4 * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
5 * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
7 * This module supports the PCA954x series of I2C multiplexer/switch chips
8 * made by Philips Semiconductors.
10 * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
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.
21 * pca954x.c from Kumar Gala <galak@kernel.crashing.org>
25 * pca954x.c from Ken Harrenstien
26 * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
29 * i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
31 * pca9540.c from Jean Delvare <jdelvare@suse.de>.
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.
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/slab.h>
46 #define PCA954X_MAX_NCHANS 8
61 struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
63 u8 last_chan; /* last register value */
68 u8 enable; /* used for muxes only */
75 /* Provide specs for the PCA954x types we know about */
76 static const struct chip_desc chips[] = {
80 .muxtype = pca954x_ismux,
84 .muxtype = pca954x_isswi,
89 .muxtype = pca954x_ismux,
93 .muxtype = pca954x_isswi,
98 .muxtype = pca954x_ismux,
102 .muxtype = pca954x_isswi,
106 static const struct i2c_device_id pca954x_id[] = {
107 { "pca9540", pca_9540 },
108 { "pca9542", pca_9540 },
109 { "pca9543", pca_9543 },
110 { "pca9544", pca_9544 },
111 { "pca9545", pca_9545 },
112 { "pca9546", pca_9545 },
113 { "pca9547", pca_9547 },
114 { "pca9548", pca_9548 },
117 MODULE_DEVICE_TABLE(i2c, pca954x_id);
119 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
120 for this as they will try to lock adapter a second time */
121 static int pca954x_reg_write(struct i2c_adapter *adap,
122 struct i2c_client *client, u8 val)
126 if (adap->algo->master_xfer) {
130 msg.addr = client->addr;
135 ret = adap->algo->master_xfer(adap, &msg, 1);
137 union i2c_smbus_data data;
138 ret = adap->algo->smbus_xfer(adap, client->addr,
141 val, I2C_SMBUS_BYTE, &data);
147 static int pca954x_select_chan(struct i2c_adapter *adap,
148 void *client, u32 chan)
150 struct pca954x *data = i2c_get_clientdata(client);
151 const struct chip_desc *chip = &chips[data->type];
155 /* we make switches look like muxes, not sure how to be smarter */
156 if (chip->muxtype == pca954x_ismux)
157 regval = chan | chip->enable;
161 /* Only select the channel if its different from the last channel */
162 if (data->last_chan != regval) {
163 ret = pca954x_reg_write(adap, client, regval);
164 data->last_chan = regval;
170 static int pca954x_deselect_mux(struct i2c_adapter *adap,
171 void *client, u32 chan)
173 struct pca954x *data = i2c_get_clientdata(client);
175 /* Deselect active channel */
177 return pca954x_reg_write(adap, client, data->last_chan);
181 * I2C init/probing/exit functions
183 static int pca954x_probe(struct i2c_client *client,
184 const struct i2c_device_id *id)
186 struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
187 struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
188 struct gpio_desc *gpio;
189 int num, force, class;
190 struct pca954x *data;
193 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
196 data = devm_kzalloc(&client->dev, sizeof(struct pca954x), GFP_KERNEL);
200 i2c_set_clientdata(client, data);
202 /* Get the mux out of reset if a reset GPIO is specified. */
203 gpio = devm_gpiod_get(&client->dev, "reset");
205 gpiod_direction_output(gpio, 0);
207 /* Write the mux register at addr to verify
208 * that the mux is in fact present. This also
209 * initializes the mux to disconnected state.
211 if (i2c_smbus_write_byte(client, 0) < 0) {
212 dev_warn(&client->dev, "probe failed\n");
216 data->type = id->driver_data;
217 data->last_chan = 0; /* force the first selection */
219 /* Now create an adapter for each channel */
220 for (num = 0; num < chips[data->type].nchans; num++) {
221 force = 0; /* dynamic adap number */
222 class = 0; /* no class by default */
224 if (num < pdata->num_modes) {
225 /* force static number */
226 force = pdata->modes[num].adap_id;
227 class = pdata->modes[num].class;
229 /* discard unconfigured channels */
233 data->virt_adaps[num] =
234 i2c_add_mux_adapter(adap, &client->dev, client,
235 force, num, class, pca954x_select_chan,
236 (pdata && pdata->modes[num].deselect_on_exit)
237 ? pca954x_deselect_mux : NULL);
239 if (data->virt_adaps[num] == NULL) {
241 dev_err(&client->dev,
242 "failed to register multiplexed adapter"
243 " %d as bus %d\n", num, force);
244 goto virt_reg_failed;
248 dev_info(&client->dev,
249 "registered %d multiplexed busses for I2C %s %s\n",
250 num, chips[data->type].muxtype == pca954x_ismux
251 ? "mux" : "switch", client->name);
256 for (num--; num >= 0; num--)
257 i2c_del_mux_adapter(data->virt_adaps[num]);
261 static int pca954x_remove(struct i2c_client *client)
263 struct pca954x *data = i2c_get_clientdata(client);
264 const struct chip_desc *chip = &chips[data->type];
267 for (i = 0; i < chip->nchans; ++i)
268 if (data->virt_adaps[i]) {
269 i2c_del_mux_adapter(data->virt_adaps[i]);
270 data->virt_adaps[i] = NULL;
276 static struct i2c_driver pca954x_driver = {
279 .owner = THIS_MODULE,
281 .probe = pca954x_probe,
282 .remove = pca954x_remove,
283 .id_table = pca954x_id,
286 module_i2c_driver(pca954x_driver);
288 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
289 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
290 MODULE_LICENSE("GPL v2");