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Michael Lawnick7f528132010-08-11 18:21:03 +02001/*
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 <khali@linux-fr.org>.
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/module.h>
39#include <linux/init.h>
40#include <linux/slab.h>
41#include <linux/device.h>
42#include <linux/i2c.h>
43#include <linux/i2c-mux.h>
44
45#include <linux/i2c/pca954x.h>
46
47#define PCA954X_MAX_NCHANS 8
48
49enum pca_type {
50 pca_9540,
51 pca_9542,
52 pca_9543,
53 pca_9544,
54 pca_9545,
55 pca_9546,
56 pca_9547,
57 pca_9548,
58};
59
60struct pca954x {
61 enum pca_type type;
62 struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
63
64 u8 last_chan; /* last register value */
65};
66
67struct chip_desc {
68 u8 nchans;
69 u8 enable; /* used for muxes only */
70 enum muxtype {
71 pca954x_ismux = 0,
72 pca954x_isswi
73 } muxtype;
74};
75
76/* Provide specs for the PCA954x types we know about */
77static const struct chip_desc chips[] = {
78 [pca_9540] = {
79 .nchans = 2,
80 .enable = 0x4,
81 .muxtype = pca954x_ismux,
82 },
83 [pca_9543] = {
84 .nchans = 2,
85 .muxtype = pca954x_isswi,
86 },
87 [pca_9544] = {
88 .nchans = 4,
89 .enable = 0x4,
90 .muxtype = pca954x_ismux,
91 },
92 [pca_9545] = {
93 .nchans = 4,
94 .muxtype = pca954x_isswi,
95 },
96 [pca_9547] = {
97 .nchans = 8,
98 .enable = 0x8,
99 .muxtype = pca954x_ismux,
100 },
101 [pca_9548] = {
102 .nchans = 8,
103 .muxtype = pca954x_isswi,
104 },
105};
106
107static const struct i2c_device_id pca954x_id[] = {
108 { "pca9540", pca_9540 },
109 { "pca9542", pca_9540 },
110 { "pca9543", pca_9543 },
111 { "pca9544", pca_9544 },
112 { "pca9545", pca_9545 },
113 { "pca9546", pca_9545 },
114 { "pca9547", pca_9547 },
115 { "pca9548", pca_9548 },
116 { }
117};
118MODULE_DEVICE_TABLE(i2c, pca954x_id);
119
120/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
121 for this as they will try to lock adapter a second time */
122static int pca954x_reg_write(struct i2c_adapter *adap,
123 struct i2c_client *client, u8 val)
124{
125 int ret = -ENODEV;
126
127 if (adap->algo->master_xfer) {
128 struct i2c_msg msg;
129 char buf[1];
130
131 msg.addr = client->addr;
132 msg.flags = 0;
133 msg.len = 1;
134 buf[0] = val;
135 msg.buf = buf;
136 ret = adap->algo->master_xfer(adap, &msg, 1);
137 } else {
138 union i2c_smbus_data data;
139 ret = adap->algo->smbus_xfer(adap, client->addr,
140 client->flags,
141 I2C_SMBUS_WRITE,
142 val, I2C_SMBUS_BYTE, &data);
143 }
144
145 return ret;
146}
147
148static int pca954x_select_chan(struct i2c_adapter *adap,
149 void *client, u32 chan)
150{
151 struct pca954x *data = i2c_get_clientdata(client);
152 const struct chip_desc *chip = &chips[data->type];
153 u8 regval;
154 int ret = 0;
155
156 /* we make switches look like muxes, not sure how to be smarter */
157 if (chip->muxtype == pca954x_ismux)
158 regval = chan | chip->enable;
159 else
160 regval = 1 << chan;
161
162 /* Only select the channel if its different from the last channel */
163 if (data->last_chan != regval) {
164 ret = pca954x_reg_write(adap, client, regval);
165 data->last_chan = regval;
166 }
167
168 return ret;
169}
170
171static int pca954x_deselect_mux(struct i2c_adapter *adap,
172 void *client, u32 chan)
173{
174 struct pca954x *data = i2c_get_clientdata(client);
175
176 /* Deselect active channel */
177 data->last_chan = 0;
178 return pca954x_reg_write(adap, client, data->last_chan);
179}
180
181/*
182 * I2C init/probing/exit functions
183 */
184static int __devinit pca954x_probe(struct i2c_client *client,
185 const struct i2c_device_id *id)
186{
187 struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
188 struct pca954x_platform_data *pdata = client->dev.platform_data;
189 int num, force;
190 struct pca954x *data;
191 int ret = -ENODEV;
192
193 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
194 goto err;
195
196 data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
197 if (!data) {
198 ret = -ENOMEM;
199 goto err;
200 }
201
202 i2c_set_clientdata(client, data);
203
204 /* Read the mux register at addr to verify
205 * that the mux is in fact present.
206 */
207 if (i2c_smbus_read_byte(client) < 0) {
208 dev_warn(&client->dev, "probe failed\n");
209 goto exit_free;
210 }
211
212 data->type = id->driver_data;
213 data->last_chan = 0; /* force the first selection */
214
215 /* Now create an adapter for each channel */
216 for (num = 0; num < chips[data->type].nchans; num++) {
217 force = 0; /* dynamic adap number */
218 if (pdata) {
219 if (num < pdata->num_modes)
220 /* force static number */
221 force = pdata->modes[num].adap_id;
222 else
223 /* discard unconfigured channels */
224 break;
225 }
226
227 data->virt_adaps[num] =
228 i2c_add_mux_adapter(adap, client,
229 force, num, pca954x_select_chan,
230 (pdata && pdata->modes[num].deselect_on_exit)
231 ? pca954x_deselect_mux : NULL);
232
233 if (data->virt_adaps[num] == NULL) {
234 ret = -ENODEV;
235 dev_err(&client->dev,
236 "failed to register multiplexed adapter"
237 " %d as bus %d\n", num, force);
238 goto virt_reg_failed;
239 }
240 }
241
242 dev_info(&client->dev,
243 "registered %d multiplexed busses for I2C %s %s\n",
244 num, chips[data->type].muxtype == pca954x_ismux
245 ? "mux" : "switch", client->name);
246
247 return 0;
248
249virt_reg_failed:
250 for (num--; num >= 0; num--)
251 i2c_del_mux_adapter(data->virt_adaps[num]);
252exit_free:
253 kfree(data);
254err:
255 return ret;
256}
257
258static int __devexit pca954x_remove(struct i2c_client *client)
259{
260 struct pca954x *data = i2c_get_clientdata(client);
261 const struct chip_desc *chip = &chips[data->type];
262 int i, err;
263
264 for (i = 0; i < chip->nchans; ++i)
265 if (data->virt_adaps[i]) {
266 err = i2c_del_mux_adapter(data->virt_adaps[i]);
267 if (err)
268 return err;
269 data->virt_adaps[i] = NULL;
270 }
271
272 kfree(data);
273 return 0;
274}
275
276static struct i2c_driver pca954x_driver = {
277 .driver = {
278 .name = "pca954x",
279 .owner = THIS_MODULE,
280 },
281 .probe = pca954x_probe,
282 .remove = __devexit_p(pca954x_remove),
283 .id_table = pca954x_id,
284};
285
286static int __init pca954x_init(void)
287{
288 return i2c_add_driver(&pca954x_driver);
289}
290
291static void __exit pca954x_exit(void)
292{
293 i2c_del_driver(&pca954x_driver);
294}
295
296module_init(pca954x_init);
297module_exit(pca954x_exit);
298
299MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
300MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
301MODULE_LICENSE("GPL v2");