1 /*
2 * I2C multiplexer
3 *
4 * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
5 * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
6 *
7 * This module supports the PCA954x and PCA954x series of I2C multiplexer/switch
8 * chips made by NXP Semiconductors.
9 * This includes the:
10 * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547,
11 * PCA9548, PCA9846, PCA9847, PCA9848 and PCA9849.
12 *
13 * These chips are all controlled via the I2C bus itself, and all have a
14 * single 8-bit register. The upstream "parent" bus fans out to two,
15 * four, or eight downstream busses or channels; which of these
16 * are selected is determined by the chip type and register contents. A
17 * mux can select only one sub-bus at a time; a switch can select any
18 * combination simultaneously.
19 *
20 * Based on:
21 * pca954x.c from Kumar Gala <galak@kernel.crashing.org>
22 * Copyright (C) 2006
23 *
24 * Based on:
25 * pca954x.c from Ken Harrenstien
26 * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
27 *
28 * Based on:
29 * i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
30 * and
31 * pca9540.c from Jean Delvare <jdelvare@suse.de>.
32 *
33 * This file is licensed under the terms of the GNU General Public
34 * License version 2. This program is licensed "as is" without any
35 * warranty of any kind, whether express or implied.
36 */
37
38 #include <linux/device.h>
39 #include <linux/delay.h>
40 #include <linux/gpio/consumer.h>
41 #include <linux/i2c.h>
42 #include <linux/i2c-mux.h>
43 #include <linux/interrupt.h>
44 #include <linux/irq.h>
45 #include <linux/module.h>
46 #include <linux/of.h>
47 #include <linux/of_device.h>
48 #include <linux/of_irq.h>
49 #include <linux/pm.h>
50 #include <linux/slab.h>
51 #include <linux/spinlock.h>
52 #include <dt-bindings/mux/mux.h>
53
54 #define PCA954X_MAX_NCHANS 8
55
56 #define PCA954X_IRQ_OFFSET 4
57
58 enum pca_type {
59 pca_9540,
60 pca_9542,
61 pca_9543,
62 pca_9544,
63 pca_9545,
64 pca_9546,
65 pca_9547,
66 pca_9548,
67 pca_9846,
68 pca_9847,
69 pca_9848,
70 pca_9849,
71 };
72
73 struct chip_desc {
74 u8 nchans;
75 u8 enable; /* used for muxes only */
76 u8 has_irq;
77 enum muxtype {
78 pca954x_ismux = 0,
79 pca954x_isswi
80 } muxtype;
81 struct i2c_device_identity id;
82 };
83
84 struct pca954x {
85 const struct chip_desc *chip;
86
87 u8 last_chan; /* last register value */
88 /* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
89 s8 idle_state;
90
91 struct i2c_client *client;
92
93 struct irq_domain *irq;
94 unsigned int irq_mask;
95 raw_spinlock_t lock;
96 };
97
98 /* Provide specs for the PCA954x types we know about */
99 static const struct chip_desc chips[] = {
100 [pca_9540] = {
101 .nchans = 2,
102 .enable = 0x4,
103 .muxtype = pca954x_ismux,
104 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
105 },
106 [pca_9542] = {
107 .nchans = 2,
108 .enable = 0x4,
109 .has_irq = 1,
110 .muxtype = pca954x_ismux,
111 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
112 },
113 [pca_9543] = {
114 .nchans = 2,
115 .has_irq = 1,
116 .muxtype = pca954x_isswi,
117 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
118 },
119 [pca_9544] = {
120 .nchans = 4,
121 .enable = 0x4,
122 .has_irq = 1,
123 .muxtype = pca954x_ismux,
124 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
125 },
126 [pca_9545] = {
127 .nchans = 4,
128 .has_irq = 1,
129 .muxtype = pca954x_isswi,
130 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
131 },
132 [pca_9546] = {
133 .nchans = 4,
134 .muxtype = pca954x_isswi,
135 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
136 },
137 [pca_9547] = {
138 .nchans = 8,
139 .enable = 0x8,
140 .muxtype = pca954x_ismux,
141 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
142 },
143 [pca_9548] = {
144 .nchans = 8,
145 .muxtype = pca954x_isswi,
146 .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
147 },
148 [pca_9846] = {
149 .nchans = 4,
150 .muxtype = pca954x_isswi,
151 .id = {
152 .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
153 .part_id = 0x10b,
154 },
155 },
156 [pca_9847] = {
157 .nchans = 8,
158 .enable = 0x8,
159 .muxtype = pca954x_ismux,
160 .id = {
161 .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
162 .part_id = 0x108,
163 },
164 },
165 [pca_9848] = {
166 .nchans = 8,
167 .muxtype = pca954x_isswi,
168 .id = {
169 .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
170 .part_id = 0x10a,
171 },
172 },
173 [pca_9849] = {
174 .nchans = 4,
175 .enable = 0x4,
176 .muxtype = pca954x_ismux,
177 .id = {
