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7f528135 ML |
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 <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 | ||
49 | enum 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 | ||
60 | struct 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 | ||
67 | struct 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 */ | |
77 | static 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 | ||
107 | static 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 | }; | |
118 | MODULE_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 */ | |
122 | static 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 | ||
148 | static 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 | ||
171 | static 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 | */ | |
184 | static 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 | ||
249 | virt_reg_failed: | |
250 | for (num--; num >= 0; num--) | |
251 | i2c_del_mux_adapter(data->virt_adaps[num]); | |
252 | exit_free: | |
253 | kfree(data); | |
254 | err: | |
255 | return ret; | |
256 | } | |
257 | ||
258 | static 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 | ||
276 | static 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 | ||
286 | static int __init pca954x_init(void) | |
287 | { | |
288 | return i2c_add_driver(&pca954x_driver); | |
289 | } | |
290 | ||
291 | static void __exit pca954x_exit(void) | |
292 | { | |
293 | i2c_del_driver(&pca954x_driver); | |
294 | } | |
295 | ||
296 | module_init(pca954x_init); | |
297 | module_exit(pca954x_exit); | |
298 | ||
299 | MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); | |
300 | MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); | |
301 | MODULE_LICENSE("GPL v2"); |