[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>
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index c85d75e..4fa959f 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -135,7 +135,7 @@
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_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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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);
+ /* 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);
- if (id_bit && comp_bit)
+ /** Read two bits and write one bit */
+ triplet_ret = w1_triplet(dev, search_bit);
+
+ /* quit if no device responded */
+ if ( (triplet_ret & 0x03) == 0x03 )
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 both directions were valid, and we took the 0 path... */
+ if (triplet_ret == 0)
+ last_zero = i;
- if (search_bit == 0) {
- last_zero = i;
- if (last_zero < 9)
- last_family_desc = last_zero;
- }
-
- } else
- search_bit = id_bit;
-
- tmp = search_bit;
- rn |= (tmp << i);
-
- /*
- * 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);
-
+ /* 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);
+ }
}
}