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_client_setup.h>
 19#include <drm/drm_drv.h>
 20#include <drm/drm_fbdev_dma.h>
 21#include <drm/drm_gem_atomic_helper.h>
 22#include <drm/drm_gem_dma_helper.h>
 23#include <drm/drm_managed.h>
 24#include <drm/drm_mipi_dbi.h>
 25#include <drm/drm_modes.h>
 26#include <drm/drm_modeset_helper.h>
 27
 28#include <video/mipi_display.h>
 29
 30struct panel_mipi_dbi_format {
 31	const char *name;
 32	u32 fourcc;
 33	unsigned int bpp;
 34};
 35
 36static const struct panel_mipi_dbi_format panel_mipi_dbi_formats[] = {
 37	{ "r5g6b5", DRM_FORMAT_RGB565, 16 },
 38	{ "b6x2g6x2r6x2", DRM_FORMAT_RGB888, 24 },
 39};
 40
 41static int panel_mipi_dbi_get_format(struct device *dev, u32 *formats, unsigned int *bpp)
 42{
 43	const char *format_name;
 44	unsigned int i;
 45	int ret;
 46
 47	formats[1] = DRM_FORMAT_XRGB8888;
 48
 49	ret = device_property_read_string(dev, "format", &format_name);
 50	if (ret) {
 51		/* Old Device Trees don't have this property */
 52		formats[0] = DRM_FORMAT_RGB565;
 53		*bpp = 16;
 54		return 0;
 55	}
 56
 57	for (i = 0; i < ARRAY_SIZE(panel_mipi_dbi_formats); i++) {
 58		const struct panel_mipi_dbi_format *format = &panel_mipi_dbi_formats[i];
 59
 60		if (strcmp(format_name, format->name))
 61			continue;
 62
 63		formats[0] = format->fourcc;
 64		*bpp = format->bpp;
 65		return 0;
 66	}
 67
 68	dev_err(dev, "Pixel format is not supported: '%s'\n", format_name);
 69
 70	return -EINVAL;
 71}
 72
 73static const u8 panel_mipi_dbi_magic[15] = { 'M', 'I', 'P', 'I', ' ', 'D', 'B', 'I',
 74					     0, 0, 0, 0, 0, 0, 0 };
 75
 76/*
 77 * The display controller configuration is stored in a firmware file.
 78 * The Device Tree 'compatible' property value with a '.bin' suffix is passed
 79 * to request_firmware() to fetch this file.
 80 */
 81struct panel_mipi_dbi_config {
 82	/* Magic string: panel_mipi_dbi_magic */
 83	u8 magic[15];
 84
 85	/* Config file format version */
 86	u8 file_format_version;
 87
 88	/*
 89	 * MIPI commands to execute when the display pipeline is enabled.
 90	 * This is used to configure the display controller.
 91	 *
 92	 * The commands are stored in a byte array with the format:
 93	 *     command, num_parameters, [ parameter, ...], command, ...
 94	 *
 95	 * Some commands require a pause before the next command can be received.
 96	 * Inserting a delay in the command sequence is done by using the NOP command with one
 97	 * parameter: delay in miliseconds (the No Operation command is part of the MIPI Display
 98	 * Command Set where it has no parameters).
