iio: dac: cio-dac: Migrate to the regmap API

The regmap API supports IO port accessors so we can take advantage of
regmap abstractions rather than handling access to the device registers
directly in the driver.

Includes trivial header inclusion tidy up.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/20230311140218.74920-1-william.gray@linaro.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/Kconfig

@@ -277,6 +277,7 @@ config CIO_DAC
 	tristate "Measurement Computing CIO-DAC IIO driver"
 	depends on X86 && (ISA_BUS || PC104)
 	select ISA_BUS_API
+	select REGMAP_MMIO
 	help
 	  Say yes here to build support for the Measurement Computing CIO-DAC
 	  analog output device family (CIO-DAC16, CIO-DAC08, PC104-DAC06). The

drivers/iio/dac/cio-dac.c

@@ -6,16 +6,15 @@
  * This driver supports the following Measurement Computing devices: CIO-DAC16,
  * CIO-DAC08, and PC104-DAC06.
  */
-#include <linux/bitops.h>
+#include <linux/bits.h>
 #include <linux/device.h>
-#include <linux/errno.h>
+#include <linux/err.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/types.h>
-#include <linux/io.h>
-#include <linux/ioport.h>
 #include <linux/isa.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/regmap.h>
 #include <linux/types.h>
 
 #define CIO_DAC_NUM_CHAN 16
@@ -35,25 +34,51 @@ 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");
 
+#define CIO_DAC_BASE 0x00
+#define CIO_DAC_CHANNEL_STRIDE 2
+
+static bool cio_dac_precious_reg(struct device *dev, unsigned int reg)
+{
+	/*
+	 * All registers are considered precious; if the XFER jumper is set on
+	 * the device, then no update occurs until a DAC register is read.
+	 */
+	return true;
+}
+
+static const struct regmap_config cio_dac_regmap_config = {
+	.reg_bits = 16,
+	.reg_stride = 2,
+	.val_bits = 16,
+	.io_port = true,
+	.max_register = 0x1F,
+	.precious_reg = cio_dac_precious_reg,
+};
+
 /**
  * struct cio_dac_iio - IIO device private data structure
- * @chan_out_states:	channels' output states
- * @base:		base memory address of the DAC device
+ * @map: Regmap for the device
  */
 struct cio_dac_iio {
-	int chan_out_states[CIO_DAC_NUM_CHAN];
-	u16 __iomem *base;
+	struct regmap *map;
 };
 
 static int cio_dac_read_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 offset = chan->channel * CIO_DAC_CHANNEL_STRIDE;
+	int err;
+	unsigned int dac_val;
 
 	if (mask != IIO_CHAN_INFO_RAW)
 		return -EINVAL;
 
-	*val = priv->chan_out_states[chan->channel];
+	err = regmap_read(priv->map, CIO_DAC_BASE + offset, &dac_val);
+	if (err)
+		return err;
+
+	*val = dac_val;
 
 	return IIO_VAL_INT;
 }
@@ -62,6 +87,7 @@ 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 offset = chan->channel * CIO_DAC_CHANNEL_STRIDE;
 
 	if (mask != IIO_CHAN_INFO_RAW)
 		return -EINVAL;
@@ -70,10 +96,7 @@ static int cio_dac_write_raw(struct iio_dev *indio_dev,
 	if ((unsigned int)val > 65535)
 		return -EINVAL;
 
-	priv->chan_out_states[chan->channel] = val;
-	iowrite16(val, priv->base + chan->channel);
-
-	return 0;
+	return regmap_write(priv->map, CIO_DAC_BASE + offset, val);
 }
 
 static const struct iio_info cio_dac_info = {
@@ -92,7 +115,7 @@ static int cio_dac_probe(struct device *dev, unsigned int id)
 {
 	struct iio_dev *indio_dev;
 	struct cio_dac_iio *priv;
-	unsigned int i;
+	void __iomem *regs;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
 	if (!indio_dev)
@@ -105,21 +128,22 @@ static int cio_dac_probe(struct device *dev, unsigned int id)
 		return -EBUSY;
 	}
 
-	priv = iio_priv(indio_dev);
-	priv->base = devm_ioport_map(dev, base[id], CIO_DAC_EXTENT);
-	if (!priv->base)
+	regs = devm_ioport_map(dev, base[id], CIO_DAC_EXTENT);
+	if (!regs)
 		return -ENOMEM;
 
+	priv = iio_priv(indio_dev);
+	priv->map = devm_regmap_init_mmio(dev, regs, &cio_dac_regmap_config);
+	if (IS_ERR(priv->map))
+		return dev_err_probe(dev, PTR_ERR(priv->map),
+				     "Unable to initialize register map\n");
+
 	indio_dev->info = &cio_dac_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = cio_dac_channels;
 	indio_dev->num_channels = CIO_DAC_NUM_CHAN;
 	indio_dev->name = dev_name(dev);
 
-	/* initialize DAC outputs to 0V */
-	for (i = 0; i < CIO_DAC_NUM_CHAN; i++)
-		iowrite16(0, priv->base + i);
-
 	return devm_iio_device_register(dev, indio_dev);
 }