Signed-off-by: Steffen Trumtrar s.trumtrar@pengutronix.de --- .../devicetree/bindings/video/display-timings.txt | 139 +++++++++++++++ drivers/of/Kconfig | 6 + drivers/of/Makefile | 1 + drivers/of/of_display_timings.c | 185 ++++++++++++++++++++ include/linux/of_display_timings.h | 20 +++ 5 files changed, 351 insertions(+) create mode 100644 Documentation/devicetree/bindings/video/display-timings.txt create mode 100644 drivers/of/of_display_timings.c create mode 100644 include/linux/of_display_timings.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..04c94a3 --- /dev/null +++ b/Documentation/devicetree/bindings/video/display-timings.txt @@ -0,0 +1,139 @@ +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 = <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 = <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>; + }; + + +Usage in backend +================ + +A backend driver may choose to use the display-timings directly and convert the timing +ranges to a suitable mode. Or it may just use the conversion of the display timings +to the required mode via the generic videomode struct. + + dtb + | + | of_get_display_timing_list + ↓ + struct display_timings + | + | videomode_from_timing + ↓ + --- struct videomode --- + | | + videomode_to_displaymode | | videomode_to_fb_videomode + ↓ ↓ + drm_display_mode fb_videomode + +The functions of_get_fb_videomode and of_get_display_mode are provided +to conveniently get the respective mode representation from the devicetree. + +Conversion to videomode +======================= + +As device drivers normally work with some kind of video mode, the timings can be +converted (may be just a simple copying of the typical value) to a generic videomode +structure which then can be converted to the according mode used by the backend. diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index dfba3e6..781e773 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -83,4 +83,10 @@ config OF_MTD depends on MTD def_bool y
+config OF_DISPLAY_TIMINGS + def_bool y + depends on DISPLAY_TIMING + help + helper to parse display timings from the devicetree + endmenu # OF diff --git a/drivers/of/Makefile b/drivers/of/Makefile index e027f44..c8e9603 100644 --- a/drivers/of/Makefile +++ b/drivers/of/Makefile @@ -11,3 +11,4 @@ obj-$(CONFIG_OF_MDIO) += of_mdio.o obj-$(CONFIG_OF_PCI) += of_pci.o obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o obj-$(CONFIG_OF_MTD) += of_mtd.o +obj-$(CONFIG_OF_DISPLAY_TIMINGS) += of_display_timings.o diff --git a/drivers/of/of_display_timings.c b/drivers/of/of_display_timings.c new file mode 100644 index 0000000..388fe4c --- /dev/null +++ b/drivers/of/of_display_timings.c @@ -0,0 +1,185 @@ +/* + * 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; + int cells; + int 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_array(np, name, &result->typ, cells); + 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 + **/ +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; +} +EXPORT_SYMBOL_GPL(of_get_display_timing); + +/** + * of_get_display_timing_list - parse all display_timing entries from a device_node + * @np: device_node with the subnodes + **/ +struct display_timings *of_get_display_timing_list(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); + + 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); + 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_timing_list); + +/** + * 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; + struct device_node *default_np; + + if (!np) + return -EINVAL; + + timings_np = of_parse_phandle(np, "display-timings", 0); + if (!timings_np) + return -EINVAL; + + return -EINVAL; +} +EXPORT_SYMBOL_GPL(of_display_timings_exists); diff --git a/include/linux/of_display_timings.h b/include/linux/of_display_timings.h new file mode 100644 index 0000000..e4e1f22 --- /dev/null +++ b/include/linux/of_display_timings.h @@ -0,0 +1,20 @@ +/* + * 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_timing_list(struct device_node *np); +struct display_timing *of_get_display_timing(struct device_node *np); +int of_display_timings_exists(struct device_node *np); + +#endif