[PATCH] w1: Added the triplet w1 master method and changes w1_search() to use it.

Adds the triplet w1 master method and changes w1_search() to use it.

Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 65 insertions, 73 deletions

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index c85d75ed835a..4fa959f08554 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -135,7 +135,7 @@ struct device w1_device = {
 
 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
 {
-        struct w1_master *md = container_of (dev, struct w1_master, dev);
+        struct w1_master *md = container_of(dev, struct w1_master, dev);
         ssize_t count;
 
         if (down_interruptible (&md->mutex))
@@ -212,7 +212,6 @@ static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct d
 }
 
 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
-
 {
         struct w1_master *md = container_of(dev, struct w1_master, dev);
         int c = PAGE_SIZE;
@@ -286,13 +285,13 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
         sl->dev.release = &w1_slave_release;
 
         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
-                  "%02x-%012llx",
-                  (unsigned int) sl->reg_num.family,
-                  (unsigned long long) sl->reg_num.id);
-        snprintf (&sl->name[0], sizeof(sl->name),
-                  "%02x-%012llx",
-                  (unsigned int) sl->reg_num.family,
-                  (unsigned long long) sl->reg_num.id);
+                 "%02x-%012llx",
+                 (unsigned int) sl->reg_num.family,
+                 (unsigned long long) sl->reg_num.id);
+        snprintf(&sl->name[0], sizeof(sl->name),
+                 "%02x-%012llx",
+                 (unsigned int) sl->reg_num.family,
+                 (unsigned long long) sl->reg_num.id);
 
         dev_dbg(&sl->dev, "%s: registering %s.\n", __func__,
                 &sl->dev.bus_id[0]);
@@ -300,8 +299,8 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
         err = device_register(&sl->dev);
         if (err < 0) {
                 dev_err(&sl->dev,
-                         "Device registration [%s] failed. err=%d\n",
-                         sl->dev.bus_id, err);
+                        "Device registration [%s] failed. err=%d\n",
+                        sl->dev.bus_id, err);
                 return err;
         }
 
@@ -314,8 +313,8 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
         err = device_create_file(&sl->dev, &sl->attr_name);
         if (err < 0) {
                 dev_err(&sl->dev,
-                         "sysfs file creation for [%s] failed. err=%d\n",
-                         sl->dev.bus_id, err);
+                        "sysfs file creation for [%s] failed. err=%d\n",
+                        sl->dev.bus_id, err);
                 device_unregister(&sl->dev);
                 return err;
         }
@@ -323,8 +322,8 @@ static int __w1_attach_slave_device(struct w1_slave *sl)
         err = sysfs_create_bin_file(&sl->dev.kobj, &sl->attr_bin);
         if (err < 0) {
                 dev_err(&sl->dev,
-                         "sysfs file creation for [%s] failed. err=%d\n",
-                         sl->dev.bus_id, err);
+                        "sysfs file creation for [%s] failed. err=%d\n",
+                        sl->dev.bus_id, err);
                 device_remove_file(&sl->dev, &sl->attr_name);
                 device_unregister(&sl->dev);
                 return err;
@@ -483,26 +482,39 @@ static void w1_slave_found(unsigned long data, u64 rn)
         atomic_dec(&dev->refcnt);
 }
 
-void w1_search(struct w1_master *dev)
+/**
+ * Performs a ROM Search & registers any devices found.
+ * The 1-wire search is a simple binary tree search.
+ * For each bit of the address, we read two bits and write one bit.
+ * The bit written will put to sleep all devies that don't match that bit.
+ * When the two reads differ, the direction choice is obvious.
+ * When both bits are 0, we must choose a path to take.
+ * When we can scan all 64 bits without having to choose a path, we are done.
+ *
+ * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
+ *
+ * @dev        The master device to search
+ * @cb         Function to call when a device is found
+ */
+void w1_search(struct w1_master *dev, w1_slave_found_callback cb)
 {
-        u64 last, rn, tmp;
-        int i, count = 0;
-        int last_family_desc, last_zero, last_device;
-        int search_bit, id_bit, comp_bit, desc_bit;
+        u64 last_rn, rn, tmp64;
+        int i, slave_count = 0;
+        int last_zero, last_device;
+        int search_bit, desc_bit;
+        u8  triplet_ret = 0;
 
