linux/drivers/video/of_display_timing.c
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   1/*
   2 * OF helpers for parsing display timings
   3 *
   4 * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
   5 *
   6 * based on of_videomode.c by Sascha Hauer <s.hauer@pengutronix.de>
   7 *
   8 * This file is released under the GPLv2
   9 */
  10#include <linux/export.h>
  11#include <linux/of.h>
  12#include <linux/slab.h>
  13#include <video/display_timing.h>
  14#include <video/of_display_timing.h>
  15
  16/**
  17 * parse_timing_property - parse timing_entry from device_node
  18 * @np: device_node with the property
  19 * @name: name of the property
  20 * @result: will be set to the return value
  21 *
  22 * DESCRIPTION:
  23 * Every display_timing can be specified with either just the typical value or
  24 * a range consisting of min/typ/max. This function helps handling this
  25 **/
  26static int parse_timing_property(const struct device_node *np, const char *name,
  27                          struct timing_entry *result)
  28{
  29        struct property *prop;
  30        int length, cells, ret;
  31
  32        prop = of_find_property(np, name, &length);
  33        if (!prop) {
  34                pr_err("%s: could not find property %s\n",
  35                        of_node_full_name(np), name);
  36                return -EINVAL;
  37        }
  38
  39        cells = length / sizeof(u32);
  40        if (cells == 1) {
  41                ret = of_property_read_u32(np, name, &result->typ);
  42                result->min = result->typ;
  43                result->max = result->typ;
  44        } else if (cells == 3) {
  45                ret = of_property_read_u32_array(np, name, &result->min, cells);
  46        } else {
  47                pr_err("%s: illegal timing specification in %s\n",
  48                        of_node_full_name(np), name);
  49                return -EINVAL;
  50        }
  51
  52        return ret;
  53}
  54
  55/**
  56 * of_parse_display_timing - parse display_timing entry from device_node
  57 * @np: device_node with the properties
  58 **/
  59static int of_parse_display_timing(const struct device_node *np,
  60                struct display_timing *dt)
  61{
  62        u32 val = 0;
  63        int ret = 0;
  64
  65        memset(dt, 0, sizeof(*dt));
  66
  67        ret |= parse_timing_property(np, "hback-porch", &dt->hback_porch);
  68        ret |= parse_timing_property(np, "hfront-porch", &dt->hfront_porch);
  69        ret |= parse_timing_property(np, "hactive", &dt->hactive);
  70        ret |= parse_timing_property(np, "hsync-len", &dt->hsync_len);
  71        ret |= parse_timing_property(np, "vback-porch", &dt->vback_porch);
  72        ret |= parse_timing_property(np, "vfront-porch", &dt->vfront_porch);
  73        ret |= parse_timing_property(np, "vactive", &dt->vactive);
  74        ret |= parse_timing_property(np, "vsync-len", &dt->vsync_len);
  75        ret |= parse_timing_property(np, "clock-frequency", &dt->pixelclock);
  76
  77        dt->flags = 0;
  78        if (!of_property_read_u32(np, "vsync-active", &val))
  79                dt->flags |= val ? DISPLAY_FLAGS_VSYNC_HIGH :
  80                                DISPLAY_FLAGS_VSYNC_LOW;
  81        if (!of_property_read_u32(np, "hsync-active", &val))
  82                dt->flags |= val ? DISPLAY_FLAGS_HSYNC_HIGH :
  83                                DISPLAY_FLAGS_HSYNC_LOW;
  84        if (!of_property_read_u32(np, "de-active", &val))
  85                dt->flags |= val ? DISPLAY_FLAGS_DE_HIGH :
  86                                DISPLAY_FLAGS_DE_LOW;
  87        if (!of_property_read_u32(np, "pixelclk-active", &val))
  88                dt->flags |= val ? DISPLAY_FLAGS_PIXDATA_POSEDGE :
  89                                DISPLAY_FLAGS_PIXDATA_NEGEDGE;
  90
  91        if (of_property_read_bool(np, "interlaced"))
  92                dt->flags |= DISPLAY_FLAGS_INTERLACED;
  93        if (of_property_read_bool(np, "doublescan"))
  94                dt->flags |= DISPLAY_FLAGS_DOUBLESCAN;
  95        if (of_property_read_bool(np, "doubleclk"))
  96                dt->flags |= DISPLAY_FLAGS_DOUBLECLK;
  97
  98        if (ret) {
  99                pr_err("%s: error reading timing properties\n",
 100                        of_node_full_name(np));
 101                return -EINVAL;
 102        }
 103
 104        return 0;
 105}
 106
 107/**
 108 * of_get_display_timing - parse a display_timing entry
 109 * @np: device_node with the timing subnode
 110 * @name: name of the timing node
 111 * @dt: display_timing struct to fill
 112 **/
 113int of_get_display_timing(struct device_node *np, const char *name,
 114                struct display_timing *dt)
 115{
 116        struct device_node *timing_np;
 117
 118        if (!np) {
 119                pr_err("%s: no devicenode given\n", of_node_full_name(np));
 120                return -EINVAL;
 121        }
 122
 123        timing_np = of_find_node_by_name(np, name);
 124        if (!timing_np) {
 125                pr_err("%s: could not find node '%s'\n",
 126                        of_node_full_name(np), name);
