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w1: Add support for DS28EA00 sequence to w1-therm 

This patch provides support for the DS28EA00 digital thermometer.

The DS28EA00 provides an additional two pins for implementing a sequence
detection algorithm.  This feature allows you to determine the physical
location of the chip in the 1-wire bus without needing pre-existing
knowledge of the bus ordering.  Support is provided through the sysfs
w1_seq file.  The file will contain a single line with an integer value
representing the device index in the bus starting at 0.

Signed-off-by: Matt Campbell <mattrcampbell@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Matt Campbell 2015-04-28 07:44:17 -04:00 committed by Greg Kroah-Hartman
parent f7134eea05
commit d9411e57dc
3 changed files with 117 additions and 2 deletions
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6
Documentation/ABI/stable/sysfs-driver-w1_ds28ea00 Normal file
View File

@ -0,0 +1,6 @@
What: /sys/bus/w1/devices/.../w1_seq
Date: Apr 2015
Contact: Matt Campbell <mattrcampbell@gmail.com>
Description: Support for the DS28EA00 chain sequence function
see Documentation/w1/slaves/w1_therm for detailed information
Users: any user space application which wants to communicate with DS28EA00

11
Documentation/w1/slaves/w1_therm
View File

@ -11,12 +11,14 @@ Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Description
-----------
w1_therm provides basic temperature conversion for ds18*20 devices.
w1_therm provides basic temperature conversion for ds18*20 devices, and the
ds28ea00 device.
supported family codes:
W1_THERM_DS18S20 0x10
W1_THERM_DS1822 0x22
W1_THERM_DS18B20 0x28
W1_THERM_DS1825 0x3B
W1_THERM_DS28EA00 0x42
Support is provided through the sysfs w1_slave file. Each open and
read sequence will initiate a temperature conversion then provide two
@ -48,3 +50,10 @@ resistor). The DS18b20 temperature sensor specification lists a
maximum current draw of 1.5mA and that a 5k pullup resistor is not
sufficient. The strong pullup is designed to provide the additional
current required.
The DS28EA00 provides an additional two pins for implementing a sequence
detection algorithm. This feature allows you to determine the physical
location of the chip in the 1-wire bus without needing pre-existing
knowledge of the bus ordering. Support is provided through the sysfs
w1_seq file. The file will contain a single line with an integer value
representing the device index in the bus starting at 0.

102
drivers/w1/slaves/w1_therm.c
View File

@ -92,13 +92,24 @@ static void w1_therm_remove_slave(struct w1_slave *sl)
static ssize_t w1_slave_show(struct device *device,
struct device_attribute *attr, char *buf);
static ssize_t w1_seq_show(struct device *device,
struct device_attribute *attr, char *buf);
static DEVICE_ATTR_RO(w1_slave);
static DEVICE_ATTR_RO(w1_seq);
static struct attribute *w1_therm_attrs[] = {
&dev_attr_w1_slave.attr,
NULL,
};
static struct attribute *w1_ds28ea00_attrs[] = {
&dev_attr_w1_slave.attr,
&dev_attr_w1_seq.attr,
NULL,
};
ATTRIBUTE_GROUPS(w1_therm);
ATTRIBUTE_GROUPS(w1_ds28ea00);
static struct w1_family_ops w1_therm_fops = {
.add_slave = w1_therm_add_slave,
@ -106,6 +117,12 @@ static struct w1_family_ops w1_therm_fops = {
.groups = w1_therm_groups,
};
static struct w1_family_ops w1_ds28ea00_fops = {
.add_slave = w1_therm_add_slave,
.remove_slave = w1_therm_remove_slave,
.groups = w1_ds28ea00_groups,
};
static struct w1_family w1_therm_family_DS18S20 = {
.fid = W1_THERM_DS18S20,
.fops = &w1_therm_fops,
@ -123,7 +140,7 @@ static struct w1_family w1_therm_family_DS1822 = {
static struct w1_family w1_therm_family_DS28EA00 = {
.fid = W1_THERM_DS28EA00,
.fops = &w1_therm_fops,
.fops = &w1_ds28ea00_fops,
};
static struct w1_family w1_therm_family_DS1825 = {
@ -316,6 +333,89 @@ post_unlock:
return ret;
}
#define W1_42_CHAIN 0x99
#define W1_42_CHAIN_OFF 0x3C
#define W1_42_CHAIN_OFF_INV 0xC3
#define W1_42_CHAIN_ON 0x5A
#define W1_42_CHAIN_ON_INV 0xA5
#define W1_42_CHAIN_DONE 0x96
#define W1_42_CHAIN_DONE_INV 0x69
#define W1_42_COND_READ 0x0F
#define W1_42_SUCCESS_CONFIRM_BYTE 0xAA
#define W1_42_FINISHED_BYTE 0xFF
static ssize_t w1_seq_show(struct device *device,
struct device_attribute *attr, char *buf)
{
struct w1_slave *sl = dev_to_w1_slave(device);
ssize_t c = PAGE_SIZE;
int rv;
int i;
u8 ack;
u64 rn;
struct w1_reg_num *reg_num;
int seq = 0;
mutex_lock(&sl->master->mutex);
/* Place all devices in CHAIN state */
if (w1_reset_bus(sl->master))
goto error;
w1_write_8(sl->master, W1_SKIP_ROM);
w1_write_8(sl->master, W1_42_CHAIN);
w1_write_8(sl->master, W1_42_CHAIN_ON);
w1_write_8(sl->master, W1_42_CHAIN_ON_INV);
msleep(sl->master->pullup_duration);
/* check for acknowledgment */
ack = w1_read_8(sl->master);
if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
goto error;
/* In case the bus fails to send 0xFF, limit*/
for (i = 0; i <= 64; i++) {
if (w1_reset_bus(sl->master))
goto error;
w1_write_8(sl->master, W1_42_COND_READ);
rv = w1_read_block(sl->master, (u8 *)&rn, 8);
reg_num = (struct w1_reg_num *) &rn;
if ((char)reg_num->family == W1_42_FINISHED_BYTE)
break;
if (sl->reg_num.id == reg_num->id)
seq = i;
w1_write_8(sl->master, W1_42_CHAIN);
w1_write_8(sl->master, W1_42_CHAIN_DONE);
w1_write_8(sl->master, W1_42_CHAIN_DONE_INV);
w1_read_block(sl->master, &ack, sizeof(ack));
/* check for acknowledgment */
ack = w1_read_8(sl->master);
if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
goto error;
}
/* Exit from CHAIN state */
if (w1_reset_bus(sl->master))
goto error;
w1_write_8(sl->master, W1_SKIP_ROM);
w1_write_8(sl->master, W1_42_CHAIN);
w1_write_8(sl->master, W1_42_CHAIN_OFF);
w1_write_8(sl->master, W1_42_CHAIN_OFF_INV);
/* check for acknowledgment */
ack = w1_read_8(sl->master);
if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
goto error;
mutex_unlock(&sl->master->mutex);
c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", seq);
return PAGE_SIZE - c;
error:
mutex_unlock(&sl->master->bus_mutex);
return -EIO;
}
static int __init w1_therm_init(void)
{
int err, i;