 99	 *
100	 * Example:
101	 *     command 0x11
102	 *     sleep 120ms
103	 *     command 0xb1 parameters 0x01, 0x2c, 0x2d
104	 *     command 0x29
105	 *
106	 * Byte sequence:
107	 *     0x11 0x00
108	 *     0x00 0x01 0x78
109	 *     0xb1 0x03 0x01 0x2c 0x2d
110	 *     0x29 0x00
111	 */
112	u8 commands[];
113};
114
115struct panel_mipi_dbi_commands {
116	const u8 *buf;
117	size_t len;
118};
119
120static struct panel_mipi_dbi_commands *
121panel_mipi_dbi_check_commands(struct device *dev, const struct firmware *fw)
122{
123	const struct panel_mipi_dbi_config *config = (struct panel_mipi_dbi_config *)fw->data;
124	struct panel_mipi_dbi_commands *commands;
125	size_t size = fw->size, commands_len;
126	unsigned int i = 0;
127
128	if (size < sizeof(*config) + 2) { /* At least 1 command */
129		dev_err(dev, "config: file size=%zu is too small\n", size);
130		return ERR_PTR(-EINVAL);
131	}
132
133	if (memcmp(config->magic, panel_mipi_dbi_magic, sizeof(config->magic))) {
134		dev_err(dev, "config: Bad magic: %15ph\n", config->magic);
135		return ERR_PTR(-EINVAL);
136	}
137
138	if (config->file_format_version != 1) {
139		dev_err(dev, "config: version=%u is not supported\n", config->file_format_version);
140		return ERR_PTR(-EINVAL);
141	}
142
143	drm_dev_dbg(dev, DRM_UT_DRIVER, "size=%zu version=%u\n", size, config->file_format_version);
144
145	commands_len = size - sizeof(*config);
146
147	while ((i + 1) < commands_len) {
148		u8 command = config->commands[i++];
149		u8 num_parameters = config->commands[i++];
150		const u8 *parameters = &config->commands[i];
151
152		i += num_parameters;
153		if (i > commands_len) {
154			dev_err(dev, "config: command=0x%02x num_parameters=%u overflows\n",
155				command, num_parameters);
156			return ERR_PTR(-EINVAL);
157		}
158
159		if (command == 0x00 && num_parameters == 1)
160			drm_dev_dbg(dev, DRM_UT_DRIVER, "sleep %ums\n", parameters[0]);
161		else
162			drm_dev_dbg(dev, DRM_UT_DRIVER, "command %02x %*ph\n",
163				    command, num_parameters, parameters);
164	}
165
166	if (i != commands_len) {
167		dev_err(dev, "config: malformed command array\n");
168		return ERR_PTR(-EINVAL);
169	}
170
171	commands = devm_kzalloc(dev, sizeof(*commands), GFP_KERNEL);
172	if (!commands)
173		return ERR_PTR(-ENOMEM);
174
175	commands->len = commands_len;
176	commands->buf = devm_kmemdup(dev, config->commands, commands->len, GFP_KERNEL);
177	if (!commands->buf)
178		return ERR_PTR(-ENOMEM);
179
180	return commands;
181}
182
183static struct panel_mipi_dbi_commands *panel_mipi_dbi_commands_from_fw(struct device *dev)
184{
185	struct panel_mipi_dbi_commands *commands;
186	const struct firmware *fw;
187	const char *compatible;
188	char fw_name[40];
189	int ret;
190
191	ret = of_property_read_string_index(dev->of_node, "compatible", 0, &compatible);
192	if (ret)
193		return ERR_PTR(ret);
194
195	snprintf(fw_name, sizeof(fw_name), "%s.bin", compatible);
196	ret = request_firmware(&fw, fw_name, dev);
197	if (ret) {
198		dev_err(dev, "No config file found for compatible '%s' (error=%d)\n",
199			compatible, ret);
200
201		return ERR_PTR(ret);
202	}
203
204	commands = panel_mipi_dbi_check_commands(dev, fw);
205	release_firmware(fw);
206
207	return commands;
208}
209
210static void panel_mipi_dbi_commands_execute(struct mipi_dbi *dbi,
211					    struct panel_mipi_dbi_commands *commands)
212{
213	unsigned int i = 0;
214
215	if (!commands)
216		return;
217
218	while (i < commands->len) {
219		u8 command = commands->buf[i++];
220		u8 num_parameters = commands->buf[i++];
221		const u8 *parameters = &commands->buf[i];
222
