w1: introduce an ability to specify microseconds bus scanning intervals (c3098356) · Commits · e / devices / android_kernel_fairphone_FP4

Documentation/ABI/stable/sysfs-bus-w1

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+11 −0

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		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

Documentation/w1/w1.generic

+19 −11

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		@@ -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
		------------------------------------------------------------------

drivers/w1/w1.c

+16 −1

Original line number	Diff line number	Diff line
		@@ -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;