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 series of I2C multiplexer/switch chips
8  * made by Philips Semiconductors.
9  * This includes the:
10  *	 PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
11  *	 and PCA9548.
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/gpio/consumer.h>
40 #include <linux/i2c.h>
41 #include <linux/i2c-mux.h>
42 #include <linux/interrupt.h>
43 #include <linux/irq.h>
44 #include <linux/module.h>
45 #include <linux/of.h>
46 #include <linux/of_device.h>
47 #include <linux/of_irq.h>
48 #include <linux/platform_data/pca954x.h>
49 #include <linux/pm.h>
50 #include <linux/slab.h>
51 #include <linux/spinlock.h>
52 
53 #define PCA954X_MAX_NCHANS 8
54 
55 #define PCA954X_IRQ_OFFSET 4
56 
57 enum pca_type {
58 	pca_9540,
59 	pca_9542,
60 	pca_9543,
61 	pca_9544,
62 	pca_9545,
63 	pca_9546,
64 	pca_9547,
65 	pca_9548,
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 };
77 
78 struct pca954x {
79 	const struct chip_desc *chip;
80 
81 	u8 last_chan;		/* last register value */
82 	u8 deselect;
83 	struct i2c_client *client;
84 
85 	struct irq_domain *irq;
86 	unsigned int irq_mask;
87 	raw_spinlock_t lock;
88 };
89 
90 /* Provide specs for the PCA954x types we know about */
91 static const struct chip_desc chips[] = {
92 	[pca_9540] = {
93 		.nchans = 2,
94 		.enable = 0x4,
95 		.muxtype = pca954x_ismux,
96 	},
97 	[pca_9542] = {
98 		.nchans = 2,
99 		.enable = 0x4,
100 		.has_irq = 1,
101 		.muxtype = pca954x_ismux,
102 	},
103 	[pca_9543] = {
104 		.nchans = 2,
105 		.has_irq = 1,
106 		.muxtype = pca954x_isswi,
107 	},
108 	[pca_9544] = {
109 		.nchans = 4,
110 		.enable = 0x4,
111 		.has_irq = 1,
112 		.muxtype = pca954x_ismux,
113 	},
114 	[pca_9545] = {
115 		.nchans = 4,
116 		.has_irq = 1,
117 		.muxtype = pca954x_isswi,
118 	},
119 	[pca_9546] = {
120 		.nchans = 4,
121 		.muxtype = pca954x_isswi,
122 	},
123 	[pca_9547] = {
124 		.nchans = 8,
125 		.enable = 0x8,
126 		.muxtype = pca954x_ismux,
127 	},
128 	[pca_9548] = {
129 		.nchans = 8,
130 		.muxtype = pca954x_isswi,
131 	},
132 };
133 
134 static const struct i2c_device_id pca954x_id[] = {
135 	{ "pca9540", pca_9540 },
136 	{ "pca9542", pca_9542 },
137 	{ "pca9543", pca_9543 },
138 	{ "pca9544", pca_9544 },
139 	{ "pca9545", pca_9545 },
140 	{ "pca9546", pca_9546 },
141 	{ "pca9547", pca_9547 },
142 	{ "pca9548", pca_9548 },
143 	{ }
144 };
145 MODULE_DEVICE_TABLE(i2c, pca954x_id);
146 
147 #ifdef CONFIG_OF
148 static const struct of_device_id pca954x_of_match[] = {
149 	{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
150 	{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
151 	{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
152 	{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
153 	{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
154 	{ .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
155 	{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
156 	{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
157 	{}
158 };
159 MODULE_DEVICE_TABLE(of, pca954x_of_match);
160 #endif
161 
162 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
163    for this as they will try to lock adapter a second time */
164 static int pca954x_reg_write(struct i2c_adapter *adap,
165 			     struct i2c_client *client, u8 val)
166 {
167 	int ret = -ENODEV;
168 
169 	if (adap->algo->master_xfer) {
170 		struct i2c_msg msg;
171 		char buf[1];
172 
173 		msg.addr = client->addr;
174 		msg.flags = 0;
175 		msg.len = 1;
176 		buf[0] = val;
177 		msg.buf = buf;
178 		ret = __i2c_transfer(adap, &msg, 1);
179 
180 		if (ret >= 0 && ret != 1)
181 			ret = -EREMOTEIO;
182 	} else {
183 		union i2c_smbus_data data;
184 		ret = adap->algo->smbus_xfer(adap, client->addr,
185 					     client->flags,
186 					     I2C_SMBUS_WRITE,
187 					     val, I2C_SMBUS_BYTE, &data);
188 	}
189 
190 	return ret;
191 }
192 
193 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
194 {
195 	struct pca954x *data = i2c_mux_priv(muxc);
196 	struct i2c_client *client = data->client;
