1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * I2C multiplexer
4  *
5  * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
6  * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
7  *
8  * This module supports the PCA954x and PCA984x series of I2C multiplexer/switch
9  * chips made by NXP Semiconductors.
10  * This includes the:
11  *	 PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547,
12  *	 PCA9548, PCA9846, PCA9847, PCA9848 and PCA9849.
13  *
14  * These chips are all controlled via the I2C bus itself, and all have a
15  * single 8-bit register. The upstream "parent" bus fans out to two,
16  * four, or eight downstream busses or channels; which of these
17  * are selected is determined by the chip type and register contents. A
18  * mux can select only one sub-bus at a time; a switch can select any
19  * combination simultaneously.
20  *
21  * Based on:
22  *	pca954x.c from Kumar Gala <galak@kernel.crashing.org>
23  * Copyright (C) 2006
24  *
25  * Based on:
26  *	pca954x.c from Ken Harrenstien
27  * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
28  *
29  * Based on:
30  *	i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
31  * and
32  *	pca9540.c from Jean Delvare <jdelvare@suse.de>.
33  */
34 
35 #include <linux/device.h>
36 #include <linux/delay.h>
37 #include <linux/gpio/consumer.h>
38 #include <linux/i2c.h>
39 #include <linux/i2c-mux.h>
40 #include <linux/interrupt.h>
41 #include <linux/irq.h>
42 #include <linux/module.h>
43 #include <linux/pm.h>
44 #include <linux/property.h>
45 #include <linux/slab.h>
46 #include <linux/spinlock.h>
47 #include <dt-bindings/mux/mux.h>
48 
49 #define PCA954X_MAX_NCHANS 8
50 
51 #define PCA954X_IRQ_OFFSET 4
52 
53 enum pca_type {
54 	pca_9540,
55 	pca_9542,
56 	pca_9543,
57 	pca_9544,
58 	pca_9545,
59 	pca_9546,
60 	pca_9547,
61 	pca_9548,
62 	pca_9846,
63 	pca_9847,
64 	pca_9848,
65 	pca_9849,
66 };
67 
68 struct chip_desc {
69 	u8 nchans;
70 	u8 enable;	/* used for muxes only */
71 	u8 has_irq;
72 	enum muxtype {
73 		pca954x_ismux = 0,
74 		pca954x_isswi
75 	} muxtype;
76 	struct i2c_device_identity id;
77 };
78 
79 struct pca954x {
80 	const struct chip_desc *chip;
81 
82 	u8 last_chan;		/* last register value */
83 	/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
84 	s32 idle_state;
85 
86 	struct i2c_client *client;
87 
88 	struct irq_domain *irq;
89 	unsigned int irq_mask;
90 	raw_spinlock_t lock;
91 };
92 
93 /* Provide specs for the PCA954x types we know about */
94 static const struct chip_desc chips[] = {
95 	[pca_9540] = {
96 		.nchans = 2,
97 		.enable = 0x4,
98 		.muxtype = pca954x_ismux,
99 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
100 	},
101 	[pca_9542] = {
102 		.nchans = 2,
103 		.enable = 0x4,
104 		.has_irq = 1,
105 		.muxtype = pca954x_ismux,
106 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
107 	},
108 	[pca_9543] = {
109 		.nchans = 2,
110 		.has_irq = 1,
111 		.muxtype = pca954x_isswi,
112 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
113 	},
114 	[pca_9544] = {
115 		.nchans = 4,
116 		.enable = 0x4,
117 		.has_irq = 1,
118 		.muxtype = pca954x_ismux,
119 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
120 	},
121 	[pca_9545] = {
122 		.nchans = 4,
123 		.has_irq = 1,
124 		.muxtype = pca954x_isswi,
125 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
126 	},
127 	[pca_9546] = {
128 		.nchans = 4,
129 		.muxtype = pca954x_isswi,
130 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
131 	},
132 	[pca_9547] = {
133 		.nchans = 8,
134 		.enable = 0x8,
135 		.muxtype = pca954x_ismux,
136 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
137 	},
138 	[pca_9548] = {
139 		.nchans = 8,
140 		.muxtype = pca954x_isswi,
141 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
142 	},
143 	[pca_9846] = {
144 		.nchans = 4,
145 		.muxtype = pca954x_isswi,
146 		.id = {
147 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
148 			.part_id = 0x10b,
149 		},
150 	},
151 	[pca_9847] = {
152 		.nchans = 8,
153 		.enable = 0x8,
154 		.muxtype = pca954x_ismux,
155 		.id = {
156 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
157 			.part_id = 0x108,
158 		},
159 	},
160 	[pca_9848] = {
161 		.nchans = 8,
162 		.muxtype = pca954x_isswi,
163 		.id = {
164 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
165 			.part_id = 0x10a,
166 		},
167 	},
168 	[pca_9849] = {
169 		.nchans = 4,
170 		.enable = 0x4,
