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
50enum 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
61struct 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
68struct 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 */
78static 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
108static 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};
119MODULE_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 */
123static 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
149static 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
172static 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 */
185static 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
265virt_reg_failed:
266	for (num--; num >= 0; num--)
267		i2c_del_mux_adapter(data->virt_adaps[num]);
268	return ret;
269}
270
271static 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
287static 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
297static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
298
299static 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
309module_i2c_driver(pca954x_driver);
310
311MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
312MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
313MODULE_LICENSE("GPL v2");
314