197 	const struct chip_desc *chip = data->chip;
198 	u8 regval;
199 	int ret = 0;
200 
201 	/* we make switches look like muxes, not sure how to be smarter */
202 	if (chip->muxtype == pca954x_ismux)
203 		regval = chan | chip->enable;
204 	else
205 		regval = 1 << chan;
206 
207 	/* Only select the channel if its different from the last channel */
208 	if (data->last_chan != regval) {
209 		ret = pca954x_reg_write(muxc->parent, client, regval);
210 		data->last_chan = ret < 0 ? 0 : regval;
211 	}
212 
213 	return ret;
214 }
215 
216 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
217 {
218 	struct pca954x *data = i2c_mux_priv(muxc);
219 	struct i2c_client *client = data->client;
220 
221 	if (!(data->deselect & (1 << chan)))
222 		return 0;
223 
224 	/* Deselect active channel */
225 	data->last_chan = 0;
226 	return pca954x_reg_write(muxc->parent, client, data->last_chan);
227 }
228 
229 static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
230 {
231 	struct pca954x *data = dev_id;
232 	unsigned int child_irq;
233 	int ret, i, handled = 0;
234 
235 	ret = i2c_smbus_read_byte(data->client);
236 	if (ret < 0)
237 		return IRQ_NONE;
238 
239 	for (i = 0; i < data->chip->nchans; i++) {
240 		if (ret & BIT(PCA954X_IRQ_OFFSET + i)) {
241 			child_irq = irq_linear_revmap(data->irq, i);
242 			handle_nested_irq(child_irq);
243 			handled++;
244 		}
245 	}
246 	return handled ? IRQ_HANDLED : IRQ_NONE;
247 }
248 
249 static void pca954x_irq_mask(struct irq_data *idata)
250 {
251 	struct pca954x *data = irq_data_get_irq_chip_data(idata);
252 	unsigned int pos = idata->hwirq;
253 	unsigned long flags;
254 
255 	raw_spin_lock_irqsave(&data->lock, flags);
256 
257 	data->irq_mask &= ~BIT(pos);
258 	if (!data->irq_mask)
259 		disable_irq(data->client->irq);
260 
261 	raw_spin_unlock_irqrestore(&data->lock, flags);
262 }
263 
264 static void pca954x_irq_unmask(struct irq_data *idata)
265 {
266 	struct pca954x *data = irq_data_get_irq_chip_data(idata);
267 	unsigned int pos = idata->hwirq;
268 	unsigned long flags;
269 
270 	raw_spin_lock_irqsave(&data->lock, flags);
271 
272 	if (!data->irq_mask)
273 		enable_irq(data->client->irq);
274 	data->irq_mask |= BIT(pos);
275 
276 	raw_spin_unlock_irqrestore(&data->lock, flags);
277 }
278 
279 static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
280 {
281 	if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
282 		return -EINVAL;
283 	return 0;
284 }
285 
286 static struct irq_chip pca954x_irq_chip = {
287 	.name = "i2c-mux-pca954x",
288 	.irq_mask = pca954x_irq_mask,
289 	.irq_unmask = pca954x_irq_unmask,
290 	.irq_set_type = pca954x_irq_set_type,
291 };
292 
293 static int pca954x_irq_setup(struct i2c_mux_core *muxc)
294 {
295 	struct pca954x *data = i2c_mux_priv(muxc);
296 	struct i2c_client *client = data->client;
297 	int c, err, irq;
298 
299 	if (!data->chip->has_irq || client->irq <= 0)
300 		return 0;
301 
302 	raw_spin_lock_init(&data->lock);
303 
304 	data->irq = irq_domain_add_linear(client->dev.of_node,
305 					  data->chip->nchans,
306 					  &irq_domain_simple_ops, data);
307 	if (!data->irq)
308 		return -ENODEV;
309 
310 	for (c = 0; c < data->chip->nchans; c++) {
311 		irq = irq_create_mapping(data->irq, c);
312 		irq_set_chip_data(irq, data);
313 		irq_set_chip_and_handler(irq, &pca954x_irq_chip,
314 			handle_simple_irq);
315 	}
316 
317 	err = devm_request_threaded_irq(&client->dev, data->client->irq, NULL,
318 					pca954x_irq_handler,
319 					IRQF_ONESHOT | IRQF_SHARED,
320 					"pca954x", data);
321 	if (err)
322 		goto err_req_irq;
323 
324 	disable_irq(data->client->irq);
325 
326 	return 0;
327 err_req_irq:
328 	for (c = 0; c < data->chip->nchans; c++) {
329 		irq = irq_find_mapping(data->irq, c);
330 		irq_dispose_mapping(irq);
331 	}
332 	irq_domain_remove(data->irq);
333 
334 	return err;
335 }
336 
337 /*
338  * I2C init/probing/exit functions
339  */
340 static int pca954x_probe(struct i2c_client *client,
341 			 const struct i2c_device_id *id)
342 {
343 	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
