[PATCH] w1: Added the triplet w1 master method and changes w1_search() to use it.
From: Greg KH
Date: Wed Jun 22 2005 - 00:22:28 EST
[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@xxxxxxxxxx>
Signed-off-by: Evgeniy Polyakov <johnpol@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
commit 6b729861831177b270a2932a13e79cb41d673146
tree 443c86578d04ba42d9b4e483d6ebee91ba30d25e
parent be57ce267fd558c52d2389530c15618681b7cfa7
author Evgeniy Polyakov <johnpol@xxxxxxxxxxx> Sat, 04 Jun 2005 01:30:43 +0400
committer Greg Kroah-Hartman <gregkh@xxxxxxx> Tue, 21 Jun 2005 21:43:11 -0700
drivers/w1/w1.c | 144 +++++++++++++++++++++++++---------------------------
drivers/w1/w1.h | 83 +++++++++++++++++++++++-------
drivers/w1/w1_io.c | 43 +++++++++++++++-
drivers/w1/w1_io.h | 1
4 files changed, 176 insertions(+), 95 deletions(-)
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
--- 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_
}
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(stru
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(stru
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(stru
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(stru
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
atomic_dec(&dev->refcnt);
}
-void w1_search(struct w1_master *dev)
-{
- 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;
-
- search_bit = id_bit = comp_bit = 0;
- rn = tmp = last = 0;
- last_device = last_zero = last_family_desc = 0;
+/**
+ * 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, rn, tmp64;
+ int i, slave_count = 0;
+ int last_zero, last_device;
+ int search_bit, desc_bit;
+ u8 triplet_ret = 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;
- }
-
- } 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);
+ /* 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
- w1_write_bit(dev, search_bit);
+ search_bit = ((last_rn >> i) & 0x1);
- }
-#endif
+ /** Read two bits and write one bit */
+ triplet_ret = w1_triplet(dev, search_bit);
- if (desc_bit == last_zero)
- last_device = 1;
+ /* quit if no device responded */
+ if ( (triplet_ret & 0x03) == 0x03 )
+ break;
- desc_bit = last_zero;
+ /* 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);
+ }
- 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);
+ }
}
}
diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -25,9 +25,9 @@
struct w1_reg_num
{
#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u64 family:8,
- id:48,
- crc:8;
+ __u64 family:8,
+ id:48,
+ crc:8;
#elif defined(__BIG_ENDIAN_BITFIELD)
__u64 crc:8,
id:48,
@@ -84,24 +84,71 @@ struct w1_slave
typedef void (* w1_slave_found_callback)(unsigned long, u64);
+
+/**
+ * Note: read_bit and write_bit are very low level functions and should only
+ * be used with hardware that doesn't really support 1-wire operations,
+ * like a parallel/serial port.
+ * Either define read_bit and write_bit OR define, at minimum, touch_bit and
+ * reset_bus.
+ */
struct w1_bus_master
{
- unsigned long data;
-
- u8 (*read_bit)(unsigned long);
- void (*write_bit)(unsigned long, u8);
-
- u8 (*read_byte)(unsigned long);
- void (*write_byte)(unsigned long, u8);
-
- u8 (*read_block)(unsigned long, u8 *, int);
- void (*write_block)(unsigned long, u8 *, int);
-
- u8 (*touch_bit)(unsigned long, u8);
+ /** the first parameter in all the functions below */
+ unsigned long data;
- u8 (*reset_bus)(unsigned long);
+ /**
+ * Sample the line level
+ * @return the level read (0 or 1)
+ */
+ u8 (*read_bit)(unsigned long);
+
+ /** Sets the line level */
+ void (*write_bit)(unsigned long, u8);
+
+ /**
+ * touch_bit is the lowest-level function for devices that really
+ * support the 1-wire protocol.
+ * touch_bit(0) = write-0 cycle
+ * touch_bit(1) = write-1 / read cycle
+ * @return the bit read (0 or 1)
+ */
+ u8 (*touch_bit)(unsigned long, u8);
+
+ /**
+ * Reads a bytes. Same as 8 touch_bit(1) calls.
