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/i2c/pca954x.h>
43 #include <linux/module.h>
44 #include <linux/of.h>
45 #include <linux/pm.h>
46 #include <linux/slab.h>
47 
48 #define PCA954X_MAX_NCHANS 8
49 
50 enum pca_type {
51 	pca_9540,
52 	pca_9542,
53 	pca_9543,
54 	pca_9544,
55 	pca_9545,
56 	pca_9546,
57 	pca_9547,
58 	pca_9548,
59 };
60 
61 struct pca954x {
62 	enum pca_type type;
63 	struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
64 
65 	u8 last_chan;		/* last register value */
66 };
67 
68 struct chip_desc {
69 	u8 nchans;
70 	u8 enable;	/* used for muxes only */
71 	enum muxtype {
72 		pca954x_ismux = 0,
73 		pca954x_isswi
74 	} muxtype;
75 };
76 
77 /* Provide specs for the PCA954x types we know about */
78 static const struct chip_desc chips[] = {
79 	[pca_9540] = {
80 		.nchans = 2,
81 		.enable = 0x4,
82 		.muxtype = pca954x_ismux,
83 	},
84 	[pca_9543] = {
85 		.nchans = 2,
86 		.muxtype = pca954x_isswi,
87 	},
88 	[pca_9544] = {
89 		.nchans = 4,
90 		.enable = 0x4,
91 		.muxtype = pca954x_ismux,
92 	},
93 	[pca_9545] = {
94 		.nchans = 4,
95 		.muxtype = pca954x_isswi,
96 	},
97 	[pca_9547] = {
98 		.nchans = 8,
99 		.enable = 0x8,
100 		.muxtype = pca954x_ismux,
101 	},
102 	[pca_9548] = {
103 		.nchans = 8,
104 		.muxtype = pca954x_isswi,
105 	},
106 };
107 
108 static const struct i2c_device_id pca954x_id[] = {
109 	{ "pca9540", pca_9540 },
110 	{ "pca9542", pca_9540 },
111 	{ "pca9543", pca_9543 },
112 	{ "pca9544", pca_9544 },
113 	{ "pca9545", pca_9545 },
114 	{ "pca9546", pca_9545 },
115 	{ "pca9547", pca_9547 },
116 	{ "pca9548", pca_9548 },
117 	{ }
118 };
119 MODULE_DEVICE_TABLE(i2c, pca954x_id);
120 
121 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
122    for this as they will try to lock adapter a second time */
123 static int pca954x_reg_write(struct i2c_adapter *adap,
124 			     struct i2c_client *client, u8 val)
125 {
126 	int ret = -ENODEV;
127 
128 	if (adap->algo->master_xfer) {
129 		struct i2c_msg msg;
130 		char buf[1];
131 
132 		msg.addr = client->addr;
133 		msg.flags = 0;
134 		msg.len = 1;
135 		buf[0] = val;
136 		msg.buf = buf;
137 		ret = __i2c_transfer(adap, &msg, 1);
138 	} else {
139 		union i2c_smbus_data data;
140 		ret = adap->algo->smbus_xfer(adap, client->addr,
141 					     client->flags,
142 					     I2C_SMBUS_WRITE,
143 					     val, I2C_SMBUS_BYTE, &data);
144 	}
145 
146 	return ret;
147 }
148 
149 static int pca954x_select_chan(struct i2c_adapter *adap,
150 			       void *client, u32 chan)
151 {
152 	struct pca954x *data = i2c_get_clientdata(client);
153 	const struct chip_desc *chip = &chips[data->type];
154 	u8 regval;
155 	int ret = 0;
156 
157 	/* we make switches look like muxes, not sure how to be smarter */
158 	if (chip->muxtype == pca954x_ismux)
159 		regval = chan | chip->enable;
160 	else
161 		regval = 1 << chan;
162 
163 	/* Only select the channel if its different from the last channel */
164 	if (data->last_chan != regval) {
165 		ret = pca954x_reg_write(adap, client, regval);
166 		data->last_chan = regval;
167 	}
168 
169 	return ret;
170 }
171 
172 static int pca954x_deselect_mux(struct i2c_adapter *adap,
173 				void *client, u32 chan)
174 {
175 	struct pca954x *data = i2c_get_clientdata(client);
176 
177 	/* Deselect active channel */
178 	data->last_chan = 0;
179 	return pca954x_reg_write(adap, client, data->last_chan);
180 }
181 
182 /*
183  * I2C init/probing/exit functions
184  */
185 static int pca954x_probe(struct i2c_client *client,
186 			 const struct i2c_device_id *id)
187 {
188 	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
189 	struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
190 	struct device_node *of_node = client->dev.of_node;
191 	bool idle_disconnect_dt;
192 	struct gpio_desc *gpio;
193 	int num, force, class;
194 	struct pca954x *data;
195 	int ret;
196 
197 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
198 		return -ENODEV;
199 
200 	data = devm_kzalloc(&client->dev, sizeof(struct pca954x), GFP_KERNEL);
201 	if (!data)
202 		return -ENOMEM;
203 
204 	i2c_set_clientdata(client, data);
205 
206 	/* Get the mux out of reset if a reset GPIO is specified. */
207 	gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
208 	if (IS_ERR(gpio))
209 		return PTR_ERR(gpio);
210 
211 	/* Write the mux register at addr to verify
212 	 * that the mux is in fact present. This also
213 	 * initializes the mux to disconnected state.
