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  **/
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  **/
56 static 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  **/
118 int 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 }
137 EXPORT_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  **/
143 struct 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 
239 timingfail:
240 	of_node_put(native_mode);
241 	display_timings_release(disp);
242 	disp = NULL;
243 entryfail:
244 	kfree(disp);
245 dispfail:
246 	of_node_put(timings_np);
247 	return NULL;
248 }
249 EXPORT_SYMBOL_GPL(of_get_display_timings);
250