w1: add fast search for single slave bus

This enables a much more efficient way of device searching. It uses the
1-wire read-rom operation which allows the direct reading of the slave
address. BUT this works only with exactly one slave on the bus.

Signed-off-by: Hubert Feurstein <h.feurstein@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>

index c374978..9761950 100644
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index c37497823851..9761950697b4 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -892,6 +892,16 @@ void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb
                         break;
                 }
 
+                /* Do fast search on single slave bus */
+                if (dev->max_slave_count == 1) {
+                        w1_write_8(dev, W1_READ_ROM);
+
+                        if (w1_read_block(dev, (u8 *)&rn, 8) == 8 && rn)
+                                cb(dev, rn);
+
+                        break;
+                }
+
                 /* Start the search */
                 w1_write_8(dev, search_type);
                 for (i = 0; i < 64; ++i) {