214 	 */
215 	if (i2c_smbus_write_byte(client, 0) < 0) {
216 		dev_warn(&client->dev, "probe failed\n");
217 		return -ENODEV;
218 	}
219 
220 	data->type = id->driver_data;
221 	data->last_chan = 0;		   /* force the first selection */
222 
223 	idle_disconnect_dt = of_node &&
224 		of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
225 
226 	/* Now create an adapter for each channel */
227 	for (num = 0; num < chips[data->type].nchans; num++) {
228 		bool idle_disconnect_pd = false;
229 
230 		force = 0;			  /* dynamic adap number */
231 		class = 0;			  /* no class by default */
232 		if (pdata) {
233 			if (num < pdata->num_modes) {
234 				/* force static number */
235 				force = pdata->modes[num].adap_id;
236 				class = pdata->modes[num].class;
237 			} else
238 				/* discard unconfigured channels */
239 				break;
240 			idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
241 		}
242 
243 		data->virt_adaps[num] =
244 			i2c_add_mux_adapter(adap, &client->dev, client,
245 				force, num, class, pca954x_select_chan,
246 				(idle_disconnect_pd || idle_disconnect_dt)
247 					? pca954x_deselect_mux : NULL);
248 
249 		if (data->virt_adaps[num] == NULL) {
250 			ret = -ENODEV;
251 			dev_err(&client->dev,
252 				"failed to register multiplexed adapter"
253 				" %d as bus %d\n", num, force);
254 			goto virt_reg_failed;
255 		}
256 	}
257 
258 	dev_info(&client->dev,
259 		 "registered %d multiplexed busses for I2C %s %s\n",
260 		 num, chips[data->type].muxtype == pca954x_ismux
261 				? "mux" : "switch", client->name);
262 
263 	return 0;
264 
265 virt_reg_failed:
266 	for (num--; num >= 0; num--)
267 		i2c_del_mux_adapter(data->virt_adaps[num]);
268 	return ret;
269 }
270 
271 static int pca954x_remove(struct i2c_client *client)
272 {
273 	struct pca954x *data = i2c_get_clientdata(client);
274 	const struct chip_desc *chip = &chips[data->type];
275 	int i;
276 
277 	for (i = 0; i < chip->nchans; ++i)
278 		if (data->virt_adaps[i]) {
279 			i2c_del_mux_adapter(data->virt_adaps[i]);
280 			data->virt_adaps[i] = NULL;
281 		}
282 
283 	return 0;
284 }
285 
286 #ifdef CONFIG_PM_SLEEP
287 static int pca954x_resume(struct device *dev)
288 {
289 	struct i2c_client *client = to_i2c_client(dev);
290 	struct pca954x *data = i2c_get_clientdata(client);
291 
292 	data->last_chan = 0;
293 	return i2c_smbus_write_byte(client, 0);
294 }
295 #endif
296 
297 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
298 
299 static struct i2c_driver pca954x_driver = {
300 	.driver		= {
301 		.name	= "pca954x",
302 		.pm	= &pca954x_pm,
303 	},
304 	.probe		= pca954x_probe,
305 	.remove		= pca954x_remove,
306 	.id_table	= pca954x_id,
307 };
308 
309 module_i2c_driver(pca954x_driver);
310 
311 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
312 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
313 MODULE_LICENSE("GPL v2");
314