tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
w1: new w1_ds2406 driver
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>
authored by
Scott Alfter
and committed by
Greg Kroah-Hartman
94859308
7242d42a
+202
+25
Documentation/w1/slaves/w1_ds2406
+25
Documentation/w1/slaves/w1_ds2406
···
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w1_ds2406 kernel driver
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=======================
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Supported chips:
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* Maxim DS2406 (and other family 0x12) addressable switches
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Author: Scott Alfter <scott@alfter.us>
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Description
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-----------
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The w1_ds2406 driver allows connected devices to be switched on and off.
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These chips also provide 128 bytes of OTP EPROM, but reading/writing it is
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not supported. In TSOC-6 form, the DS2406 provides two switch outputs and
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can be provided with power on a dedicated input. In TO-92 form, it provides
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one output and uses parasitic power only.
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The driver provides two sysfs files. state is readable; it gives the
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current state of each switch, with PIO A in bit 0 and PIO B in bit 1. The
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driver ORs this state with 0x30, so shell scripts get an ASCII 0/1/2/3 to
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work with. output is writable; bits 0 and 1 control PIO A and B,
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respectively. Bits 2-7 are ignored, so it's safe to write ASCII data.
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CRCs are checked on read and write. Failed checks cause an I/O error to be
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returned. On a failed write, the switch status is not changed.
+7
drivers/w1/slaves/Kconfig
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drivers/w1/slaves/Kconfig
···
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Say Y here if you want to use a 1-wire
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DS2413 Dual Channel Addressable Switch device support
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config W1_SLAVE_DS2406
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tristate "Dual Channel Addressable Switch 0x12 family support (DS2406)"
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help
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Say Y or M here if you want to use a 1-wire
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DS2406 Dual Channel Addressable Switch. EPROM read/write
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support for these devices is not implemented.
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config W1_SLAVE_DS2423
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tristate "Counter 1-wire device (DS2423)"
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select CRC16
+1
drivers/w1/slaves/Makefile
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drivers/w1/slaves/Makefile
···
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obj-$(CONFIG_W1_SLAVE_SMEM) += w1_smem.o
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obj-$(CONFIG_W1_SLAVE_DS2408) += w1_ds2408.o
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obj-$(CONFIG_W1_SLAVE_DS2413) += w1_ds2413.o
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obj-$(CONFIG_W1_SLAVE_DS2406) += w1_ds2406.o
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obj-$(CONFIG_W1_SLAVE_DS2423) += w1_ds2423.o
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obj-$(CONFIG_W1_SLAVE_DS2431) += w1_ds2431.o
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obj-$(CONFIG_W1_SLAVE_DS2433) += w1_ds2433.o
+168
drivers/w1/slaves/w1_ds2406.c
+168
drivers/w1/slaves/w1_ds2406.c
···
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/*
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* w1_ds2406.c - w1 family 12 (DS2406) driver
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* based on w1_ds2413.c by Mariusz Bialonczyk <manio@skyboo.net>
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*
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* Copyright (c) 2014 Scott Alfter <scott@alfter.us>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/device.h>
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#include <linux/types.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/crc16.h>
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#include "../w1.h"
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#include "../w1_int.h"
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#include "../w1_family.h"
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Scott Alfter <scott@alfter.us>");
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MODULE_DESCRIPTION("w1 family 12 driver for DS2406 2 Pin IO");
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#define W1_F12_FUNC_READ_STATUS 0xAA
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#define W1_F12_FUNC_WRITE_STATUS 0x55
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static ssize_t w1_f12_read_state(
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struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t off, size_t count)
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{
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u8 w1_buf[6]={W1_F12_FUNC_READ_STATUS, 7, 0, 0, 0, 0};
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struct w1_slave *sl = kobj_to_w1_slave(kobj);
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u16 crc=0;
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int i;
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ssize_t rtnval=1;
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if (off != 0)
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return 0;
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if (!buf)
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return -EINVAL;
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mutex_lock(&sl->master->bus_mutex);
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if (w1_reset_select_slave(sl)) {
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mutex_unlock(&sl->master->bus_mutex);
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return -EIO;
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}
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w1_write_block(sl->master, w1_buf, 3);
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w1_read_block(sl->master, w1_buf+3, 3);
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for (i=0; i<6; i++)
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crc=crc16_byte(crc, w1_buf[i]);
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if (crc==0xb001) /* good read? */
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*buf=((w1_buf[3]>>5)&3)|0x30;
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else
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rtnval=-EIO;
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mutex_unlock(&sl->master->bus_mutex);
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return rtnval;
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}
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static ssize_t w1_f12_write_output(
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struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t off, size_t count)
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{
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struct w1_slave *sl = kobj_to_w1_slave(kobj);
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u8 w1_buf[6]={W1_F12_FUNC_WRITE_STATUS, 7, 0, 0, 0, 0};
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u16 crc=0;
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int i;
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ssize_t rtnval=1;
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if (count != 1 || off != 0)
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return -EFAULT;
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mutex_lock(&sl->master->bus_mutex);
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if (w1_reset_select_slave(sl)) {
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mutex_unlock(&sl->master->bus_mutex);
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return -EIO;
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}
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w1_buf[3] = (((*buf)&3)<<5)|0x1F;
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w1_write_block(sl->master, w1_buf, 4);
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w1_read_block(sl->master, w1_buf+4, 2);
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for (i=0; i<6; i++)
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crc=crc16_byte(crc, w1_buf[i]);
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if (crc==0xb001) /* good read? */
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w1_write_8(sl->master, 0xFF);
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else
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rtnval=-EIO;
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mutex_unlock(&sl->master->bus_mutex);
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return rtnval;
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}
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#define NB_SYSFS_BIN_FILES 2
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static struct bin_attribute w1_f12_sysfs_bin_files[NB_SYSFS_BIN_FILES] = {
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{
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.attr = {
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.name = "state",
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.mode = S_IRUGO,
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},
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.size = 1,
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.read = w1_f12_read_state,
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},
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{
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.attr = {
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.name = "output",
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.mode = S_IRUGO | S_IWUSR | S_IWGRP,
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},
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.size = 1,
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.write = w1_f12_write_output,
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}
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};
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static int w1_f12_add_slave(struct w1_slave *sl)
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{
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int err = 0;
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int i;
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for (i = 0; i < NB_SYSFS_BIN_FILES && !err; ++i)
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err = sysfs_create_bin_file(
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&sl->dev.kobj,
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&(w1_f12_sysfs_bin_files[i]));
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if (err)
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while (--i >= 0)
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sysfs_remove_bin_file(&sl->dev.kobj,
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&(w1_f12_sysfs_bin_files[i]));
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return err;
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}
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static void w1_f12_remove_slave(struct w1_slave *sl)
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{
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int i;
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for (i = NB_SYSFS_BIN_FILES - 1; i >= 0; --i)
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sysfs_remove_bin_file(&sl->dev.kobj,
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&(w1_f12_sysfs_bin_files[i]));
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}
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static struct w1_family_ops w1_f12_fops = {
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.add_slave = w1_f12_add_slave,
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.remove_slave = w1_f12_remove_slave,
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};
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static struct w1_family w1_family_12 = {
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.fid = W1_FAMILY_DS2406,
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.fops = &w1_f12_fops,
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};
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static int __init w1_f12_init(void)
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{
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return w1_register_family(&w1_family_12);
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}
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static void __exit w1_f12_exit(void)
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{
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w1_unregister_family(&w1_family_12);
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}
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module_init(w1_f12_init);
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module_exit(w1_f12_exit);