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/platform_data/pca954x.h>
50 #include <linux/pm.h>
51 #include <linux/slab.h>
52 #include <linux/spinlock.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 	u8 deselect;
89 	struct i2c_client *client;
90 
91 	struct irq_domain *irq;
92 	unsigned int irq_mask;
93 	raw_spinlock_t lock;
94 };
95 
96 /* Provide specs for the PCA954x types we know about */
97 static const struct chip_desc chips[] = {
98 	[pca_9540] = {
99 		.nchans = 2,
100 		.enable = 0x4,
101 		.muxtype = pca954x_ismux,
102 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
103 	},
104 	[pca_9542] = {
105 		.nchans = 2,
106 		.enable = 0x4,
107 		.has_irq = 1,
108 		.muxtype = pca954x_ismux,
109 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
110 	},
111 	[pca_9543] = {
112 		.nchans = 2,
113 		.has_irq = 1,
114 		.muxtype = pca954x_isswi,
115 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
116 	},
117 	[pca_9544] = {
118 		.nchans = 4,
119 		.enable = 0x4,
120 		.has_irq = 1,
121 		.muxtype = pca954x_ismux,
122 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
123 	},
124 	[pca_9545] = {
125 		.nchans = 4,
126 		.has_irq = 1,
127 		.muxtype = pca954x_isswi,
128 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
129 	},
130 	[pca_9546] = {
131 		.nchans = 4,
132 		.muxtype = pca954x_isswi,
133 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
134 	},
135 	[pca_9547] = {
136 		.nchans = 8,
137 		.enable = 0x8,
138 		.muxtype = pca954x_ismux,
139 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
140 	},
141 	[pca_9548] = {
142 		.nchans = 8,
143 		.muxtype = pca954x_isswi,
144 		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
145 	},
146 	[pca_9846] = {
147 		.nchans = 4,
148 		.muxtype = pca954x_isswi,
149 		.id = {
150 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
151 			.part_id = 0x10b,
152 		},
153 	},
154 	[pca_9847] = {
155 		.nchans = 8,
156 		.enable = 0x8,
157 		.muxtype = pca954x_ismux,
158 		.id = {
159 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
160 			.part_id = 0x108,
161 		},
162 	},
163 	[pca_9848] = {
164 		.nchans = 8,
165 		.muxtype = pca954x_isswi,
166 		.id = {
167 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
168 			.part_id = 0x10a,
169 		},
170 	},
171 	[pca_9849] = {
172 		.nchans = 4,
173 		.enable = 0x4,
174 		.muxtype = pca954x_ismux,
175 		.id = {
176 			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
177 			.part_id = 0x109,
178 		},
179 	},
180 };
181 
182 static const struct i2c_device_id pca954x_id[] = {
183 	{ "pca9540", pca_9540 },
184 	{ "pca9542", pca_9542 },
185 	{ "pca9543", pca_9543 },
186 	{ "pca9544", pca_9544 },
187 	{ "pca9545", pca_9545 },
188 	{ "pca9546", pca_9546 },
189 	{ "pca9547", pca_9547 },
190 	{ "pca9548", pca_9548 },
191 	{ "pca9846", pca_9846 },
192 	{ "pca9847", pca_9847 },
193 	{ "pca9848", pca_9848 },
194 	{ "pca9849", pca_9849 },
195 	{ }
196 };
197 MODULE_DEVICE_TABLE(i2c, pca954x_id);
198 
199 #ifdef CONFIG_OF
200 static const struct of_device_id pca954x_of_match[] = {
201 	{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
202 	{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
203 	{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
204 	{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
205 	{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
206 	{ .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
207 	{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
208 	{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
209 	{ .compatible = "nxp,pca9846", .data = &chips[pca_9846] },
210 	{ .compatible = "nxp,pca9847", .data = &chips[pca_9847] },
211 	{ .compatible = "nxp,pca9848", .data = &chips[pca_9848] },
212 	{ .compatible = "nxp,pca9849", .data = &chips[pca_9849] },
213 	{}
214 };
215 MODULE_DEVICE_TABLE(of, pca954x_of_match);
216 #endif
217 
218 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
219    for this as they will try to lock adapter a second time */
