4 files changed, 131 insertions, 5 deletions

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 9b5c11701c37..32418d4e555a 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -246,10 +246,14 @@ static ssize_t w1_master_attribute_store_search(struct device * dev,
                                                 struct device_attribute *attr,
                                                 const char * buf, size_t count)
 {
+        long tmp;
         struct w1_master *md = dev_to_w1_master(dev);
 
+        if (strict_strtol(buf, 0, &tmp) == -EINVAL)
+                return -EINVAL;
+
         mutex_lock(&md->mutex);
-        md->search_count = simple_strtol(buf, NULL, 0);
+        md->search_count = tmp;
         mutex_unlock(&md->mutex);
         wake_up_process(md->thread);
 
@@ -270,6 +274,38 @@ static ssize_t w1_master_attribute_show_search(struct device *dev,
         return count;
 }
 
+static ssize_t w1_master_attribute_store_pullup(struct device *dev,
+                                                struct device_attribute *attr,
+                                                const char *buf, size_t count)
+{
+        long tmp;
+        struct w1_master *md = dev_to_w1_master(dev);
+
+        if (strict_strtol(buf, 0, &tmp) == -EINVAL)
+                return -EINVAL;
+
+        mutex_lock(&md->mutex);
+        md->enable_pullup = tmp;
+        mutex_unlock(&md->mutex);
+        wake_up_process(md->thread);
+
+        return count;
+}
+
+static ssize_t w1_master_attribute_show_pullup(struct device *dev,
+                                               struct device_attribute *attr,
+                                               char *buf)
+{
+        struct w1_master *md = dev_to_w1_master(dev);
+        ssize_t count;
+
+        mutex_lock(&md->mutex);
+        count = sprintf(buf, "%d\n", md->enable_pullup);
+        mutex_unlock(&md->mutex);
+
+        return count;
+}
+
 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
 {
         struct w1_master *md = dev_to_w1_master(dev);
@@ -365,6 +401,7 @@ static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
+static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUGO);
 
 static struct attribute *w1_master_default_attrs[] = {
         &w1_master_attribute_name.attr,
@@ -375,6 +412,7 @@ static struct attribute *w1_master_default_attrs[] = {
         &w1_master_attribute_timeout.attr,
         &w1_master_attribute_pointer.attr,
         &w1_master_attribute_search.attr,
+        &w1_master_attribute_pullup.attr,
         NULL
 };
 
diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
index 34ee01e008ad..00b84ab22808 100644
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -142,6 +142,12 @@ struct w1_bus_master
          */
         u8              (*reset_bus)(void *);
 
+        /**
+         * Put out a strong pull-up pulse of the specified duration.
+         * @return -1=Error, 0=completed
+         */
+        u8              (*set_pullup)(void *, int);
+
         /** Really nice hardware can handles the different types of ROM search
          *  w1_master* is passed to the slave found callback.
          */
@@ -167,6 +173,11 @@ struct w1_master
         void                    *priv;
         int                     priv_size;
 
+        /** 5V strong pullup enabled flag, 1 enabled, zero disabled. */
+        int                     enable_pullup;
+        /** 5V strong pullup duration in milliseconds, zero disabled. */
+        int                     pullup_duration;
+
         struct task_struct      *thread;
         struct mutex            mutex;
 
@@ -201,6 +212,7 @@ u8 w1_calc_crc8(u8 *, int);
 void w1_write_block(struct w1_master *, const u8 *, int);
 u8 w1_read_block(struct w1_master *, u8 *, int);
 int w1_reset_select_slave(struct w1_slave *sl);
+void w1_next_pullup(struct w1_master *, int);
 
 static inline struct w1_slave* dev_to_w1_slave(struct device *dev)
 {
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)
diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
index 0056ef69009b..97b338a16abc 100644
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -93,6 +93,40 @@ static void w1_write_bit(struct w1_master *dev, int bit)
 }
 
 /**
+ * Pre-write operation, currently only supporting strong pullups.
+ * Program the hardware for a strong pullup, if one has been requested and
+ * the hardware supports it.
+ *
+ * @param dev     the master device
+ */
+static void w1_pre_write(struct w1_master *dev)
+{
+        if (dev->pullup_duration &&
+                dev->enable_pullup && dev->bus_master->set_pullup) {
+                dev->bus_master->set_pullup(dev->bus_master->data,
+                        dev->pullup_duration);
+        }
+}
+
+/**
+ * Post-write operation, currently only supporting strong pullups.
+ * If a strong pullup was requested, clear it if the hardware supports
+ * them, or execute the delay otherwise, in either case clear the request.
+ *
+ * @param dev     the master device
+ */
+static void w1_post_write(struct w1_master *dev)
+{
+        if (dev->pullup_duration) {
+                if (dev->enable_pullup && dev->bus_master->set_pullup)
+                        dev->bus_master->set_pullup(dev->bus_master->data, 0);
+                else
+                        msleep(dev->pullup_duration);
+                dev->pullup_duration = 0;
+        }
+}
+
+/**
  * Writes 8 bits.
  *
  * @param dev     the master device
@@ -102,11 +136,17 @@ void w1_write_8(struct w1_master *dev, u8 byte)
 {
         int i;
 
-        if (dev->bus_master->write_byte)
+        if (dev->bus_master->write_byte) {
+                w1_pre_write(dev);
                 dev->bus_master->write_byte(dev->bus_master->data, byte);
+        }
         else
-                for (i = 0; i < 8; ++i)
+                for (i = 0; i < 8; ++i) {
+                        if (i == 7)
+                                w1_pre_write(dev);
                         w1_touch_bit(dev, (byte >> i) & 0x1);
+                }
+        w1_post_write(dev);
 }
 EXPORT_SYMBOL_GPL(w1_write_8);
 
@@ -203,11 +243,14 @@ void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
 {
         int i;
 
-        if (dev->bus_master->write_block)
+        if (dev->bus_master->write_block) {
+                w1_pre_write(dev);
                 dev->bus_master->write_block(dev->bus_master->data, buf, len);
+        }
         else
                 for (i = 0; i < len; ++i)
-                        w1_write_8(dev, buf[i]);
+                        w1_write_8(dev, buf[i]); /* calls w1_pre_write */
+        w1_post_write(dev);
 }
 EXPORT_SYMBOL_GPL(w1_write_block);
 
@@ -306,3 +349,20 @@ int w1_reset_select_slave(struct w1_slave *sl)
         return 0;
 }
 EXPORT_SYMBOL_GPL(w1_reset_select_slave);
+
+/**
+ * Put out a strong pull-up of the specified duration after the next write
+ * operation.  Not all hardware supports strong pullups.  Hardware that
+ * doesn't support strong pullups will sleep for the given time after the
+ * write operation without a strong pullup.  This is a one shot request for
+ * the next write, specifying zero will clear a previous request.
+ * The w1 master lock must be held.
+ *
+ * @param delay time in milliseconds
+ * @return      0=success, anything else=error
+ */
+void w1_next_pullup(struct w1_master *dev, int delay)
+{
+        dev->pullup_duration = delay;
+}
+EXPORT_SYMBOL_GPL(w1_next_pullup);