i2c: Add generic I2C multiplexer using GPIO API
Add an i2c mux driver providing access to i2c bus segments using a hardware MUX sitting on a master bus and controlled through gpio pins. E.G. something like: ---------- ---------- Bus segment 1 - - - - - | | SCL/SDA | |-------------- | | | |------------| | | | | | Bus segment 2 | | | Linux | GPIO 1..N | MUX |--------------- Devices | |------------| | | | | | | | Bus segment M | | | |---------------| | ---------- ---------- - - - - - SCL/SDA of the master I2C bus is multiplexed to bus segment 1..M according to the settings of the GPIO pins 1..N. Signed-off-by: Peter Korsgaard <peter.korsgaard@barco.com> Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Peter Korsgaard
committed by
Jean Delvare
Jean Delvare
parent
b18a5c80eb
commit
92ed1a76ca
@@ -5,6 +5,18 @@
|
||||
menu "Multiplexer I2C Chip support"
|
||||
depends on I2C_MUX
|
||||
|
||||
config I2C_MUX_GPIO
|
||||
tristate "GPIO-based I2C multiplexer"
|
||||
depends on GENERIC_GPIO
|
||||
help
|
||||
If you say yes to this option, support will be included for a
|
||||
GPIO based I2C multiplexer. This driver provides access to
|
||||
I2C busses connected through a MUX, which is controlled
|
||||
through GPIO pins.
|
||||
|
||||
This driver can also be built as a module. If so, the module
|
||||
will be called gpio-i2cmux.
|
||||
|
||||
config I2C_MUX_PCA9541
|
||||
tristate "NXP PCA9541 I2C Master Selector"
|
||||
depends on EXPERIMENTAL
|
||||
|
||||
@@ -1,6 +1,7 @@
|
||||
#
|
||||
# Makefile for multiplexer I2C chip drivers.
|
||||
|
||||
obj-$(CONFIG_I2C_MUX_GPIO) += gpio-i2cmux.o
|
||||
obj-$(CONFIG_I2C_MUX_PCA9541) += pca9541.o
|
||||
obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o
|
||||
|
||||
|
||||
184
drivers/i2c/muxes/gpio-i2cmux.c
Normal file
184
drivers/i2c/muxes/gpio-i2cmux.c
Normal file
@@ -0,0 +1,184 @@
|
||||
/*
|
||||
* I2C multiplexer using GPIO API
|
||||
*
|
||||
* Peter Korsgaard <peter.korsgaard@barco.com>
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License version 2 as
|
||||
* published by the Free Software Foundation.
|
||||
*/
|
||||
|
||||
#include <linux/i2c.h>
|
||||
#include <linux/i2c-mux.h>
|
||||
#include <linux/gpio-i2cmux.h>
|
||||
#include <linux/platform_device.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/slab.h>
|
||||
#include <linux/gpio.h>
|
||||
|
||||
struct gpiomux {
|
||||
struct i2c_adapter *parent;
|
||||
struct i2c_adapter **adap; /* child busses */
|
||||
struct gpio_i2cmux_platform_data data;
|
||||
};
|
||||
|
||||
static void gpiomux_set(const struct gpiomux *mux, unsigned val)
|
||||
{
|
||||
int i;
|
||||
|
||||
for (i = 0; i < mux->data.n_gpios; i++)
|
||||
gpio_set_value(mux->data.gpios[i], val & (1 << i));
|
||||
}
|
||||
|
||||
static int gpiomux_select(struct i2c_adapter *adap, void *data, u32 chan)
|
||||
{
|
||||
struct gpiomux *mux = data;
|
||||
|
||||
gpiomux_set(mux, mux->data.values[chan]);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int gpiomux_deselect(struct i2c_adapter *adap, void *data, u32 chan)
|
||||
{
|
||||
struct gpiomux *mux = data;
|
||||
|
||||
gpiomux_set(mux, mux->data.idle);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int __devinit gpiomux_probe(struct platform_device *pdev)
|
||||
{
|
||||
struct gpiomux *mux;
|
||||
struct gpio_i2cmux_platform_data *pdata;
|
||||
struct i2c_adapter *parent;
|
||||
int (*deselect) (struct i2c_adapter *, void *, u32);
|
||||
unsigned initial_state;
