[PATCH v8 2/6] video: add of helper for videomode

Steffen Trumtrar
2012-11-12T15:38:09Z

This adds support for reading display timings from DT or/and convert one of those
timings to a videomode.
The of_display_timing implementation supports multiple children where each
property can have up to 3 values. All children are read into an array, that
can be queried.
of_get_videomode converts exactly one of that timings to a struct videomode.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
.../devicetree/bindings/video/display-timings.txt | 107 +++++++++++
drivers/video/Kconfig | 13 ++
drivers/video/Makefile | 2 +
drivers/video/of_display_timing.c | 186 ++++++++++++++++++++
drivers/video/of_videomode.c | 47 +++++
include/linux/of_display_timings.h | 19 ++
include/linux/of_videomode.h | 15 ++
7 files changed, 389 insertions(+)
create mode 100644 Documentation/devicetree/bindings/video/display-timings.txt
create mode 100644 drivers/video/of_display_timing.c
create mode 100644 drivers/video/of_videomode.c
create mode 100644 include/linux/of_display_timings.h
create mode 100644 include/linux/of_videomode.h

diff --git a/Documentation/devicetree/bindings/video/display-timings.txt b/Documentation/devicetree/bindings/video/display-timings.txt
new file mode 100644
index 0000000..e22e2fd
--- /dev/null
+++ b/Documentation/devicetree/bindings/video/display-timings.txt
@@ -0,0 +1,107 @@
+display-timings bindings
+========================
+
+display-timings-node
+--------------------
+
+required properties:
+ - none
+
+optional properties:
+ - native-mode: the native mode for the display, in case multiple modes are
+ provided. When omitted, assume the first node is the native.
+
+timings-subnode
+---------------
+
+required properties:
+ - hactive, vactive: Display resolution
+ - hfront-porch, hback-porch, hsync-len: Horizontal Display timing parameters
+ in pixels
+ vfront-porch, vback-porch, vsync-len: Vertical display timing parameters in
+ lines
+ - clock-frequency: displayclock in Hz
+
+optional properties:
+ - hsync-active : Hsync pulse is active low/high/ignored
+ - vsync-active : Vsync pulse is active low/high/ignored
+ - de-active : Data-Enable pulse is active low/high/ignored
+ - pixelclk-inverted : pixelclock is inverted/non-inverted/ignored
+ - interlaced (bool)
+ - doublescan (bool)
+
+All the optional properties that are not bool follow the following logic:
+ <1> : high active
+ <0> : low active
+ omitted : not used on hardware
+
+There are different ways of describing the capabilities of a display. The devicetree
+representation corresponds to the one commonly found in datasheets for displays.
+If a display supports multiple signal timings, the native-mode can be specified.
+
+The parameters are defined as
+
+struct display_timing
+=====================
+
+ +----------+---------------------------------------------+----------+-------+
+ | | ↑ | | |
+ | | |vback_porch | | |
+ | | ↓ | | |
+ +----------###############################################----------+-------+
+ | # ↑ # | |
+ | # | # | |
+ | hback # | # hfront | hsync |
+ | porch # | hactive # porch | len |
+ |<-------->#<---------------+--------------------------->#<-------->|<----->|
+ | # | # | |
+ | # |vactive # | |
+ | # | # | |
+ | # ↓ # | |
+ +----------###############################################----------+-------+
+ | | ↑ | | |
+ | | |vfront_porch | | |
+ | | ↓ | | |
+ +----------+---------------------------------------------+----------+-------+
+ | | ↑ | | |
+ | | |vsync_len | | |
+ | | ↓ | | |
+ +----------+---------------------------------------------+----------+-------+
+
+
+Example:
+
+ display-timings {
+ native-mode = <&timing0>;
+ timing0: 1920p24 {
+ /* 1920x1080p24 */
+ clock-frequency = <52000000>;
+ hactive = <1920>;
+ vactive = <1080>;
+ hfront-porch = <25>;
+ hback-porch = <25>;
+ hsync-len = <25>;
+ vback-porch = <2>;
+ vfront-porch = <2>;
+ vsync-len = <2>;
+ hsync-active = <1>;
+ };
+ };
+
+Every required property also supports the use of ranges, so the commonly used
+datasheet description with <min typ max>-tuples can be used.
