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 **/
parse_timing_property(const struct device_node * np,const char * name,struct timing_entry * result)25 static 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 **/
of_parse_display_timing(const struct device_node * np,struct display_timing * dt)57 static 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 **/
of_get_display_timing(const struct device_node * np,const char * name,struct display_timing * dt)119 int 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 }
138 EXPORT_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 **/
of_get_display_timings(const struct device_node * np)144 struct 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
240 timingfail:
241 of_node_put(native_mode);
242 display_timings_release(disp);
243 disp = NULL;
244 entryfail:
245 kfree(disp);
246 dispfail:
247 of_node_put(timings_np);
248 return NULL;
249 }
250 EXPORT_SYMBOL_GPL(of_get_display_timings);
251