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 	const struct drm_display_mode *display_modes;
53 	unsigned int num_modes;
54 	u16 width_mm, height_mm;
55 	u32 bus_format, bus_flags;
56 };
57 
58 struct nt39016 {
59 	struct drm_panel drm_panel;
60 	struct device *dev;
61 	struct regmap *map;
62 	struct regulator *supply;
63 	const struct nt39016_panel_info *panel_info;
64 
65 	struct gpio_desc *reset_gpio;
66 
67 	struct backlight_device *backlight;
68 };
69 
70 static inline struct nt39016 *to_nt39016(struct drm_panel *panel)
71 {
72 	return container_of(panel, struct nt39016, drm_panel);
73 }
74 
75 #define RV(REG, VAL) { .reg = (REG), .def = (VAL), .delay_us = 2 }
76 static const struct reg_sequence nt39016_panel_regs[] = {
77 	RV(NT39016_REG_SYSTEM, 0x00),
78 	RV(NT39016_REG_TIMING, 0x00),
79 	RV(NT39016_REG_OP, 0x03),
80 	RV(NT39016_REG_DATA_IN, 0xCC),
81 	RV(NT39016_REG_SRC_TIMING_DELAY, 0x46),
82 	RV(NT39016_REG_GATE_TIMING_DELAY, 0x05),
83 	RV(NT39016_REG_RESERVED, 0x00),
84 	RV(NT39016_REG_INITIAL_FUNC, 0x00),
85 	RV(NT39016_REG_CONTRAST, 0x08),
86 	RV(NT39016_REG_BRIGHTNESS, 0x40),
87 	RV(NT39016_REG_HUE_SATURATION, 0x88),
88 	RV(NT39016_REG_RB_SUBCONTRAST, 0x88),
89 	RV(NT39016_REG_R_SUBBRIGHTNESS, 0x20),
90 	RV(NT39016_REG_B_SUBBRIGHTNESS, 0x20),
91 	RV(NT39016_REG_VCOMDC, 0x67),
92 	RV(NT39016_REG_VCOMAC, 0xA4),
93 	RV(NT39016_REG_VGAM2, 0x04),
94 	RV(NT39016_REG_VGAM34, 0x24),
95 	RV(NT39016_REG_VGAM56, 0x24),
96 	RV(NT39016_REG_DISPLAY_MODE, 0x00),
97 };
98 
99 #undef RV
100 
101 static const struct regmap_range nt39016_regmap_no_ranges[] = {
102 	regmap_reg_range(0x13, 0x1D),
103 	regmap_reg_range(0x1F, 0x1F),
104 };
105 
106 static const struct regmap_access_table nt39016_regmap_access_table = {
107 	.no_ranges = nt39016_regmap_no_ranges,
108 	.n_no_ranges = ARRAY_SIZE(nt39016_regmap_no_ranges),
109 };
110 
111 static const struct regmap_config nt39016_regmap_config = {
112 	.reg_bits = 6,
113 	.pad_bits = 2,
114 	.val_bits = 8,
115 
116 	.max_register = NT39016_REG_DISPLAY_MODE,
117 	.wr_table = &nt39016_regmap_access_table,
118 	.write_flag_mask = 0x02,
119 
120 	.cache_type = REGCACHE_FLAT,
121 };
122 
123 static int nt39016_prepare(struct drm_panel *drm_panel)
124 {
125 	struct nt39016 *panel = to_nt39016(drm_panel);
126 	int err;
127 
128 	err = regulator_enable(panel->supply);
129 	if (err) {
130 		dev_err(panel->dev, "Failed to enable power supply: %d", err);
131 		return err;
132 	}
133 
134 	/*
135 	 * Reset the NT39016.
136 	 * The documentation says the reset pulse should be at least 40 us to
137 	 * pass the glitch filter, but when testing I see some resets fail and
138 	 * some succeed when using a 70 us delay, so we use 100 us instead.
