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/delay.h>
10 #include <linux/device.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/media-bus-format.h>
13 #include <linux/module.h>
14 #include <linux/of.h>
15 #include <linux/of_device.h>
16 #include <linux/regmap.h>
17 #include <linux/regulator/consumer.h>
18 #include <linux/spi/spi.h>
19 
20 #include <drm/drm_modes.h>
21 #include <drm/drm_panel.h>
22 
23 enum nt39016_regs {
24 	NT39016_REG_SYSTEM,
25 	NT39016_REG_TIMING,
26 	NT39016_REG_OP,
27 	NT39016_REG_DATA_IN,
28 	NT39016_REG_SRC_TIMING_DELAY,
29 	NT39016_REG_GATE_TIMING_DELAY,
30 	NT39016_REG_RESERVED,
31 	NT39016_REG_INITIAL_FUNC,
32 	NT39016_REG_CONTRAST,
33 	NT39016_REG_BRIGHTNESS,
34 	NT39016_REG_HUE_SATURATION,
35 	NT39016_REG_RB_SUBCONTRAST,
36 	NT39016_REG_R_SUBBRIGHTNESS,
37 	NT39016_REG_B_SUBBRIGHTNESS,
38 	NT39016_REG_VCOMDC,
39 	NT39016_REG_VCOMAC,
40 	NT39016_REG_VGAM2,
41 	NT39016_REG_VGAM34,
42 	NT39016_REG_VGAM56,
43 	NT39016_REG_VCOMDC_TRIM = 0x1e,
44 	NT39016_REG_DISPLAY_MODE = 0x20,
45 };
46 
47 #define NT39016_SYSTEM_RESET_N	BIT(0)
48 #define NT39016_SYSTEM_STANDBY	BIT(1)
49 
50 struct nt39016_panel_info {
51 	const struct drm_display_mode *display_modes;
52 	unsigned int num_modes;
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 regmap *map;
60 	struct regulator *supply;
61 	const struct nt39016_panel_info *panel_info;
62 
63 	struct gpio_desc *reset_gpio;
64 };
65 
to_nt39016(struct drm_panel * panel)66 static inline struct nt39016 *to_nt39016(struct drm_panel *panel)
67 {
68 	return container_of(panel, struct nt39016, drm_panel);
69 }
70 
71 #define RV(REG, VAL) { .reg = (REG), .def = (VAL), .delay_us = 2 }
72 static const struct reg_sequence nt39016_panel_regs[] = {
73 	RV(NT39016_REG_SYSTEM, 0x00),
74 	RV(NT39016_REG_TIMING, 0x00),
75 	RV(NT39016_REG_OP, 0x03),
76 	RV(NT39016_REG_DATA_IN, 0xCC),
77 	RV(NT39016_REG_SRC_TIMING_DELAY, 0x46),
78 	RV(NT39016_REG_GATE_TIMING_DELAY, 0x05),
79 	RV(NT39016_REG_RESERVED, 0x00),
80 	RV(NT39016_REG_INITIAL_FUNC, 0x00),
81 	RV(NT39016_REG_CONTRAST, 0x08),
82 	RV(NT39016_REG_BRIGHTNESS, 0x40),
83 	RV(NT39016_REG_HUE_SATURATION, 0x88),
84 	RV(NT39016_REG_RB_SUBCONTRAST, 0x88),
85 	RV(NT39016_REG_R_SUBBRIGHTNESS, 0x20),
86 	RV(NT39016_REG_B_SUBBRIGHTNESS, 0x20),
87 	RV(NT39016_REG_VCOMDC, 0x67),
88 	RV(NT39016_REG_VCOMAC, 0xA4),
89 	RV(NT39016_REG_VGAM2, 0x04),
90 	RV(NT39016_REG_VGAM34, 0x24),
91 	RV(NT39016_REG_VGAM56, 0x24),
92 	RV(NT39016_REG_DISPLAY_MODE, 0x00),
93 };
94 
95 #undef RV
96 
97 static const struct regmap_range nt39016_regmap_no_ranges[] = {
98 	regmap_reg_range(0x13, 0x1D),
99 	regmap_reg_range(0x1F, 0x1F),
100 };
101 
102 static const struct regmap_access_table nt39016_regmap_access_table = {
103 	.no_ranges = nt39016_regmap_no_ranges,
104 	.n_no_ranges = ARRAY_SIZE(nt39016_regmap_no_ranges),
105 };
106 
107 static const struct regmap_config nt39016_regmap_config = {
108 	.reg_bits = 6,
109 	.pad_bits = 2,
110 	.val_bits = 8,
111 
112 	.max_register = NT39016_REG_DISPLAY_MODE,
113 	.wr_table = &nt39016_regmap_access_table,
114 	.write_flag_mask = 0x02,
115 
116 	.cache_type = REGCACHE_FLAT,
117 };
118 
nt39016_prepare(struct drm_panel * drm_panel)119 static int nt39016_prepare(struct drm_panel *drm_panel)
120 {
121 	struct nt39016 *panel = to_nt39016(drm_panel);
122 	int err;
123 
124 	err = regulator_enable(panel->supply);
125 	if (err) {
126 		dev_err(drm_panel->dev, "Failed to enable power supply: %d\n", err);
127 		return err;
128 	}
129 
130 	/*
131 	 * Reset the NT39016.
