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Diffstat (limited to 'drivers/w1/w1_int.c')
-rw-r--r--drivers/w1/w1_int.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index bd877b24ce42..9d723efdf915 100644
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -31,6 +31,9 @@
static u32 w1_ids = 1;
+static int w1_enable_pullup = 1;
+module_param_named(enable_pullup, w1_enable_pullup, int, 0);
+
static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
struct device_driver *driver,
struct device *device)
@@ -59,6 +62,7 @@ static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
dev->initialized = 0;
dev->id = id;
dev->slave_ttl = slave_ttl;
+ dev->enable_pullup = w1_enable_pullup;
dev->search_count = -1; /* continual scan */
/* 1 for w1_process to decrement
@@ -107,6 +111,18 @@ int w1_add_master_device(struct w1_bus_master *master)
printk(KERN_ERR "w1_add_master_device: invalid function set\n");
return(-EINVAL);
}
+ /* While it would be electrically possible to make a device that
+ * generated a strong pullup in bit bang mode, only hardare that
+ * controls 1-wire time frames are even expected to support a strong
+ * pullup. w1_io.c would need to support calling set_pullup before
+ * the last write_bit operation of a w1_write_8 which it currently
+ * doesn't.
+ */
+ if (!master->write_byte && !master->touch_bit && master->set_pullup) {
+ printk(KERN_ERR "w1_add_master_device: set_pullup requires "
+ "write_byte or touch_bit, disabling\n");
+ master->set_pullup = NULL;
+ }
dev = w1_alloc_dev(w1_ids++, w1_max_slave_count, w1_max_slave_ttl, &w1_master_driver, &w1_master_device);
if (!dev)