1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * DRM driver for MIPI DBI compatible display panels
4  *
5  * Copyright 2022 Noralf Trønnes
6  */
7 
8 #include <linux/backlight.h>
9 #include <linux/delay.h>
10 #include <linux/firmware.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/module.h>
13 #include <linux/property.h>
14 #include <linux/regulator/consumer.h>
15 #include <linux/spi/spi.h>
16 
17 #include <drm/drm_atomic_helper.h>
18 #include <drm/drm_drv.h>
19 #include <drm/drm_fbdev_generic.h>
20 #include <drm/drm_gem_atomic_helper.h>
21 #include <drm/drm_gem_dma_helper.h>
22 #include <drm/drm_managed.h>
23 #include <drm/drm_mipi_dbi.h>
24 #include <drm/drm_modes.h>
25 #include <drm/drm_modeset_helper.h>
26 
27 #include <video/mipi_display.h>
28 
29 static const u8 panel_mipi_dbi_magic[15] = { 'M', 'I', 'P', 'I', ' ', 'D', 'B', 'I',
30 					     0, 0, 0, 0, 0, 0, 0 };
31 
32 /*
33  * The display controller configuration is stored in a firmware file.
34  * The Device Tree 'compatible' property value with a '.bin' suffix is passed
35  * to request_firmware() to fetch this file.
36  */
37 struct panel_mipi_dbi_config {
38 	/* Magic string: panel_mipi_dbi_magic */
39 	u8 magic[15];
40 
41 	/* Config file format version */
42 	u8 file_format_version;
43 
44 	/*
45 	 * MIPI commands to execute when the display pipeline is enabled.
46 	 * This is used to configure the display controller.
47 	 *
48 	 * The commands are stored in a byte array with the format:
49 	 *     command, num_parameters, [ parameter, ...], command, ...
50 	 *
51 	 * Some commands require a pause before the next command can be received.
52 	 * Inserting a delay in the command sequence is done by using the NOP command with one
53 	 * parameter: delay in miliseconds (the No Operation command is part of the MIPI Display
54 	 * Command Set where it has no parameters).
55 	 *
56 	 * Example:
57 	 *     command 0x11
58 	 *     sleep 120ms
59 	 *     command 0xb1 parameters 0x01, 0x2c, 0x2d
60 	 *     command 0x29
61 	 *
62 	 * Byte sequence:
63 	 *     0x11 0x00
64 	 *     0x00 0x01 0x78
65 	 *     0xb1 0x03 0x01 0x2c 0x2d
66 	 *     0x29 0x00
67 	 */
68 	u8 commands[];
69 };
70 
71 struct panel_mipi_dbi_commands {
72 	const u8 *buf;
73 	size_t len;
74 };
75 
76 static struct panel_mipi_dbi_commands *
77 panel_mipi_dbi_check_commands(struct device *dev, const struct firmware *fw)
78 {
79 	const struct panel_mipi_dbi_config *config = (struct panel_mipi_dbi_config *)fw->data;
80 	struct panel_mipi_dbi_commands *commands;
81 	size_t size = fw->size, commands_len;
82 	unsigned int i = 0;
83 
84 	if (size < sizeof(*config) + 2) { /* At least 1 command */
85 		dev_err(dev, "config: file size=%zu is too small\n", size);
86 		return ERR_PTR(-EINVAL);
87 	}
88 
89 	if (memcmp(config->magic, panel_mipi_dbi_magic, sizeof(config->magic))) {
90 		dev_err(dev, "config: Bad magic: %15ph\n", config->magic);
91 		return ERR_PTR(-EINVAL);
92 	}
93 
94 	if (config->file_format_version != 1) {
95 		dev_err(dev, "config: version=%u is not supported\n", config->file_format_version);
96 		return ERR_PTR(-EINVAL);
97 	}
98 
