1/*
  2 * Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
  3 * Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)
  4
  5 * Copyright (c) 2017, Collabora Ltd.
  6 * Copyright (c) 2017, General Electric Company
  7
  8 * This program is free software; you can redistribute it and/or modify it
  9 * under the terms and conditions of the GNU General Public License,
 10 * version 2, as published by the Free Software Foundation.
 11
 12 * This program is distributed in the hope it will be useful, but WITHOUT
 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 14 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 15 * more details.
 16
 17 * You should have received a copy of the GNU General Public License
 18 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 19
 20 * This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
 21 * display bridge of the GE B850v3. There are two physical bridges on the video
 22 * signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
 23 * physical bridges are automatically configured by the input video signal, and
 24 * the driver has no access to the video processing pipeline. The driver is
 25 * only needed to read EDID from the STDP2690 and to handle HPD events from the
 26 * STDP4028. The driver communicates with both bridges over i2c. The video
 27 * signal pipeline is as follows:
 28 *
 29 *   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
 30 *
 31 */
 32
 33#include <linux/gpio.h>
 34#include <linux/i2c.h>
 35#include <linux/module.h>
 36#include <linux/of.h>
 37#include <drm/drm_atomic.h>
 38#include <drm/drm_atomic_helper.h>
 39#include <drm/drm_crtc_helper.h>
 40#include <drm/drm_edid.h>
 41#include <drm/drmP.h>
 42
 43#define EDID_EXT_BLOCK_CNT 0x7E
 44
 45#define STDP4028_IRQ_OUT_CONF_REG 0x02
 46#define STDP4028_DPTX_IRQ_EN_REG 0x3C
 47#define STDP4028_DPTX_IRQ_STS_REG 0x3D
 48#define STDP4028_DPTX_STS_REG 0x3E
 49
 50#define STDP4028_DPTX_DP_IRQ_EN 0x1000
 51
 52#define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
 53#define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
 54#define STDP4028_DPTX_IRQ_CONFIG \
 55		(STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)
 56
 57#define STDP4028_DPTX_HOTPLUG_STS 0x0200
 58#define STDP4028_DPTX_LINK_STS 0x1000
 59#define STDP4028_CON_STATE_CONNECTED \
 60		(STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)
 61
 62#define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
 63#define STDP4028_DPTX_LINK_CH_STS 0x2000
 64#define STDP4028_DPTX_IRQ_CLEAR \
 65		(STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)
 66
 67static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);
 68
 69struct ge_b850v3_lvds {
 70	struct drm_connector connector;
 71	struct drm_bridge bridge;
 72	struct i2c_client *stdp4028_i2c;
 73	struct i2c_client *stdp2690_i2c;
 74	struct edid *edid;
 75};
 76
 77static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;
 78
 79static u8 *stdp2690_get_edid(struct i2c_client *client)
 80{
 81	struct i2c_adapter *adapter = client->adapter;
 82	unsigned char start = 0x00;
 83	unsigned int total_size;
 84	u8 *block = kmalloc(EDID_LENGTH, GFP_KERNEL);
 85
 86	struct i2c_msg msgs[] = {
 87		{
 88			.addr	= client->addr,
 89			.flags	= 0,
 90			.len	= 1,
 91			.buf	= &start,
 92		}, {
 93			.addr	= client->addr,
 94			.flags	= I2C_M_RD,
 95			.len	= EDID_LENGTH,
 96			.buf	= block,
 97		}
 98	};
 99
100	if (!block)
101		return NULL;
102
103	if (i2c_transfer(adapter, msgs, 2) != 2) {
104		DRM_ERROR("Unable to read EDID.\n");
105		goto err;
106	}
107
108	if (!drm_edid_block_valid(block, 0, false, NULL)) {
109		DRM_ERROR("Invalid EDID data\n");
110		goto err;
111	}
112
113	total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH;
114	if (total_size > EDID_LENGTH) {
115		kfree(block);
116		block = kmalloc(total_size, GFP_KERNEL);
117		if (!block)
118			return NULL;
119
120		/* Yes, read the entire buffer, and do not skip the first
121		 * EDID_LENGTH bytes.
