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/acpi.h>
39 #include <linux/device.h>
40 #include <linux/gpio/consumer.h>
41 #include <linux/i2c.h>
42 #include <linux/i2c-mux.h>
43 #include <linux/i2c/pca954x.h>
44 #include <linux/module.h>
45 #include <linux/of.h>
46 #include <linux/of_device.h>
47 #include <linux/pm.h>
48 #include <linux/slab.h>
49 
50 #define PCA954X_MAX_NCHANS 8
51 
52 enum pca_type {
53 	pca_9540,
54 	pca_9542,
55 	pca_9543,
56 	pca_9544,
57 	pca_9545,
58 	pca_9546,
59 	pca_9547,
60 	pca_9548,
61 };
62 
63 struct chip_desc {
64 	u8 nchans;
65 	u8 enable;	/* used for muxes only */
66 	enum muxtype {
67 		pca954x_ismux = 0,
68 		pca954x_isswi
69 	} muxtype;
70 };
71 
72 struct pca954x {
73 	const struct chip_desc *chip;
74 
75 	u8 last_chan;		/* last register value */
76 	u8 deselect;
77 	struct i2c_client *client;
78 };
79 
80 /* Provide specs for the PCA954x types we know about */
81 static const struct chip_desc chips[] = {
82 	[pca_9540] = {
83 		.nchans = 2,
84 		.enable = 0x4,
85 		.muxtype = pca954x_ismux,
86 	},
87 	[pca_9543] = {
88 		.nchans = 2,
89 		.muxtype = pca954x_isswi,
90 	},
91 	[pca_9544] = {
92 		.nchans = 4,
93 		.enable = 0x4,
94 		.muxtype = pca954x_ismux,
95 	},
96 	[pca_9545] = {
97 		.nchans = 4,
98 		.muxtype = pca954x_isswi,
99 	},
100 	[pca_9547] = {
101 		.nchans = 8,
102 		.enable = 0x8,
103 		.muxtype = pca954x_ismux,
104 	},
105 	[pca_9548] = {
106 		.nchans = 8,
107 		.muxtype = pca954x_isswi,
108 	},
109 };
110 
111 static const struct i2c_device_id pca954x_id[] = {
112 	{ "pca9540", pca_9540 },
113 	{ "pca9542", pca_9540 },
114 	{ "pca9543", pca_9543 },
115 	{ "pca9544", pca_9544 },
116 	{ "pca9545", pca_9545 },
117 	{ "pca9546", pca_9545 },
118 	{ "pca9547", pca_9547 },
119 	{ "pca9548", pca_9548 },
120 	{ }
121 };
122 MODULE_DEVICE_TABLE(i2c, pca954x_id);
123 
124 #ifdef CONFIG_ACPI
125 static const struct acpi_device_id pca954x_acpi_ids[] = {
126 	{ .id = "PCA9540", .driver_data = pca_9540 },
127 	{ .id = "PCA9542", .driver_data = pca_9540 },
128 	{ .id = "PCA9543", .driver_data = pca_9543 },
129 	{ .id = "PCA9544", .driver_data = pca_9544 },
130 	{ .id = "PCA9545", .driver_data = pca_9545 },
131 	{ .id = "PCA9546", .driver_data = pca_9545 },
132 	{ .id = "PCA9547", .driver_data = pca_9547 },
133 	{ .id = "PCA9548", .driver_data = pca_9548 },
134 	{ }
135 };
136 MODULE_DEVICE_TABLE(acpi, pca954x_acpi_ids);
137 #endif
138 
139 #ifdef CONFIG_OF
140 static const struct of_device_id pca954x_of_match[] = {
141 	{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
142 	{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
143 	{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
144 	{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
145 	{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
146 	{ .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
147 	{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
148 	{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
149 	{}
150 };
151 #endif
152 
153 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
154    for this as they will try to lock adapter a second time */
155 static int pca954x_reg_write(struct i2c_adapter *adap,
156 			     struct i2c_client *client, u8 val)
157 {
158 	int ret = -ENODEV;
159 
160 	if (adap->algo->master_xfer) {
161 		struct i2c_msg msg;
162 		char buf[1];
163 
164 		msg.addr = client->addr;
165 		msg.flags = 0;
166 		msg.len = 1;
167 		buf[0] = val;
168 		msg.buf = buf;
169 		ret = __i2c_transfer(adap, &msg, 1);
170 
171 		if (ret >= 0 && ret != 1)
172 			ret = -EREMOTEIO;
173 	} else {
174 		union i2c_smbus_data data;
175 		ret = adap->algo->smbus_xfer(adap, client->addr,
176 					     client->flags,
177 					     I2C_SMBUS_WRITE,
178 					     val, I2C_SMBUS_BYTE, &data);
179 	}
180 
181 	return ret;
182 }
183 
184 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
185 {
186 	struct pca954x *data = i2c_mux_priv(muxc);
187 	struct i2c_client *client = data->client;
188 	const struct chip_desc *chip = data->chip;
189 	u8 regval;
190 	int ret = 0;
191 
192 	/* we make switches look like muxes, not sure how to be smarter */
193 	if (chip->muxtype == pca954x_ismux)
194 		regval = chan | chip->enable;
195 	else
196 		regval = 1 << chan;
197 
198 	/* Only select the channel if its different from the last channel */
199 	if (data->last_chan != regval) {
200 		ret = pca954x_reg_write(muxc->parent, client, regval);
201 		data->last_chan = ret < 0 ? 0 : regval;
202 	}
203 
204 	return ret;
205 }
206 
207 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
208 {