99 	drm_dev_dbg(dev, DRM_UT_DRIVER, "size=%zu version=%u\n", size, config->file_format_version);
100 
101 	commands_len = size - sizeof(*config);
102 
103 	while ((i + 1) < commands_len) {
104 		u8 command = config->commands[i++];
105 		u8 num_parameters = config->commands[i++];
106 		const u8 *parameters = &config->commands[i];
107 
108 		i += num_parameters;
109 		if (i > commands_len) {
110 			dev_err(dev, "config: command=0x%02x num_parameters=%u overflows\n",
111 				command, num_parameters);
112 			return ERR_PTR(-EINVAL);
113 		}
114 
115 		if (command == 0x00 && num_parameters == 1)
116 			drm_dev_dbg(dev, DRM_UT_DRIVER, "sleep %ums\n", parameters[0]);
117 		else
118 			drm_dev_dbg(dev, DRM_UT_DRIVER, "command %02x %*ph\n",
119 				    command, num_parameters, parameters);
120 	}
121 
122 	if (i != commands_len) {
123 		dev_err(dev, "config: malformed command array\n");
124 		return ERR_PTR(-EINVAL);
125 	}
126 
127 	commands = devm_kzalloc(dev, sizeof(*commands), GFP_KERNEL);
128 	if (!commands)
129 		return ERR_PTR(-ENOMEM);
130 
131 	commands->len = commands_len;
132 	commands->buf = devm_kmemdup(dev, config->commands, commands->len, GFP_KERNEL);
133 	if (!commands->buf)
134 		return ERR_PTR(-ENOMEM);
135 
136 	return commands;
137 }
138 
139 static struct panel_mipi_dbi_commands *panel_mipi_dbi_commands_from_fw(struct device *dev)
140 {
141 	struct panel_mipi_dbi_commands *commands;
142 	const struct firmware *fw;
143 	const char *compatible;
144 	char fw_name[40];
145 	int ret;
146 
147 	ret = of_property_read_string_index(dev->of_node, "compatible", 0, &compatible);
148 	if (ret)
149 		return ERR_PTR(ret);
150 
151 	snprintf(fw_name, sizeof(fw_name), "%s.bin", compatible);
152 	ret = request_firmware(&fw, fw_name, dev);
153 	if (ret) {
154 		dev_err(dev, "No config file found for compatible '%s' (error=%d)\n",
155 			compatible, ret);
156 
157 		return ERR_PTR(ret);
158 	}
159 
160 	commands = panel_mipi_dbi_check_commands(dev, fw);
161 	release_firmware(fw);
162 
163 	return commands;
164 }
165 
166 static void panel_mipi_dbi_commands_execute(struct mipi_dbi *dbi,
167 					    struct panel_mipi_dbi_commands *commands)
168 {
169 	unsigned int i = 0;
170 
171 	if (!commands)
172 		return;
173 
174 	while (i < commands->len) {
175 		u8 command = commands->buf[i++];
176 		u8 num_parameters = commands->buf[i++];
177 		const u8 *parameters = &commands->buf[i];
178 
179 		if (command == 0x00 && num_parameters == 1)
180 			msleep(parameters[0]);
181 		else if (num_parameters)
182 			mipi_dbi_command_stackbuf(dbi, command, parameters, num_parameters);
183 		else
184 			mipi_dbi_command(dbi, command);
185 
186 		i += num_parameters;
187 	}
188 }
189 
190 static void panel_mipi_dbi_enable(struct drm_simple_display_pipe *pipe,
191 				  struct drm_crtc_state *crtc_state,
192 				  struct drm_plane_state *plane_state)
193 {
194 	struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);
195 	struct mipi_dbi *dbi = &dbidev->dbi;
196 	int ret, idx;
197 
198 	if (!drm_dev_enter(pipe->crtc.dev, &idx))
199 		return;
200 
201 	drm_dbg(pipe->crtc.dev, "\n");
202 
203 	ret = mipi_dbi_poweron_conditional_reset(dbidev);
204 	if (ret < 0)
205 		goto out_exit;
