1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
  4 * Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)
  5
  6 * Copyright (c) 2017, Collabora Ltd.
  7 * Copyright (c) 2017, General Electric Company
  8
  9
 10 * This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
 11 * display bridge of the GE B850v3. There are two physical bridges on the video
 12 * signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
 13 * physical bridges are automatically configured by the input video signal, and
 14 * the driver has no access to the video processing pipeline. The driver is
 15 * only needed to read EDID from the STDP2690 and to handle HPD events from the
 16 * STDP4028. The driver communicates with both bridges over i2c. The video
 17 * signal pipeline is as follows:
 18 *
 19 *   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
 20 */
 21
 22#include <linux/i2c.h>
 23#include <linux/module.h>
 24#include <linux/of.h>
 25
 26#include <drm/drm_atomic.h>
 27#include <drm/drm_atomic_helper.h>
 28#include <drm/drm_edid.h>
 29#include <drm/drm_print.h>
 30#include <drm/drm_probe_helper.h>
 31
 32#define EDID_EXT_BLOCK_CNT 0x7E
 33
 34#define STDP4028_IRQ_OUT_CONF_REG 0x02
 35#define STDP4028_DPTX_IRQ_EN_REG 0x3C
 36#define STDP4028_DPTX_IRQ_STS_REG 0x3D
 37#define STDP4028_DPTX_STS_REG 0x3E
 38
 39#define STDP4028_DPTX_DP_IRQ_EN 0x1000
 40
 41#define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
 42#define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
 43#define STDP4028_DPTX_IRQ_CONFIG \
 44		(STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)
 45
 46#define STDP4028_DPTX_HOTPLUG_STS 0x0200
 47#define STDP4028_DPTX_LINK_STS 0x1000
 48#define STDP4028_CON_STATE_CONNECTED \
 49		(STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)
 50
 51#define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
 52#define STDP4028_DPTX_LINK_CH_STS 0x2000
 53#define STDP4028_DPTX_IRQ_CLEAR \
 54		(STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)
 55
 56static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);
 57
 58struct ge_b850v3_lvds {
 59	struct drm_connector connector;
 60	struct drm_bridge bridge;
 61	struct i2c_client *stdp4028_i2c;
 62	struct i2c_client *stdp2690_i2c;
 63	struct edid *edid;
 64};
 65
 66static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;
 67
 68static u8 *stdp2690_get_edid(struct i2c_client *client)
 69{
 70	struct i2c_adapter *adapter = client->adapter;
 71	unsigned char start = 0x00;
 72	unsigned int total_size;
 73	u8 *block = kmalloc(EDID_LENGTH, GFP_KERNEL);
 74
 75	struct i2c_msg msgs[] = {
 76		{
 77			.addr	= client->addr,
 78			.flags	= 0,
 79			.len	= 1,
 80			.buf	= &start,
 81		}, {
 82			.addr	= client->addr,
 83			.flags	= I2C_M_RD,
 84			.len	= EDID_LENGTH,
 85			.buf	= block,
 86		}
 87	};
 88
 89	if (!block)
 90		return NULL;
 91
 92	if (i2c_transfer(adapter, msgs, 2) != 2) {
 93		DRM_ERROR("Unable to read EDID.\n");
 94		goto err;
 95	}
 96
 97	if (!drm_edid_block_valid(block, 0, false, NULL)) {
 98		DRM_ERROR("Invalid EDID data\n");
 99		goto err;
100	}
101
102	total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH;
103	if (total_size > EDID_LENGTH) {
104		kfree(block);
105		block = kmalloc(total_size, GFP_KERNEL);
106		if (!block)
107			return NULL;
108
109		/* Yes, read the entire buffer, and do not skip the first
110		 * EDID_LENGTH bytes.