122		 */
123		start = 0x00;
124		msgs[1].len = total_size;
125		msgs[1].buf = block;
126
127		if (i2c_transfer(adapter, msgs, 2) != 2) {
128			DRM_ERROR("Unable to read EDID extension blocks.\n");
129			goto err;
130		}
131		if (!drm_edid_block_valid(block, 1, false, NULL)) {
132			DRM_ERROR("Invalid EDID data\n");
133			goto err;
134		}
135	}
136
137	return block;
138
139err:
140	kfree(block);
141	return NULL;
142}
143
144static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
145{
146	struct i2c_client *client;
147	int num_modes = 0;
148
149	client = ge_b850v3_lvds_ptr->stdp2690_i2c;
150
151	kfree(ge_b850v3_lvds_ptr->edid);
152	ge_b850v3_lvds_ptr->edid = (struct edid *)stdp2690_get_edid(client);
153
154	if (ge_b850v3_lvds_ptr->edid) {
155		drm_mode_connector_update_edid_property(connector,
156						      ge_b850v3_lvds_ptr->edid);
157		num_modes = drm_add_edid_modes(connector,
158					       ge_b850v3_lvds_ptr->edid);
159	}
160
161	return num_modes;
162}
163
164static enum drm_mode_status ge_b850v3_lvds_mode_valid(
165		struct drm_connector *connector, struct drm_display_mode *mode)
166{
167	return MODE_OK;
168}
169
170static const struct
171drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
172	.get_modes = ge_b850v3_lvds_get_modes,
173	.mode_valid = ge_b850v3_lvds_mode_valid,
174};
175
176static enum drm_connector_status ge_b850v3_lvds_detect(
177		struct drm_connector *connector, bool force)
178{
179	struct i2c_client *stdp4028_i2c =
180			ge_b850v3_lvds_ptr->stdp4028_i2c;
181	s32 link_state;
182
183	link_state = i2c_smbus_read_word_data(stdp4028_i2c,
184					      STDP4028_DPTX_STS_REG);
185
186	if (link_state == STDP4028_CON_STATE_CONNECTED)
187		return connector_status_connected;
188
189	if (link_state == 0)
190		return connector_status_disconnected;
191
192	return connector_status_unknown;
193}
194
195static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
196	.fill_modes = drm_helper_probe_single_connector_modes,
197	.detect = ge_b850v3_lvds_detect,
198	.destroy = drm_connector_cleanup,
199	.reset = drm_atomic_helper_connector_reset,
200	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
201	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
202};
203
204static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
205{
206	struct i2c_client *stdp4028_i2c
207			= ge_b850v3_lvds_ptr->stdp4028_i2c;
208
209	i2c_smbus_write_word_data(stdp4028_i2c,
210				  STDP4028_DPTX_IRQ_STS_REG,
211				  STDP4028_DPTX_IRQ_CLEAR);
212
213	if (ge_b850v3_lvds_ptr->connector.dev)
214		drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->connector.dev);
215
216	return IRQ_HANDLED;
217}
218
219static int ge_b850v3_lvds_attach(struct drm_bridge *bridge)
220{
221	struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
222	struct i2c_client *stdp4028_i2c
223			= ge_b850v3_lvds_ptr->stdp4028_i2c;
224	int ret;
225
226	if (!bridge->encoder) {
227		DRM_ERROR("Parent encoder object not found");
228		return -ENODEV;
229	}
230
231	connector->polled = DRM_CONNECTOR_POLL_HPD;
232
233	drm_connector_helper_add(connector,
234				 &ge_b850v3_lvds_connector_helper_funcs);
235
236	ret = drm_connector_init(bridge->dev, connector,
237				 &ge_b850v3_lvds_connector_funcs,
238				 DRM_MODE_CONNECTOR_DisplayPort);
239	if (ret) {
240		DRM_ERROR("Failed to initialize connector with drm\n");
241		return ret;
242	}
243
244	ret = drm_mode_connector_attach_encoder(connector, bridge->encoder);
245	if (ret)
246		return ret;
247
248	/* Configures the bridge to re-enable interrupts after each ack. */
249	i2c_smbus_write_word_data(stdp4028_i2c,
250				  STDP4028_IRQ_OUT_CONF_REG,
251				  STDP4028_DPTX_DP_IRQ_EN);
252
253	/* Enable interrupts */
254	i2c_smbus_write_word_data(stdp4028_i2c,
255				  STDP4028_DPTX_IRQ_EN_REG,
256				  STDP4028_DPTX_IRQ_CONFIG);
257
258	return 0;
259}
260
261static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
262	.attach = ge_b850v3_lvds_attach,
263};
264
265static int ge_b850v3_lvds_init(struct device *dev)
266{
267	mutex_lock(&ge_b850v3_lvds_dev_mutex);
268
269	if (ge_b850v3_lvds_ptr)
270		goto success;
271
272	ge_b850v3_lvds_ptr = devm_kzalloc(dev,
273					  sizeof(*ge_b850v3_lvds_ptr),
274					  GFP_KERNEL);
275
276	if (!ge_b850v3_lvds_ptr) {
277		mutex_unlock(&ge_b850v3_lvds_dev_mutex);
