP_XP] =
-		devm_regulator_get_optional(&pdev->dev, "vref-xp");
-	priv->vref[MX25_ADC_REFP_YP] =
-		devm_regulator_get_optional(&pdev->dev, "vref-yp");
-
 	for_each_child_of_node(np, child) {
 		u32 reg;
 		u32 refp = MX25_ADCQ_CFG_REFP_INT;
@@ -233,11 +244,10 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
 		case MX25_ADC_REFP_EXT:
 		case MX25_ADC_REFP_XP:
 		case MX25_ADC_REFP_YP:
-			if (IS_ERR(priv->vref[refp])) {
-				dev_err(dev, "Error, trying to use external voltage reference without a vref-%s regulator.",
-					mx25_gcq_refp_names[refp]);
+			ret = mx25_gcq_ext_regulator_setup(&pdev->dev, priv, refp);
+			if (ret) {
 				of_node_put(child);
-				return PTR_ERR(priv->vref[refp]);
+				return ret;
 			}
 			priv->channel_vref_mv[reg] =
 				regulator_get_voltage(priv->vref[refp]);
@@ -253,8 +263,6 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
 			return -EINVAL;
 		}
 
-		++refp_used[refp];
-
 		/*
 		 * Shift the read values to the correct positions within the
 		 * register.
@@ -285,15 +293,6 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
 	regmap_write(priv->regs, MX25_ADCQ_CR,
 		     MX25_ADCQ_CR_PDMSK | MX25_ADCQ_CR_QSM_FQS);
 
-	/* Remove unused regulators */
-	for (i = 0; i != 4; ++i) {
-		if (!refp_used[i]) {
-			if (!IS_ERR_OR_NULL(priv->vref[i]))
-				devm_regulator_put(priv->vref[i]);
-			priv->vref[i] = NULL;
-		}
-	}
-
 	return 0;
 }
 
-- 
2.31.1