139 	 */
140 	gpiod_set_value_cansleep(panel->reset_gpio, 1);
141 	usleep_range(100, 1000);
142 	gpiod_set_value_cansleep(panel->reset_gpio, 0);
143 	udelay(2);
144 
145 	/* Init all registers. */
146 	err = regmap_multi_reg_write(panel->map, nt39016_panel_regs,
147 				     ARRAY_SIZE(nt39016_panel_regs));
148 	if (err) {
149 		dev_err(panel->dev, "Failed to init registers: %d", err);
150 		goto err_disable_regulator;
151 	}
152 
153 	return 0;
154 
155 err_disable_regulator:
156 	regulator_disable(panel->supply);
157 	return err;
158 }
159 
160 static int nt39016_unprepare(struct drm_panel *drm_panel)
161 {
162 	struct nt39016 *panel = to_nt39016(drm_panel);
163 
164 	gpiod_set_value_cansleep(panel->reset_gpio, 1);
165 
166 	regulator_disable(panel->supply);
167 
168 	return 0;
169 }
170 
171 static int nt39016_enable(struct drm_panel *drm_panel)
172 {
173 	struct nt39016 *panel = to_nt39016(drm_panel);
174 	int ret;
175 
176 	ret = regmap_write(panel->map, NT39016_REG_SYSTEM,
177 			   NT39016_SYSTEM_RESET_N | NT39016_SYSTEM_STANDBY);
178 	if (ret) {
179 		dev_err(panel->dev, "Unable to enable panel: %d", ret);
180 		return ret;
181 	}
182 
183 	if (panel->backlight) {
184 		/* Wait for the picture to be ready before enabling backlight */
185 		msleep(150);
186 
187 		ret = backlight_enable(panel->backlight);
188 	}
189 
190 	return ret;
191 }
192 
193 static int nt39016_disable(struct drm_panel *drm_panel)
194 {
195 	struct nt39016 *panel = to_nt39016(drm_panel);
196 	int err;
197 
198 	backlight_disable(panel->backlight);
199 
200 	err = regmap_write(panel->map, NT39016_REG_SYSTEM,
201 			   NT39016_SYSTEM_RESET_N);
202 	if (err) {
203 		dev_err(panel->dev, "Unable to disable panel: %d", err);
204 		return err;
205 	}
206 
207 	return 0;
208 }
209 
210 static int nt39016_get_modes(struct drm_panel *drm_panel,
211 			     struct drm_connector *connector)
212 {
213 	struct nt39016 *panel = to_nt39016(drm_panel);
214 	const struct nt39016_panel_info *panel_info = panel->panel_info;
215 	struct drm_display_mode *mode;
216 	unsigned int i;
217 
218 	for (i = 0; i < panel_info->num_modes; i++) {
219 		mode = drm_mode_duplicate(connector->dev,
220 					  &panel_info->display_modes[i]);
221 		if (!mode)
222 			return -ENOMEM;
223 
224 		drm_mode_set_name(mode);
225 
226 		mode->type = DRM_MODE_TYPE_DRIVER;
227 		if (panel_info->num_modes == 1)
228 			mode->type |= DRM_MODE_TYPE_PREFERRED;
229 
230 		drm_mode_probed_add(connector, mode);
231 	}
232 
233 	connector->display_info.bpc = 8;
234 	connector->display_info.width_mm = panel_info->width_mm;
235 	connector->display_info.height_mm = panel_info->height_mm;
236 
237 	drm_display_info_set_bus_formats(&connector->display_info,
238 					 &panel_info->bus_format, 1);
239 	connector->display_info.bus_flags = panel_info->bus_flags;
240 
241 	return panel_info->num_modes;
242 }
243 
244 static const struct drm_panel_funcs nt39016_funcs = {
245 	.prepare	= nt39016_prepare,
246 	.unprepare	= nt39016_unprepare,
247 	.enable		= nt39016_enable,
248 	.disable	= nt39016_disable,
249 	.get_modes	= nt39016_get_modes,
250 };
251 
252 static int nt39016_probe(struct spi_device *spi)
253 {
254 	struct device *dev = &spi->dev;
255 	struct nt39016 *panel;
256 	int err;
257 
258 	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
259 	if (!panel)
260 		return -ENOMEM;
261 
262 	panel->dev = dev;
263 	spi_set_drvdata(spi, panel);
264 