278		return -ENOMEM;
279	}
280
281success:
282	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
283	return 0;
284}
285
286static void ge_b850v3_lvds_remove(void)
287{
288	mutex_lock(&ge_b850v3_lvds_dev_mutex);
289	/*
290	 * This check is to avoid both the drivers
291	 * removing the bridge in their remove() function
292	 */
293	if (!ge_b850v3_lvds_ptr)
294		goto out;
295
296	drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);
297
298	kfree(ge_b850v3_lvds_ptr->edid);
299
300	ge_b850v3_lvds_ptr = NULL;
301out:
302	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
303}
304
305static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c,
306				       const struct i2c_device_id *id)
307{
308	struct device *dev = &stdp4028_i2c->dev;
309
310	ge_b850v3_lvds_init(dev);
311
312	ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
313	i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);
314
315	/* drm bridge initialization */
316	ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
317	ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
318	drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);
319
320	/* Clear pending interrupts since power up. */
321	i2c_smbus_write_word_data(stdp4028_i2c,
322				  STDP4028_DPTX_IRQ_STS_REG,
323				  STDP4028_DPTX_IRQ_CLEAR);
324
325	if (!stdp4028_i2c->irq)
326		return 0;
327
328	return devm_request_threaded_irq(&stdp4028_i2c->dev,
329			stdp4028_i2c->irq, NULL,
330			ge_b850v3_lvds_irq_handler,
331			IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
332			"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
333}
334
335static int stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
336{
337	ge_b850v3_lvds_remove();
338
339	return 0;
340}
341
342static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
343	{"stdp4028_ge_fw", 0},
344	{},
345};
346MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);
347
348static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
349	{ .compatible = "megachips,stdp4028-ge-b850v3-fw" },
350	{},
351};
352MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);
353
354static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
355	.id_table	= stdp4028_ge_b850v3_fw_i2c_table,
356	.probe		= stdp4028_ge_b850v3_fw_probe,
357	.remove		= stdp4028_ge_b850v3_fw_remove,
358	.driver		= {
359		.name		= "stdp4028-ge-b850v3-fw",
360		.of_match_table = stdp4028_ge_b850v3_fw_match,
361	},
362};
363
364static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c,
365				       const struct i2c_device_id *id)
366{
367	struct device *dev = &stdp2690_i2c->dev;
368
369	ge_b850v3_lvds_init(dev);
370
371	ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
372	i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);
373
374	return 0;
375}
376
377static int stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
378{
379	ge_b850v3_lvds_remove();
380
381	return 0;
382}
383
384static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
385	{"stdp2690_ge_fw", 0},
386	{},
387};
388MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);
389
390static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
391	{ .compatible = "megachips,stdp2690-ge-b850v3-fw" },
392	{},
393};
394MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);
395
396static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
397	.id_table	= stdp2690_ge_b850v3_fw_i2c_table,
398	.probe		= stdp2690_ge_b850v3_fw_probe,
399	.remove		= stdp2690_ge_b850v3_fw_remove,
400	.driver		= {
401		.name		= "stdp2690-ge-b850v3-fw",
402		.of_match_table = stdp2690_ge_b850v3_fw_match,
403	},
404};
405
406static int __init stdpxxxx_ge_b850v3_init(void)
407{
408	int ret;
409
410	ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
411	if (ret)
412		return ret;
413
414	return i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
415}
416module_init(stdpxxxx_ge_b850v3_init);
417
418static void __exit stdpxxxx_ge_b850v3_exit(void)
419{
420	i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
421	i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
422}
423module_exit(stdpxxxx_ge_b850v3_exit);
424
425MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
426MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
427MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
428MODULE_LICENSE("GPL v2");