gpio: virtio: Fix config space reading.

Quote from the virtio specification chapter 4.2.2.2:

"For the device-specific configuration space, the driver MUST use 8 bit
wide accesses for 8 bit wide fields, 16 bit wide and aligned accesses
for 16 bit wide fields and 32 bit wide and aligned accesses for 32 and
64 bit wide fields."

Signed-off-by: Harald Mommer <[email protected]>
Cc: [email protected]
Fixes: 3a29355 ("gpio: Add virtio-gpio driver")
Acked-by: Viresh Kumar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Bartosz Golaszewski <[email protected]>

Author: Harald Mommer

drivers/gpio/gpio-virtio.c

@@ -527,7 +527,6 @@ static const char **virtio_gpio_get_names(struct virtio_gpio *vgpio,
 
 static int virtio_gpio_probe(struct virtio_device *vdev)
 {
-	struct virtio_gpio_config config;
 	struct device *dev = &vdev->dev;
 	struct virtio_gpio *vgpio;
 	struct irq_chip *gpio_irq_chip;
@@ -540,9 +539,11 @@ static int virtio_gpio_probe(struct virtio_device *vdev)
 		return -ENOMEM;
 
 	/* Read configuration */
-	virtio_cread_bytes(vdev, 0, &config, sizeof(config));
-	gpio_names_size = le32_to_cpu(config.gpio_names_size);
-	ngpio = le16_to_cpu(config.ngpio);
+	gpio_names_size =
+		virtio_cread32(vdev, offsetof(struct virtio_gpio_config,
+					      gpio_names_size));
+	ngpio =  virtio_cread16(vdev, offsetof(struct virtio_gpio_config,
+					       ngpio));
 	if (!ngpio) {
 		dev_err(dev, "Number of GPIOs can't be zero\n");
 		return -EINVAL;