w1-gpio: add GPIO w1 bus master driver

Add a GPIO 1-wire bus master driver.  The driver used the GPIO API to
control the wire and the GPIO pin can be specified using platform data
similar to i2c-gpio.  The driver was tested with AT91SAM9260 + DS2401.

Signed-off-by: Ville Syrjala <syrjala@sci.fi>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ville Syrjala 2008-02-06 01:39:01 -08:00 committed by Linus Torvalds
parent 4cdf854f7d
commit ad8dc96e3b
6 changed files with 193 additions and 0 deletions

View file

@ -4,3 +4,5 @@ ds2482
- The Maxim/Dallas Semiconductor DS2482 provides 1-wire busses.
ds2490
- The Maxim/Dallas Semiconductor DS2490 builds USB <-> W1 bridges.
w1-gpio
- GPIO 1-wire bus master driver.

View file

@ -0,0 +1,33 @@
Kernel driver w1-gpio
=====================
Author: Ville Syrjala <syrjala@sci.fi>
Description
-----------
GPIO 1-wire bus master driver. The driver uses the GPIO API to control the
wire and the GPIO pin can be specified using platform data.
Example (mach-at91)
-------------------
#include <linux/w1-gpio.h>
static struct w1_gpio_platform_data foo_w1_gpio_pdata = {
.pin = AT91_PIN_PB20,
.is_open_drain = 1,
};
static struct platform_device foo_w1_device = {
.name = "w1-gpio",
.id = -1,
.dev.platform_data = &foo_w1_gpio_pdata,
};
...
at91_set_GPIO_periph(foo_w1_gpio_pdata.pin, 1);
at91_set_multi_drive(foo_w1_gpio_pdata.pin, 1);
platform_device_register(&foo_w1_device);

View file

@ -42,5 +42,15 @@ config W1_MASTER_DS1WM
in HP iPAQ devices like h5xxx, h2200, and ASIC3-based like
hx4700.
config W1_MASTER_GPIO
tristate "GPIO 1-wire busmaster"
depends on GENERIC_GPIO
help
Say Y here if you want to communicate with your 1-wire devices using
GPIO pins. This driver uses the GPIO API to control the wire.
This support is also available as a module. If so, the module
will be called w1-gpio.ko.
endmenu

View file

@ -6,3 +6,4 @@ obj-$(CONFIG_W1_MASTER_MATROX) += matrox_w1.o
obj-$(CONFIG_W1_MASTER_DS2490) += ds2490.o
obj-$(CONFIG_W1_MASTER_DS2482) += ds2482.o
obj-$(CONFIG_W1_MASTER_DS1WM) += ds1wm.o
obj-$(CONFIG_W1_MASTER_GPIO) += w1-gpio.o

View file

@ -0,0 +1,124 @@
/*
* w1-gpio - GPIO w1 bus master driver
*
* Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
*
* 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/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/w1-gpio.h>
#include "../w1.h"
#include "../w1_int.h"
#include <asm/gpio.h>
static void w1_gpio_write_bit_dir(void *data, u8 bit)
{
struct w1_gpio_platform_data *pdata = data;
if (bit)
gpio_direction_input(pdata->pin);
else
gpio_direction_output(pdata->pin, 0);
}
static void w1_gpio_write_bit_val(void *data, u8 bit)
{
struct w1_gpio_platform_data *pdata = data;
gpio_set_value(pdata->pin, bit);
}
static u8 w1_gpio_read_bit(void *data)
{
struct w1_gpio_platform_data *pdata = data;
return gpio_get_value(pdata->pin);
}
static int __init w1_gpio_probe(struct platform_device *pdev)
{
struct w1_bus_master *master;
struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
int err;
if (!pdata)
return -ENXIO;
master = kzalloc(sizeof(struct w1_bus_master), GFP_KERNEL);
if (!master)
return -ENOMEM;
err = gpio_request(pdata->pin, "w1");
if (err)
goto free_master;
master->data = pdata;
master->read_bit = w1_gpio_read_bit;
if (pdata->is_open_drain) {
gpio_direction_output(pdata->pin, 1);
master->write_bit = w1_gpio_write_bit_val;
} else {
gpio_direction_input(pdata->pin);
master->write_bit = w1_gpio_write_bit_dir;
}
err = w1_add_master_device(master);
if (err)
goto free_gpio;
platform_set_drvdata(pdev, master);
return 0;
free_gpio:
gpio_free(pdata->pin);
free_master:
kfree(master);
return err;
}
static int __exit w1_gpio_remove(struct platform_device *pdev)
{
struct w1_bus_master *master = platform_get_drvdata(pdev);
struct w1_gpio_platform_data *pdata = pdev->dev.platform_data;
w1_remove_master_device(master);
gpio_free(pdata->pin);
kfree(master);
return 0;
}
static struct platform_driver w1_gpio_driver = {
.driver = {
.name = "w1-gpio",
.owner = THIS_MODULE,
},
.remove = __exit_p(w1_gpio_remove),
};
static int __init w1_gpio_init(void)
{
return platform_driver_probe(&w1_gpio_driver, w1_gpio_probe);
}
static void __exit w1_gpio_exit(void)
{
platform_driver_unregister(&w1_gpio_driver);
}
module_init(w1_gpio_init);
module_exit(w1_gpio_exit);
MODULE_DESCRIPTION("GPIO w1 bus master driver");
MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
MODULE_LICENSE("GPL");

23
include/linux/w1-gpio.h Normal file
View file

@ -0,0 +1,23 @@
/*
* w1-gpio interface to platform code
*
* Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
*
* 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.
*/
#ifndef _LINUX_W1_GPIO_H
#define _LINUX_W1_GPIO_H
/**
* struct w1_gpio_platform_data - Platform-dependent data for w1-gpio
* @pin: GPIO pin to use
* @is_open_drain: GPIO pin is configured as open drain
*/
struct w1_gpio_platform_data {
unsigned int pin;
unsigned int is_open_drain:1;
};
#endif /* _LINUX_W1_GPIO_H */