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linux-next/drivers/i2c/muxes/i2c-mux-pca954x.c
Lars-Peter Clausen a205e63d12 i2c: Ignore the return value of i2c_del_mux_adapter()
i2c_del_mux_adapter() always returns 0. So all checks testing whether it will be
non zero will always evaluate to false and the conditional code is dead code.
This patch updates all callers of i2c_del_mux_adapter() to ignore its return
value and assume that it will always succeed (which it will). A subsequent
patch will make the return type of i2c_del_mux_adapter() void.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2013-04-02 07:07:29 +02:00

292 lines
6.8 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 <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, class;
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 */
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]);
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;
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;
}
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,
};
module_i2c_driver(pca954x_driver);
MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
MODULE_LICENSE("GPL v2");