305 lines
7.3 KiB
C
305 lines
7.3 KiB
C
/*
|
|
* 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 <jdelvare@suse.de>.
|
|
*
|
|
* 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/device.h>
|
|
#include <linux/gpio/consumer.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/i2c-mux.h>
|
|
#include <linux/i2c/pca954x.h>
|
|
#include <linux/module.h>
|
|
#include <linux/pm.h>
|
|
#include <linux/slab.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 = dev_get_platdata(&client->dev);
|
|
struct gpio_desc *gpio;
|
|
int num, force, class;
|
|
struct pca954x *data;
|
|
int ret;
|
|
|
|
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
|
|
return -ENODEV;
|
|
|
|
data = devm_kzalloc(&client->dev, sizeof(struct pca954x), GFP_KERNEL);
|
|
if (!data)
|
|
return -ENOMEM;
|
|
|
|
i2c_set_clientdata(client, data);
|
|
|
|
/* Get the mux out of reset if a reset GPIO is specified. */
|
|
gpio = devm_gpiod_get(&client->dev, "reset");
|
|
if (!IS_ERR(gpio))
|
|
gpiod_direction_output(gpio, 0);
|
|
|
|
/* 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");
|
|
return -ENODEV;
|
|
}
|
|
|
|
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 */
|
|
class = 0; /* no class by default */
|
|
if (pdata) {
|
|
if (num < pdata->num_modes) {
|
|
/* force static number */
|
|
force = pdata->modes[num].adap_id;
|
|
class = pdata->modes[num].class;
|
|
} else
|
|
/* discard unconfigured channels */
|
|
break;
|
|
}
|
|
|
|
data->virt_adaps[num] =
|
|
i2c_add_mux_adapter(adap, &client->dev, client,
|
|
force, num, class, 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]);
|
|
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;
|
|
|
|
for (i = 0; i < chip->nchans; ++i)
|
|
if (data->virt_adaps[i]) {
|
|
i2c_del_mux_adapter(data->virt_adaps[i]);
|
|
data->virt_adaps[i] = NULL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_PM_SLEEP
|
|
static int pca954x_resume(struct device *dev)
|
|
{
|
|
struct i2c_client *client = to_i2c_client(dev);
|
|
struct pca954x *data = i2c_get_clientdata(client);
|
|
|
|
data->last_chan = 0;
|
|
return i2c_smbus_write_byte(client, 0);
|
|
}
|
|
#endif
|
|
|
|
static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
|
|
|
|
static struct i2c_driver pca954x_driver = {
|
|
.driver = {
|
|
.name = "pca954x",
|
|
.pm = &pca954x_pm,
|
|
.owner = THIS_MODULE,
|
|
},
|
|
.probe = pca954x_probe,
|
|
.remove = pca954x_remove,
|
|
.id_table = pca954x_id,
|
|
};
|
|
|
|
module_i2c_driver(pca954x_driver);
|
|
|
|
MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
|
|
MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
|
|
MODULE_LICENSE("GPL v2");
|