linux/drivers/video/of_display_timing.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * OF helpers for parsing display timings
   4 *
   5 * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
   6 *
   7 * based on of_videomode.c by Sascha Hauer <s.hauer@pengutronix.de>
   8 */
   9#include <linux/export.h>
  10#include <linux/of.h>
  11#include <linux/slab.h>
  12#include <video/display_timing.h>
  13#include <video/of_display_timing.h>
  14
  15/**
  16 * parse_timing_property - parse timing_entry from device_node
  17 * @np: device_node with the property
  18 * @name: name of the property
  19 * @result: will be set to the return value
  20 *
  21 * DESCRIPTION:
  22 * Every display_timing can be specified with either just the typical value or
  23 * a range consisting of min/typ/max. This function helps handling this
  24 **/
  25static int parse_timing_property(const struct device_node *np, const char *name,
  26                          struct timing_entry *result)
  27{
  28        struct property *prop;
  29        int length, cells, ret;
  30
  31        prop = of_find_property(np, name, &length);
  32        if (!prop) {
  33                pr_err("%pOF: could not find property %s\n", np, name);
  34                return -EINVAL;
  35        }
  36
  37        cells = length / sizeof(u32);
  38        if (cells == 1) {
  39                ret = of_property_read_u32(np, name, &result->typ);
  40                result->min = result->typ;
  41                result->max = result->typ;
  42        } else if (cells == 3) {
  43                ret = of_property_read_u32_array(np, name, &result->min, cells);
  44        } else {
  45                pr_err("%pOF: illegal timing specification in %s\n", np, name);
  46                return -EINVAL;
  47        }
  48
  49        return ret;
  50}
  51
  52/**
  53 * of_parse_display_timing - parse display_timing entry from device_node
  54 * @np: device_node with the properties
  55 * @dt: display_timing that contains the result. I may be partially written in case of errors
  56 **/
  57static int of_parse_display_timing(const struct device_node *np,
  58                struct display_timing *dt)
  59{
  60        u32 val = 0;
  61        int ret = 0;
  62
  63        memset(dt, 0, sizeof(*dt));
  64
  65        ret |= parse_timing_property(np, "hback-porch", &dt->hback_porch);
  66        ret |= parse_timing_property(np, "hfront-porch", &dt->hfront_porch);
  67        ret |= parse_timing_property(np, "hactive", &dt->hactive);
  68        ret |= parse_timing_property(np, "hsync-len", &dt->hsync_len);
  69        ret |= parse_timing_property(np, "vback-porch", &dt->vback_porch);
  70        ret |= parse_timing_property(np, "vfront-porch", &dt->vfront_porch);
  71        ret |= parse_timing_property(np, "vactive", &dt->vactive);
  72        ret |= parse_timing_property(np, "vsync-len", &dt->vsync_len);
  73        ret |= parse_timing_property(np, "clock-frequency", &dt->pixelclock);
  74
  75        dt->flags = 0;
  76        if (!of_property_read_u32(np, "vsync-active", &val))
  77                dt->flags |= val ? DISPLAY_FLAGS_VSYNC_HIGH :
  78                                DISPLAY_FLAGS_VSYNC_LOW;
  79        if (!of_property_read_u32(np, "hsync-active", &val))
  80                dt->flags |= val ? DISPLAY_FLAGS_HSYNC_HIGH :
  81                                DISPLAY_FLAGS_HSYNC_LOW;
  82        if (!of_property_read_u32(np, "de-active", &val))
  83                dt->flags |= val ? DISPLAY_FLAGS_DE_HIGH :
  84                                DISPLAY_FLAGS_DE_LOW;
  85        if (!of_property_read_u32(np, "pixelclk-active", &val))
  86                dt->flags |= val ? DISPLAY_FLAGS_PIXDATA_POSEDGE :
  87                                DISPLAY_FLAGS_PIXDATA_NEGEDGE;
  88
  89        if (!of_property_read_u32(np, "syncclk-active", &val))
  90                dt->flags |= val ? DISPLAY_FLAGS_SYNC_POSEDGE :
  91                                DISPLAY_FLAGS_SYNC_NEGEDGE;
  92        else if (dt->flags & (DISPLAY_FLAGS_PIXDATA_POSEDGE |
  93                              DISPLAY_FLAGS_PIXDATA_NEGEDGE))
  94                dt->flags |= dt->flags & DISPLAY_FLAGS_PIXDATA_POSEDGE ?
