gpio: 104-idio-16: Implement and utilize register structures

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

Tested-by: Fred Eckert <Frede@cmslaser.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Cc: John Hentges <jhentges@accesio.com>
Cc: Jay Dolan <jay.dolan@accesio.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

Author: William Breathitt Gray

drivers/gpio/gpio-104-idio-16.c

@@ -6,7 +6,7 @@
  * This driver supports the following ACCES devices: 104-IDIO-16,
  * 104-IDIO-16E, 104-IDO-16, 104-IDIO-8, 104-IDIO-8E, and 104-IDO-8.
  */
-#include <linux/bitops.h>
+#include <linux/bits.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/gpio/driver.h>
@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/spinlock.h>
+#include <linux/types.h>
 
 #define IDIO_16_EXTENT 8
 #define MAX_NUM_IDIO_16 max_num_isa_dev(IDIO_16_EXTENT)
@@ -32,19 +33,42 @@ static unsigned int irq[MAX_NUM_IDIO_16];
 module_param_hw_array(irq, uint, irq, NULL, 0);
 MODULE_PARM_DESC(irq, "ACCES 104-IDIO-16 interrupt line numbers");
 
+/**
+ * struct idio_16_reg - device registers structure
+ * @out0_7:	Read: N/A
+ *		Write: FET Drive Outputs 0-7
+ * @in0_7:	Read: Isolated Inputs 0-7
+ *		Write: Clear Interrupt
+ * @irq_ctl:	Read: Enable IRQ
+ *		Write: Disable IRQ
+ * @unused:	N/A
+ * @out8_15:	Read: N/A
+ *		Write: FET Drive Outputs 8-15
+ * @in8_15:	Read: Isolated Inputs 8-15
+ *		Write: N/A
+ */
+struct idio_16_reg {
+	u8 out0_7;
+	u8 in0_7;
+	u8 irq_ctl;
+	u8 unused;
+	u8 out8_15;
+	u8 in8_15;
+};
+
 /**
  * struct idio_16_gpio - GPIO device private data structure
  * @chip:	instance of the gpio_chip
  * @lock:	synchronization lock to prevent I/O race conditions
  * @irq_mask:	I/O bits affected by interrupts
- * @base:	base port address of the GPIO device
+ * @reg:	I/O address offset for the device registers
  * @out_state:	output bits state
  */
 struct idio_16_gpio {
 	struct gpio_chip chip;
 	raw_spinlock_t lock;
 	unsigned long irq_mask;
-	void __iomem *base;
+	struct idio_16_reg __iomem *reg;
 	unsigned int out_state;
 };
 
@@ -79,9 +103,9 @@ static int idio_16_gpio_get(struct gpio_chip *chip, unsigned int offset)
 		return -EINVAL;
 
 	if (offset < 24)
-		return !!(ioread8(idio16gpio->base + 1) & mask);
+		return !!(ioread8(&idio16gpio->reg->in0_7) & mask);
 
-	return !!(ioread8(idio16gpio->base + 5) & (mask>>8));
+	return !!(ioread8(&idio16gpio->reg->in8_15) & (mask>>8));
 }
 
 static int idio_16_gpio_get_multiple(struct gpio_chip *chip,
@@ -91,9 +115,9 @@ static int idio_16_gpio_get_multiple(struct gpio_chip *chip,
 
 	*bits = 0;
 	if (*mask & GENMASK(23, 16))
-		*bits |= (unsigned long)ioread8(idio16gpio->base + 1) << 16;
+		*bits |= (unsigned long)ioread8(&idio16gpio->reg->in0_7) << 16;
 	if (*mask & GENMASK(31, 24))
-		*bits |= (unsigned long)ioread8(idio16gpio->base + 5) << 24;
+		*bits |= (unsigned long)ioread8(&idio16gpio->reg->in8_15) << 24;
 
 	return 0;
 }
@@ -116,9 +140,9 @@ static void idio_16_gpio_set(struct gpio_chip *chip, unsigned int offset,
 		idio16gpio->out_state &= ~mask;
 
 	if (offset > 7)
-		iowrite8(idio16gpio->out_state >> 8, idio16gpio->base + 4);
+		iowrite8(idio16gpio->out_state >> 8, &idio16gpio->reg->out8_15);
 	else
-		iowrite8(idio16gpio->out_state, idio16gpio->base);
+		iowrite8(idio16gpio->out_state, &idio16gpio->reg->out0_7);
 
 	raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
 }
@@ -135,9 +159,9 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
 	idio16gpio->out_state |= *mask & *bits;
 
 	if (*mask & 0xFF)
-		iowrite8(idio16gpio->out_state, idio16gpio->base);
+		iowrite8(idio16gpio->out_state, &idio16gpio->reg->out0_7);
 	if ((*mask >> 8) & 0xFF)
-		iowrite8(idio16gpio->out_state >> 8, idio16gpio->base + 4);
+		iowrite8(idio16gpio->out_state >> 8, &idio16gpio->reg->out8_15);
 
 	raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
 }
@@ -158,7 +182,7 @@ static void idio_16_irq_mask(struct irq_data *data)
 	if (!idio16gpio->irq_mask) {
 		raw_spin_lock_irqsave(&idio16gpio->lock, flags);
 
-		iowrite8(0, idio16gpio->base + 2);
+		iowrite8(0, &idio16gpio->reg->irq_ctl);
 
 		raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
 	}
@@ -177,7 +201,7 @@ static void idio_16_irq_unmask(struct irq_data *data)
 	if (!prev_irq_mask) {
 		raw_spin_lock_irqsave(&idio16gpio->lock, flags);
 
-		ioread8(idio16gpio->base + 2);
+		ioread8(&idio16gpio->reg->irq_ctl);
 
 		raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
 	}
@@ -212,7 +236,7 @@ static irqreturn_t idio_16_irq_handler(int irq, void *dev_id)
 
 	raw_spin_lock(&idio16gpio->lock);
 
-	iowrite8(0, idio16gpio->base + 1);
+	iowrite8(0, &idio16gpio->reg->in0_7);
 
 	raw_spin_unlock(&idio16gpio->lock);
 
@@ -232,8 +256,8 @@ static int idio_16_irq_init_hw(struct gpio_chip *gc)
 	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(gc);
 
 	/* Disable IRQ by default */
-	iowrite8(0, idio16gpio->base + 2);
-	iowrite8(0, idio16gpio->base + 1);
+	iowrite8(0, &idio16gpio->reg->irq_ctl);
+	iowrite8(0, &idio16gpio->reg->in0_7);
 
 	return 0;
 }
@@ -255,8 +279,8 @@ static int idio_16_probe(struct device *dev, unsigned int id)
 		return -EBUSY;
 	}
 
-	idio16gpio->base = devm_ioport_map(dev, base[id], IDIO_16_EXTENT);
-	if (!idio16gpio->base)
+	idio16gpio->reg = devm_ioport_map(dev, base[id], IDIO_16_EXTENT);
+	if (!idio16gpio->reg)
 		return -ENOMEM;
 
 	idio16gpio->chip.label = name;