+
+Example:
+
+ timing1: timing {
+ /* 1920x1080p24 */
+ clock-frequency = <148500000>;
+ hactive = <1920>;
+ vactive = <1080>;
+ hsync-len = <0 44 60>;
+ hfront-porch = <80 88 95>;
+ hback-porch = <100 148 160>;
+ vfront-porch = <0 4 6>;
+ vback-porch = <0 36 50>;
+ vsync-len = <0 5 6>;
+ };
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 2a23b18..a324457 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -39,6 +39,19 @@ config DISPLAY_TIMING
config VIDEOMODE
bool

+config OF_DISPLAY_TIMING
+ def_bool y
+ select DISPLAY_TIMING
+ help
+ helper to parse display timings from the devicetree
+
+config OF_VIDEOMODE
+ def_bool y
+ select VIDEOMODE
+ select OF_DISPLAY_TIMING
+ help
+ helper to get videomodes from the devicetree
+
menuconfig FB
tristate "Support for frame buffer devices"
---help---
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index fc30439..b936b00 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -168,4 +168,6 @@ 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_OF_DISPLAY_TIMING) += of_display_timing.o
obj-$(CONFIG_VIDEOMODE) += videomode.o
+obj-$(CONFIG_OF_VIDEOMODE) += of_videomode.o
diff --git a/drivers/video/of_display_timing.c b/drivers/video/of_display_timing.c
new file mode 100644
index 0000000..0bd30cc
--- /dev/null
+++ b/drivers/video/of_display_timing.c
@@ -0,0 +1,186 @@
+/*
+ * OF helpers for parsing display timings
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
+ *
+ * based on of_videomode.c by Sascha Hauer <s.hauer@pengutronix.de>
+ *
+ * This file is released under the GPLv2
+ */
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/of_display_timings.h>
+
+/**
+ * parse_property - parse timing_entry from device_node
+ * @np: device_node with the property
+ * @name: name of the property
+ * @result: will be set to the return value
+ *
+ * DESCRIPTION:
+ * Every display_timing can be specified with either just the typical value or
+ * a range consisting of min/typ/max. This function helps handling this
+ **/
+static int parse_property(struct device_node *np, char *name,
+ struct timing_entry *result)
+{
+ struct property *prop;
+ int length, cells, ret;
+
+ prop = of_find_property(np, name, &length);
+ if (!prop) {
+ pr_err("%s: could not find property %s\n", __func__, name);
+ return -EINVAL;
+ }
+
+ cells = length / sizeof(u32);
+ if (cells == 1) {
+ ret = of_property_read_u32(np, name, &result->typ);
+ result->min = result->typ;
+ result->max = result->typ;
+ } else if (cells == 3) {
+ ret = of_property_read_u32_array(np, name, &result->min, cells);
+ } else {
+ pr_err("%s: illegal timing specification in %s\n", __func__, name);
+ return -EINVAL;
+ }
+
+ return ret;
+}
+
+/**
+ * of_get_display_timing - parse display_timing entry from device_node
+ * @np: device_node with the properties
+ **/
+static struct display_timing *of_get_display_timing(struct device_node *np)
+{
+ struct display_timing *dt;
+ int ret = 0;
+
+ dt = kzalloc(sizeof(*dt), GFP_KERNEL);
+ if (!dt) {
+ pr_err("%s: could not allocate display_timing struct\n", __func__);
+ return NULL;
+ }
+
+ ret |= parse_property(np, "hback-porch", &dt->hback_porch);
+ ret |= parse_property(np, "hfront-porch", &dt->hfront_porch);
+ ret |= parse_property(np, "hactive", &dt->hactive);
+ ret |= parse_property(np, "hsync-len", &dt->hsync_len);
+ ret |= parse_property(np, "vback-porch", &dt->vback_porch);
+ ret |= parse_property(np, "vfront-porch", &dt->vfront_porch);
+ ret |= parse_property(np, "vactive", &dt->vactive);
+ ret |= parse_property(np, "vsync-len", &dt->vsync_len);
+ ret |= parse_property(np, "clock-frequency", &dt->pixelclock);
+
+ of_property_read_u32(np, "vsync-active", &dt->vsync_pol_active);
+ of_property_read_u32(np, "hsync-active", &dt->hsync_pol_active);
+ of_property_read_u32(np, "de-active", &dt->de_pol_active);
+ of_property_read_u32(np, "pixelclk-inverted", &dt->pixelclk_pol);
+ dt->interlaced = of_property_read_bool(np, "interlaced");
+ dt->doublescan = of_property_read_bool(np, "doublescan");
+
+ if (ret) {
+ pr_err("%s: error reading timing properties\n", __func__);
+ return NULL;
+ }
+
+ return dt;
+}
+
+/**
+ * of_get_display_timings - parse all display_timing entries from a device_node
+ * @np: device_node with the subnodes
+ **/
+struct display_timings *of_get_display_timings(struct device_node *np)
+{
+ struct device_node *timings_np;
+ struct device_node *entry;
+ struct device_node *native_mode;
+ struct display_timings *disp;
+
+ if (!np) {
+ pr_err("%s: no devicenode given\n", __func__);
+ return NULL;
+ }
+
+ timings_np = of_find_node_by_name(np, "display-timings");
