1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Novatek NT39016 TFT LCD panel driver
4  *
5  * Copyright (C) 2017, Maarten ter Huurne <maarten@treewalker.org>
6  * Copyright (C) 2019, Paul Cercueil <paul@crapouillou.net>
7  */
8 
9 #include <linux/backlight.h>
10 #include <linux/delay.h>
11 #include <linux/device.h>
12 #include <linux/gpio/consumer.h>
13 #include <linux/media-bus-format.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/of_device.h>
17 #include <linux/regmap.h>
18 #include <linux/regulator/consumer.h>
19 #include <linux/spi/spi.h>
20 
21 #include <drm/drm_modes.h>
22 #include <drm/drm_panel.h>
23 
24 enum nt39016_regs {
25 	NT39016_REG_SYSTEM,
26 	NT39016_REG_TIMING,
27 	NT39016_REG_OP,
28 	NT39016_REG_DATA_IN,
29 	NT39016_REG_SRC_TIMING_DELAY,
30 	NT39016_REG_GATE_TIMING_DELAY,
31 	NT39016_REG_RESERVED,
32 	NT39016_REG_INITIAL_FUNC,
33 	NT39016_REG_CONTRAST,
34 	NT39016_REG_BRIGHTNESS,
35 	NT39016_REG_HUE_SATURATION,
36 	NT39016_REG_RB_SUBCONTRAST,
37 	NT39016_REG_R_SUBBRIGHTNESS,
38 	NT39016_REG_B_SUBBRIGHTNESS,
39 	NT39016_REG_VCOMDC,
40 	NT39016_REG_VCOMAC,
41 	NT39016_REG_VGAM2,
42 	NT39016_REG_VGAM34,
43 	NT39016_REG_VGAM56,
44 	NT39016_REG_VCOMDC_TRIM = 0x1e,
45 	NT39016_REG_DISPLAY_MODE = 0x20,
46 };
47 
48 #define NT39016_SYSTEM_RESET_N	BIT(0)
49 #define NT39016_SYSTEM_STANDBY	BIT(1)
50 
51 struct nt39016_panel_info {
52 	struct drm_display_mode display_mode;
53 	u16 width_mm, height_mm;
54 	u32 bus_format, bus_flags;
55 };
56 
57 struct nt39016 {
58 	struct drm_panel drm_panel;
59 	struct device *dev;
60 	struct regmap *map;
61 	struct regulator *supply;
62 	const struct nt39016_panel_info *panel_info;
63 
64 	struct gpio_desc *reset_gpio;
65 
66 	struct backlight_device *backlight;
67 };
68 
69 static inline struct nt39016 *to_nt39016(struct drm_panel *panel)
70 {
71 	return container_of(panel, struct nt39016, drm_panel);
72 }
73 
74 #define RV(REG, VAL) { .reg = (REG), .def = (VAL), .delay_us = 2 }
75 static const struct reg_sequence nt39016_panel_regs[] = {
76 	RV(NT39016_REG_SYSTEM, 0x00),
77 	RV(NT39016_REG_TIMING, 0x00),
78 	RV(NT39016_REG_OP, 0x03),
79 	RV(NT39016_REG_DATA_IN, 0xCC),
80 	RV(NT39016_REG_SRC_TIMING_DELAY, 0x46),
81 	RV(NT39016_REG_GATE_TIMING_DELAY, 0x05),
82 	RV(NT39016_REG_RESERVED, 0x00),
83 	RV(NT39016_REG_INITIAL_FUNC, 0x00),
84 	RV(NT39016_REG_CONTRAST, 0x08),
85 	RV(NT39016_REG_BRIGHTNESS, 0x40),
86 	RV(NT39016_REG_HUE_SATURATION, 0x88),
87 	RV(NT39016_REG_RB_SUBCONTRAST, 0x88),
88 	RV(NT39016_REG_R_SUBBRIGHTNESS, 0x20),
89 	RV(NT39016_REG_B_SUBBRIGHTNESS, 0x20),
90 	RV(NT39016_REG_VCOMDC, 0x67),
91 	RV(NT39016_REG_VCOMAC, 0xA4),
92 	RV(NT39016_REG_VGAM2, 0x04),
93 	RV(NT39016_REG_VGAM34, 0x24),
94 	RV(NT39016_REG_VGAM56, 0x24),
95 	RV(NT39016_REG_DISPLAY_MODE, 0x00),
96 };
97 
98 #undef RV
99 
100 static const struct regmap_range nt39016_regmap_no_ranges[] = {
101 	regmap_reg_range(0x13, 0x1D),
102 	regmap_reg_range(0x1F, 0x1F),
103 };
104 
105 static const struct regmap_access_table nt39016_regmap_access_table = {
106 	.no_ranges = nt39016_regmap_no_ranges,
107 	.n_no_ranges = ARRAY_SIZE(nt39016_regmap_no_ranges),
108 };
109 
110 static const struct regmap_config nt39016_regmap_config = {
111 	.reg_bits = 6,
112 	.pad_bits = 2,
113 	.val_bits = 8,
114 
115 	.max_register = NT39016_REG_DISPLAY_MODE,
116 	.wr_table = &nt39016_regmap_access_table,
117 	.write_flag_mask = 0x02,
118 
119 	.cache_type = REGCACHE_FLAT,
120 };
121 
122 static int nt39016_prepare(struct drm_panel *drm_panel)
123 {
124 	struct nt39016 *panel = to_nt39016(drm_panel);
125 	int err;
126 
127 	err = regulator_enable(panel->supply);
128 	if (err) {
129 		dev_err(panel->dev, "Failed to enable power supply: %d", err);
130 		return err;
131 	}
132 
133 	/*
134 	 * Reset the NT39016.