223		if (command == 0x00 && num_parameters == 1)
224			msleep(parameters[0]);
225		else if (num_parameters)
226			mipi_dbi_command_stackbuf(dbi, command, parameters, num_parameters);
227		else
228			mipi_dbi_command(dbi, command);
229
230		i += num_parameters;
231	}
232}
233
234static void panel_mipi_dbi_enable(struct drm_simple_display_pipe *pipe,
235				  struct drm_crtc_state *crtc_state,
236				  struct drm_plane_state *plane_state)
237{
238	struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);
239	struct mipi_dbi *dbi = &dbidev->dbi;
240	int ret, idx;
241
242	if (!drm_dev_enter(pipe->crtc.dev, &idx))
243		return;
244
245	drm_dbg(pipe->crtc.dev, "\n");
246
247	ret = mipi_dbi_poweron_conditional_reset(dbidev);
248	if (ret < 0)
249		goto out_exit;
250	if (!ret)
251		panel_mipi_dbi_commands_execute(dbi, dbidev->driver_private);
252
253	mipi_dbi_enable_flush(dbidev, crtc_state, plane_state);
254out_exit:
255	drm_dev_exit(idx);
256}
257
258static const struct drm_simple_display_pipe_funcs panel_mipi_dbi_pipe_funcs = {
259	DRM_MIPI_DBI_SIMPLE_DISPLAY_PIPE_FUNCS(panel_mipi_dbi_enable),
260};
261
262DEFINE_DRM_GEM_DMA_FOPS(panel_mipi_dbi_fops);
263
264static const struct drm_driver panel_mipi_dbi_driver = {
265	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
266	.fops			= &panel_mipi_dbi_fops,
267	DRM_GEM_DMA_DRIVER_OPS_VMAP,
268	DRM_FBDEV_DMA_DRIVER_OPS,
269	.debugfs_init		= mipi_dbi_debugfs_init,
270	.name			= "panel-mipi-dbi",
271	.desc			= "MIPI DBI compatible display panel",
272	.date			= "20220103",
273	.major			= 1,
274	.minor			= 0,
275};
276
277static int panel_mipi_dbi_get_mode(struct mipi_dbi_dev *dbidev, struct drm_display_mode *mode)
278{
279	struct device *dev = dbidev->drm.dev;
280	u16 hback_porch, vback_porch;
281	int ret;
282
283	ret = of_get_drm_panel_display_mode(dev->of_node, mode, NULL);
284	if (ret) {
285		dev_err(dev, "%pOF: failed to get panel-timing (error=%d)\n", dev->of_node, ret);
286		return ret;
287	}
288
289	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
290
291	hback_porch = mode->htotal - mode->hsync_end;
292	vback_porch = mode->vtotal - mode->vsync_end;
293
294	/*
295	 * Make sure width and height are set and that only back porch and
296	 * pixelclock are set in the other timing values. Also check that
297	 * width and height don't exceed the 16-bit value specified by MIPI DCS.
298	 */
299	if (!mode->hdisplay || !mode->vdisplay || mode->flags ||
300	    mode->hsync_end > mode->hdisplay || (hback_porch + mode->hdisplay) > 0xffff ||
301	    mode->vsync_end > mode->vdisplay || (vback_porch + mode->vdisplay) > 0xffff) {
302		dev_err(dev, "%pOF: panel-timing out of bounds\n", dev->of_node);
303		return -EINVAL;
304	}
305
306	/* The driver doesn't use the pixel clock but it is mandatory so fake one if not set */
307	if (!mode->clock)
308		mode->clock = mode->htotal * mode->vtotal * 60 / 1000;
309
310	dbidev->top_offset = vback_porch;
311	dbidev->left_offset = hback_porch;
312
313	return 0;
314}
315
316static int panel_mipi_dbi_spi_probe(struct spi_device *spi)
317{
318	struct device *dev = &spi->dev;
319	struct drm_display_mode mode;
320	struct mipi_dbi_dev *dbidev;
321	struct drm_device *drm;
322	struct mipi_dbi *dbi;
323	struct gpio_desc *dc;
324	unsigned int bpp;
325	size_t buf_size;
326	u32 formats[2];
327	int ret;
328
329	dbidev = devm_drm_dev_alloc(dev, &panel_mipi_dbi_driver, struct mipi_dbi_dev, drm);
330	if (IS_ERR(dbidev))
331		return PTR_ERR(dbidev);
332
333	dbi = &dbidev->dbi;
334	drm = &dbidev->drm;
335
336	ret = panel_mipi_dbi_get_mode(dbidev, &mode);
337	if (ret)
338		return ret;
339