220 static int pca954x_reg_write(struct i2c_adapter *adap,
221 			     struct i2c_client *client, u8 val)
222 {
223 	union i2c_smbus_data dummy;
224 
225 	return __i2c_smbus_xfer(adap, client->addr, client->flags,
226 				I2C_SMBUS_WRITE, val,
227 				I2C_SMBUS_BYTE, &dummy);
228 }
229 
230 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
231 {
232 	struct pca954x *data = i2c_mux_priv(muxc);
233 	struct i2c_client *client = data->client;
234 	const struct chip_desc *chip = data->chip;
235 	u8 regval;
236 	int ret = 0;
237 
238 	/* we make switches look like muxes, not sure how to be smarter */
239 	if (chip->muxtype == pca954x_ismux)
240 		regval = chan | chip->enable;
241 	else
242 		regval = 1 << chan;
243 
244 	/* Only select the channel if its different from the last channel */
245 	if (data->last_chan != regval) {
246 		ret = pca954x_reg_write(muxc->parent, client, regval);
247 		data->last_chan = ret < 0 ? 0 : regval;
248 	}
249 
250 	return ret;
251 }
252 
253 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
254 {
255 	struct pca954x *data = i2c_mux_priv(muxc);
256 	struct i2c_client *client = data->client;
257 
258 	if (!(data->deselect & (1 << chan)))
259 		return 0;
260 
261 	/* Deselect active channel */
262 	data->last_chan = 0;
263 	return pca954x_reg_write(muxc->parent, client, data->last_chan);
264 }
265 
266 static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
267 {
268 	struct pca954x *data = dev_id;
269 	unsigned int child_irq;
270 	int ret, i, handled = 0;
271 
272 	ret = i2c_smbus_read_byte(data->client);
273 	if (ret < 0)
274 		return IRQ_NONE;
275 
276 	for (i = 0; i < data->chip->nchans; i++) {
277 		if (ret & BIT(PCA954X_IRQ_OFFSET + i)) {
278 			child_irq = irq_linear_revmap(data->irq, i);
279 			handle_nested_irq(child_irq);
280 			handled++;
281 		}
282 	}
283 	return handled ? IRQ_HANDLED : IRQ_NONE;
284 }
285 
286 static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
287 {
288 	if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
289 		return -EINVAL;
290 	return 0;
291 }
292 
293 static struct irq_chip pca954x_irq_chip = {
294 	.name = "i2c-mux-pca954x",
295 	.irq_set_type = pca954x_irq_set_type,
296 };
297 
298 static int pca954x_irq_setup(struct i2c_mux_core *muxc)
299 {
300 	struct pca954x *data = i2c_mux_priv(muxc);
301 	struct i2c_client *client = data->client;
302 	int c, irq;
303 
304 	if (!data->chip->has_irq || client->irq <= 0)
305 		return 0;
306 
307 	raw_spin_lock_init(&data->lock);
308 
309 	data->irq = irq_domain_add_linear(client->dev.of_node,
310 					  data->chip->nchans,
311 					  &irq_domain_simple_ops, data);
312 	if (!data->irq)
313 		return -ENODEV;
314 
315 	for (c = 0; c < data->chip->nchans; c++) {
316 		irq = irq_create_mapping(data->irq, c);
317 		if (!irq) {
318 			dev_err(&client->dev, "failed irq create map\n");
319 			return -EINVAL;
320 		}
321 		irq_set_chip_data(irq, data);
322 		irq_set_chip_and_handler(irq, &pca954x_irq_chip,
323 			handle_simple_irq);
324 	}
325 
326 	return 0;
327 }
328 
329 static void pca954x_cleanup(struct i2c_mux_core *muxc)
330 {
331 	struct pca954x *data = i2c_mux_priv(muxc);
332 	int c, irq;
333 
334 	if (data->irq) {
335 		for (c = 0; c < data->chip->nchans; c++) {
336 			irq = irq_find_mapping(data->irq, c);
337 			irq_dispose_mapping(irq);
338 		}
339 		irq_domain_remove(data->irq);
340 	}
341 	i2c_mux_del_adapters(muxc);
342 }
343 
344 /*
345  * I2C init/probing/exit functions
346  */
347 static int pca954x_probe(struct i2c_client *client,
348 			 const struct i2c_device_id *id)
349 {
350 	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
351 	struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
352 	struct device *dev = &client->dev;
353 	struct device_node *np = dev->of_node;
354 	bool idle_disconnect_dt;
355 	struct gpio_desc *gpio;
356 	int num, force, class;
357 	struct i2c_mux_core *muxc;
358 	struct pca954x *data;
359 	int ret;
360 
361 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
362 		return -ENODEV;
363 