344 	struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
345 	struct device_node *of_node = client->dev.of_node;
346 	bool idle_disconnect_dt;
347 	struct gpio_desc *gpio;
348 	int num, force, class;
349 	struct i2c_mux_core *muxc;
350 	struct pca954x *data;
351 	const struct of_device_id *match;
352 	int ret;
353 
354 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
355 		return -ENODEV;
356 
357 	muxc = i2c_mux_alloc(adap, &client->dev,
358 			     PCA954X_MAX_NCHANS, sizeof(*data), 0,
359 			     pca954x_select_chan, pca954x_deselect_mux);
360 	if (!muxc)
361 		return -ENOMEM;
362 	data = i2c_mux_priv(muxc);
363 
364 	i2c_set_clientdata(client, muxc);
365 	data->client = client;
366 
367 	/* Get the mux out of reset if a reset GPIO is specified. */
368 	gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
369 	if (IS_ERR(gpio))
370 		return PTR_ERR(gpio);
371 
372 	/* Write the mux register at addr to verify
373 	 * that the mux is in fact present. This also
374 	 * initializes the mux to disconnected state.
375 	 */
376 	if (i2c_smbus_write_byte(client, 0) < 0) {
377 		dev_warn(&client->dev, "probe failed\n");
378 		return -ENODEV;
379 	}
380 
381 	match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
382 	if (match)
383 		data->chip = of_device_get_match_data(&client->dev);
384 	else
385 		data->chip = &chips[id->driver_data];
386 
387 	data->last_chan = 0;		   /* force the first selection */
388 
389 	idle_disconnect_dt = of_node &&
390 		of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
391 
392 	ret = pca954x_irq_setup(muxc);
393 	if (ret)
394 		goto fail_del_adapters;
395 
396 	/* Now create an adapter for each channel */
397 	for (num = 0; num < data->chip->nchans; num++) {
398 		bool idle_disconnect_pd = false;
399 
400 		force = 0;			  /* dynamic adap number */
401 		class = 0;			  /* no class by default */
402 		if (pdata) {
403 			if (num < pdata->num_modes) {
404 				/* force static number */
405 				force = pdata->modes[num].adap_id;
406 				class = pdata->modes[num].class;
407 			} else
408 				/* discard unconfigured channels */
409 				break;
410 			idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
411 		}
412 		data->deselect |= (idle_disconnect_pd ||
413 				   idle_disconnect_dt) << num;
414 
415 		ret = i2c_mux_add_adapter(muxc, force, num, class);
416 		if (ret)
417 			goto fail_del_adapters;
418 	}
419 
420 	dev_info(&client->dev,
421 		 "registered %d multiplexed busses for I2C %s %s\n",
422 		 num, data->chip->muxtype == pca954x_ismux
423 				? "mux" : "switch", client->name);
424 
425 	return 0;
426 
427 fail_del_adapters:
428 	i2c_mux_del_adapters(muxc);
429 	return ret;
430 }
431 
432 static int pca954x_remove(struct i2c_client *client)
433 {
434 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
435 	struct pca954x *data = i2c_mux_priv(muxc);
436 	int c, irq;
437 
438 	if (data->irq) {
439 		for (c = 0; c < data->chip->nchans; c++) {
440 			irq = irq_find_mapping(data->irq, c);
441 			irq_dispose_mapping(irq);
442 		}
443 		irq_domain_remove(data->irq);
444 	}
445 
446 	i2c_mux_del_adapters(muxc);
447 	return 0;
448 }
449 
450 #ifdef CONFIG_PM_SLEEP
451 static int pca954x_resume(struct device *dev)
452 {
453 	struct i2c_client *client = to_i2c_client(dev);
454 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
455 	struct pca954x *data = i2c_mux_priv(muxc);
456 
457 	data->last_chan = 0;
458 	return i2c_smbus_write_byte(client, 0);
459 }
460 #endif
461 
462 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
463 
464 static struct i2c_driver pca954x_driver = {
465 	.driver		= {
466 		.name	= "pca954x",
467 		.pm	= &pca954x_pm,
468 		.of_match_table = of_match_ptr(pca954x_of_match),
469 	},
470 	.probe		= pca954x_probe,
471 	.remove		= pca954x_remove,
472 	.id_table	= pca954x_id,
473 };
474 
475 module_i2c_driver(pca954x_driver);
476 
477 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
478 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
479 MODULE_LICENSE("GPL v2");
480