132 	 * The documentation says the reset pulse should be at least 40 us to
133 	 * pass the glitch filter, but when testing I see some resets fail and
134 	 * some succeed when using a 70 us delay, so we use 100 us instead.
135 	 */
136 	gpiod_set_value_cansleep(panel->reset_gpio, 1);
137 	usleep_range(100, 1000);
138 	gpiod_set_value_cansleep(panel->reset_gpio, 0);
139 	udelay(2);
140 
141 	/* Init all registers. */
142 	err = regmap_multi_reg_write(panel->map, nt39016_panel_regs,
143 				     ARRAY_SIZE(nt39016_panel_regs));
144 	if (err) {
145 		dev_err(drm_panel->dev, "Failed to init registers: %d\n", err);
146 		goto err_disable_regulator;
147 	}
148 
149 	return 0;
150 
151 err_disable_regulator:
152 	regulator_disable(panel->supply);
153 	return err;
154 }
155 
nt39016_unprepare(struct drm_panel * drm_panel)156 static int nt39016_unprepare(struct drm_panel *drm_panel)
157 {
158 	struct nt39016 *panel = to_nt39016(drm_panel);
159 
160 	gpiod_set_value_cansleep(panel->reset_gpio, 1);
161 
162 	regulator_disable(panel->supply);
163 
164 	return 0;
165 }
166 
nt39016_enable(struct drm_panel * drm_panel)167 static int nt39016_enable(struct drm_panel *drm_panel)
168 {
169 	struct nt39016 *panel = to_nt39016(drm_panel);
170 	int ret;
171 
172 	ret = regmap_write(panel->map, NT39016_REG_SYSTEM,
173 			   NT39016_SYSTEM_RESET_N | NT39016_SYSTEM_STANDBY);
174 	if (ret) {
175 		dev_err(drm_panel->dev, "Unable to enable panel: %d\n", ret);
176 		return ret;
177 	}
178 
179 	if (drm_panel->backlight) {
180 		/* Wait for the picture to be ready before enabling backlight */
181 		msleep(150);
182 	}
183 
184 	return 0;
185 }
186 
nt39016_disable(struct drm_panel * drm_panel)187 static int nt39016_disable(struct drm_panel *drm_panel)
188 {
189 	struct nt39016 *panel = to_nt39016(drm_panel);
190 	int err;
191 
192 	err = regmap_write(panel->map, NT39016_REG_SYSTEM,
193 			   NT39016_SYSTEM_RESET_N);
194 	if (err) {
195 		dev_err(drm_panel->dev, "Unable to disable panel: %d\n", err);
196 		return err;
197 	}
198 
199 	return 0;
200 }
201 
nt39016_get_modes(struct drm_panel * drm_panel,struct drm_connector * connector)202 static int nt39016_get_modes(struct drm_panel *drm_panel,
203 			     struct drm_connector *connector)
204 {
205 	struct nt39016 *panel = to_nt39016(drm_panel);
206 	const struct nt39016_panel_info *panel_info = panel->panel_info;
207 	struct drm_display_mode *mode;
208 	unsigned int i;
209 
210 	for (i = 0; i < panel_info->num_modes; i++) {
211 		mode = drm_mode_duplicate(connector->dev,
212 					  &panel_info->display_modes[i]);
213 		if (!mode)
214 			return -ENOMEM;
215 
216 		drm_mode_set_name(mode);
217 
218 		mode->type = DRM_MODE_TYPE_DRIVER;
219 		if (panel_info->num_modes == 1)
220 			mode->type |= DRM_MODE_TYPE_PREFERRED;
221 
222 		drm_mode_probed_add(connector, mode);
223 	}
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 panel_info->num_modes;
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 
nt39016_probe(struct spi_device * spi)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 	spi_set_drvdata(spi, panel);
255 
256 	panel->panel_info = of_device_get_match_data(dev);
257 	if (!panel->panel_info)