111		 */
112		start = 0x00;
113		msgs[1].len = total_size;
114		msgs[1].buf = block;
115
116		if (i2c_transfer(adapter, msgs, 2) != 2) {
117			DRM_ERROR("Unable to read EDID extension blocks.\n");
118			goto err;
119		}
120		if (!drm_edid_block_valid(block, 1, false, NULL)) {
121			DRM_ERROR("Invalid EDID data\n");
122			goto err;
123		}
124	}
125
126	return block;
127
128err:
129	kfree(block);
130	return NULL;
131}
132
133static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
134{
135	struct i2c_client *client;
136	int num_modes = 0;
137
138	client = ge_b850v3_lvds_ptr->stdp2690_i2c;
139
140	kfree(ge_b850v3_lvds_ptr->edid);
141	ge_b850v3_lvds_ptr->edid = (struct edid *)stdp2690_get_edid(client);
142
143	if (ge_b850v3_lvds_ptr->edid) {
144		drm_connector_update_edid_property(connector,
145						      ge_b850v3_lvds_ptr->edid);
146		num_modes = drm_add_edid_modes(connector,
147					       ge_b850v3_lvds_ptr->edid);
148	}
149
150	return num_modes;
151}
152
153static enum drm_mode_status ge_b850v3_lvds_mode_valid(
154		struct drm_connector *connector, struct drm_display_mode *mode)
155{
156	return MODE_OK;
157}
158
159static const struct
160drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
161	.get_modes = ge_b850v3_lvds_get_modes,
162	.mode_valid = ge_b850v3_lvds_mode_valid,
163};
164
165static enum drm_connector_status ge_b850v3_lvds_detect(
166		struct drm_connector *connector, bool force)
167{
168	struct i2c_client *stdp4028_i2c =
169			ge_b850v3_lvds_ptr->stdp4028_i2c;
170	s32 link_state;
171
172	link_state = i2c_smbus_read_word_data(stdp4028_i2c,
173					      STDP4028_DPTX_STS_REG);
174
175	if (link_state == STDP4028_CON_STATE_CONNECTED)
176		return connector_status_connected;
177
178	if (link_state == 0)
179		return connector_status_disconnected;
180
181	return connector_status_unknown;
182}
183
184static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
185	.fill_modes = drm_helper_probe_single_connector_modes,
186	.detect = ge_b850v3_lvds_detect,
187	.destroy = drm_connector_cleanup,
188	.reset = drm_atomic_helper_connector_reset,
189	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
190	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
191};
192
193static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
194{
195	struct i2c_client *stdp4028_i2c
196			= ge_b850v3_lvds_ptr->stdp4028_i2c;
197
198	i2c_smbus_write_word_data(stdp4028_i2c,
199				  STDP4028_DPTX_IRQ_STS_REG,
200				  STDP4028_DPTX_IRQ_CLEAR);
201
202	if (ge_b850v3_lvds_ptr->connector.dev)
203		drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->connector.dev);
204
205	return IRQ_HANDLED;
206}
207
208static int ge_b850v3_lvds_attach(struct drm_bridge *bridge)
209{
210	struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
211	struct i2c_client *stdp4028_i2c
212			= ge_b850v3_lvds_ptr->stdp4028_i2c;
213	int ret;
214
215	if (!bridge->encoder) {
216		DRM_ERROR("Parent encoder object not found");
217		return -ENODEV;
218	}
219
220	connector->polled = DRM_CONNECTOR_POLL_HPD;
221
222	drm_connector_helper_add(connector,
223				 &ge_b850v3_lvds_connector_helper_funcs);
224
225	ret = drm_connector_init(bridge->dev, connector,
226				 &ge_b850v3_lvds_connector_funcs,
227				 DRM_MODE_CONNECTOR_DisplayPort);
228	if (ret) {
229		DRM_ERROR("Failed to initialize connector with drm\n");
230		return ret;
231	}
232
233	ret = drm_connector_attach_encoder(connector, bridge->encoder);
234	if (ret)
235		return ret;
236
237	/* Configures the bridge to re-enable interrupts after each ack. */
238	i2c_smbus_write_word_data(stdp4028_i2c,
239				  STDP4028_IRQ_OUT_CONF_REG,
240				  STDP4028_DPTX_DP_IRQ_EN);
241
242	/* Enable interrupts */
243	i2c_smbus_write_word_data(stdp4028_i2c,
244				  STDP4028_DPTX_IRQ_EN_REG,
245				  STDP4028_DPTX_IRQ_CONFIG);
246
247	return 0;
248}
249
250static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
251	.attach = ge_b850v3_lvds_attach,
252};
253
254static int ge_b850v3_lvds_init(struct device *dev)
255{
256	mutex_lock(&ge_b850v3_lvds_dev_mutex);
257
258	if (ge_b850v3_lvds_ptr)
259		goto success;
260
261	ge_b850v3_lvds_ptr = devm_kzalloc(dev,
262					  sizeof(*ge_b850v3_lvds_ptr),
263					  GFP_KERNEL);
264
265	if (!ge_b850v3_lvds_ptr) {
266		mutex_unlock(&ge_b850v3_lvds_dev_mutex);