206 	if (!ret)
207 		panel_mipi_dbi_commands_execute(dbi, dbidev->driver_private);
208 
209 	mipi_dbi_enable_flush(dbidev, crtc_state, plane_state);
210 out_exit:
211 	drm_dev_exit(idx);
212 }
213 
214 static const struct drm_simple_display_pipe_funcs panel_mipi_dbi_pipe_funcs = {
215 	DRM_MIPI_DBI_SIMPLE_DISPLAY_PIPE_FUNCS(panel_mipi_dbi_enable),
216 };
217 
218 DEFINE_DRM_GEM_DMA_FOPS(panel_mipi_dbi_fops);
219 
220 static const struct drm_driver panel_mipi_dbi_driver = {
221 	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
222 	.fops			= &panel_mipi_dbi_fops,
223 	DRM_GEM_DMA_DRIVER_OPS_VMAP,
224 	.debugfs_init		= mipi_dbi_debugfs_init,
225 	.name			= "panel-mipi-dbi",
226 	.desc			= "MIPI DBI compatible display panel",
227 	.date			= "20220103",
228 	.major			= 1,
229 	.minor			= 0,
230 };
231 
232 static int panel_mipi_dbi_get_mode(struct mipi_dbi_dev *dbidev, struct drm_display_mode *mode)
233 {
234 	struct device *dev = dbidev->drm.dev;
235 	u16 hback_porch, vback_porch;
236 	int ret;
237 
238 	ret = of_get_drm_panel_display_mode(dev->of_node, mode, NULL);
239 	if (ret) {
240 		dev_err(dev, "%pOF: failed to get panel-timing (error=%d)\n", dev->of_node, ret);
241 		return ret;
242 	}
243 
244 	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
245 
246 	hback_porch = mode->htotal - mode->hsync_end;
247 	vback_porch = mode->vtotal - mode->vsync_end;
248 
249 	/*
250 	 * Make sure width and height are set and that only back porch and
251 	 * pixelclock are set in the other timing values. Also check that
252 	 * width and height don't exceed the 16-bit value specified by MIPI DCS.
253 	 */
254 	if (!mode->hdisplay || !mode->vdisplay || mode->flags ||
255 	    mode->hsync_end > mode->hdisplay || (hback_porch + mode->hdisplay) > 0xffff ||
256 	    mode->vsync_end > mode->vdisplay || (vback_porch + mode->vdisplay) > 0xffff) {
257 		dev_err(dev, "%pOF: panel-timing out of bounds\n", dev->of_node);
258 		return -EINVAL;
259 	}
260 
261 	/* The driver doesn't use the pixel clock but it is mandatory so fake one if not set */
262 	if (!mode->clock)
263 		mode->clock = mode->htotal * mode->vtotal * 60 / 1000;
264 
265 	dbidev->top_offset = vback_porch;
266 	dbidev->left_offset = hback_porch;
267 
268 	return 0;
269 }
270 
271 static int panel_mipi_dbi_spi_probe(struct spi_device *spi)
272 {
273 	struct device *dev = &spi->dev;
274 	struct drm_display_mode mode;
275 	struct mipi_dbi_dev *dbidev;
276 	struct drm_device *drm;
277 	struct mipi_dbi *dbi;
278 	struct gpio_desc *dc;
279 	int ret;
280 
281 	dbidev = devm_drm_dev_alloc(dev, &panel_mipi_dbi_driver, struct mipi_dbi_dev, drm);
282 	if (IS_ERR(dbidev))
283 		return PTR_ERR(dbidev);
284 
285 	dbi = &dbidev->dbi;
286 	drm = &dbidev->drm;
287 
288 	ret = panel_mipi_dbi_get_mode(dbidev, &mode);
289 	if (ret)
290 		return ret;
291 
292 	dbidev->regulator = devm_regulator_get(dev, "power");
293 	if (IS_ERR(dbidev->regulator))
294 		return dev_err_probe(dev, PTR_ERR(dbidev->regulator),
295 				     "Failed to get regulator 'power'\n");
296 
297 	dbidev->io_regulator = devm_regulator_get(dev, "io");
298 	if (IS_ERR(dbidev->io_regulator))
