drm/i915: remove confusing GPIO vs PCH_GPIO

Instead of defining all registers twice, define just a PCH_GPIO_BASE
that has the same address as PCH_GPIO_A and use that to calculate all
the others. This also brings VLV and !HAS_GMCH_DISPLAY in line, doing
the same thing.

v2: Fix GMBUS registers to be relative to gpio base; create GPIO()
    macro to return a particular gpio address and move the enum out of
    i915_reg.h (suggested by Jani)

v3: Move base offset inside the GPIO() macro so the GMBUS defines don't
    actually need to be changed (suggested by Daniel/Ville)

v4: Move definition of i915_gpio to intel_display.h and remove
    GMBUS/GPIO handling from gvt since now they have their own
    defines.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180727193647.8639-3-lucas.demarchi@intel.com

drivers/gpu/drm/i915/intel_i2c.c

@@ -37,7 +37,7 @@
 
 struct gmbus_pin {
 	const char *name;
-	i915_reg_t reg;
+	enum i915_gpio gpio;
 };
 
 /* Map gmbus pin pairs to names and registers. */
@@ -121,8 +121,7 @@ bool intel_gmbus_is_valid_pin(struct drm_i915_private *dev_priv,
 	else
 		size = ARRAY_SIZE(gmbus_pins);
 
-	return pin < size &&
-		i915_mmio_reg_valid(get_gmbus_pin(dev_priv, pin)->reg);
+	return pin < size && get_gmbus_pin(dev_priv, pin)->name;
 }
 
 /* Intel GPIO access functions */
@@ -292,8 +291,7 @@ intel_gpio_setup(struct intel_gmbus *bus, unsigned int pin)
 
 	algo = &bus->bit_algo;
 
-	bus->gpio_reg = _MMIO(dev_priv->gpio_mmio_base +
-			      i915_mmio_reg_offset(get_gmbus_pin(dev_priv, pin)->reg));
+	bus->gpio_reg = GPIO(get_gmbus_pin(dev_priv, pin)->gpio);
 	bus->adapter.algo_data = algo;
 	algo->setsda = set_data;
 	algo->setscl = set_clock;
@@ -825,9 +823,11 @@ int intel_setup_gmbus(struct drm_i915_private *dev_priv)
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
 		dev_priv->gpio_mmio_base = VLV_DISPLAY_BASE;
 	else if (!HAS_GMCH_DISPLAY(dev_priv))
-		dev_priv->gpio_mmio_base =
-			i915_mmio_reg_offset(PCH_GPIOA) -
-			i915_mmio_reg_offset(GPIOA);
+		/*
+		 * Broxton uses the same PCH offsets for South Display Engine,
+		 * even though it doesn't have a PCH.
+		 */
+		dev_priv->gpio_mmio_base = PCH_DISPLAY_BASE;
 
 	mutex_init(&dev_priv->gmbus_mutex);
 	init_waitqueue_head(&dev_priv->gmbus_wait_queue);