364 	muxc = i2c_mux_alloc(adap, dev, PCA954X_MAX_NCHANS, sizeof(*data), 0,
365 			     pca954x_select_chan, pca954x_deselect_mux);
366 	if (!muxc)
367 		return -ENOMEM;
368 	data = i2c_mux_priv(muxc);
369 
370 	i2c_set_clientdata(client, muxc);
371 	data->client = client;
372 
373 	/* Reset the mux if a reset GPIO is specified. */
374 	gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
375 	if (IS_ERR(gpio))
376 		return PTR_ERR(gpio);
377 	if (gpio) {
378 		udelay(1);
379 		gpiod_set_value_cansleep(gpio, 0);
380 		/* Give the chip some time to recover. */
381 		udelay(1);
382 	}
383 
384 	data->chip = of_device_get_match_data(dev);
385 	if (!data->chip)
386 		data->chip = &chips[id->driver_data];
387 
388 	if (data->chip->id.manufacturer_id != I2C_DEVICE_ID_NONE) {
389 		struct i2c_device_identity id;
390 
391 		ret = i2c_get_device_id(client, &id);
392 		if (ret && ret != -EOPNOTSUPP)
393 			return ret;
394 
395 		if (!ret &&
396 		    (id.manufacturer_id != data->chip->id.manufacturer_id ||
397 		     id.part_id != data->chip->id.part_id)) {
398 			dev_warn(dev, "unexpected device id %03x-%03x-%x\n",
399 				 id.manufacturer_id, id.part_id,
400 				 id.die_revision);
401 			return -ENODEV;
402 		}
403 	}
404 
405 	/* Write the mux register at addr to verify
406 	 * that the mux is in fact present. This also
407 	 * initializes the mux to disconnected state.
408 	 */
409 	if (i2c_smbus_write_byte(client, 0) < 0) {
410 		dev_warn(dev, "probe failed\n");
411 		return -ENODEV;
412 	}
413 
414 	data->last_chan = 0;		   /* force the first selection */
415 
416 	idle_disconnect_dt = np &&
417 		of_property_read_bool(np, "i2c-mux-idle-disconnect");
418 
419 	ret = pca954x_irq_setup(muxc);
420 	if (ret)
421 		goto fail_cleanup;
422 
423 	/* Now create an adapter for each channel */
424 	for (num = 0; num < data->chip->nchans; num++) {
425 		bool idle_disconnect_pd = false;
426 
427 		force = 0;			  /* dynamic adap number */
428 		class = 0;			  /* no class by default */
429 		if (pdata) {
430 			if (num < pdata->num_modes) {
431 				/* force static number */
432 				force = pdata->modes[num].adap_id;
433 				class = pdata->modes[num].class;
434 			} else
435 				/* discard unconfigured channels */
436 				break;
437 			idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
438 		}
439 		data->deselect |= (idle_disconnect_pd ||
440 				   idle_disconnect_dt) << num;
441 
442 		ret = i2c_mux_add_adapter(muxc, force, num, class);
443 		if (ret)
444 			goto fail_cleanup;
445 	}
446 
447 	if (data->irq) {
448 		ret = devm_request_threaded_irq(dev, data->client->irq,
449 						NULL, pca954x_irq_handler,
450 						IRQF_ONESHOT | IRQF_SHARED,
451 						"pca954x", data);
452 		if (ret)
453 			goto fail_cleanup;
454 	}
455 
456 	dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
457 		 num, data->chip->muxtype == pca954x_ismux
458 				? "mux" : "switch", client->name);
459 
460 	return 0;
461 
462 fail_cleanup:
463 	pca954x_cleanup(muxc);
464 	return ret;
465 }
466 
467 static int pca954x_remove(struct i2c_client *client)
468 {
469 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
470 
471 	pca954x_cleanup(muxc);
472 	return 0;
473 }
474 
475 #ifdef CONFIG_PM_SLEEP
476 static int pca954x_resume(struct device *dev)
477 {
478 	struct i2c_client *client = to_i2c_client(dev);
479 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
480 	struct pca954x *data = i2c_mux_priv(muxc);
481 
482 	data->last_chan = 0;
483 	return i2c_smbus_write_byte(client, 0);
484 }
485 #endif
486 
487 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
488 
489 static struct i2c_driver pca954x_driver = {
490 	.driver		= {
491 		.name	= "pca954x",
492 		.pm	= &pca954x_pm,
493 		.of_match_table = of_match_ptr(pca954x_of_match),
494 	},
495 	.probe		= pca954x_probe,
496 	.remove		= pca954x_remove,
497 	.id_table	= pca954x_id,
498 };
499 
500 module_i2c_driver(pca954x_driver);
501 
502 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
503 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
504 MODULE_LICENSE("GPL v2");
505