-        search_bit = id_bit = comp_bit = 0;
-        rn = tmp = last = 0;
-        last_device = last_zero = last_family_desc = 0;
+        search_bit = 0;
+        rn = last_rn = 0;
+        last_device = 0;
+        last_zero = -1;
 
         desc_bit = 64;
 
-        while (!(id_bit && comp_bit) && !last_device &&
-               count++ < dev->max_slave_count) {
-                last = rn;
+        while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
+                last_rn = rn;
                 rn = 0;
 
-                last_family_desc = 0;
-
                 /*
                  * Reset bus and all 1-wire device state machines
                  * so they can respond to our requests.
@@ -514,59 +526,39 @@ void w1_search(struct w1_master *dev)
                         break;
                 }
 
-#if 1
+                /* Start the search */
                 w1_write_8(dev, W1_SEARCH);
                 for (i = 0; i < 64; ++i) {
-                        /*
-                         * Read 2 bits from bus.
-                         * All who don't sleep must send ID bit and COMPLEMENT ID bit.
-                         * They actually are ANDed between all senders.
-                         */
-                        id_bit = w1_touch_bit(dev, 1);
-                        comp_bit = w1_touch_bit(dev, 1);
-
-                        if (id_bit && comp_bit)
-                                break;
-
-                        if (id_bit == 0 && comp_bit == 0) {
-                                if (i == desc_bit)
-                                        search_bit = 1;
-                                else if (i > desc_bit)
-                                        search_bit = 0;
-                                else
-                                        search_bit = ((last >> i) & 0x1);
-
-                                if (search_bit == 0) {
-                                        last_zero = i;
-                                        if (last_zero < 9)
-                                                last_family_desc = last_zero;
-                                }
+                        /* Determine the direction/search bit */
+                        if (i == desc_bit)
+                                search_bit = 1;   /* took the 0 path last time, so take the 1 path */
+                        else if (i > desc_bit)
+                                search_bit = 0;   /* take the 0 path on the next branch */
+                        else
+                                search_bit = ((last_rn >> i) & 0x1);
 
-                        } else
-                                search_bit = id_bit;
+                        /** Read two bits and write one bit */
+                        triplet_ret = w1_triplet(dev, search_bit);
 
-                        tmp = search_bit;
-                        rn |= (tmp << i);
+                        /* quit if no device responded */
+                        if ( (triplet_ret & 0x03) == 0x03 )
+                                break;
 
-                        /*
-                         * Write 1 bit to bus
-                         * and make all who don't have "search_bit" in "i"'th position
-                         * in it's registration number sleep.
-                         */
-                        if (dev->bus_master->touch_bit)
-                                w1_touch_bit(dev, search_bit);
-                        else
-                                w1_write_bit(dev, search_bit);
+                        /* If both directions were valid, and we took the 0 path... */
+                        if (triplet_ret == 0)
+                                last_zero = i;
 
+                        /* extract the direction taken & update the device number */
+                        tmp64 = (triplet_ret >> 2);
+                        rn |= (tmp64 << i);
                 }
-#endif
-
-                if (desc_bit == last_zero)
-                        last_device = 1;
 
-                desc_bit = last_zero;
-
-                w1_slave_found(dev->bus_master->data, rn);
+                if ( (triplet_ret & 0x03) != 0x03 ) {
+                        if ( (desc_bit == last_zero) || (last_zero < 0))
+                                last_device = 1;
+                        desc_bit = last_zero;
+                        cb(dev->bus_master->data, rn);
+                }
         }
 }