267		return -ENOMEM;
268	}
269
270success:
271	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
272	return 0;
273}
274
275static void ge_b850v3_lvds_remove(void)
276{
277	mutex_lock(&ge_b850v3_lvds_dev_mutex);
278	/*
279	 * This check is to avoid both the drivers
280	 * removing the bridge in their remove() function
281	 */
282	if (!ge_b850v3_lvds_ptr)
283		goto out;
284
285	drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);
286
287	kfree(ge_b850v3_lvds_ptr->edid);
288
289	ge_b850v3_lvds_ptr = NULL;
290out:
291	mutex_unlock(&ge_b850v3_lvds_dev_mutex);
292}
293
294static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c,
295				       const struct i2c_device_id *id)
296{
297	struct device *dev = &stdp4028_i2c->dev;
298
299	ge_b850v3_lvds_init(dev);
300
301	ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
302	i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);
303
304	/* drm bridge initialization */
305	ge_b850v3_lvds_ptr->bridge.funcs = &ge_b850v3_lvds_funcs;
306	ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
307	drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);
308
309	/* Clear pending interrupts since power up. */
310	i2c_smbus_write_word_data(stdp4028_i2c,
311				  STDP4028_DPTX_IRQ_STS_REG,
312				  STDP4028_DPTX_IRQ_CLEAR);
313
314	if (!stdp4028_i2c->irq)
315		return 0;
316
317	return devm_request_threaded_irq(&stdp4028_i2c->dev,
318			stdp4028_i2c->irq, NULL,
319			ge_b850v3_lvds_irq_handler,
320			IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
321			"ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
322}
323
324static int stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
325{
326	ge_b850v3_lvds_remove();
327
328	return 0;
329}
330
331static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
332	{"stdp4028_ge_fw", 0},
333	{},
334};
335MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);
336
337static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
338	{ .compatible = "megachips,stdp4028-ge-b850v3-fw" },
339	{},
340};
341MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);
342
343static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
344	.id_table	= stdp4028_ge_b850v3_fw_i2c_table,
345	.probe		= stdp4028_ge_b850v3_fw_probe,
346	.remove		= stdp4028_ge_b850v3_fw_remove,
347	.driver		= {
348		.name		= "stdp4028-ge-b850v3-fw",
349		.of_match_table = stdp4028_ge_b850v3_fw_match,
350	},
351};
352
353static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c,
354				       const struct i2c_device_id *id)
355{
356	struct device *dev = &stdp2690_i2c->dev;
357
358	ge_b850v3_lvds_init(dev);
359
360	ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
361	i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);
362
363	return 0;
364}
365
366static int stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
367{
368	ge_b850v3_lvds_remove();
369
370	return 0;
371}
372
373static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
374	{"stdp2690_ge_fw", 0},
375	{},
376};
377MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);
378
379static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
380	{ .compatible = "megachips,stdp2690-ge-b850v3-fw" },
381	{},
382};
383MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);
384
385static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
386	.id_table	= stdp2690_ge_b850v3_fw_i2c_table,
387	.probe		= stdp2690_ge_b850v3_fw_probe,
388	.remove		= stdp2690_ge_b850v3_fw_remove,
389	.driver		= {
390		.name		= "stdp2690-ge-b850v3-fw",
391		.of_match_table = stdp2690_ge_b850v3_fw_match,
392	},
393};
394
395static int __init stdpxxxx_ge_b850v3_init(void)
396{
397	int ret;
398
399	ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
400	if (ret)
401		return ret;
402
403	return i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
404}
405module_init(stdpxxxx_ge_b850v3_init);
406
407static void __exit stdpxxxx_ge_b850v3_exit(void)
408{
409	i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
410	i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
411}
412module_exit(stdpxxxx_ge_b850v3_exit);
413
414MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
415MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
416MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
417MODULE_LICENSE("GPL v2");