Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 94859308 authored by Scott Alfter's avatar Scott Alfter Committed by Greg Kroah-Hartman
Browse files

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: default avatarScott Alfter <scott@alfter.us>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7242d42a

Documentation/w1/slaves/w1_ds2406

0 → 100644
+25 −0
Original line number Diff line number Diff line 
w1_ds2406 kernel driver

=======================



Supported chips:

  * Maxim DS2406 (and other family 0x12) addressable switches



Author: Scott Alfter <scott@alfter.us>



Description

-----------



The w1_ds2406 driver allows connected devices to be switched on and off. 

These chips also provide 128 bytes of OTP EPROM, but reading/writing it is

not supported.  In TSOC-6 form, the DS2406 provides two switch outputs and

can be provided with power on a dedicated input.  In TO-92 form, it provides

one output and uses parasitic power only.



The driver provides two sysfs files.  state is readable; it gives the

current state of each switch, with PIO A in bit 0 and PIO B in bit 1.  The

driver ORs this state with 0x30, so shell scripts get an ASCII 0/1/2/3 to

work with.  output is writable; bits 0 and 1 control PIO A and B,

respectively.  Bits 2-7 are ignored, so it's safe to write ASCII data.



CRCs are checked on read and write.  Failed checks cause an I/O error to be

returned.  On a failed write, the switch status is not changed.

drivers/w1/slaves/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -38,6 +38,13 @@ config W1_SLAVE_DS2413 
	  Say Y here if you want to use a 1-wire

	  DS2413 Dual Channel Addressable Switch device support



config W1_SLAVE_DS2406

	tristate "Dual Channel Addressable Switch 0x12 family support (DS2406)"

	help

	  Say Y or M here if you want to use a 1-wire

	  DS2406 Dual Channel Addressable Switch.  EPROM read/write

	  support for these devices is not implemented.



config W1_SLAVE_DS2423

	tristate "Counter 1-wire device (DS2423)"

	select CRC16

drivers/w1/slaves/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ obj-$(CONFIG_W1_SLAVE_THERM) += w1_therm.o 
obj-$(CONFIG_W1_SLAVE_SMEM)	+= w1_smem.o

obj-$(CONFIG_W1_SLAVE_DS2408)	+= w1_ds2408.o

obj-$(CONFIG_W1_SLAVE_DS2413)	+= w1_ds2413.o

obj-$(CONFIG_W1_SLAVE_DS2406)	+= w1_ds2406.o

obj-$(CONFIG_W1_SLAVE_DS2423)	+= w1_ds2423.o

obj-$(CONFIG_W1_SLAVE_DS2431)	+= w1_ds2431.o

obj-$(CONFIG_W1_SLAVE_DS2433)	+= w1_ds2433.o

drivers/w1/slaves/w1_ds2406.c

0 → 100644
+168 −0
Original line number Diff line number Diff line 
/*

 * 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);

drivers/w1/w1_family.h

+1 −0
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#define W1_FAMILY_DS2760	0x30

#define W1_FAMILY_DS2780	0x32

#define W1_FAMILY_DS2413	0x3A

#define W1_FAMILY_DS2406	0x12

#define W1_THERM_DS1825		0x3B

#define W1_FAMILY_DS2781	0x3D

#define W1_THERM_DS28EA00	0x42