Commit c3098356 authored by Dmitry Khromov's avatar Dmitry Khromov Committed by Greg Kroah-Hartman

w1: introduce an ability to specify microseconds bus scanning intervals

Some of 1-Wire devices commonly associated with physical access control
systems are attached/generate presence for as short as 100 ms - hence
the tens-to-hundreds milliseconds scan intervals are required.
Signed-off-by: default avatarDmitry Khromov <dk@icelogic.net>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 99b7e93c
What: /sys/bus/w1/devices/.../w1_master_timeout_us
Date: April 2015
Contact: Dmitry Khromov <dk@icelogic.net>
Description: Bus scanning interval, microseconds component.
Some of 1-Wire devices commonly associated with physical access
control systems are attached/generate presence for as short as
100 ms - hence the tens-to-hundreds milliseconds scan intervals
are required.
see Documentation/w1/w1.generic for detailed information.
Users: any user space application which wants to know bus scanning
interval
......@@ -76,21 +76,24 @@ See struct w1_bus_master definition in w1.h for details.
w1 master sysfs interface
------------------------------------------------------------------
<xx-xxxxxxxxxxxxx> - a directory for a found device. The format is family-serial
<xx-xxxxxxxxxxxxx> - A directory for a found device. The format is family-serial
bus - (standard) symlink to the w1 bus
driver - (standard) symlink to the w1 driver
w1_master_add - Manually register a slave device
w1_master_attempts - the number of times a search was attempted
w1_master_add - (rw) manually register a slave device
w1_master_attempts - (ro) the number of times a search was attempted
w1_master_max_slave_count
- maximum number of slaves to search for at a time
w1_master_name - the name of the device (w1_bus_masterX)
w1_master_pullup - 5V strong pullup 0 enabled, 1 disabled
w1_master_remove - Manually remove a slave device
w1_master_search - the number of searches left to do, -1=continual (default)
- (rw) maximum number of slaves to search for at a time
w1_master_name - (ro) the name of the device (w1_bus_masterX)
w1_master_pullup - (rw) 5V strong pullup 0 enabled, 1 disabled
w1_master_remove - (rw) manually remove a slave device
w1_master_search - (rw) the number of searches left to do,
-1=continual (default)
w1_master_slave_count
- the number of slaves found
w1_master_slaves - the names of the slaves, one per line
w1_master_timeout - the delay in seconds between searches
- (ro) the number of slaves found
w1_master_slaves - (ro) the names of the slaves, one per line
w1_master_timeout - (ro) the delay in seconds between searches
w1_master_timeout_us
- (ro) the delay in microseconds beetwen searches
If you have a w1 bus that never changes (you don't add or remove devices),
you can set the module parameter search_count to a small positive number
......@@ -101,6 +104,11 @@ generally only make sense when searching is disabled, as a search will
redetect manually removed devices that are present and timeout manually
added devices that aren't on the bus.
Bus searches occur at an interval, specified as a summ of timeout and
timeout_us module parameters (either of which may be 0) for as long as
w1_master_search remains greater than 0 or is -1. Each search attempt
decrements w1_master_search by 1 (down to 0) and increments
w1_master_attempts by 1.
w1 slave sysfs interface
------------------------------------------------------------------
......
......@@ -46,11 +46,15 @@ MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
static int w1_timeout = 10;
static int w1_timeout_us = 0;
int w1_max_slave_count = 64;
int w1_max_slave_ttl = 10;
module_param_named(timeout, w1_timeout, int, 0);
MODULE_PARM_DESC(timeout, "time in seconds between automatic slave searches");
module_param_named(timeout_us, w1_timeout_us, int, 0);
MODULE_PARM_DESC(timeout, "time in microseconds between automatic slave"
" searches");
/* A search stops when w1_max_slave_count devices have been found in that
* search. The next search will start over and detect the same set of devices
* on a static 1-wire bus. Memory is not allocated based on this number, just
......@@ -317,6 +321,14 @@ static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct devic
return count;
}
static ssize_t w1_master_attribute_show_timeout_us(struct device *dev,
struct device_attribute *attr, char *buf)
{
ssize_t count;
count = sprintf(buf, "%d\n", w1_timeout_us);
return count;
}
static ssize_t w1_master_attribute_store_max_slave_count(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
......@@ -543,6 +555,7 @@ static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
static W1_MASTER_ATTR_RW(max_slave_count, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
static W1_MASTER_ATTR_RO(timeout_us, S_IRUGO);
static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUSR | S_IWGRP);
......@@ -556,6 +569,7 @@ static struct attribute *w1_master_default_attrs[] = {
&w1_master_attribute_max_slave_count.attr,
&w1_master_attribute_attempts.attr,
&w1_master_attribute_timeout.attr,
&w1_master_attribute_timeout_us.attr,
&w1_master_attribute_pointer.attr,
&w1_master_attribute_search.attr,
&w1_master_attribute_pullup.attr,
......@@ -1108,7 +1122,8 @@ int w1_process(void *data)
/* As long as w1_timeout is only set by a module parameter the sleep
* time can be calculated in jiffies once.
*/
const unsigned long jtime = msecs_to_jiffies(w1_timeout * 1000);
const unsigned long jtime =
usecs_to_jiffies(w1_timeout * 1000000 + w1_timeout_us);
/* remainder if it woke up early */
unsigned long jremain = 0;
......
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