258 		return -EINVAL;
259 
260 	panel->supply = devm_regulator_get(dev, "power");
261 	if (IS_ERR(panel->supply))
262 		return dev_err_probe(dev, PTR_ERR(panel->supply),
263 				     "Failed to get power supply\n");
264 
265 	panel->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
266 	if (IS_ERR(panel->reset_gpio))
267 		return dev_err_probe(dev, PTR_ERR(panel->reset_gpio), "Failed to get reset GPIO\n");
268 
269 	spi->bits_per_word = 8;
270 	spi->mode = SPI_MODE_3 | SPI_3WIRE;
271 	err = spi_setup(spi);
272 	if (err) {
273 		dev_err(dev, "Failed to setup SPI\n");
274 		return err;
275 	}
276 
277 	panel->map = devm_regmap_init_spi(spi, &nt39016_regmap_config);
278 	if (IS_ERR(panel->map)) {
279 		dev_err(dev, "Failed to init regmap\n");
280 		return PTR_ERR(panel->map);
281 	}
282 
283 	drm_panel_init(&panel->drm_panel, dev, &nt39016_funcs,
284 		       DRM_MODE_CONNECTOR_DPI);
285 
286 	err = drm_panel_of_backlight(&panel->drm_panel);
287 	if (err)
288 		return dev_err_probe(dev, err, "Failed to get backlight handle\n");
289 
290 	drm_panel_add(&panel->drm_panel);
291 
292 	return 0;
293 }
294 
nt39016_remove(struct spi_device * spi)295 static void nt39016_remove(struct spi_device *spi)
296 {
297 	struct nt39016 *panel = spi_get_drvdata(spi);
298 
299 	drm_panel_remove(&panel->drm_panel);
300 
301 	nt39016_disable(&panel->drm_panel);
302 	nt39016_unprepare(&panel->drm_panel);
303 }
304 
305 static const struct drm_display_mode kd035g6_display_modes[] = {
306 	{	/* 60 Hz */
307 		.clock = 6000,
308 		.hdisplay = 320,
309 		.hsync_start = 320 + 10,
310 		.hsync_end = 320 + 10 + 50,
311 		.htotal = 320 + 10 + 50 + 20,
312 		.vdisplay = 240,
313 		.vsync_start = 240 + 5,
314 		.vsync_end = 240 + 5 + 1,
315 		.vtotal = 240 + 5 + 1 + 4,
316 		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
317 	},
318 	{	/* 50 Hz */
319 		.clock = 5400,
320 		.hdisplay = 320,
321 		.hsync_start = 320 + 42,
322 		.hsync_end = 320 + 42 + 50,
323 		.htotal = 320 + 42 + 50 + 20,
324 		.vdisplay = 240,
325 		.vsync_start = 240 + 5,
326 		.vsync_end = 240 + 5 + 1,
327 		.vtotal = 240 + 5 + 1 + 4,
328 		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
329 	},
330 };
331 
332 static const struct nt39016_panel_info kd035g6_info = {
333 	.display_modes = kd035g6_display_modes,
334 	.num_modes = ARRAY_SIZE(kd035g6_display_modes),
335 	.width_mm = 71,
336 	.height_mm = 53,
337 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
338 	.bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
339 };
340 
341 static const struct of_device_id nt39016_of_match[] = {
342 	{ .compatible = "kingdisplay,kd035g6-54nt", .data = &kd035g6_info },
343 	{ /* sentinel */ }
344 };
345 MODULE_DEVICE_TABLE(of, nt39016_of_match);
346 
347 static struct spi_driver nt39016_driver = {
348 	.driver = {
349 		.name = "nt39016",
350 		.of_match_table = nt39016_of_match,
351 	},
352 	.probe = nt39016_probe,
353 	.remove = nt39016_remove,
354 };
355 
356 module_spi_driver(nt39016_driver);
357 
358 MODULE_AUTHOR("Maarten ter Huurne <maarten@treewalker.org>");
359 MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
360 MODULE_LICENSE("GPL v2");
361