178 .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
179 .part_id = 0x109,
180 },
181 },
182 };
183
184 static const struct i2c_device_id pca954x_id[] = {
185 { "pca9540", pca_9540 },
186 { "pca9542", pca_9542 },
187 { "pca9543", pca_9543 },
188 { "pca9544", pca_9544 },
189 { "pca9545", pca_9545 },
190 { "pca9546", pca_9546 },
191 { "pca9547", pca_9547 },
192 { "pca9548", pca_9548 },
193 { "pca9846", pca_9846 },
194 { "pca9847", pca_9847 },
195 { "pca9848", pca_9848 },
196 { "pca9849", pca_9849 },
197 { }
198 };
199 MODULE_DEVICE_TABLE(i2c, pca954x_id);
200
201 #ifdef CONFIG_OF
202 static const struct of_device_id pca954x_of_match[] = {
203 { .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
204 { .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
205 { .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
206 { .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
207 { .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
208 { .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
209 { .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
210 { .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
211 { .compatible = "nxp,pca9846", .data = &chips[pca_9846] },
212 { .compatible = "nxp,pca9847", .data = &chips[pca_9847] },
213 { .compatible = "nxp,pca9848", .data = &chips[pca_9848] },
214 { .compatible = "nxp,pca9849", .data = &chips[pca_9849] },
215 {}
216 };
217 MODULE_DEVICE_TABLE(of, pca954x_of_match);
218 #endif
219
220 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
221 for this as they will try to lock adapter a second time */
pca954x_reg_write(struct i2c_adapter * adap,struct i2c_client * client,u8 val)222 static int pca954x_reg_write(struct i2c_adapter *adap,
223 struct i2c_client *client, u8 val)
224 {
225 union i2c_smbus_data dummy;
226
227 return __i2c_smbus_xfer(adap, client->addr, client->flags,
228 I2C_SMBUS_WRITE, val,
229 I2C_SMBUS_BYTE, &dummy);
230 }
231
pca954x_select_chan(struct i2c_mux_core * muxc,u32 chan)232 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
233 {
234 struct pca954x *data = i2c_mux_priv(muxc);
235 struct i2c_client *client = data->client;
236 const struct chip_desc *chip = data->chip;
237 u8 regval;
238 int ret = 0;
239
240 /* we make switches look like muxes, not sure how to be smarter */
241 if (chip->muxtype == pca954x_ismux)
242 regval = chan | chip->enable;
243 else
244 regval = 1 << chan;
245
246 /* Only select the channel if its different from the last channel */
247 if (data->last_chan != regval) {
248 ret = pca954x_reg_write(muxc->parent, client, regval);
249 data->last_chan = ret < 0 ? 0 : regval;
250 }
251
252 return ret;
253 }
254
pca954x_deselect_mux(struct i2c_mux_core * muxc,u32 chan)255 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
256 {
257 struct pca954x *data = i2c_mux_priv(muxc);
258 struct i2c_client *client = data->client;
259 s8 idle_state;
260
261 idle_state = READ_ONCE(data->idle_state);
262 if (idle_state >= 0)
263 /* Set the mux back to a predetermined channel */
264 return pca954x_select_chan(muxc, idle_state);
265
266 if (idle_state == MUX_IDLE_DISCONNECT) {
267 /* Deselect active channel */
268 data->last_chan = 0;
269 return pca954x_reg_write(muxc->parent, client,
270 data->last_chan);
271 }
272
273 /* otherwise leave as-is */
274
275 return 0;
276 }
277
idle_state_show(struct device * dev,struct device_attribute * attr,char * buf)278 static ssize_t idle_state_show(struct device *dev,
279 struct device_attribute *attr,
280 char *buf)
281 {
282 struct i2c_client *client = to_i2c_client(dev);
283 struct i2c_mux_core *muxc = i2c_get_clientdata(client);
284 struct pca954x *data = i2c_mux_priv(muxc);
285
286 return sprintf(buf, "%d\n", READ_ONCE(data->idle_state));
287 }
288
idle_state_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)289 static ssize_t idle_state_store(struct device *dev,
290 struct device_attribute *attr,
291 const char *buf, size_t count)
292 {
293 struct i2c_client *client = to_i2c_client(dev);
294 struct i2c_mux_core *muxc = i2c_get_clientdata(client);
295 struct pca954x *data = i2c_mux_priv(muxc);
296 int val;
297 int ret;
298
299 ret = kstrtoint(buf, 0, &val);
300 if (ret < 0)
301 return ret;
302
303 if (val != MUX_IDLE_AS_IS && val != MUX_IDLE_DISCONNECT &&
304 (val < 0 || val >= data->chip->nchans))
305 return -EINVAL;
306
307 i2c_lock_bus(muxc->parent, I2C_LOCK_SEGMENT);
308
309 WRITE_ONCE(data->idle_state, val);
310 /*
311 * Set the mux into a state consistent with the new
312 * idle_state.
