![Scott Alfter](/assets/img/avatar_default.png)
Some preliminary work at making use of this driver led me to implement CRC-16 checks on read and write to deal with the occasional glitchiness of the 1-Wire bus. The revised driver (attached) returns an I/O error if the CRC check fails. When reading the chip's state, either you get a valid indication or you get an I/O error. When changing its state, either the change is successful or an I/O error is returned. Signed-off-by: Scott Alfter <scott@alfter.us> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
169 lines
3.6 KiB
C
169 lines
3.6 KiB
C
/*
|
|
* w1_ds2406.c - w1 family 12 (DS2406) driver
|
|
* based on w1_ds2413.c by Mariusz Bialonczyk <manio@skyboo.net>
|
|
*
|
|
* Copyright (c) 2014 Scott Alfter <scott@alfter.us>
|
|
*
|
|
* This source code is licensed under the GNU General Public License,
|
|
* Version 2. See the file COPYING for more details.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/moduleparam.h>
|
|
#include <linux/device.h>
|
|
#include <linux/types.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/crc16.h>
|
|
|
|
#include "../w1.h"
|
|
#include "../w1_int.h"
|
|
#include "../w1_family.h"
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Scott Alfter <scott@alfter.us>");
|
|
MODULE_DESCRIPTION("w1 family 12 driver for DS2406 2 Pin IO");
|
|
|
|
#define W1_F12_FUNC_READ_STATUS 0xAA
|
|
#define W1_F12_FUNC_WRITE_STATUS 0x55
|
|
|
|
static ssize_t w1_f12_read_state(
|
|
struct file *filp, struct kobject *kobj,
|
|
struct bin_attribute *bin_attr,
|
|
char *buf, loff_t off, size_t count)
|
|
{
|
|
u8 w1_buf[6]={W1_F12_FUNC_READ_STATUS, 7, 0, 0, 0, 0};
|
|
struct w1_slave *sl = kobj_to_w1_slave(kobj);
|
|
u16 crc=0;
|
|
int i;
|
|
ssize_t rtnval=1;
|
|
|
|
if (off != 0)
|
|
return 0;
|
|
if (!buf)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&sl->master->bus_mutex);
|
|
|
|
if (w1_reset_select_slave(sl)) {
|
|
mutex_unlock(&sl->master->bus_mutex);
|
|
return -EIO;
|
|
}
|
|
|
|
w1_write_block(sl->master, w1_buf, 3);
|
|
w1_read_block(sl->master, w1_buf+3, 3);
|
|
for (i=0; i<6; i++)
|
|
crc=crc16_byte(crc, w1_buf[i]);
|
|
if (crc==0xb001) /* good read? */
|
|
*buf=((w1_buf[3]>>5)&3)|0x30;
|
|
else
|
|
rtnval=-EIO;
|
|
|
|
mutex_unlock(&sl->master->bus_mutex);
|
|
|
|
return rtnval;
|
|
}
|
|
|
|
static ssize_t w1_f12_write_output(
|
|
struct file *filp, struct kobject *kobj,
|
|
struct bin_attribute *bin_attr,
|
|
char *buf, loff_t off, size_t count)
|
|
{
|
|
struct w1_slave *sl = kobj_to_w1_slave(kobj);
|
|
u8 w1_buf[6]={W1_F12_FUNC_WRITE_STATUS, 7, 0, 0, 0, 0};
|
|
u16 crc=0;
|
|
int i;
|
|
ssize_t rtnval=1;
|
|
|
|
if (count != 1 || off != 0)
|
|
return -EFAULT;
|
|
|
|
mutex_lock(&sl->master->bus_mutex);
|
|
|
|
if (w1_reset_select_slave(sl)) {
|
|
mutex_unlock(&sl->master->bus_mutex);
|
|
return -EIO;
|
|
}
|
|
|
|
w1_buf[3] = (((*buf)&3)<<5)|0x1F;
|
|
w1_write_block(sl->master, w1_buf, 4);
|
|
w1_read_block(sl->master, w1_buf+4, 2);
|
|
for (i=0; i<6; i++)
|
|
crc=crc16_byte(crc, w1_buf[i]);
|
|
if (crc==0xb001) /* good read? */
|
|
w1_write_8(sl->master, 0xFF);
|
|
else
|
|
rtnval=-EIO;
|
|
|
|
mutex_unlock(&sl->master->bus_mutex);
|
|
return rtnval;
|
|
}
|
|
|
|
#define NB_SYSFS_BIN_FILES 2
|
|
static struct bin_attribute w1_f12_sysfs_bin_files[NB_SYSFS_BIN_FILES] = {
|
|
{
|
|
.attr = {
|
|
.name = "state",
|
|
.mode = S_IRUGO,
|
|
},
|
|
.size = 1,
|
|
.read = w1_f12_read_state,
|
|
},
|
|
{
|
|
.attr = {
|
|
.name = "output",
|
|
.mode = S_IRUGO | S_IWUSR | S_IWGRP,
|
|
},
|
|
.size = 1,
|
|
.write = w1_f12_write_output,
|
|
}
|
|
};
|
|
|
|
static int w1_f12_add_slave(struct w1_slave *sl)
|
|
{
|
|
int err = 0;
|
|
int i;
|
|
|
|
for (i = 0; i < NB_SYSFS_BIN_FILES && !err; ++i)
|
|
err = sysfs_create_bin_file(
|
|
&sl->dev.kobj,
|
|
&(w1_f12_sysfs_bin_files[i]));
|
|
if (err)
|
|
while (--i >= 0)
|
|
sysfs_remove_bin_file(&sl->dev.kobj,
|
|
&(w1_f12_sysfs_bin_files[i]));
|
|
return err;
|
|
}
|
|
|
|
static void w1_f12_remove_slave(struct w1_slave *sl)
|
|
{
|
|
int i;
|
|
for (i = NB_SYSFS_BIN_FILES - 1; i >= 0; --i)
|
|
sysfs_remove_bin_file(&sl->dev.kobj,
|
|
&(w1_f12_sysfs_bin_files[i]));
|
|
}
|
|
|
|
static struct w1_family_ops w1_f12_fops = {
|
|
.add_slave = w1_f12_add_slave,
|
|
.remove_slave = w1_f12_remove_slave,
|
|
};
|
|
|
|
static struct w1_family w1_family_12 = {
|
|
.fid = W1_FAMILY_DS2406,
|
|
.fops = &w1_f12_fops,
|
|
};
|
|
|
|
static int __init w1_f12_init(void)
|
|
{
|
|
return w1_register_family(&w1_family_12);
|
|
}
|
|
|
|
static void __exit w1_f12_exit(void)
|
|
{
|
|
w1_unregister_family(&w1_family_12);
|
|
}
|
|
|
|
module_init(w1_f12_init);
|
|
module_exit(w1_f12_exit);
|