 127                return -ENOENT;
 128        }
 129
 130        return of_parse_display_timing(timing_np, dt);
 131}
 132EXPORT_SYMBOL_GPL(of_get_display_timing);
 133
 134/**
 135 * of_get_display_timings - parse all display_timing entries from a device_node
 136 * @np: device_node with the subnodes
 137 **/
 138struct display_timings *of_get_display_timings(struct device_node *np)
 139{
 140        struct device_node *timings_np;
 141        struct device_node *entry;
 142        struct device_node *native_mode;
 143        struct display_timings *disp;
 144
 145        if (!np) {
 146                pr_err("%s: no devicenode given\n", of_node_full_name(np));
 147                return NULL;
 148        }
 149
 150        timings_np = of_find_node_by_name(np, "display-timings");
 151        if (!timings_np) {
 152                pr_err("%s: could not find display-timings node\n",
 153                        of_node_full_name(np));
 154                return NULL;
 155        }
 156
 157        disp = kzalloc(sizeof(*disp), GFP_KERNEL);
 158        if (!disp) {
 159                pr_err("%s: could not allocate struct disp'\n",
 160                        of_node_full_name(np));
 161                goto dispfail;
 162        }
 163
 164        entry = of_parse_phandle(timings_np, "native-mode", 0);
 165        /* assume first child as native mode if none provided */
 166        if (!entry)
 167                entry = of_get_next_child(np, NULL);
 168        /* if there is no child, it is useless to go on */
 169        if (!entry) {
 170                pr_err("%s: no timing specifications given\n",
 171                        of_node_full_name(np));
 172                goto entryfail;
 173        }
 174
 175        pr_debug("%s: using %s as default timing\n",
 176                of_node_full_name(np), entry->name);
 177
 178        native_mode = entry;
 179
 180        disp->num_timings = of_get_child_count(timings_np);
 181        if (disp->num_timings == 0) {
 182                /* should never happen, as entry was already found above */
 183                pr_err("%s: no timings specified\n", of_node_full_name(np));
 184                goto entryfail;
 185        }
 186
 187        disp->timings = kzalloc(sizeof(struct display_timing *) *
 188                                disp->num_timings, GFP_KERNEL);
 189        if (!disp->timings) {
 190                pr_err("%s: could not allocate timings array\n",
 191                        of_node_full_name(np));
 192                goto entryfail;
 193        }
 194
 195        disp->num_timings = 0;
 196        disp->native_mode = 0;
 197
 198        for_each_child_of_node(timings_np, entry) {
 199                struct display_timing *dt;
 200                int r;
 201
 202                dt = kzalloc(sizeof(*dt), GFP_KERNEL);
 203                if (!dt) {
 204                        pr_err("%s: could not allocate display_timing struct\n",
 205                                        of_node_full_name(np));
 206                        goto timingfail;
 207                }
 208
 209                r = of_parse_display_timing(entry, dt);
 210                if (r) {
 211                        /*
 212                         * to not encourage wrong devicetrees, fail in case of
 213                         * an error
 214                         */
 215                        pr_err("%s: error in timing %d\n",
 216                                of_node_full_name(np), disp->num_timings + 1);
 217                        goto timingfail;
 218                }
 219
 220                if (native_mode == entry)
 221                        disp->native_mode = disp->num_timings;
 222
 223                disp->timings[disp->num_timings] = dt;
 224                disp->num_timings++;
 225        }
 226        of_node_put(timings_np);
 227        /*
 228         * native_mode points to the device_node returned by of_parse_phandle
 229         * therefore call of_node_put on it
 230         */
 231        of_node_put(native_mode);
 232
 233        pr_debug("%s: got %d timings. Using timing #%d as default\n",
 234                of_node_full_name(np), disp->num_timings,
 235                disp->native_mode + 1);
 236
 237        return disp;
 238
 239timingfail:
 240        if (native_mode)
 241                of_node_put(native_mode);
 242        display_timings_release(disp);
 243entryfail:
 244        kfree(disp);
 245dispfail:
 246        of_node_put(timings_np);
 247        return NULL;
 248}
 249EXPORT_SYMBOL_GPL(of_get_display_timings);
 250
 251/**
 252 * of_display_timings_exist - check if a display-timings node is provided
 253 * @np: device_node with the timing
 254 **/
 255int of_display_timings_exist(struct device_node *np)
 256{
 257        struct device_node *timings_np;
 258
 259        if (!np)
 260                return -EINVAL;
 261
 262        timings_np = of_parse_phandle(np, "display-timings", 0);
 263        if (!timings_np)
 264                return -EINVAL;
 265
 266        of_node_put(timings_np);
 267        return 1;
 268}
 269EXPORT_SYMBOL_GPL(of_display_timings_exist);
 270
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