drm/i915: extract intel_bios.h functions from i915_drv.h

It used to be handy that we only had a couple of headers, but over time
i915_drv.h has become unwieldy. Extract declarations to a separate
header file corresponding to the implementation module, clarifying the
modularity of the driver.

Ensure the header remains self-contained, and do so with minimal further
includes, using forward declarations as needed.

No functional changes.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/cf9b17d56489e15d82356575037432ad04712475.1556540890.git.jani.nikula@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -3281,22 +3281,6 @@ static inline bool intel_gmbus_is_forced_bit(struct i2c_adapter *adapter)
 }
 extern void intel_i2c_reset(struct drm_i915_private *dev_priv);
 
-/* intel_bios.c */
-void intel_bios_init(struct drm_i915_private *dev_priv);
-void intel_bios_cleanup(struct drm_i915_private *dev_priv);
-bool intel_bios_is_valid_vbt(const void *buf, size_t size);
-bool intel_bios_is_tv_present(struct drm_i915_private *dev_priv);
-bool intel_bios_is_lvds_present(struct drm_i915_private *dev_priv, u8 *i2c_pin);
-bool intel_bios_is_port_present(struct drm_i915_private *dev_priv, enum port port);
-bool intel_bios_is_port_edp(struct drm_i915_private *dev_priv, enum port port);
-bool intel_bios_is_port_dp_dual_mode(struct drm_i915_private *dev_priv, enum port port);
-bool intel_bios_is_dsi_present(struct drm_i915_private *dev_priv, enum port *port);
-bool intel_bios_is_port_hpd_inverted(struct drm_i915_private *dev_priv,
-				     enum port port);
-bool intel_bios_is_lspcon_present(struct drm_i915_private *dev_priv,
-				enum port port);
-enum aux_ch intel_bios_port_aux_ch(struct drm_i915_private *dev_priv, enum port port);
-
 /* intel_acpi.c */
 #ifdef CONFIG_ACPI
 extern void intel_register_dsm_handler(void);

drivers/gpu/drm/i915/intel_bios.h

@@ -32,6 +32,10 @@
 
 #include <linux/types.h>
 
+#include <drm/i915_drm.h>
+
+struct drm_i915_private;
+
 enum intel_backlight_type {
 	INTEL_BACKLIGHT_PMIC,
 	INTEL_BACKLIGHT_LPSS,
@@ -222,4 +226,19 @@ struct mipi_pps_data {
 	u16 panel_power_cycle_delay;
 } __packed;
 
+void intel_bios_init(struct drm_i915_private *dev_priv);
+void intel_bios_cleanup(struct drm_i915_private *dev_priv);
+bool intel_bios_is_valid_vbt(const void *buf, size_t size);
+bool intel_bios_is_tv_present(struct drm_i915_private *dev_priv);
+bool intel_bios_is_lvds_present(struct drm_i915_private *dev_priv, u8 *i2c_pin);
+bool intel_bios_is_port_present(struct drm_i915_private *dev_priv, enum port port);
+bool intel_bios_is_port_edp(struct drm_i915_private *dev_priv, enum port port);
+bool intel_bios_is_port_dp_dual_mode(struct drm_i915_private *dev_priv, enum port port);
+bool intel_bios_is_dsi_present(struct drm_i915_private *dev_priv, enum port *port);
+bool intel_bios_is_port_hpd_inverted(struct drm_i915_private *dev_priv,
+				     enum port port);
+bool intel_bios_is_lspcon_present(struct drm_i915_private *dev_priv,
+				  enum port port);
+enum aux_ch intel_bios_port_aux_ch(struct drm_i915_private *dev_priv, enum port port);
+
 #endif /* _INTEL_BIOS_H_ */