[PATCH v2 0/2] iio: Implement and utilize register structures for ISA drivers

[PATCH v2 0/2] iio: Implement and utilize register structures for ISA drivers

[William Breathitt Gray]

Changes in v2:
 - Rename 'ad' member to 'ssr_ad' to indicate access to Software Strobe
   Register as well; relevant comments updated
 - Dereference DAC channel address via array subscripts in the
   stx104_write_raw() function in order to match rest of code
 - Replace struct cio_dac_reg with direct u16 pointer to the DAC
   address; this greatly simplifies the cio-dac patch

The STX104 and CIO-DAC drivers were updated to use I/O memory accessor
calls such as ioread8()/iowrite8() in previous patch series [1]. This
patch series is a continuation of the effort to improve the code
readability and reduce magic numbers by implementing and utilizing named
register data structures.

[1] https://lore.kernel.org/all/cover.1652201921.git.william.gray@linaro.org/

William Breathitt Gray (2):
  iio: adc: stx104: Implement and utilize register structures
  iio: dac: cio-dac: Cleanup indexing for DAC writes

 drivers/iio/adc/stx104.c  | 74 ++++++++++++++++++++++++++-------------
 drivers/iio/dac/cio-dac.c | 10 +++---
 2 files changed, 55 insertions(+), 29 deletions(-)


base-commit: 338222d8e1121bcb78a86fb39982eddcc367a5bc
-- 
2.36.1

[PATCH v2 1/2] iio: adc: stx104: Implement and utilize register structures

[William Breathitt Gray]

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

Tested-by: Fred Eckert <Frede@cmslaser.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 drivers/iio/adc/stx104.c | 74 +++++++++++++++++++++++++++-------------
 1 file changed, 50 insertions(+), 24 deletions(-)

diff --git a/drivers/iio/adc/stx104.c b/drivers/iio/adc/stx104.c
index 7552351bfed9..48a91a95e597 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
+ * @ssr_ad:	Software Strobe Register and 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 ssr_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 +115,26 @@ 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));
+		/* trigger ADC sample capture by writing to the 8-bit
+		 * Software Strobe Register and wait for completion
+		 */
+		iowrite8(0, &reg->ssr_ad);
+		while (ioread8(&reg->cir_asr) & BIT(7));
 
-		*val = ioread16(priv->base);
+		*val = ioread16(&reg->ssr_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 +156,16 @@ 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 +179,7 @@ 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 +333,15 @@ 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 +352,14 @@ 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 +374,7 @@ 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

[PATCH v2 2/2] iio: dac: cio-dac: Cleanup indexing for DAC writes

[William Breathitt Gray]

Simplify DAC write code by defining base member as u16 __iomem *; DAC
registers are 16-bit so this allows us to index each DAC channel
directly in a loop rather than calculating the offsets by multipling by
2 each time.

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 drivers/iio/dac/cio-dac.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/dac/cio-dac.c b/drivers/iio/dac/cio-dac.c
index 8080984dcb03..791dd999cf29 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
 
@@ -37,11 +38,11 @@ MODULE_PARM_DESC(base, "Measurement Computing CIO-DAC base addresses");
 /**
  * struct cio_dac_iio - IIO device private data structure
  * @chan_out_states:	channels' output states
- * @base:		base port address of the IIO device
+ * @base:		base memory address of the DAC device
  */
 struct cio_dac_iio {
 	int chan_out_states[CIO_DAC_NUM_CHAN];
-	void __iomem *base;
+	u16 __iomem *base;
 };
 
 static int cio_dac_read_raw(struct iio_dev *indio_dev,
@@ -61,7 +62,6 @@ 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 +71,7 @@ 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->base + chan->channel);
 
 	return 0;
 }
@@ -117,7 +117,7 @@ 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)
+	for (i = 0; i < CIO_DAC_NUM_CHAN; i++)
 		iowrite16(0, priv->base + i);
 
 	return devm_iio_device_register(dev, indio_dev);
-- 
2.36.1

Re: [PATCH v2 0/2] iio: Implement and utilize register structures for ISA drivers

[Jonathan Cameron]

On Thu,  7 Jul 2022 13:21:23 -0400
William Breathitt Gray <william.gray@linaro.org> wrote:

> Changes in v2:
>  - Rename 'ad' member to 'ssr_ad' to indicate access to Software Strobe
>    Register as well; relevant comments updated
>  - Dereference DAC channel address via array subscripts in the
>    stx104_write_raw() function in order to match rest of code
>  - Replace struct cio_dac_reg with direct u16 pointer to the DAC
>    address; this greatly simplifies the cio-dac patch
> 
> The STX104 and CIO-DAC drivers were updated to use I/O memory accessor
> calls such as ioread8()/iowrite8() in previous patch series [1]. This
> patch series is a continuation of the effort to improve the code
> readability and reduce magic numbers by implementing and utilizing named
> register data structures.
Series applied to the togreg branch of iio.git.  Given timing in cycle, I'll
only push that out as testing (for 0-day etc) and then rebase it after rc1.

Thanks,

Jonathan

> 
> [1] https://lore.kernel.org/all/cover.1652201921.git.william.gray@linaro.org/
> 
> William Breathitt Gray (2):
>   iio: adc: stx104: Implement and utilize register structures
>   iio: dac: cio-dac: Cleanup indexing for DAC writes
> 
>  drivers/iio/adc/stx104.c  | 74 ++++++++++++++++++++++++++-------------
>  drivers/iio/dac/cio-dac.c | 10 +++---
>  2 files changed, 55 insertions(+), 29 deletions(-)
> 
> 
> base-commit: 338222d8e1121bcb78a86fb39982eddcc367a5bc