drivers/video/of_display_timing.c

   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  **/
  26 static int parse_timing_property(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_get_display_timing - parse display_timing entry from device_node
  57  * @np: device_node with the properties
  58  **/
  59 static struct display_timing *of_get_display_timing(struct device_node *np)
  60 {
  61         struct display_timing *dt;
  62         u32 val = 0;
  63         int ret = 0;
  64
  65         dt = kzalloc(sizeof(*dt), GFP_KERNEL);
  66         if (!dt) {
  67                 pr_err("%s: could not allocate display_timing struct\n",
  68                         of_node_full_name(np));
  69                 return NULL;
  70         }
  71
  72         ret |= parse_timing_property(np, "hback-porch", &dt->hback_porch);
  73         ret |= parse_timing_property(np, "hfront-porch", &dt->hfront_porch);
  74         ret |= parse_timing_property(np, "hactive", &dt->hactive);
  75         ret |= parse_timing_property(np, "hsync-len", &dt->hsync_len);
  76         ret |= parse_timing_property(np, "vback-porch", &dt->vback_porch);
  77         ret |= parse_timing_property(np, "vfront-porch", &dt->vfront_porch);
  78         ret |= parse_timing_property(np, "vactive", &dt->vactive);
  79         ret |= parse_timing_property(np, "vsync-len", &dt->vsync_len);
  80         ret |= parse_timing_property(np, "clock-frequency", &dt->pixelclock);
  81
  82         dt->flags = 0;
  83         if (!of_property_read_u32(np, "vsync-active", &val))
  84                 dt->flags |= val ? DISPLAY_FLAGS_VSYNC_HIGH :
  85                                 DISPLAY_FLAGS_VSYNC_LOW;
  86         if (!of_property_read_u32(np, "hsync-active", &val))
  87                 dt->flags |= val ? DISPLAY_FLAGS_HSYNC_HIGH :
  88                                 DISPLAY_FLAGS_HSYNC_LOW;
  89         if (!of_property_read_u32(np, "de-active", &val))
  90                 dt->flags |= val ? DISPLAY_FLAGS_DE_HIGH :
  91                                 DISPLAY_FLAGS_DE_LOW;
  92         if (!of_property_read_u32(np, "pixelclk-active", &val))
  93                 dt->flags |= val ? DISPLAY_FLAGS_PIXDATA_POSEDGE :
  94                                 DISPLAY_FLAGS_PIXDATA_NEGEDGE;
  95
  96         if (of_property_read_bool(np, "interlaced"))
  97                 dt->flags |= DISPLAY_FLAGS_INTERLACED;
  98         if (of_property_read_bool(np, "doublescan"))
  99                 dt->flags |= DISPLAY_FLAGS_DOUBLESCAN;
 100
 101         if (ret) {
 102                 pr_err("%s: error reading timing properties\n",
 103                         of_node_full_name(np));
 104                 kfree(dt);
 105                 return NULL;
 106         }
 107
 108         return dt;
 109 }
 110
 111 /**
 112  * of_get_display_timings - parse all display_timing entries from a device_node
 113  * @np: device_node with the subnodes
 114  **/
 115 struct display_timings *of_get_display_timings(struct device_node *np)
 116 {
 117         struct device_node *timings_np;
 118         struct device_node *entry;
 119         struct device_node *native_mode;
 120         struct display_timings *disp;
 121
 122         if (!np) {
 123                 pr_err("%s: no devicenode given\n", of_node_full_name(np));
 124                 return NULL;
 125         }
 126
 127         timings_np = of_find_node_by_name(np, "display-timings");
 128         if (!timings_np) {
 129                 pr_err("%s: could not find display-timings node\n",
 130                         of_node_full_name(np));
 131                 return NULL;
 132         }
 133
 134         disp = kzalloc(sizeof(*disp), GFP_KERNEL);
 135         if (!disp) {
 136                 pr_err("%s: could not allocate struct disp'\n",
 137                         of_node_full_name(np));
 138                 goto dispfail;
 139         }
 140
 141         entry = of_parse_phandle(timings_np, "native-mode", 0);
 142         /* assume first child as native mode if none provided */
 143         if (!entry)
 144                 entry = of_get_next_child(np, NULL);
 145         /* if there is no child, it is useless to go on */
 146         if (!entry) {
 147                 pr_err("%s: no timing specifications given\n",
 148                         of_node_full_name(np));
 149                 goto entryfail;
 150         }
 151
 152         pr_debug("%s: using %s as default timing\n",
 153                 of_node_full_name(np), entry->name);
 154
 155         native_mode = entry;
 156
 157         disp->num_timings = of_get_child_count(timings_np);
 158         if (disp->num_timings == 0) {
 159                 /* should never happen, as entry was already found above */
 160                 pr_err("%s: no timings specified\n", of_node_full_name(np));
 161                 goto entryfail;
 162         }
 163
 164         disp->timings = kzalloc(sizeof(struct display_timing *) *
 165                                 disp->num_timings, GFP_KERNEL);
 166         if (!disp->timings) {
 167                 pr_err("%s: could not allocate timings array\n",
 168                         of_node_full_name(np));
 169                 goto entryfail;
 170         }
 171
 172         disp->num_timings = 0;
 173         disp->native_mode = 0;
 174
 175         for_each_child_of_node(timings_np, entry) {
 176                 struct display_timing *dt;
 177
 178                 dt = of_get_display_timing(entry);
 179                 if (!dt) {
 180                         /*
 181                          * to not encourage wrong devicetrees, fail in case of
 182                          * an error
 183                          */
 184                         pr_err("%s: error in timing %d\n",
 185                                 of_node_full_name(np), disp->num_timings + 1);
 186                         goto timingfail;
 187                 }
 188
 189                 if (native_mode == entry)
 190                         disp->native_mode = disp->num_timings;
 191
 192                 disp->timings[disp->num_timings] = dt;
 193                 disp->num_timings++;
 194         }
 195         of_node_put(timings_np);
 196         /*
 197          * native_mode points to the device_node returned by of_parse_phandle
 198          * therefore call of_node_put on it
 199          */
 200         of_node_put(native_mode);
 201
 202         pr_debug("%s: got %d timings. Using timing #%d as default\n",
 203                 of_node_full_name(np), disp->num_timings,
 204                 disp->native_mode + 1);
 205
 206         return disp;
 207
 208 timingfail:
 209         if (native_mode)
 210                 of_node_put(native_mode);
 211         display_timings_release(disp);
 212 entryfail:
 213         kfree(disp);
 214 dispfail:
 215         of_node_put(timings_np);
 216         return NULL;
 217 }
 218 EXPORT_SYMBOL_GPL(of_get_display_timings);
 219
 220 /**
 221  * of_display_timings_exist - check if a display-timings node is provided
 222  * @np: device_node with the timing
 223  **/
 224 int of_display_timings_exist(struct device_node *np)
 225 {
 226         struct device_node *timings_np;
 227
 228         if (!np)
 229                 return -EINVAL;
 230
 231         timings_np = of_parse_phandle(np, "display-timings", 0);
 232         if (!timings_np)
 233                 return -EINVAL;
 234
 235         of_node_put(timings_np);
 236         return 1;
 237 }
 238 EXPORT_SYMBOL_GPL(of_display_timings_exist);