171 		.muxtype = pca954x_ismux,
172 		.id = {
173 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
174 			.part_id = 0x109,
175 		},
176 	},
177 };
178 
179 static const struct i2c_device_id pca954x_id[] = {
180 	{ "pca9540", pca_9540 },
181 	{ "pca9542", pca_9542 },
182 	{ "pca9543", pca_9543 },
183 	{ "pca9544", pca_9544 },
184 	{ "pca9545", pca_9545 },
185 	{ "pca9546", pca_9546 },
186 	{ "pca9547", pca_9547 },
187 	{ "pca9548", pca_9548 },
188 	{ "pca9846", pca_9846 },
189 	{ "pca9847", pca_9847 },
190 	{ "pca9848", pca_9848 },
191 	{ "pca9849", pca_9849 },
192 	{ }
193 };
194 MODULE_DEVICE_TABLE(i2c, pca954x_id);
195 
196 static const struct of_device_id pca954x_of_match[] = {
197 	{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
198 	{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
199 	{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
200 	{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
201 	{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
202 	{ .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
203 	{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
204 	{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
205 	{ .compatible = "nxp,pca9846", .data = &chips[pca_9846] },
206 	{ .compatible = "nxp,pca9847", .data = &chips[pca_9847] },
207 	{ .compatible = "nxp,pca9848", .data = &chips[pca_9848] },
208 	{ .compatible = "nxp,pca9849", .data = &chips[pca_9849] },
209 	{}
210 };
211 MODULE_DEVICE_TABLE(of, pca954x_of_match);
212 
213 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
214    for this as they will try to lock adapter a second time */
215 static int pca954x_reg_write(struct i2c_adapter *adap,
216 			     struct i2c_client *client, u8 val)
217 {
218 	union i2c_smbus_data dummy;
219 
220 	return __i2c_smbus_xfer(adap, client->addr, client->flags,
221 				I2C_SMBUS_WRITE, val,
222 				I2C_SMBUS_BYTE, &dummy);
223 }
224 
225 static u8 pca954x_regval(struct pca954x *data, u8 chan)
226 {
227 	/* We make switches look like muxes, not sure how to be smarter. */
228 	if (data->chip->muxtype == pca954x_ismux)
229 		return chan | data->chip->enable;
230 	else
231 		return 1 << chan;
232 }
233 
234 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
235 {
236 	struct pca954x *data = i2c_mux_priv(muxc);
237 	struct i2c_client *client = data->client;
238 	u8 regval;
239 	int ret = 0;
240 
241 	regval = pca954x_regval(data, chan);
242 	/* Only select the channel if its different from the last channel */
243 	if (data->last_chan != regval) {
244 		ret = pca954x_reg_write(muxc->parent, client, regval);
245 		data->last_chan = ret < 0 ? 0 : regval;
246 	}
247 
248 	return ret;
249 }
250 
251 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
252 {
253 	struct pca954x *data = i2c_mux_priv(muxc);
254 	struct i2c_client *client = data->client;
255 	s32 idle_state;
256 
257 	idle_state = READ_ONCE(data->idle_state);
258 	if (idle_state >= 0)
259 		/* Set the mux back to a predetermined channel */
260 		return pca954x_select_chan(muxc, idle_state);
261 
262 	if (idle_state == MUX_IDLE_DISCONNECT) {
263 		/* Deselect active channel */
264 		data->last_chan = 0;
265 		return pca954x_reg_write(muxc->parent, client,
266 					 data->last_chan);
267 	}
268 
269 	/* otherwise leave as-is */
270 
271 	return 0;
272 }
273 
274 static ssize_t idle_state_show(struct device *dev,
275 				    struct device_attribute *attr,
276 				    char *buf)
277 {
278 	struct i2c_client *client = to_i2c_client(dev);
279 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
280 	struct pca954x *data = i2c_mux_priv(muxc);
281 
282 	return sprintf(buf, "%d\n", READ_ONCE(data->idle_state));
283 }
284 
285 static ssize_t idle_state_store(struct device *dev,
286 				struct device_attribute *attr,
287 				const char *buf, size_t count)
288 {
289 	struct i2c_client *client = to_i2c_client(dev);
290 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
291 	struct pca954x *data = i2c_mux_priv(muxc);
292 	int val;
293 	int ret;
294 
295 	ret = kstrtoint(buf, 0, &val);
296 	if (ret < 0)
297 		return ret;
298 
299 	if (val != MUX_IDLE_AS_IS && val != MUX_IDLE_DISCONNECT &&
300 	    (val < 0 || val >= data->chip->nchans))
301 		return -EINVAL;
302 
303 	i2c_lock_bus(muxc->parent, I2C_LOCK_SEGMENT);
304 
305 	WRITE_ONCE(data->idle_state, val);
306 	/*
307 	 * Set the mux into a state consistent with the new
308 	 * idle_state.
