[PATCH 1/2] iio: adc: stx104: Implement and utilize register structures

William Breathitt Gray
2022-06-06T14:15:42Z

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

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
drivers/iio/adc/stx104.c | 70 +++++++++++++++++++++++++++-------------
1 file changed, 47 insertions(+), 23 deletions(-)

diff --git a/drivers/iio/adc/stx104.c b/drivers/iio/adc/stx104.c
index 7552351bfed9..7656b363e281 100644
--- a/drivers/iio/adc/stx104.c
+++ b/drivers/iio/adc/stx104.c
@@ -16,6 +16,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
+#include <linux/types.h>

#define STX104_OUT_CHAN(chan) { \
.type = IIO_VOLTAGE, \
@@ -44,14 +45,36 @@ static unsigned int num_stx104;
module_param_hw_array(base, uint, ioport, &num_stx104, 0);
MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");

+/**
+ * struct stx104_reg - device register structure
+ * @ad: ADC Data
+ * @achan: ADC Channel
+ * @dio: Digital I/O
+ * @dac: DAC Channels
+ * @cir_asr: Clear Interrupts and ADC Status
+ * @acr: ADC Control
+ * @pccr_fsh: Pacer Clock Control and FIFO Status MSB
+ * @acfg: ADC Configuration
+ */
+struct stx104_reg {
+ u16 ad;
+ u8 achan;
+ u8 dio;
+ u16 dac[2];
+ u8 cir_asr;
+ u8 acr;
+ u8 pccr_fsh;
+ u8 acfg;
+};
+
/**
* struct stx104_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 stx104_iio {
unsigned int chan_out_states[STX104_NUM_OUT_CHAN];
- void __iomem *base;
+ struct stx104_reg __iomem *reg;
};

/**
@@ -64,7 +87,7 @@ struct stx104_iio {
struct stx104_gpio {
struct gpio_chip chip;
spinlock_t lock;
- void __iomem *base;
+ u8 __iomem *base;
unsigned int out_state;
};

@@ -72,6 +95,7 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val, int *val2, long mask)
{
struct stx104_iio *const priv = iio_priv(indio_dev);
+ struct stx104_reg __iomem *const reg = priv->reg;
unsigned int adc_config;
int adbu;
int gain;
@@ -79,7 +103,7 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_HARDWAREGAIN:
/* get gain configuration */
- adc_config = ioread8(priv->base + 11);
+ adc_config = ioread8(&reg->acfg);
gain = adc_config & 0x3;

*val = 1 << gain;
@@ -91,24 +115,24 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
}

/* select ADC channel */
- iowrite8(chan->channel | (chan->channel << 4), priv->base + 2);
+ iowrite8(chan->channel | (chan->channel << 4), &reg->achan);

/* trigger ADC sample capture and wait for completion */
- iowrite8(0, priv->base);
- while (ioread8(priv->base + 8) & BIT(7));
+ iowrite8(0, &reg->ad);
+ while (ioread8(&reg->cir_asr) & BIT(7));

- *val = ioread16(priv->base);
+ *val = ioread16(&reg->ad);
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
/* get ADC bipolar/unipolar configuration */
- adc_config = ioread8(priv->base + 11);
+ adc_config = ioread8(&reg->acfg);
adbu = !(adc_config & BIT(2));

*val = -32768 * adbu;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
/* get ADC bipolar/unipolar and gain configuration */
- adc_config = ioread8(priv->base + 11);
+ adc_config = ioread8(&reg->acfg);
adbu = !(adc_config & BIT(2));
gain = adc_config & 0x3;

@@ -130,16 +154,16 @@ static int stx104_write_raw(struct iio_dev *indio_dev,
/* Only four gain states (x1, x2, x4, x8) */
switch (val) {
case 1:
- iowrite8(0, priv->base + 11);
+ iowrite8(0, &priv->reg->acfg);
break;
case 2:
- iowrite8(1, priv->base + 11);
+ iowrite8(1, &priv->reg->acfg);
break;
case 4:
- iowrite8(2, priv->base + 11);
+ iowrite8(2, &priv->reg->acfg);
break;
case 8:
- iowrite8(3, priv->base + 11);
+ iowrite8(3, &priv->reg->acfg);
break;
default:
return -EINVAL;
@@ -153,7 +177,7 @@ static int stx104_write_raw(struct iio_dev *indio_dev,
return -EINVAL;

priv->chan_out_states[chan->channel] = val;
- iowrite16(val, priv->base + 4 + 2 * chan->channel);
+ iowrite16(val, priv->reg->dac + chan->channel);

return 0;
}
@@ -307,15 +331,15 @@ static int stx104_probe(struct device *dev, unsigned int id)
}

priv = iio_priv(indio_dev);
- priv->base = devm_ioport_map(dev, base[id], STX104_EXTENT);
- if (!priv->base)
+ priv->reg = devm_ioport_map(dev, base[id], STX104_EXTENT);
+ if (!priv->reg)
return -ENOMEM;

indio_dev->info = &stx104_info;
indio_dev->modes = INDIO_DIRECT_MODE;

/* determine if differential inputs */
- if (ioread8(priv->base + 8) & BIT(5)) {
+ if (ioread8(&priv->reg->cir_asr) & BIT(5)) {
indio_dev->num_channels = ARRAY_SIZE(stx104_channels_diff);
indio_dev->channels = stx104_channels_diff;
} else {
@@ -326,14 +350,14 @@ static int stx104_probe(struct device *dev, unsigned int id)
indio_dev->name = dev_name(dev);

/* configure device for software trigger operation */
- iowrite8(0, priv->base + 9);
+ iowrite8(0, &priv->reg->acr);

/* initialize gain setting to x1 */
- iowrite8(0, priv->base + 11);
+ iowrite8(0, &priv->reg->acfg);

/* initialize DAC output to 0V */
- iowrite16(0, priv->base + 4);
- iowrite16(0, priv->base + 6);
+ iowrite16(0, &priv->reg->dac[0]);
+ iowrite16(0, &priv->reg->dac[1]);

stx104gpio->chip.label = dev_name(dev);
stx104gpio->chip.parent = dev;
@@ -348,7 +372,7 @@ static int stx104_probe(struct device *dev, unsigned int id)
stx104gpio->chip.get_multiple = stx104_gpio_get_multiple;
stx104gpio->chip.set = stx104_gpio_set;
stx104gpio->chip.set_multiple = stx104_gpio_set_multiple;
- stx104gpio->base = priv->base + 3;
+ stx104gpio->base = &priv->reg->dio;
stx104gpio->out_state = 0x0;

spin_lock_init(&stx104gpio->lock);
--
2.36.1