+ if (!timings_np) {
+ pr_err("%s: could not find display-timings node\n", __func__);
+ return NULL;
+ }
+
+ disp = kzalloc(sizeof(*disp), GFP_KERNEL);
+ if (!disp)
+ return -ENOMEM;
+
+ entry = of_parse_phandle(timings_np, "native-mode", 0);
+ /* assume first child as native mode if none provided */
+ if (!entry)
+ entry = of_get_next_child(np, NULL);
+ if (!entry) {
+ pr_err("%s: no timing specifications given\n", __func__);
+ return NULL;
+ }
+
+ pr_info("%s: using %s as default timing\n", __func__, entry->name);
+
+ native_mode = entry;
+
+ disp->num_timings = of_get_child_count(timings_np);
+ disp->timings = kzalloc(sizeof(struct display_timing *)*disp->num_timings,
+ GFP_KERNEL);
+ if (!disp->timings)
+ return -ENOMEM;
+
+ disp->num_timings = 0;
+ disp->native_mode = 0;
+
+ for_each_child_of_node(timings_np, entry) {
+ struct display_timing *dt;
+
+ dt = of_get_display_timing(entry);
+ if (!dt) {
+ /* to not encourage wrong devicetrees, fail in case of an error */
+ pr_err("%s: error in timing %d\n", __func__, disp->num_timings+1);
+ return NULL;
+ }
+
+ if (native_mode == entry)
+ disp->native_mode = disp->num_timings;
+
+ disp->timings[disp->num_timings] = dt;
+ disp->num_timings++;
+ }
+ of_node_put(timings_np);
+
+ if (disp->num_timings > 0)
+ pr_info("%s: got %d timings. Using timing #%d as default\n", __func__,
+ disp->num_timings , disp->native_mode + 1);
+ else {
+ pr_err("%s: no valid timings specified\n", __func__);
+ return NULL;
+ }
+ return disp;
+}
+EXPORT_SYMBOL_GPL(of_get_display_timings);
+
+/**
+ * of_display_timings_exists - check if a display-timings node is provided
+ * @np: device_node with the timing
+ **/
+int of_display_timings_exists(struct device_node *np)
+{
+ struct device_node *timings_np;
+
+ if (!np)
+ return -EINVAL;
+
+ timings_np = of_parse_phandle(np, "display-timings", 0);
+ if (!timings_np)
+ return -EINVAL;
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(of_display_timings_exists);
diff --git a/drivers/video/of_videomode.c b/drivers/video/of_videomode.c
new file mode 100644
index 0000000..7051701
--- /dev/null
+++ b/drivers/video/of_videomode.c
@@ -0,0 +1,47 @@
+/*
+ * generic videomode helper
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
+ *
+ * This file is released under the GPLv2
+ */
+#include <linux/of.h>
+#include <linux/of_display_timings.h>
+#include <linux/of_videomode.h>
+#include <linux/export.h>
+
+/**
+ * of_get_videomode - get the videomode #<index> from devicetree
+ * @np - devicenode with the display_timings
+ * @vm - set to return value
+ * @index - index into list of display_timings
+ * DESCRIPTION:
+ * Get a list of all display timings and put the one
+ * specified by index into *vm. This function should only be used, if
+ * only one videomode is to be retrieved. A driver that needs to work
+ * with multiple/all videomodes should work with
+ * of_get_display_timings instead.
+ **/
+int of_get_videomode(struct device_node *np, struct videomode *vm, int index)
+{
+ struct display_timings *disp;
+ int ret;
+
+ disp = of_get_display_timings(np);
+ if (!disp) {
+ pr_err("%s: no timings specified\n", __func__);
+ return -EINVAL;
+ }
+
+ if (index == OF_USE_NATIVE_MODE)
+ index = disp->native_mode;
+
+ ret = videomode_from_timing(disp, vm, index);
+ if (ret)
+ return ret;
+
+ display_timings_release(disp);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_get_videomode);
diff --git a/include/linux/of_display_timings.h b/include/linux/of_display_timings.h
new file mode 100644
index 0000000..ccf6814
--- /dev/null
+++ b/include/linux/of_display_timings.h
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>
+ *
+ * display timings of helpers
+ *
+ * This file is released under the GPLv2
+ */
+
+#ifndef __LINUX_OF_DISPLAY_TIMINGS_H
+#define __LINUX_OF_DISPLAY_TIMINGS_H
+
+#include <linux/display_timing.h>
+
+#define OF_USE_NATIVE_MODE -1
+
+struct display_timings *of_get_display_timings(struct device_node *np);
+int of_display_timings_exists(struct device_node *np);
+
+#endif
diff --git a/include/linux/of_videomode.h b/include/linux/of_videomode.h
new file mode 100644
index 0000000..01518e6
--- /dev/null
+++ b/include/linux/of_videomode.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>
+ *
+ * videomode of-helpers
+ *
+ * This file is released under the GPLv2
+ */
+
+#ifndef __LINUX_OF_VIDEOMODE_H
+#define __LINUX_OF_VIDEOMODE_H
+
+#include <linux/videomode.h>
+
+int of_get_videomode(struct device_node *np, struct videomode *vm, int index);
+#endif /* __LINUX_OF_VIDEOMODE_H */
--
1.7.10.4