309 	 */
310 	if (data->last_chan || val != MUX_IDLE_DISCONNECT)
311 		ret = pca954x_deselect_mux(muxc, 0);
312 
313 	i2c_unlock_bus(muxc->parent, I2C_LOCK_SEGMENT);
314 
315 	return ret < 0 ? ret : count;
316 }
317 
318 static DEVICE_ATTR_RW(idle_state);
319 
320 static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
321 {
322 	struct pca954x *data = dev_id;
323 	unsigned long pending;
324 	int ret, i;
325 
326 	ret = i2c_smbus_read_byte(data->client);
327 	if (ret < 0)
328 		return IRQ_NONE;
329 
330 	pending = (ret >> PCA954X_IRQ_OFFSET) & (BIT(data->chip->nchans) - 1);
331 	for_each_set_bit(i, &pending, data->chip->nchans)
332 		handle_nested_irq(irq_linear_revmap(data->irq, i));
333 
334 	return IRQ_RETVAL(pending);
335 }
336 
337 static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
338 {
339 	if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
340 		return -EINVAL;
341 	return 0;
342 }
343 
344 static struct irq_chip pca954x_irq_chip = {
345 	.name = "i2c-mux-pca954x",
346 	.irq_set_type = pca954x_irq_set_type,
347 };
348 
349 static int pca954x_irq_setup(struct i2c_mux_core *muxc)
350 {
351 	struct pca954x *data = i2c_mux_priv(muxc);
352 	struct i2c_client *client = data->client;
353 	int c, irq;
354 
355 	if (!data->chip->has_irq || client->irq <= 0)
356 		return 0;
357 
358 	raw_spin_lock_init(&data->lock);
359 
360 	data->irq = irq_domain_add_linear(client->dev.of_node,
361 					  data->chip->nchans,
362 					  &irq_domain_simple_ops, data);
363 	if (!data->irq)
364 		return -ENODEV;
365 
366 	for (c = 0; c < data->chip->nchans; c++) {
367 		irq = irq_create_mapping(data->irq, c);
368 		if (!irq) {
369 			dev_err(&client->dev, "failed irq create map\n");
370 			return -EINVAL;
371 		}
372 		irq_set_chip_data(irq, data);
373 		irq_set_chip_and_handler(irq, &pca954x_irq_chip,
374 			handle_simple_irq);
375 	}
376 
377 	return 0;
378 }
379 
380 static void pca954x_cleanup(struct i2c_mux_core *muxc)
381 {
382 	struct pca954x *data = i2c_mux_priv(muxc);
383 	int c, irq;
384 
385 	if (data->irq) {
386 		for (c = 0; c < data->chip->nchans; c++) {
387 			irq = irq_find_mapping(data->irq, c);
388 			irq_dispose_mapping(irq);
389 		}
390 		irq_domain_remove(data->irq);
391 	}
392 	i2c_mux_del_adapters(muxc);
393 }
394 
395 static int pca954x_init(struct i2c_client *client, struct pca954x *data)
396 {
397 	int ret;
398 
399 	if (data->idle_state >= 0)
400 		data->last_chan = pca954x_regval(data, data->idle_state);
401 	else
402 		data->last_chan = 0; /* Disconnect multiplexer */
403 
404 	ret = i2c_smbus_write_byte(client, data->last_chan);
405 	if (ret < 0)
406 		data->last_chan = 0;
407 
408 	return ret;
409 }
410 
411 /*
412  * I2C init/probing/exit functions
413  */
414 static int pca954x_probe(struct i2c_client *client,
415 			 const struct i2c_device_id *id)
416 {
417 	struct i2c_adapter *adap = client->adapter;
418 	struct device *dev = &client->dev;
419 	struct gpio_desc *gpio;
420 	struct i2c_mux_core *muxc;
421 	struct pca954x *data;
422 	int num;
423 	int ret;
424 
425 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
426 		return -ENODEV;
427 
428 	muxc = i2c_mux_alloc(adap, dev, PCA954X_MAX_NCHANS, sizeof(*data), 0,
429 			     pca954x_select_chan, pca954x_deselect_mux);
430 	if (!muxc)
431 		return -ENOMEM;
432 	data = i2c_mux_priv(muxc);
433 
434 	i2c_set_clientdata(client, muxc);
435 	data->client = client;
436 
437 	/* Reset the mux if a reset GPIO is specified. */
438 	gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
439 	if (IS_ERR(gpio))