265 	panel->panel_info = of_device_get_match_data(dev);
266 	if (!panel->panel_info)
267 		return -EINVAL;
268 
269 	panel->supply = devm_regulator_get(dev, "power");
270 	if (IS_ERR(panel->supply)) {
271 		dev_err(dev, "Failed to get power supply");
272 		return PTR_ERR(panel->supply);
273 	}
274 
275 	panel->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
276 	if (IS_ERR(panel->reset_gpio)) {
277 		dev_err(dev, "Failed to get reset GPIO");
278 		return PTR_ERR(panel->reset_gpio);
279 	}
280 
281 	spi->bits_per_word = 8;
282 	spi->mode = SPI_MODE_3 | SPI_3WIRE;
283 	err = spi_setup(spi);
284 	if (err) {
285 		dev_err(dev, "Failed to setup SPI");
286 		return err;
287 	}
288 
289 	panel->map = devm_regmap_init_spi(spi, &nt39016_regmap_config);
290 	if (IS_ERR(panel->map)) {
291 		dev_err(dev, "Failed to init regmap");
292 		return PTR_ERR(panel->map);
293 	}
294 
295 	panel->backlight = devm_of_find_backlight(dev);
296 	if (IS_ERR(panel->backlight)) {
297 		err = PTR_ERR(panel->backlight);
298 		if (err != -EPROBE_DEFER)
299 			dev_err(dev, "Failed to get backlight handle");
300 		return err;
301 	}
302 
303 	drm_panel_init(&panel->drm_panel, dev, &nt39016_funcs,
304 		       DRM_MODE_CONNECTOR_DPI);
305 
306 	err = drm_panel_add(&panel->drm_panel);
307 	if (err < 0) {
308 		dev_err(dev, "Failed to register panel");
309 		return err;
310 	}
311 
312 	return 0;
313 }
314 
315 static int nt39016_remove(struct spi_device *spi)
316 {
317 	struct nt39016 *panel = spi_get_drvdata(spi);
318 
319 	drm_panel_remove(&panel->drm_panel);
320 
321 	nt39016_disable(&panel->drm_panel);
322 	nt39016_unprepare(&panel->drm_panel);
323 
324 	return 0;
325 }
326 
327 static const struct drm_display_mode kd035g6_display_modes[] = {
328 	{	/* 60 Hz */
329 		.clock = 6000,
330 		.hdisplay = 320,
331 		.hsync_start = 320 + 10,
332 		.hsync_end = 320 + 10 + 50,
333 		.htotal = 320 + 10 + 50 + 20,
334 		.vdisplay = 240,
335 		.vsync_start = 240 + 5,
336 		.vsync_end = 240 + 5 + 1,
337 		.vtotal = 240 + 5 + 1 + 4,
338 		.vrefresh = 60,
339 		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
340 	},
341 	{	/* 50 Hz */
342 		.clock = 5400,
343 		.hdisplay = 320,
344 		.hsync_start = 320 + 42,
345 		.hsync_end = 320 + 42 + 50,
346 		.htotal = 320 + 42 + 50 + 20,
347 		.vdisplay = 240,
348 		.vsync_start = 240 + 5,
349 		.vsync_end = 240 + 5 + 1,
350 		.vtotal = 240 + 5 + 1 + 4,
351 		.vrefresh = 50,
352 		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
353 	},
354 };
355 
356 static const struct nt39016_panel_info kd035g6_info = {
357 	.display_modes = kd035g6_display_modes,
358 	.num_modes = ARRAY_SIZE(kd035g6_display_modes),
359 	.width_mm = 71,
360 	.height_mm = 53,
361 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
362 	.bus_flags = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
363 };
364 
365 static const struct of_device_id nt39016_of_match[] = {
366 	{ .compatible = "kingdisplay,kd035g6-54nt", .data = &kd035g6_info },
367 	{ /* sentinel */ }
368 };
369 MODULE_DEVICE_TABLE(of, nt39016_of_match);
370 
371 static struct spi_driver nt39016_driver = {
372 	.driver = {
373 		.name = "nt39016",
374 		.of_match_table = nt39016_of_match,
375 	},
376 	.probe = nt39016_probe,
377 	.remove = nt39016_remove,
378 };
379 
380 module_spi_driver(nt39016_driver);
381 
382 MODULE_AUTHOR("Maarten ter Huurne <maarten@treewalker.org>");
383 MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
384 MODULE_LICENSE("GPL v2");
385