209 	struct pca954x *data = i2c_mux_priv(muxc);
210 	struct i2c_client *client = data->client;
211 
212 	if (!(data->deselect & (1 << chan)))
213 		return 0;
214 
215 	/* Deselect active channel */
216 	data->last_chan = 0;
217 	return pca954x_reg_write(muxc->parent, client, data->last_chan);
218 }
219 
220 /*
221  * I2C init/probing/exit functions
222  */
223 static int pca954x_probe(struct i2c_client *client,
224 			 const struct i2c_device_id *id)
225 {
226 	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
227 	struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
228 	struct device_node *of_node = client->dev.of_node;
229 	bool idle_disconnect_dt;
230 	struct gpio_desc *gpio;
231 	int num, force, class;
232 	struct i2c_mux_core *muxc;
233 	struct pca954x *data;
234 	const struct of_device_id *match;
235 	int ret;
236 
237 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
238 		return -ENODEV;
239 
240 	muxc = i2c_mux_alloc(adap, &client->dev,
241 			     PCA954X_MAX_NCHANS, sizeof(*data), 0,
242 			     pca954x_select_chan, pca954x_deselect_mux);
243 	if (!muxc)
244 		return -ENOMEM;
245 	data = i2c_mux_priv(muxc);
246 
247 	i2c_set_clientdata(client, muxc);
248 	data->client = client;
249 
250 	/* Get the mux out of reset if a reset GPIO is specified. */
251 	gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
252 	if (IS_ERR(gpio))
253 		return PTR_ERR(gpio);
254 
255 	/* Write the mux register at addr to verify
256 	 * that the mux is in fact present. This also
257 	 * initializes the mux to disconnected state.
258 	 */
259 	if (i2c_smbus_write_byte(client, 0) < 0) {
260 		dev_warn(&client->dev, "probe failed\n");
261 		return -ENODEV;
262 	}
263 
264 	match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
265 	if (match)
266 		data->chip = of_device_get_match_data(&client->dev);
267 	else if (id)
268 		data->chip = &chips[id->driver_data];
269 	else {
270 		const struct acpi_device_id *acpi_id;
271 
272 		acpi_id = acpi_match_device(ACPI_PTR(pca954x_acpi_ids),
273 						&client->dev);
274 		if (!acpi_id)
275 			return -ENODEV;
276 		data->chip = &chips[acpi_id->driver_data];
277 	}
278 
279 	data->last_chan = 0;		   /* force the first selection */
280 
281 	idle_disconnect_dt = of_node &&
282 		of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
283 
284 	/* Now create an adapter for each channel */
285 	for (num = 0; num < data->chip->nchans; num++) {
286 		bool idle_disconnect_pd = false;
287 
288 		force = 0;			  /* dynamic adap number */
289 		class = 0;			  /* no class by default */
290 		if (pdata) {
291 			if (num < pdata->num_modes) {
292 				/* force static number */
293 				force = pdata->modes[num].adap_id;
294 				class = pdata->modes[num].class;
295 			} else
296 				/* discard unconfigured channels */
297 				break;
298 			idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
299 		}
300 		data->deselect |= (idle_disconnect_pd ||
301 				   idle_disconnect_dt) << num;
302 
303 		ret = i2c_mux_add_adapter(muxc, force, num, class);
304 
305 		if (ret) {
306 			dev_err(&client->dev,
307 				"failed to register multiplexed adapter"
308 				" %d as bus %d\n", num, force);
309 			goto virt_reg_failed;
310 		}
311 	}
312 
313 	dev_info(&client->dev,
314 		 "registered %d multiplexed busses for I2C %s %s\n",
315 		 num, data->chip->muxtype == pca954x_ismux
316 				? "mux" : "switch", client->name);
317 
318 	return 0;
319 
320 virt_reg_failed:
321 	i2c_mux_del_adapters(muxc);
322 	return ret;
323 }
324 
325 static int pca954x_remove(struct i2c_client *client)
326 {
327 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
328 
329 	i2c_mux_del_adapters(muxc);
330 	return 0;
331 }
332 
333 #ifdef CONFIG_PM_SLEEP
334 static int pca954x_resume(struct device *dev)
335 {
336 	struct i2c_client *client = to_i2c_client(dev);
337 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
338 	struct pca954x *data = i2c_mux_priv(muxc);
339 
340 	data->last_chan = 0;
341 	return i2c_smbus_write_byte(client, 0);
342 }
343 #endif
344 
345 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
346 
347 static struct i2c_driver pca954x_driver = {
348 	.driver		= {
349 		.name	= "pca954x",
350 		.pm	= &pca954x_pm,
351 		.of_match_table = of_match_ptr(pca954x_of_match),
352 		.acpi_match_table = ACPI_PTR(pca954x_acpi_ids),
353 	},
354 	.probe		= pca954x_probe,
355 	.remove		= pca954x_remove,
356 	.id_table	= pca954x_id,
357 };
358 
359 module_i2c_driver(pca954x_driver);
360 
361 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
362 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
363 MODULE_LICENSE("GPL v2");
364