|
||||
int i, ret;
|
||||
|
||||
pdata = pdev->dev.platform_data;
|
||||
if (!pdata) {
|
||||
dev_err(&pdev->dev, "Missing platform data\n");
|
||||
return -ENODEV;
|
||||
}
|
||||
|
||||
parent = i2c_get_adapter(pdata->parent);
|
||||
if (!parent) {
|
||||
dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
|
||||
pdata->parent);
|
||||
return -ENODEV;
|
||||
}
|
||||
|
||||
mux = kzalloc(sizeof(*mux), GFP_KERNEL);
|
||||
if (!mux) {
|
||||
ret = -ENOMEM;
|
||||
goto alloc_failed;
|
||||
}
|
||||
|
||||
mux->parent = parent;
|
||||
mux->data = *pdata;
|
||||
mux->adap = kzalloc(sizeof(struct i2c_adapter *) * pdata->n_values,
|
||||
GFP_KERNEL);
|
||||
if (!mux->adap) {
|
||||
ret = -ENOMEM;
|
||||
goto alloc_failed2;
|
||||
}
|
||||
|
||||
if (pdata->idle != GPIO_I2CMUX_NO_IDLE) {
|
||||
initial_state = pdata->idle;
|
||||
deselect = gpiomux_deselect;
|
||||
} else {
|
||||
initial_state = pdata->values[0];
|
||||
deselect = NULL;
|
||||
}
|
||||
|
||||
for (i = 0; i < pdata->n_gpios; i++) {
|
||||
ret = gpio_request(pdata->gpios[i], "gpio-i2cmux");
|
||||
if (ret)
|
||||
goto err_request_gpio;
|
||||
gpio_direction_output(pdata->gpios[i],
|
||||
initial_state & (1 << i));
|
||||
}
|
||||
|
||||
for (i = 0; i < pdata->n_values; i++) {
|
||||
u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
|
||||
|
||||
mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i,
|
||||
gpiomux_select, deselect);
|
||||
if (!mux->adap[i]) {
|
||||
ret = -ENODEV;
|
||||
dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
|
||||
goto add_adapter_failed;
|
||||
}
|
||||
}
|
||||
|
||||
dev_info(&pdev->dev, "%d port mux on %s adapter\n",
|
||||
pdata->n_values, parent->name);
|
||||
|
||||
platform_set_drvdata(pdev, mux);
|
||||
|
||||
return 0;
|
||||
|
||||
add_adapter_failed:
|
||||
for (; i > 0; i--)
|
||||
i2c_del_mux_adapter(mux->adap[i - 1]);
|
||||
i = pdata->n_gpios;
|
||||
err_request_gpio:
|
||||
for (; i > 0; i--)
|
||||
gpio_free(pdata->gpios[i - 1]);
|
||||
kfree(mux->adap);
|
||||
alloc_failed2:
|
||||
kfree(mux);
|
||||
alloc_failed:
|
||||
i2c_put_adapter(parent);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int __devexit gpiomux_remove(struct platform_device *pdev)
|
||||
{
|
||||
struct gpiomux *mux = platform_get_drvdata(pdev);
|
||||
int i;
|
||||
|
||||
for (i = 0; i < mux->data.n_values; i++)
|
||||
i2c_del_mux_adapter(mux->adap[i]);
|
||||
|
||||
for (i = 0; i < mux->data.n_gpios; i++)
|
||||
gpio_free(mux->data.gpios[i]);
|
||||
|
||||
platform_set_drvdata(pdev, NULL);
|
||||
i2c_put_adapter(mux->parent);
|
||||
kfree(mux->adap);
|
||||
kfree(mux);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static struct platform_driver gpiomux_driver = {
|
||||
.probe = gpiomux_probe,
|
||||
.remove = __devexit_p(gpiomux_remove),
|
||||
.driver = {
|
||||
.owner = THIS_MODULE,
|
||||
.name = "gpio-i2cmux",
|
||||
},
|
||||
};
|
||||
|
||||
static int __init gpiomux_init(void)
|
||||
{
|
||||
return platform_driver_register(&gpiomux_driver);
|
||||
}
|
||||
|
||||
static void __exit gpiomux_exit(void)
|
||||
{
|
||||
platform_driver_unregister(&gpiomux_driver);
|
||||
}
|
||||
|
||||
module_init(gpiomux_init);
|
||||
module_exit(gpiomux_exit);
|
||||
|
||||
MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
|
||||
MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
|
||||
MODULE_LICENSE("GPL");
|
||||
MODULE_ALIAS("platform:gpio-i2cmux");
|
||||
Reference in New Issue
Block a user