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)