135 	 * The documentation says the reset pulse should be at least 40 us to
136 	 * pass the glitch filter, but when testing I see some resets fail and
137 	 * some succeed when using a 70 us delay, so we use 100 us instead.
138 	 */
139 	gpiod_set_value_cansleep(panel->reset_gpio, 1);
140 	usleep_range(100, 1000);
141 	gpiod_set_value_cansleep(panel->reset_gpio, 0);
142 	udelay(2);
143 
144 	/* Init all registers. */
145 	err = regmap_multi_reg_write(panel->map, nt39016_panel_regs,
146 				     ARRAY_SIZE(nt39016_panel_regs));
147 	if (err) {
148 		dev_err(panel->dev, "Failed to init registers: %d", err);
149 		goto err_disable_regulator;
150 	}
151 
152 	return 0;
153 
154 err_disable_regulator:
155 	regulator_disable(panel->supply);
156 	return err;
157 }
158 
159 static int nt39016_unprepare(struct drm_panel *drm_panel)
160 {
161 	struct nt39016 *panel = to_nt39016(drm_panel);
162 
163 	gpiod_set_value_cansleep(panel->reset_gpio, 1);
164 
165 	regulator_disable(panel->supply);
166 
167 	return 0;
168 }
169 
170 static int nt39016_enable(struct drm_panel *drm_panel)
171 {
172 	struct nt39016 *panel = to_nt39016(drm_panel);
173 	int ret;
174 
175 	ret = regmap_write(panel->map, NT39016_REG_SYSTEM,
176 			   NT39016_SYSTEM_RESET_N | NT39016_SYSTEM_STANDBY);
177 	if (ret) {
178 		dev_err(panel->dev, "Unable to enable panel: %d", ret);
179 		return ret;
180 	}
181 
182 	if (panel->backlight) {
183 		/* Wait for the picture to be ready before enabling backlight */
184 		msleep(150);
185 
186 		ret = backlight_enable(panel->backlight);
187 	}
188 
189 	return ret;
190 }
191 
192 static int nt39016_disable(struct drm_panel *drm_panel)
193 {
194 	struct nt39016 *panel = to_nt39016(drm_panel);
195 	int err;
196 
197 	backlight_disable(panel->backlight);
198 
199 	err = regmap_write(panel->map, NT39016_REG_SYSTEM,
200 			   NT39016_SYSTEM_RESET_N);
201 	if (err) {
202 		dev_err(panel->dev, "Unable to disable panel: %d", err);
203 		return err;
204 	}
205 
206 	return 0;
207 }
208 
209 static int nt39016_get_modes(struct drm_panel *drm_panel)
210 {
211 	struct nt39016 *panel = to_nt39016(drm_panel);
212 	const struct nt39016_panel_info *panel_info = panel->panel_info;
213 	struct drm_connector *connector = drm_panel->connector;
214 	struct drm_display_mode *mode;
215 
216 	mode = drm_mode_duplicate(drm_panel->drm, &panel_info->display_mode);
217 	if (!mode)
218 		return -ENOMEM;
219 
220 	drm_mode_set_name(mode);
221 
222 	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
223 	drm_mode_probed_add(connector, mode);
224 
225 	connector->display_info.bpc = 8;
226 	connector->display_info.width_mm = panel_info->width_mm;
227 	connector->display_info.height_mm = panel_info->height_mm;
228 
229 	drm_display_info_set_bus_formats(&connector->display_info,
230 					 &panel_info->bus_format, 1);
231 	connector->display_info.bus_flags = panel_info->bus_flags;
232 
233 	return 1;
234 }
235 
236 static const struct drm_panel_funcs nt39016_funcs = {
237 	.prepare	= nt39016_prepare,
238 	.unprepare	= nt39016_unprepare,
239 	.enable		= nt39016_enable,
240 	.disable	= nt39016_disable,
241 	.get_modes	= nt39016_get_modes,
242 };
243 
244 static int nt39016_probe(struct spi_device *spi)
