[RFC PATCH v2 2/3] gpio: mmio: add port-mapped read/write callbacks

[Jose Javier Rodriguez Barbarin <dev-josejavier.rodriguez@duagon.com>]

Implement PMIO read and write callbacks for 8-, 16- and 32-bit
register accesses using the corresponding port I/O helpers.

Signed-off-by: Jose Javier Rodriguez Barbarin <dev-josejavier.rodriguez@duagon.com>
---
 drivers/gpio/gpio-mmio.c | 94 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c
index 39326ab7e494..d23c5d275e6b 100644
--- a/drivers/gpio/gpio-mmio.c
+++ b/drivers/gpio/gpio-mmio.c
@@ -124,6 +124,60 @@ static unsigned long gpio_mmio_read32be(union gpio_chip_reg *reg)
 	return ioread32be(reg->mmio);
 }
 
+#ifdef CONFIG_HAS_IOPORT
+
+static void gpio_port_write8(union gpio_chip_reg *reg, unsigned long data)
+{
+	outb(data, reg->port);
+}
+
+static unsigned long gpio_port_read8(union gpio_chip_reg *reg)
+{
+	return inb(reg->port);
+}
+
+static void gpio_port_write16(union gpio_chip_reg *reg, unsigned long data)
+{
+	outw(data, reg->port);
+}
+
+static unsigned long gpio_port_read16(union gpio_chip_reg *reg)
+{
+	return inw(reg->port);
+}
+
+static void gpio_port_write32(union gpio_chip_reg *reg, unsigned long data)
+{
+	outl(data, reg->port);
+}
+
+static unsigned long gpio_port_read32(union gpio_chip_reg *reg)
+{
+	return inl(reg->port);
+}
+
+static void gpio_port_write16be(union gpio_chip_reg *reg, unsigned long data)
+{
+	outw(swab16(data), reg->port);
+}
+
+static unsigned long gpio_port_read16be(union gpio_chip_reg *reg)
+{
+	return swab16(inw(reg->port));
+}
+
+static void gpio_port_write32be(union gpio_chip_reg *reg, unsigned long data)
+{
+	outl(swab32(data), reg->port);
+}
+
+static unsigned long gpio_port_read32be(union gpio_chip_reg *reg)
+{
+	return swab32(inl(reg->port));
+}
+
+#endif /* CONFIG_HAS_IOPORT */
+
 static inline bool gpio_chip_reg_is_set(union gpio_chip_reg *reg)
 {
 	return reg->port != 0;
@@ -462,6 +516,46 @@ static int gpio_mmio_dir_out_val_first(struct gpio_chip *gc, unsigned int gpio,
 	return gpio_mmio_dir_return(gc, gpio, true);
 }
 
+static int gpio_port_setup_accessors(struct device *dev,
+				     struct gpio_generic_chip *chip,
+				     bool byte_be)
+{
+#ifdef CONFIG_HAS_IOPORT
+	switch (chip->bits) {
+	case 8:
+		chip->read_reg	= gpio_port_read8;
+		chip->write_reg	= gpio_port_write8;
+		break;
+	case 16:
+		if (byte_be) {
+			chip->read_reg	= gpio_port_read16be;
+			chip->write_reg	= gpio_port_write16be;
+		} else {
+			chip->read_reg	= gpio_port_read16;
+			chip->write_reg	= gpio_port_write16;
+		}
+		break;
+	case 32:
+		if (byte_be) {
+			chip->read_reg	= gpio_port_read32be;
+			chip->write_reg	= gpio_port_write32be;
+		} else {
+			chip->read_reg	= gpio_port_read32;
+			chip->write_reg	= gpio_port_write32;
+		}
+		break;
+	default:
+		dev_err(dev, "unsupported data width %u bits\n", chip->bits);
+		return -EINVAL;
+	}
+
+	return 0;
+#else
+	dev_err(dev, "not supported because of missing I/O resource\n");
+	return -ENXIO;
+#endif /* CONFIG_HAS_IOPORT */
+}
+
 static int gpio_mmio_setup_accessors(struct device *dev,
 				     struct gpio_generic_chip *chip,
 				     bool byte_be)
-- 
2.53.0