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 **/
  56static int of_parse_display_timing(const struct device_node *np,
  57                struct display_timing *dt)
  58{
  59        u32 val = 0;
  60        int ret = 0;
  61
  62        memset(dt, 0, sizeof(*dt));
  63
  64        ret |= parse_timing_property(np, "hback-porch", &dt->hback_porch);
  65        ret |= parse_timing_property(np, "hfront-porch", &dt->hfront_porch);
  66        ret |= parse_timing_property(np, "hactive", &dt->hactive);
  67        ret |= parse_timing_property(np, "hsync-len", &dt->hsync_len);
  68        ret |= parse_timing_property(np, "vback-porch", &dt->vback_porch);
  69        ret |= parse_timing_property(np, "vfront-porch", &dt->vfront_porch);
  70        ret |= parse_timing_property(np, "vactive", &dt->vactive);
  71        ret |= parse_timing_property(np, "vsync-len", &dt->vsync_len);
  72        ret |= parse_timing_property(np, "clock-frequency", &dt->pixelclock);
  73
  74        dt->flags = 0;
  75        if (!of_property_read_u32(np, "vsync-active", &val))
  76                dt->flags |= val ? DISPLAY_FLAGS_VSYNC_HIGH :
  77                                DISPLAY_FLAGS_VSYNC_LOW;
  78        if (!of_property_read_u32(np, "hsync-active", &val))
  79                dt->flags |= val ? DISPLAY_FLAGS_HSYNC_HIGH :
  80                                DISPLAY_FLAGS_HSYNC_LOW;
  81        if (!of_property_read_u32(np, "de-active", &val))
  82                dt->flags |= val ? DISPLAY_FLAGS_DE_HIGH :
  83                                DISPLAY_FLAGS_DE_LOW;
  84        if (!of_property_read_u32(np, "pixelclk-active", &val))
  85                dt->flags |= val ? DISPLAY_FLAGS_PIXDATA_POSEDGE :
  86                                DISPLAY_FLAGS_PIXDATA_NEGEDGE;
  87
  88        if (!of_property_read_u32(np, "syncclk-active", &val))
  89                dt->flags |= val ? DISPLAY_FLAGS_SYNC_POSEDGE :
  90                                DISPLAY_FLAGS_SYNC_NEGEDGE;
  91        else if (dt->flags & (DISPLAY_FLAGS_PIXDATA_POSEDGE |
  92                              DISPLAY_FLAGS_PIXDATA_NEGEDGE))
  93                dt->flags |= dt->flags & DISPLAY_FLAGS_PIXDATA_POSEDGE ?
  94                                DISPLAY_FLAGS_SYNC_POSEDGE :
  95                                DISPLAY_FLAGS_SYNC_NEGEDGE;
  96
  97        if (of_property_read_bool(np, "interlaced"))
  98                dt->flags |= DISPLAY_FLAGS_INTERLACED;
  99        if (of_property_read_bool(np, "doublescan"))
 100                dt->flags |= DISPLAY_FLAGS_DOUBLESCAN;
 101        if (of_property_read_bool(np, "doubleclk"))
 102                dt->flags |= DISPLAY_FLAGS_DOUBLECLK;
 103
 104        if (ret) {
 105                pr_err("%pOF: error reading timing properties\n", np);
 106                return -EINVAL;
 107        }
 108
 109        return 0;
 110}
 111
 112/**
 113 * of_get_display_timing - parse a display_timing entry
 114 * @np: device_node with the timing subnode
 115 * @name: name of the timing node
 116 * @dt: display_timing struct to fill
 117 **/
 118int of_get_display_timing(const struct device_node *np, const char *name,
 119                struct display_timing *dt)
 120{
 121        struct device_node *timing_np;
 122        int ret;
 123
 124        if (!np)
 125                return -EINVAL;
 126
 127        timing_np = of_get_child_by_name(np, name);
 128        if (!timing_np)
 129                return -ENOENT;
 130
 131        ret = of_parse_display_timing(timing_np, dt);
 132
 133        of_node_put(timing_np);
 134
 135        return ret;
 136}
 137EXPORT_SYMBOL_GPL(of_get_display_timing);
 138
 139/**
 140 * of_get_display_timings - parse all display_timing entries from a device_node
 141 * @np: device_node with the subnodes
 142 **/
 143struct display_timings *of_get_display_timings(const struct device_node *np)
 144{
 145        struct device_node *timings_np;
 146        struct device_node *entry;
 147        struct device_node *native_mode;
 148        struct display_timings *disp;
 149
 150        if (!np)
 151                return NULL;
 152
 153        timings_np = of_get_child_by_name(np, "display-timings");
 154        if (!timings_np) {
 155                pr_err("%pOF: could not find display-timings node\n", np);
 156                return NULL;
 157        }
 158
 159        disp = kzalloc(sizeof(*disp), GFP_KERNEL);
 160        if (!disp) {
 161                pr_err("%pOF: could not allocate struct disp'\n", np);
 162                goto dispfail;
 163        }
 164
 165        entry = of_parse_phandle(timings_np, "native-mode", 0);
 166        /* assume first child as native mode if none provided */
 167        if (!entry)
 168                entry = of_get_next_child(timings_np, NULL);
 169        /* if there is no child, it is useless to go on */
 170        if (!entry) {
 171                pr_err("%pOF: no timing specifications given\n", np);
 172                goto entryfail;
 173        }
 174
 175        pr_debug("%pOF: using %pOFn as default timing\n", np, entry);
 176
 177        native_mode = entry;
 178
 179        disp->num_timings = of_get_child_count(timings_np);
 180        if (disp->num_timings == 0) {
 181                /* should never happen, as entry was already found above */
 182                pr_err("%pOF: no timings specified\n", np);
 183                goto entryfail;
 184        }
 185
 186        disp->timings = kcalloc(disp->num_timings,
 187                                sizeof(struct display_timing *),
 188                                GFP_KERNEL);
 189        if (!disp->timings) {
 190                pr_err("%pOF: could not allocate timings array\n", np);
 191                goto entryfail;
 192        }
 193
 194        disp->num_timings = 0;
 195        disp->native_mode = 0;
 196
 197        for_each_child_of_node(timings_np, entry) {
 198                struct display_timing *dt;
 199                int r;
 200
 201                dt = kzalloc(sizeof(*dt), GFP_KERNEL);
 202                if (!dt) {
 203                        pr_err("%pOF: could not allocate display_timing struct\n",
 204                                np);
 205                        goto timingfail;
 206                }
 207
 208                r = of_parse_display_timing(entry, dt);
 209                if (r) {
 210                        /*
 211                         * to not encourage wrong devicetrees, fail in case of
 212                         * an error
 213                         */
 214                        pr_err("%pOF: error in timing %d\n",
 215                                np, disp->num_timings + 1);
 216                        kfree(dt);
 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("%pOF: got %d timings. Using timing #%d as default\n",
 234                np, disp->num_timings,
 235                disp->native_mode + 1);
 236
 237        return disp;
 238
 239timingfail:
 240        of_node_put(native_mode);
 241        display_timings_release(disp);
 242        disp = NULL;
 243entryfail:
 244        kfree(disp);
 245dispfail:
 246        of_node_put(timings_np);
 247        return NULL;
 248}
 249EXPORT_SYMBOL_GPL(of_get_display_timings);
 250