+ * @return the byte read
+ */
+ u8 (*read_byte)(unsigned long);
+
+ /**
+ * Writes a byte. Same as 8 touch_bit(x) calls.
+ */
+ void (*write_byte)(unsigned long, u8);
+
+ /**
+ * Same as a series of read_byte() calls
+ * @return the number of bytes read
+ */
+ u8 (*read_block)(unsigned long, u8 *, int);
+
+ /** Same as a series of write_byte() calls */
+ void (*write_block)(unsigned long, const u8 *, int);
+
+ /**
+ * Combines two reads and a smart write for ROM searches
+ * @return bit0=Id bit1=comp_id bit2=dir_taken
+ */
+ u8 (*triplet)(unsigned long, u8);
+
+ /**
+ * long write-0 with a read for the presence pulse detection
+ * @return -1=Error, 0=Device present, 1=No device present
+ */
+ u8 (*reset_bus)(unsigned long);
- void (*search)(unsigned long, w1_slave_found_callback);
+ /** Really nice hardware can handles the ROM searches */
+ void (*search)(unsigned long, w1_slave_found_callback);
};
struct w1_master
@@ -137,7 +184,7 @@ struct w1_master
};
int w1_create_master_attributes(struct w1_master *);
-void w1_search(struct w1_master *dev);
+void w1_search(struct w1_master *dev, w1_slave_found_callback cb);
#endif /* __KERNEL__ */
diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -130,6 +130,47 @@ static u8 w1_read_bit(struct w1_master *
}
/**
+ * Does a triplet - used for searching ROM addresses.
+ * Return bits:
+ * bit 0 = id_bit
+ * bit 1 = comp_bit
+ * bit 2 = dir_taken
+ * If both bits 0 & 1 are set, the search should be restarted.
+ *
+ * @param dev the master device
+ * @param bdir the bit to write if both id_bit and comp_bit are 0
+ * @return bit fields - see above
+ */
+u8 w1_triplet(struct w1_master *dev, int bdir)
+{
+ if ( dev->bus_master->triplet )
+ return(dev->bus_master->triplet(dev->bus_master->data, bdir));
+ else {
+ u8 id_bit = w1_touch_bit(dev, 1);
+ u8 comp_bit = w1_touch_bit(dev, 1);
+ u8 retval;
+
+ if ( id_bit && comp_bit )
+ return(0x03); /* error */
+
+ if ( !id_bit && !comp_bit ) {
+ /* Both bits are valid, take the direction given */
+ retval = bdir ? 0x04 : 0;
+ } else {
+ /* Only one bit is valid, take that direction */
+ bdir = id_bit;
+ retval = id_bit ? 0x05 : 0x02;
+ }
+
+ if ( dev->bus_master->touch_bit )
+ w1_touch_bit(dev, bdir);
+ else
+ w1_write_bit(dev, bdir);
+ return(retval);
+ }
+}
+
+/**
* Reads 8 bits.
*
* @param dev the master device
@@ -233,7 +274,7 @@ void w1_search_devices(struct w1_master
if (dev->bus_master->search)
dev->bus_master->search(dev->bus_master->data, cb);
else
- w1_search(dev);
+ w1_search(dev, cb);
}
EXPORT_SYMBOL(w1_touch_bit);
diff --git a/drivers/w1/w1_io.h b/drivers/w1/w1_io.h
--- a/drivers/w1/w1_io.h
+++ b/drivers/w1/w1_io.h
@@ -26,6 +26,7 @@
void w1_delay(unsigned long);
u8 w1_touch_bit(struct w1_master *, int);
+u8 w1_triplet(struct w1_master *dev, int bdir);
void w1_write_8(struct w1_master *, u8);
u8 w1_read_8(struct w1_master *);
int w1_reset_bus(struct w1_master *);
-
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