/*
* I2C multiplexer
*
* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
*
* This module supports the PCA954x series of I2C multiplexer/switch chips
* made by Philips Semiconductors.
* This includes the:
* PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
* and PCA9548.
*
* These chips are all controlled via the I2C bus itself, and all have a
* single 8-bit register. The upstream "parent" bus fans out to two,
* four, or eight downstream busses or channels; which of these
* are selected is determined by the chip type and register contents. A
* mux can select only one sub-bus at a time; a switch can select any
* combination simultaneously.
*
* Based on:
* pca954x.c from Kumar Gala <galak@kernel.crashing.org>
* Copyright (C) 2006
*
* Based on:
* pca954x.c from Ken Harrenstien
* Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
*
* Based on:
* i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
* and
* pca9540.c from Jean Delvare <khali@linux-fr.org>.
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/i2c/pca954x.h>
#define PCA954X_MAX_NCHANS 8
enum pca_type {
pca_9540,
pca_9542,
pca_9543,
pca_9544,
pca_9545,
pca_9546,
pca_9547,
pca_9548,
};
struct pca954x {
enum pca_type type;
struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
u8 last_chan; /* last register value */
};
struct chip_desc {
u8 nchans;
u8 enable; /* used for muxes only */
enum muxtype {
pca954x_ismux = 0,
pca954x_isswi
} muxtype;
};
/* Provide specs for the PCA954x types we know about */
static const struct chip_desc chips[] = {
[pca_9540] = {
.nchans = 2,
.enable = 0x4,
.muxtype = pca954x_ismux,
},
[pca_9543] = {
.nchans = 2,
.muxtype = pca954x_isswi,
},
[pca_9544] = {
.nchans = 4,
.enable = 0x4,
.muxtype = pca954x_ismux,
},
[pca_9545] = {
.nchans = 4,
.muxtype = pca954x_isswi,
},
[pca_9547] = {
.nchans = 8,
.enable = 0x8,
.muxtype = pca954x_ismux,
},
[pca_9548] = {
.nchans = 8,
.muxtype = pca954x_isswi,
},
};
static const struct i2c_device_id pca954x_id[] = {
{ "pca9540", pca_9540 },
{ "pca9542", pca_9540 },
{ "pca9543", pca_9543 },
{ "pca9544", pca_9544 },
{ "pca9545", pca_9545 },
{ "pca9546", pca_9545 },
{ "pca9547", pca_9547 },
{ "pca9548", pca_9548 },
{ }
};
MODULE_DEVICE_TABLE(i2c, pca954x_id);
/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
for this as they will try to lock adapter a second time */
static int pca954x_reg_write(struct i2c_adapter *adap,
struct i2c_client *client, u8 val)
{
int ret = -ENODEV;
if (adap->algo->master_xfer) {
struct i2c_msg msg;
char buf[1];
msg.addr = client->addr;
msg.flags = 0;
msg.len = 1;
buf[0] = val;
msg.buf = buf;
ret = adap->algo->master_xfer(adap, &msg, 1);
} else {
union i2c_smbus_data data;
ret = adap->algo->smbus_xfer(adap, client->addr,
client->flags,
I2C_SMBUS_WRITE,
val, I2C_SMBUS_BYTE, &data);
}
return ret;
}
static int pca954x_select_chan(struct i2c_adapter *adap,
void *client, u32 chan)
{
struct pca954x *data = i2c_get_clientdata(client);
const struct chip_desc *chip = &chips[data->type];
u8 regval;
int ret = 0;
/* we make switches look like muxes, not sure how to be smarter */
if (chip->muxtype == pca954x_ismux)
regval = chan | chip->enable;
else
regval = 1 << chan;
/* Only select the channel if its different from the last channel */
if (data->last_chan != regval) {
ret = pca954x_reg_write(adap, client, regval);
data->last_chan = regval;
}
return ret;
}
static int pca954x_deselect_mux(struct i2c_adapter *adap,
void *client, u32 chan)
{
struct pca954x *data = i2c_get_clientdata(client);
/* Deselect active channel */
data->last_chan = 0;
return pca954x_reg_write(adap, client, data->last_chan);
}
/*
* I2C init/probing/exit functions
*/
static int pca954x_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
struct pca954x_platform_data *pdata = client->dev.platform_data;
int num, force;
struct pca954x *data;
int ret = -ENODEV;
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
goto err;
data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
if (!data) {
ret = -ENOMEM;
goto err;
}
i2c_set_clientdata(client, data);
/* Write the mux register at addr to verify
* that the mux is in fact present. This also
* initializes the mux to disconnected state.
*/
if (i2c_smbus_write_byte(client, 0) < 0) {
dev_warn(&client->dev, "probe failed\n");
goto exit_free;
}
data->type = id->driver_data;
data->last_chan = 0; /* force the first selection */
/* Now create an adapter for each channel */
for (num = 0; num < chips[data->type].nchans; num++) {
force = 0; /* dynamic adap number */
if (pdata) {
if (num < pdata->num_modes)
/* force static number */
force = pdata->modes[num].adap_id;
else
/* discard unconfigured channels */
break;
}
data->virt_adaps[num] =
i2c_add_mux_adapter(adap, client,
force, num, pca954x_select_chan,
(pdata && pdata->modes[num].deselect_on_exit)
? pca954x_deselect_mux : NULL);
if (data->virt_adaps[num] == NULL) {
ret = -ENODEV;
dev_err(&client->dev,
"failed to register multiplexed adapter"
" %d as bus %d\n", num, force);
goto virt_reg_failed;
}
}
dev_info(&client->dev,
"registered %d multiplexed busses for I2C %s %s\n",
num, chips[data->type].muxtype == pca954x_ismux
? "mux" : "switch", client->name);
return 0;
virt_reg_failed:
for (num--; num >= 0; num--)
i2c_del_mux_adapter(data->virt_adaps[num]);
exit_free:
kfree(data);
err:
return ret;
}
static int pca954x_remove(struct i2c_client *client)
{
struct pca954x *data = i2c_get_clientdata(client);
const struct chip_desc *chip = &chips[data->type];
int i, err;
for (i = 0; i < chip->nchans; ++i)
if (data->virt_adaps[i]) {
err = i2c_del_mux_adapter(data->virt_adaps[i]);
if (err)
return err;
data->virt_adaps[i] = NULL;
}
kfree(data);
return 0;
}
static struct i2c_driver pca954x_driver = {
.driver = {
.name = "pca954x",
.owner = THIS_MODULE,
},
.probe = pca954x_probe,
.remove = pca954x_remove,
.id_table = pca954x_id,
};
static int __init pca954x_init(void)
{
return i2c_add_driver(&pca954x_driver);
}
static void __exit pca954x_exit(void)
{
i2c_del_driver(&pca954x_driver);
}
module_init(pca954x_init);
module_exit(pca954x_exit);
MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
MODULE_LICENSE("GPL v2");