440 		return PTR_ERR(gpio);
441 	if (gpio) {
442 		udelay(1);
443 		gpiod_set_value_cansleep(gpio, 0);
444 		/* Give the chip some time to recover. */
445 		udelay(1);
446 	}
447 
448 	data->chip = device_get_match_data(dev);
449 	if (!data->chip)
450 		data->chip = &chips[id->driver_data];
451 
452 	if (data->chip->id.manufacturer_id != I2C_DEVICE_ID_NONE) {
453 		struct i2c_device_identity id;
454 
455 		ret = i2c_get_device_id(client, &id);
456 		if (ret && ret != -EOPNOTSUPP)
457 			return ret;
458 
459 		if (!ret &&
460 		    (id.manufacturer_id != data->chip->id.manufacturer_id ||
461 		     id.part_id != data->chip->id.part_id)) {
462 			dev_warn(dev, "unexpected device id %03x-%03x-%x\n",
463 				 id.manufacturer_id, id.part_id,
464 				 id.die_revision);
465 			return -ENODEV;
466 		}
467 	}
468 
469 	data->idle_state = MUX_IDLE_AS_IS;
470 	if (device_property_read_u32(dev, "idle-state", &data->idle_state)) {
471 		if (device_property_read_bool(dev, "i2c-mux-idle-disconnect"))
472 			data->idle_state = MUX_IDLE_DISCONNECT;
473 	}
474 
475 	/*
476 	 * Write the mux register at addr to verify
477 	 * that the mux is in fact present. This also
478 	 * initializes the mux to a channel
479 	 * or disconnected state.
480 	 */
481 	ret = pca954x_init(client, data);
482 	if (ret < 0) {
483 		dev_warn(dev, "probe failed\n");
484 		return -ENODEV;
485 	}
486 
487 	ret = pca954x_irq_setup(muxc);
488 	if (ret)
489 		goto fail_cleanup;
490 
491 	/* Now create an adapter for each channel */
492 	for (num = 0; num < data->chip->nchans; num++) {
493 		ret = i2c_mux_add_adapter(muxc, 0, num, 0);
494 		if (ret)
495 			goto fail_cleanup;
496 	}
497 
498 	if (data->irq) {
499 		ret = devm_request_threaded_irq(dev, data->client->irq,
500 						NULL, pca954x_irq_handler,
501 						IRQF_ONESHOT | IRQF_SHARED,
502 						"pca954x", data);
503 		if (ret)
504 			goto fail_cleanup;
505 	}
506 
507 	/*
508 	 * The attr probably isn't going to be needed in most cases,
509 	 * so don't fail completely on error.
510 	 */
511 	device_create_file(dev, &dev_attr_idle_state);
512 
513 	dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
514 		 num, data->chip->muxtype == pca954x_ismux
515 				? "mux" : "switch", client->name);
516 
517 	return 0;
518 
519 fail_cleanup:
520 	pca954x_cleanup(muxc);
521 	return ret;
522 }
523 
524 static void pca954x_remove(struct i2c_client *client)
525 {
526 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
527 
528 	device_remove_file(&client->dev, &dev_attr_idle_state);
529 
530 	pca954x_cleanup(muxc);
531 }
532 
533 #ifdef CONFIG_PM_SLEEP
534 static int pca954x_resume(struct device *dev)
535 {
536 	struct i2c_client *client = to_i2c_client(dev);
537 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
538 	struct pca954x *data = i2c_mux_priv(muxc);
539 	int ret;
540 
541 	ret = pca954x_init(client, data);
542 	if (ret < 0)
543 		dev_err(&client->dev, "failed to verify mux presence\n");
544 
545 	return ret;
546 }
547 #endif
548 
549 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
550 
551 static struct i2c_driver pca954x_driver = {
552 	.driver		= {
553 		.name	= "pca954x",
554 		.pm	= &pca954x_pm,
555 		.of_match_table = pca954x_of_match,
556 	},
557 	.probe		= pca954x_probe,
558 	.remove		= pca954x_remove,
559 	.id_table	= pca954x_id,
560 };
561 
562 module_i2c_driver(pca954x_driver);
563 
564 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
565 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
566 MODULE_LICENSE("GPL v2");
567