  95                                DISPLAY_FLAGS_SYNC_POSEDGE :
  96                                DISPLAY_FLAGS_SYNC_NEGEDGE;
  97
  98        if (of_property_read_bool(np, "interlaced"))
  99                dt->flags |= DISPLAY_FLAGS_INTERLACED;
 100        if (of_property_read_bool(np, "doublescan"))
 101                dt->flags |= DISPLAY_FLAGS_DOUBLESCAN;
 102        if (of_property_read_bool(np, "doubleclk"))
 103                dt->flags |= DISPLAY_FLAGS_DOUBLECLK;
 104
 105        if (ret) {
 106                pr_err("%pOF: error reading timing properties\n", np);
 107                return -EINVAL;
 108        }
 109
 110        return 0;
 111}
 112
 113/**
 114 * of_get_display_timing - parse a display_timing entry
 115 * @np: device_node with the timing subnode
 116 * @name: name of the timing node
 117 * @dt: display_timing struct to fill
 118 **/
 119int of_get_display_timing(const struct device_node *np, const char *name,
 120                struct display_timing *dt)
 121{
 122        struct device_node *timing_np;
 123        int ret;
 124
 125        if (!np)
 126                return -EINVAL;
 127
 128        timing_np = of_get_child_by_name(np, name);
 129        if (!timing_np)
 130                return -ENOENT;
 131
 132        ret = of_parse_display_timing(timing_np, dt);
 133
 134        of_node_put(timing_np);
 135
 136        return ret;
 137}
 138EXPORT_SYMBOL_GPL(of_get_display_timing);
 139
 140/**
 141 * of_get_display_timings - parse all display_timing entries from a device_node
 142 * @np: device_node with the subnodes
 143 **/
 144struct display_timings *of_get_display_timings(const struct device_node *np)
 145{
 146        struct device_node *timings_np;
 147        struct device_node *entry;
 148        struct device_node *native_mode;
 149        struct display_timings *disp;
 150
 151        if (!np)
 152                return NULL;
 153
 154        timings_np = of_get_child_by_name(np, "display-timings");
 155        if (!timings_np) {
 156                pr_err("%pOF: could not find display-timings node\n", np);
 157                return NULL;
 158        }
 159
 160        disp = kzalloc(sizeof(*disp), GFP_KERNEL);
 161        if (!disp) {
 162                pr_err("%pOF: could not allocate struct disp'\n", np);
 163                goto dispfail;
 164        }
 165
 166        entry = of_parse_phandle(timings_np, "native-mode", 0);
 167        /* assume first child as native mode if none provided */
 168        if (!entry)
 169                entry = of_get_next_child(timings_np, NULL);
 170        /* if there is no child, it is useless to go on */
 171        if (!entry) {
 172                pr_err("%pOF: no timing specifications given\n", np);
 173                goto entryfail;
 174        }
 175
 176        pr_debug("%pOF: using %pOFn as default timing\n", np, entry);
 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("%pOF: no timings specified\n", np);
 184                goto entryfail;
 185        }
 186
 187        disp->timings = kcalloc(disp->num_timings,
 188                                sizeof(struct display_timing *),
 189                                GFP_KERNEL);
 190        if (!disp->timings) {
 191                pr_err("%pOF: could not allocate timings array\n", 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 = kmalloc(sizeof(*dt), GFP_KERNEL);
 203                if (!dt) {
 204                        pr_err("%pOF: could not allocate display_timing struct\n",
 205                                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("%pOF: error in timing %d\n",
 216                                np, disp->num_timings + 1);
 217                        kfree(dt);
 218                        goto timingfail;
 219                }
 220
 221                if (native_mode == entry)
 222                        disp->native_mode = disp->num_timings;
 223
 224                disp->timings[disp->num_timings] = dt;
 225                disp->num_timings++;
 226        }
 227        of_node_put(timings_np);
 228        /*
 229         * native_mode points to the device_node returned by of_parse_phandle
 230         * therefore call of_node_put on it
 231         */
 232        of_node_put(native_mode);
 233
 234        pr_debug("%pOF: got %d timings. Using timing #%d as default\n",
 235                np, disp->num_timings,
 236                disp->native_mode + 1);
 237
 238        return disp;
 239
 240timingfail:
 241        of_node_put(native_mode);
 242        display_timings_release(disp);
 243        disp = NULL;
 244entryfail:
 245        kfree(disp);
 246dispfail:
 247        of_node_put(timings_np);
 248        return NULL;
 249}
 250EXPORT_SYMBOL_GPL(of_get_display_timings);
 251