video: add display_timing and videomode

Add display_timing structure and the according helper functions. This allows
the description of a display via its supported timing parameters.

Also, add helper functions to convert from display timings to a generic videomode
structure.

The struct display_timing specifies all needed parameters to describe the signal
properties of a display in one mode. This includes
    - ranges for signals that may have min-, max- and typical values
    - single integers for signals that can be on, off or are ignored
    - booleans for signals that are either on or off

As a display may support multiple modes like this, a struct display_timings is
added, that holds all given struct display_timing pointers and declares the
native mode of the display.

Although a display may state that a signal can be in a range, it is driven with
fixed values that indicate a videomode. Therefore graphic drivers don't need all
the information of struct display_timing, but would generate a videomode from
the given set of supported signal timings and work with that.

The video subsystems all define their own structs that describe a mode and work
with that (e.g. fb_videomode or drm_display_mode). To slowly replace all those
various structures and allow code reuse across those subsystems, add struct
videomode as a generic description.

This patch only includes the most basic fields in struct videomode. All missing
fields that are needed to have a really generic video mode description can be
added at a later stage.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Afzal Mohammed <Afzal@ti.com>
Tested-by: Rob Clark <robclark@gmail.com>
Tested-by: Leela Krishna Amudala <leelakrishna.a@gmail.com>

4 files changed, 71 insertions, 0 deletions

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index e7068c508800..09a8f0d8a3d4 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -33,6 +33,12 @@ config VIDEO_OUTPUT_CONTROL
           This framework adds support for low-level control of the video 
           output switch.
 
+config DISPLAY_TIMING
+       bool
+
+config VIDEOMODE
+       bool
+
 menuconfig FB
         tristate "Support for frame buffer devices"
         ---help---
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 768a137a1bac..e0dd8202365f 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -168,3 +168,5 @@ obj-$(CONFIG_FB_VIRTUAL)          += vfb.o
 
 #video output switch sysfs driver
 obj-$(CONFIG_VIDEO_OUTPUT_CONTROL) += output.o
+obj-$(CONFIG_DISPLAY_TIMING) += display_timing.o
+obj-$(CONFIG_VIDEOMODE) += videomode.o
diff --git a/drivers/video/display_timing.c b/drivers/video/display_timing.c
new file mode 100644
index 000000000000..5e1822cef571
--- /dev/null
+++ b/drivers/video/display_timing.c
@@ -0,0 +1,24 @@
+/*
+ * generic display timing functions
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
+ *
+ * This file is released under the GPLv2
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <video/display_timing.h>
+
+void display_timings_release(struct display_timings *disp)
+{
+        if (disp->timings) {
+                unsigned int i;
+
+                for (i = 0; i < disp->num_timings; i++)
+                        kfree(disp->timings[i]);
+                kfree(disp->timings);
+        }
+        kfree(disp);
+}
+EXPORT_SYMBOL_GPL(display_timings_release);
diff --git a/drivers/video/videomode.c b/drivers/video/videomode.c
new file mode 100644
index 000000000000..21c47a202afa
--- /dev/null
+++ b/drivers/video/videomode.c
@@ -0,0 +1,39 @@
+/*
+ * generic display timing functions
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
+ *
+ * This file is released under the GPLv2
+ */
+
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <video/display_timing.h>
+#include <video/videomode.h>
+
+int videomode_from_timing(const struct display_timings *disp,
+                          struct videomode *vm, unsigned int index)
+{
+        struct display_timing *dt;
+
+        dt = display_timings_get(disp, index);
+        if (!dt)
+                return -EINVAL;
+
+        vm->pixelclock = display_timing_get_value(&dt->pixelclock, TE_TYP);
+        vm->hactive = display_timing_get_value(&dt->hactive, TE_TYP);
+        vm->hfront_porch = display_timing_get_value(&dt->hfront_porch, TE_TYP);
+        vm->hback_porch = display_timing_get_value(&dt->hback_porch, TE_TYP);
+        vm->hsync_len = display_timing_get_value(&dt->hsync_len, TE_TYP);
+
+        vm->vactive = display_timing_get_value(&dt->vactive, TE_TYP);
+        vm->vfront_porch = display_timing_get_value(&dt->vfront_porch, TE_TYP);
+        vm->vback_porch = display_timing_get_value(&dt->vback_porch, TE_TYP);
+        vm->vsync_len = display_timing_get_value(&dt->vsync_len, TE_TYP);
+
+        vm->dmt_flags = dt->dmt_flags;
+        vm->data_flags = dt->data_flags;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(videomode_from_timing);