340	dbidev->regulator = devm_regulator_get(dev, "power");
341	if (IS_ERR(dbidev->regulator))
342		return dev_err_probe(dev, PTR_ERR(dbidev->regulator),
343				     "Failed to get regulator 'power'\n");
344
345	dbidev->io_regulator = devm_regulator_get(dev, "io");
346	if (IS_ERR(dbidev->io_regulator))
347		return dev_err_probe(dev, PTR_ERR(dbidev->io_regulator),
348				     "Failed to get regulator 'io'\n");
349
350	dbidev->backlight = devm_of_find_backlight(dev);
351	if (IS_ERR(dbidev->backlight))
352		return dev_err_probe(dev, PTR_ERR(dbidev->backlight), "Failed to get backlight\n");
353
354	dbi->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
355	if (IS_ERR(dbi->reset))
356		return dev_err_probe(dev, PTR_ERR(dbi->reset), "Failed to get GPIO 'reset'\n");
357
358	/* Multiple panels can share the "dc" GPIO, but only if they are on the same SPI bus! */
359	dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
360	if (IS_ERR(dc))
361		return dev_err_probe(dev, PTR_ERR(dc), "Failed to get GPIO 'dc'\n");
362
363	ret = mipi_dbi_spi_init(spi, dbi, dc);
364	if (ret)
365		return ret;
366
367	if (device_property_present(dev, "write-only"))
368		dbi->read_commands = NULL;
369
370	dbidev->driver_private = panel_mipi_dbi_commands_from_fw(dev);
371	if (IS_ERR(dbidev->driver_private))
372		return PTR_ERR(dbidev->driver_private);
373
374	ret = panel_mipi_dbi_get_format(dev, formats, &bpp);
375	if (ret)
376		return ret;
377
378	buf_size = DIV_ROUND_UP(mode.hdisplay * mode.vdisplay * bpp, 8);
379	ret = mipi_dbi_dev_init_with_formats(dbidev, &panel_mipi_dbi_pipe_funcs,
380					     formats, ARRAY_SIZE(formats),
381					     &mode, 0, buf_size);
382	if (ret)
383		return ret;
384
385	drm_mode_config_reset(drm);
386
387	ret = drm_dev_register(drm, 0);
388	if (ret)
389		return ret;
390
391	spi_set_drvdata(spi, drm);
392
393	drm_client_setup(drm, NULL);
394
395	return 0;
396}
397
398static void panel_mipi_dbi_spi_remove(struct spi_device *spi)
399{
400	struct drm_device *drm = spi_get_drvdata(spi);
401
402	drm_dev_unplug(drm);
403	drm_atomic_helper_shutdown(drm);
404}
405
406static void panel_mipi_dbi_spi_shutdown(struct spi_device *spi)
407{
408	drm_atomic_helper_shutdown(spi_get_drvdata(spi));
409}
410
411static int __maybe_unused panel_mipi_dbi_pm_suspend(struct device *dev)
412{
413	return drm_mode_config_helper_suspend(dev_get_drvdata(dev));
414}
415
416static int __maybe_unused panel_mipi_dbi_pm_resume(struct device *dev)
417{
418	drm_mode_config_helper_resume(dev_get_drvdata(dev));
419
420	return 0;
421}
422
423static const struct dev_pm_ops panel_mipi_dbi_pm_ops = {
424	SET_SYSTEM_SLEEP_PM_OPS(panel_mipi_dbi_pm_suspend, panel_mipi_dbi_pm_resume)
425};
426
427static const struct of_device_id panel_mipi_dbi_spi_of_match[] = {
428	{ .compatible = "panel-mipi-dbi-spi" },
429	{},
430};
431MODULE_DEVICE_TABLE(of, panel_mipi_dbi_spi_of_match);
432
433static const struct spi_device_id panel_mipi_dbi_spi_id[] = {
434	{ "panel-mipi-dbi-spi", 0 },
435	{ },
436};
437MODULE_DEVICE_TABLE(spi, panel_mipi_dbi_spi_id);
438
439static struct spi_driver panel_mipi_dbi_spi_driver = {
440	.driver = {
441		.name = "panel-mipi-dbi-spi",
442		.of_match_table = panel_mipi_dbi_spi_of_match,
443		.pm = &panel_mipi_dbi_pm_ops,
444	},
445	.id_table = panel_mipi_dbi_spi_id,
446	.probe = panel_mipi_dbi_spi_probe,
447	.remove = panel_mipi_dbi_spi_remove,
448	.shutdown = panel_mipi_dbi_spi_shutdown,
449};
450module_spi_driver(panel_mipi_dbi_spi_driver);
451
452MODULE_DESCRIPTION("MIPI DBI compatible display panel driver");
453MODULE_AUTHOR("Noralf Trønnes");
454MODULE_LICENSE("GPL");