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");