245 {
246 	struct device *dev = &spi->dev;
247 	struct nt39016 *panel;
248 	int err;
249 
250 	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
251 	if (!panel)
252 		return -ENOMEM;
253 
254 	panel->dev = dev;
255 	spi_set_drvdata(spi, panel);
256 
257 	panel->panel_info = of_device_get_match_data(dev);
258 	if (!panel->panel_info)
259 		return -EINVAL;
260 
261 	panel->supply = devm_regulator_get(dev, "power");
262 	if (IS_ERR(panel->supply)) {
263 		dev_err(dev, "Failed to get power supply");
264 		return PTR_ERR(panel->supply);
265 	}
266 
267 	panel->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
268 	if (IS_ERR(panel->reset_gpio)) {
269 		dev_err(dev, "Failed to get reset GPIO");
270 		return PTR_ERR(panel->reset_gpio);
271 	}
272 
273 	spi->bits_per_word = 8;
274 	spi->mode = SPI_MODE_3 | SPI_3WIRE;
275 	err = spi_setup(spi);
276 	if (err) {
277 		dev_err(dev, "Failed to setup SPI");
278 		return err;
279 	}
280 
281 	panel->map = devm_regmap_init_spi(spi, &nt39016_regmap_config);
282 	if (IS_ERR(panel->map)) {
283 		dev_err(dev, "Failed to init regmap");
284 		return PTR_ERR(panel->map);
285 	}
286 
287 	panel->backlight = devm_of_find_backlight(dev);
288 	if (IS_ERR(panel->backlight)) {
289 		err = PTR_ERR(panel->backlight);
290 		if (err != -EPROBE_DEFER)
291 			dev_err(dev, "Failed to get backlight handle");
292 		return err;
293 	}
294 
295 	drm_panel_init(&panel->drm_panel, dev, &nt39016_funcs,
296 		       DRM_MODE_CONNECTOR_DPI);
297 
298 	err = drm_panel_add(&panel->drm_panel);
299 	if (err < 0) {
300 		dev_err(dev, "Failed to register panel");
301 		return err;
302 	}
303 
304 	return 0;
305 }
306 
307 static int nt39016_remove(struct spi_device *spi)
308 {
309 	struct nt39016 *panel = spi_get_drvdata(spi);
310 
311 	drm_panel_remove(&panel->drm_panel);
312 
313 	nt39016_disable(&panel->drm_panel);
314 	nt39016_unprepare(&panel->drm_panel);
315 
316 	return 0;
317 }
318 
319 static const struct nt39016_panel_info kd035g6_info = {
320 	.display_mode = {
321 		.clock = 6000,
322 		.hdisplay = 320,
323 		.hsync_start = 320 + 10,
324 		.hsync_end = 320 + 10 + 50,
325 		.htotal = 320 + 10 + 50 + 20,
326 		.vdisplay = 240,
327 		.vsync_start = 240 + 5,
328 		.vsync_end = 240 + 5 + 1,
329 		.vtotal = 240 + 5 + 1 + 4,
330 		.vrefresh = 60,
331 		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
332 	},
333 	.width_mm = 71,
334 	.height_mm = 53,
335 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
336 	.bus_flags = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
337 };
338 
339 static const struct of_device_id nt39016_of_match[] = {
340 	{ .compatible = "kingdisplay,kd035g6-54nt", .data = &kd035g6_info },
341 	{ /* sentinel */ }
342 };
343 MODULE_DEVICE_TABLE(of, nt39016_of_match);
344 
345 static struct spi_driver nt39016_driver = {
346 	.driver = {
347 		.name = "nt39016",
348 		.of_match_table = nt39016_of_match,
349 	},
350 	.probe = nt39016_probe,
351 	.remove = nt39016_remove,
352 };
353 
354 module_spi_driver(nt39016_driver);
355 
356 MODULE_AUTHOR("Maarten ter Huurne <maarten@treewalker.org>");
357 MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
358 MODULE_LICENSE("GPL v2");
359