299 		return dev_err_probe(dev, PTR_ERR(dbidev->io_regulator),
300 				     "Failed to get regulator 'io'\n");
301 
302 	dbidev->backlight = devm_of_find_backlight(dev);
303 	if (IS_ERR(dbidev->backlight))
304 		return dev_err_probe(dev, PTR_ERR(dbidev->backlight), "Failed to get backlight\n");
305 
306 	dbi->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
307 	if (IS_ERR(dbi->reset))
308 		return dev_err_probe(dev, PTR_ERR(dbi->reset), "Failed to get GPIO 'reset'\n");
309 
310 	/* Multiple panels can share the "dc" GPIO, but only if they are on the same SPI bus! */
311 	dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
312 	if (IS_ERR(dc))
313 		return dev_err_probe(dev, PTR_ERR(dc), "Failed to get GPIO 'dc'\n");
314 
315 	ret = mipi_dbi_spi_init(spi, dbi, dc);
316 	if (ret)
317 		return ret;
318 
319 	if (device_property_present(dev, "write-only"))
320 		dbi->read_commands = NULL;
321 
322 	dbidev->driver_private = panel_mipi_dbi_commands_from_fw(dev);
323 	if (IS_ERR(dbidev->driver_private))
324 		return PTR_ERR(dbidev->driver_private);
325 
326 	ret = mipi_dbi_dev_init(dbidev, &panel_mipi_dbi_pipe_funcs, &mode, 0);
327 	if (ret)
328 		return ret;
329 
330 	drm_mode_config_reset(drm);
331 
332 	ret = drm_dev_register(drm, 0);
333 	if (ret)
334 		return ret;
335 
336 	spi_set_drvdata(spi, drm);
337 
338 	drm_fbdev_generic_setup(drm, 0);
339 
340 	return 0;
341 }
342 
343 static void panel_mipi_dbi_spi_remove(struct spi_device *spi)
344 {
345 	struct drm_device *drm = spi_get_drvdata(spi);
346 
347 	drm_dev_unplug(drm);
348 	drm_atomic_helper_shutdown(drm);
349 }
350 
351 static void panel_mipi_dbi_spi_shutdown(struct spi_device *spi)
352 {
353 	drm_atomic_helper_shutdown(spi_get_drvdata(spi));
354 }
355 
356 static int __maybe_unused panel_mipi_dbi_pm_suspend(struct device *dev)
357 {
358 	return drm_mode_config_helper_suspend(dev_get_drvdata(dev));
359 }
360 
361 static int __maybe_unused panel_mipi_dbi_pm_resume(struct device *dev)
362 {
363 	drm_mode_config_helper_resume(dev_get_drvdata(dev));
364 
365 	return 0;
366 }
367 
368 static const struct dev_pm_ops panel_mipi_dbi_pm_ops = {
369 	SET_SYSTEM_SLEEP_PM_OPS(panel_mipi_dbi_pm_suspend, panel_mipi_dbi_pm_resume)
370 };
371 
372 static const struct of_device_id panel_mipi_dbi_spi_of_match[] = {
373 	{ .compatible = "panel-mipi-dbi-spi" },
374 	{},
375 };
376 MODULE_DEVICE_TABLE(of, panel_mipi_dbi_spi_of_match);
377 
378 static const struct spi_device_id panel_mipi_dbi_spi_id[] = {
379 	{ "panel-mipi-dbi-spi", 0 },
380 	{ },
381 };
382 MODULE_DEVICE_TABLE(spi, panel_mipi_dbi_spi_id);
383 
384 static struct spi_driver panel_mipi_dbi_spi_driver = {
385 	.driver = {
386 		.name = "panel-mipi-dbi-spi",
387 		.owner = THIS_MODULE,
388 		.of_match_table = panel_mipi_dbi_spi_of_match,
389 		.pm = &panel_mipi_dbi_pm_ops,
390 	},
391 	.id_table = panel_mipi_dbi_spi_id,
392 	.probe = panel_mipi_dbi_spi_probe,
393 	.remove = panel_mipi_dbi_spi_remove,
394 	.shutdown = panel_mipi_dbi_spi_shutdown,
395 };
396 module_spi_driver(panel_mipi_dbi_spi_driver);
397 
398 MODULE_DESCRIPTION("MIPI DBI compatible display panel driver");
399 MODULE_AUTHOR("Noralf Trønnes");
400 MODULE_LICENSE("GPL");
401