linux-kernel - [PATCH 2/2] iio: dac: cio-dac: Implement and utilize register structures

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Date:   Mon,  6 Jun 2022 10:15:18 -0400
From:   William Breathitt Gray <william.gray@...aro.org>
To:     jic23@...nel.org
Cc:     lars@...afoo.de, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        William Breathitt Gray <william.gray@...aro.org>
Subject: [PATCH 2/2] iio: dac: cio-dac: Implement and utilize register structures

Reduce magic numbers and improve code readability by implementing and
utilizing named register data structures.

Signed-off-by: William Breathitt Gray <william.gray@...aro.org>
---
 drivers/iio/dac/cio-dac.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/dac/cio-dac.c b/drivers/iio/dac/cio-dac.c
index 8080984dcb03..7860450ceaf3 100644
--- a/drivers/iio/dac/cio-dac.c
+++ b/drivers/iio/dac/cio-dac.c
@@ -16,6 +16,7 @@
 #include <linux/isa.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/types.h>
 
 #define CIO_DAC_NUM_CHAN 16
 
@@ -34,14 +35,22 @@ static unsigned int num_cio_dac;
 module_param_hw_array(base, uint, ioport, &num_cio_dac, 0);
 MODULE_PARM_DESC(base, "Measurement Computing CIO-DAC base addresses");
 
+/**
+ * struct cio_dac_reg - device register structure
+ * @da:	D/A data
+ */
+struct cio_dac_reg {
+	u16 da[CIO_DAC_NUM_CHAN];
+};
+
 /**
  * struct cio_dac_iio - IIO device private data structure
  * @chan_out_states:	channels' output states
- * @base:		base port address of the IIO device
+ * @reg:		I/O address offset for the device registers
  */
 struct cio_dac_iio {
 	int chan_out_states[CIO_DAC_NUM_CHAN];
-	void __iomem *base;
+	struct cio_dac_reg __iomem *reg;
 };
 
 static int cio_dac_read_raw(struct iio_dev *indio_dev,
@@ -61,7 +70,6 @@ static int cio_dac_write_raw(struct iio_dev *indio_dev,
 	struct iio_chan_spec const *chan, int val, int val2, long mask)
 {
 	struct cio_dac_iio *const priv = iio_priv(indio_dev);
-	const unsigned int chan_addr_offset = 2 * chan->channel;
 
 	if (mask != IIO_CHAN_INFO_RAW)
 		return -EINVAL;
@@ -71,7 +79,7 @@ static int cio_dac_write_raw(struct iio_dev *indio_dev,
 		return -EINVAL;
 
 	priv->chan_out_states[chan->channel] = val;
-	iowrite16(val, priv->base + chan_addr_offset);
+	iowrite16(val, priv->reg->da + chan->channel);
 
 	return 0;
 }
@@ -106,8 +114,8 @@ static int cio_dac_probe(struct device *dev, unsigned int id)
 	}
 
 	priv = iio_priv(indio_dev);
-	priv->base = devm_ioport_map(dev, base[id], CIO_DAC_EXTENT);
-	if (!priv->base)
+	priv->reg = devm_ioport_map(dev, base[id], CIO_DAC_EXTENT);
+	if (!priv->reg)
 		return -ENOMEM;
 
 	indio_dev->info = &cio_dac_info;
@@ -117,8 +125,8 @@ static int cio_dac_probe(struct device *dev, unsigned int id)
 	indio_dev->name = dev_name(dev);
 
 	/* initialize DAC outputs to 0V */
-	for (i = 0; i < 32; i += 2)
-		iowrite16(0, priv->base + i);
+	for (i = 0; i < CIO_DAC_NUM_CHAN; i++)
+		iowrite16(0, priv->reg->da + i);
 
 	return devm_iio_device_register(dev, indio_dev);
 }
-- 
2.36.1