linux-kernel - [PATCH v2 14/19] staging: iio: resolver: ad2s1210: refactor setting excitation frequency

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Date:   Thu, 21 Sep 2023 09:43:55 -0500
From:   David Lechner <dlechner@...libre.com>
To:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-staging@...ts.linux.dev
Cc:     linux-kernel@...r.kernel.org, Jonathan Cameron <jic23@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Nuno Sá <nuno.sa@...log.com>,
        Axel Haslam <ahaslam@...libre.com>,
        Philip Molloy <pmolloy@...libre.com>,
        David Lechner <dlechner@...libre.com>
Subject: [PATCH v2 14/19] staging: iio: resolver: ad2s1210: refactor setting excitation frequency

This combines the ad2s1210_update_frequency_control_word() and
ad2s1210_soft_reset() functions into a single function since they
both have to be called together.

Also clean up a few things while touching this:
- move AD2S1210_DEF_EXCIT macro with similar macros
- remove unnecessary dev_err() calls

Signed-off-by: David Lechner <dlechner@...libre.com>
---
 drivers/staging/iio/resolver/ad2s1210.c | 63 ++++++++++++-------------
 1 file changed, 31 insertions(+), 32 deletions(-)

diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
index fe413759deb9..f1ffee34ebbc 100644
--- a/drivers/staging/iio/resolver/ad2s1210.c
+++ b/drivers/staging/iio/resolver/ad2s1210.c
@@ -53,12 +53,11 @@
 #define AD2S1210_MIN_CLKIN	6144000
 #define AD2S1210_MAX_CLKIN	10240000
 #define AD2S1210_MIN_EXCIT	2000
+#define AD2S1210_DEF_EXCIT	10000
 #define AD2S1210_MAX_EXCIT	20000
 #define AD2S1210_MIN_FCW	0x4
 #define AD2S1210_MAX_FCW	0x50
 
-#define AD2S1210_DEF_EXCIT	10000
-
 enum ad2s1210_mode {
 	MOD_POS = 0b00,
 	MOD_VEL = 0b01,
@@ -184,18 +183,29 @@ static int ad2s1210_regmap_reg_read(void *context, unsigned int reg,
 	return 0;
 }
 
-static inline
-int ad2s1210_update_frequency_control_word(struct ad2s1210_state *st)
+/*
+ * Sets the excitation frequency and performs software reset.
+ *
+ * Must be called with lock held.
+ */
+static int ad2s1210_set_excitation_frequency(struct ad2s1210_state *st,
+					     u16 fexcit)
 {
-	unsigned char fcw;
+	int ret;
+	u8 fcw;
 
-	fcw = (unsigned char)(st->fexcit * (1 << 15) / st->fclkin);
-	if (fcw < AD2S1210_MIN_FCW || fcw > AD2S1210_MAX_FCW) {
-		dev_err(&st->sdev->dev, "ad2s1210: FCW out of range\n");
+	fcw = fexcit * (1 << 15) / st->fclkin;
+	if (fcw < AD2S1210_MIN_FCW || fcw > AD2S1210_MAX_FCW)
 		return -ERANGE;
-	}
 
-	return regmap_write(st->regmap, AD2S1210_REG_EXCIT_FREQ, fcw);
+	ret = regmap_write(st->regmap, AD2S1210_REG_EXCIT_FREQ, fcw);
+	if (ret < 0)
+		return ret;
+
+	st->fexcit = fexcit;
+
+	/* software reset reinitializes the excitation frequency output */
+	return regmap_write(st->regmap, AD2S1210_REG_SOFT_RESET, 0);
 }
 
 static int ad2s1210_set_resolution_gpios(struct ad2s1210_state *st,
@@ -210,11 +220,6 @@ static int ad2s1210_set_resolution_gpios(struct ad2s1210_state *st,
 				     bitmap);
 }
 
-static inline int ad2s1210_soft_reset(struct ad2s1210_state *st)
-{
-	return regmap_write(st->regmap, AD2S1210_REG_SOFT_RESET, 0);
-}
-
 static ssize_t ad2s1210_show_fexcit(struct device *dev,
 				    struct device_attribute *attr,
 				    char *buf)
@@ -229,27 +234,24 @@ static ssize_t ad2s1210_store_fexcit(struct device *dev,
 				     const char *buf, size_t len)
 {
 	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
-	unsigned int fexcit;
+	u16 fexcit;
 	int ret;
 
-	ret = kstrtouint(buf, 10, &fexcit);
-	if (ret < 0)
-		return ret;
-	if (fexcit < AD2S1210_MIN_EXCIT || fexcit > AD2S1210_MAX_EXCIT) {
-		dev_err(dev,
-			"ad2s1210: excitation frequency out of range\n");
+	ret = kstrtou16(buf, 10, &fexcit);
+	if (ret < 0 || fexcit < AD2S1210_MIN_EXCIT || fexcit > AD2S1210_MAX_EXCIT)
 		return -EINVAL;
-	}
+
 	mutex_lock(&st->lock);
-	st->fexcit = fexcit;
-	ret = ad2s1210_update_frequency_control_word(st);
+	ret = ad2s1210_set_excitation_frequency(st, fexcit);
 	if (ret < 0)
 		goto error_ret;
-	ret = ad2s1210_soft_reset(st);
+
+	ret = len;
+
 error_ret:
 	mutex_unlock(&st->lock);
 
-	return ret < 0 ? ret : len;
+	return ret;
 }
 
 static ssize_t ad2s1210_show_resolution(struct device *dev,
@@ -624,10 +626,8 @@ static int ad2s1210_initial(struct ad2s1210_state *st)
 	if (ret < 0)
 		goto error_ret;
 
-	ret = ad2s1210_update_frequency_control_word(st);
-	if (ret < 0)
-		goto error_ret;
-	ret = ad2s1210_soft_reset(st);
+	ret = ad2s1210_set_excitation_frequency(st, AD2S1210_DEF_EXCIT);
+
 error_ret:
 	mutex_unlock(&st->lock);
 	return ret;
@@ -773,7 +773,6 @@ static int ad2s1210_probe(struct spi_device *spi)
 	mutex_init(&st->lock);
 	st->sdev = spi;
 	st->resolution = 12;
-	st->fexcit = AD2S1210_DEF_EXCIT;
 
 	ret = ad2s1210_setup_clocks(st);
 	if (ret < 0)
-- 
2.34.1