313 */
314 if (data->last_chan || val != MUX_IDLE_DISCONNECT)
315 ret = pca954x_deselect_mux(muxc, 0);
316
317 i2c_unlock_bus(muxc->parent, I2C_LOCK_SEGMENT);
318
319 return ret < 0 ? ret : count;
320 }
321
322 static DEVICE_ATTR_RW(idle_state);
323
pca954x_irq_handler(int irq,void * dev_id)324 static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
325 {
326 struct pca954x *data = dev_id;
327 unsigned int child_irq;
328 int ret, i, handled = 0;
329
330 ret = i2c_smbus_read_byte(data->client);
331 if (ret < 0)
332 return IRQ_NONE;
333
334 for (i = 0; i < data->chip->nchans; i++) {
335 if (ret & BIT(PCA954X_IRQ_OFFSET + i)) {
336 child_irq = irq_linear_revmap(data->irq, i);
337 handle_nested_irq(child_irq);
338 handled++;
339 }
340 }
341 return handled ? IRQ_HANDLED : IRQ_NONE;
342 }
343
pca954x_irq_set_type(struct irq_data * idata,unsigned int type)344 static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
345 {
346 if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
347 return -EINVAL;
348 return 0;
349 }
350
351 static struct irq_chip pca954x_irq_chip = {
352 .name = "i2c-mux-pca954x",
353 .irq_set_type = pca954x_irq_set_type,
354 };
355
pca954x_irq_setup(struct i2c_mux_core * muxc)356 static int pca954x_irq_setup(struct i2c_mux_core *muxc)
357 {
358 struct pca954x *data = i2c_mux_priv(muxc);
359 struct i2c_client *client = data->client;
360 int c, irq;
361
362 if (!data->chip->has_irq || client->irq <= 0)
363 return 0;
364
365 raw_spin_lock_init(&data->lock);
366
367 data->irq = irq_domain_add_linear(client->dev.of_node,
368 data->chip->nchans,
369 &irq_domain_simple_ops, data);
370 if (!data->irq)
371 return -ENODEV;
372
373 for (c = 0; c < data->chip->nchans; c++) {
374 irq = irq_create_mapping(data->irq, c);
375 if (!irq) {
376 dev_err(&client->dev, "failed irq create map\n");
377 return -EINVAL;
378 }
379 irq_set_chip_data(irq, data);
380 irq_set_chip_and_handler(irq, &pca954x_irq_chip,
381 handle_simple_irq);
382 }
383
384 return 0;
385 }
386
pca954x_cleanup(struct i2c_mux_core * muxc)387 static void pca954x_cleanup(struct i2c_mux_core *muxc)
388 {
389 struct pca954x *data = i2c_mux_priv(muxc);
390 struct i2c_client *client = data->client;
391 int c, irq;
392
393 device_remove_file(&client->dev, &dev_attr_idle_state);
394
395 if (data->irq) {
396 for (c = 0; c < data->chip->nchans; c++) {
397 irq = irq_find_mapping(data->irq, c);
398 irq_dispose_mapping(irq);
399 }
400 irq_domain_remove(data->irq);
401 }
402 i2c_mux_del_adapters(muxc);
403 }
404
405 /*
406 * I2C init/probing/exit functions
407 */
pca954x_probe(struct i2c_client * client,const struct i2c_device_id * id)408 static int pca954x_probe(struct i2c_client *client,
409 const struct i2c_device_id *id)
410 {
411 struct i2c_adapter *adap = client->adapter;
412 struct device *dev = &client->dev;
413 struct device_node *np = dev->of_node;
414 bool idle_disconnect_dt;
415 struct gpio_desc *gpio;
416 struct i2c_mux_core *muxc;
417 struct pca954x *data;
418 int num;
419 int ret;
420
421 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
422 return -ENODEV;
423
424 muxc = i2c_mux_alloc(adap, dev, PCA954X_MAX_NCHANS, sizeof(*data), 0,
425 pca954x_select_chan, pca954x_deselect_mux);
426 if (!muxc)
427 return -ENOMEM;
428 data = i2c_mux_priv(muxc);
429
430 i2c_set_clientdata(client, muxc);
431 data->client = client;
432
433 /* Reset the mux if a reset GPIO is specified. */
