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  * @dt: display_timing that contains the result. I may be partially written in case of errors
56  **/
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  **/
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  **/
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 = kzalloc(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