[PATCH 04/14] w1: increase w1_max_slave_count, allow write access

David Fries
2013-12-29T06:53:55Z

w1_max_slave_count is only used to abort the search early
or take a fast search (when 1), so there isn't any reason to not allow
it to be updated through sysfs. Memory is not allocated based on
the current value and 10 is a rather low base number, increasing to
64, and printing a message the first time the count is reached and
there were more devices to discover to let the user know why not
all the devices were found.

Signed-off-by: David Fries <David@Fries.net>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
---
drivers/w1/w1.c | 30 ++++++++++++++++++++++++++++--
drivers/w1/w1.h | 2 ++
2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 92766a9..34ffdc6 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -46,7 +46,7 @@ MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");

static int w1_timeout = 10;
-int w1_max_slave_count = 10;
+int w1_max_slave_count = 64;
int w1_max_slave_ttl = 10;

module_param_named(timeout, w1_timeout, int, 0);
@@ -316,6 +316,24 @@ static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct devic
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)
+{
+ long tmp;
+ struct w1_master *md = dev_to_w1_master(dev);
+
+ if (kstrtol(buf, 0, &tmp) == -EINVAL || tmp < 1)
+ return -EINVAL;
+
+ mutex_lock(&md->mutex);
+ md->max_slave_count = tmp;
+ /* allow each time the max_slave_count is updated */
+ clear_bit(W1_WARN_MAX_COUNT, &md->flags);
+ mutex_unlock(&md->mutex);
+
+ return count;
+}
+
static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
{
struct w1_master *md = dev_to_w1_master(dev);
@@ -518,7 +536,7 @@ static ssize_t w1_master_attribute_store_remove(struct device *dev,
static W1_MASTER_ATTR_RO(name, S_IRUGO);
static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
-static W1_MASTER_ATTR_RO(max_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(pointer, S_IRUGO);
@@ -976,6 +994,14 @@ void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb
desc_bit = last_zero;
cb(dev, rn);
}
+
+ if (!last_device && slave_count == dev->max_slave_count &&
+ !test_bit(W1_WARN_MAX_COUNT, &dev->flags)) {
+ dev_info(&dev->dev, "%s: max_slave_count %d reached, "
+ "additional sensors ignored\n", __func__,
+ dev->max_slave_count);
+ set_bit(W1_WARN_MAX_COUNT, &dev->flags);
+ }
}
}

diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
index bc329d2..bd10b3c 100644
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -158,9 +158,11 @@ struct w1_bus_master
/**
* enum w1_master_flags - bitfields used in w1_master.flags
* @W1_ABORT_SEARCH: abort searching early on shutdown
+ * @W1_WARN_MAX_COUNT: limit warning when the maximum count is reached
*/
enum w1_master_flags {
W1_ABORT_SEARCH = 0,
+ W1_WARN_MAX_COUNT = 1,
};

struct w1_master
--
1.7.10.4