434 gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
435 if (IS_ERR(gpio))
436 return PTR_ERR(gpio);
437 if (gpio) {
438 udelay(1);
439 gpiod_set_value_cansleep(gpio, 0);
440 /* Give the chip some time to recover. */
441 udelay(1);
442 }
443
444 data->chip = of_device_get_match_data(dev);
445 if (!data->chip)
446 data->chip = &chips[id->driver_data];
447
448 if (data->chip->id.manufacturer_id != I2C_DEVICE_ID_NONE) {
449 struct i2c_device_identity id;
450
451 ret = i2c_get_device_id(client, &id);
452 if (ret && ret != -EOPNOTSUPP)
453 return ret;
454
455 if (!ret &&
456 (id.manufacturer_id != data->chip->id.manufacturer_id ||
457 id.part_id != data->chip->id.part_id)) {
458 dev_warn(dev, "unexpected device id %03x-%03x-%x\n",
459 id.manufacturer_id, id.part_id,
460 id.die_revision);
461 return -ENODEV;
462 }
463 }
464
465 /* Write the mux register at addr to verify
466 * that the mux is in fact present. This also
467 * initializes the mux to disconnected state.
468 */
469 if (i2c_smbus_write_byte(client, 0) < 0) {
470 dev_warn(dev, "probe failed\n");
471 return -ENODEV;
472 }
473
474 data->last_chan = 0; /* force the first selection */
475 data->idle_state = MUX_IDLE_AS_IS;
476
477 idle_disconnect_dt = np &&
478 of_property_read_bool(np, "i2c-mux-idle-disconnect");
479 if (idle_disconnect_dt)
480 data->idle_state = MUX_IDLE_DISCONNECT;
481
482 ret = pca954x_irq_setup(muxc);
483 if (ret)
484 goto fail_cleanup;
485
486 /* Now create an adapter for each channel */
487 for (num = 0; num < data->chip->nchans; num++) {
488 ret = i2c_mux_add_adapter(muxc, 0, num, 0);
489 if (ret)
490 goto fail_cleanup;
491 }
492
493 if (data->irq) {
494 ret = devm_request_threaded_irq(dev, data->client->irq,
495 NULL, pca954x_irq_handler,
496 IRQF_ONESHOT | IRQF_SHARED,
497 "pca954x", data);
498 if (ret)
499 goto fail_cleanup;
500 }
501
502 /*
503 * The attr probably isn't going to be needed in most cases,
504 * so don't fail completely on error.
505 */
506 device_create_file(dev, &dev_attr_idle_state);
507
508 dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
509 num, data->chip->muxtype == pca954x_ismux
510 ? "mux" : "switch", client->name);
511
512 return 0;
513
514 fail_cleanup:
515 pca954x_cleanup(muxc);
516 return ret;
517 }
518
pca954x_remove(struct i2c_client * client)519 static int pca954x_remove(struct i2c_client *client)
520 {
521 struct i2c_mux_core *muxc = i2c_get_clientdata(client);
522
523 pca954x_cleanup(muxc);
524 return 0;
525 }
526
527 #ifdef CONFIG_PM_SLEEP
pca954x_resume(struct device * dev)528 static int pca954x_resume(struct device *dev)
529 {
530 struct i2c_client *client = to_i2c_client(dev);
531 struct i2c_mux_core *muxc = i2c_get_clientdata(client);
532 struct pca954x *data = i2c_mux_priv(muxc);
533
534 data->last_chan = 0;
535 return i2c_smbus_write_byte(client, 0);
536 }
537 #endif
538
539 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
540
541 static struct i2c_driver pca954x_driver = {
542 .driver = {
543 .name = "pca954x",
544 .pm = &pca954x_pm,
545 .of_match_table = of_match_ptr(pca954x_of_match),
546 },
547 .probe = pca954x_probe,
548 .remove = pca954x_remove,
549 .id_table = pca954x_id,
550 };
551
552 module_i2c_driver(pca954x_driver);
553
554 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
555 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
556 MODULE_LICENSE("GPL v2");
557
