W1: be able to manually add and remove slaves

sysfs entries were added to manually add and remove slave devices.  This
is useful if the automatic bus searching is disabled, and the device ids
are already known.

[akpm@linux-foundation.org: fix printk types]
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 137 insertions, 1 deletions

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index 32418d4e555a..f3be2991e6e8 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -56,6 +56,8 @@ module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
 DEFINE_MUTEX(w1_mlock);
 LIST_HEAD(w1_masters);
 
+static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn);
+
 static int w1_master_match(struct device *dev, struct device_driver *drv)
 {
         return 1;
@@ -357,7 +359,8 @@ static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct d
         return count;
 }
 
-static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
+static ssize_t w1_master_attribute_show_slaves(struct device *dev,
+        struct device_attribute *attr, char *buf)
 {
         struct w1_master *md = dev_to_w1_master(dev);
         int c = PAGE_SIZE;
@@ -382,6 +385,135 @@ static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device
         return PAGE_SIZE - c;
 }
 
+static ssize_t w1_master_attribute_show_add(struct device *dev,
+        struct device_attribute *attr, char *buf)
+{
+        int c = PAGE_SIZE;
+        c -= snprintf(buf+PAGE_SIZE - c, c,
+                "write device id xx-xxxxxxxxxxxx to add slave\n");
+        return PAGE_SIZE - c;
+}
+
+static int w1_atoreg_num(struct device *dev, const char *buf, size_t count,
+        struct w1_reg_num *rn)
+{
+        unsigned int family;
+        unsigned long long id;
+        int i;
+        u64 rn64_le;
+
+        /* The CRC value isn't read from the user because the sysfs directory
+         * doesn't include it and most messages from the bus search don't
+         * print it either.  It would be unreasonable for the user to then
+         * provide it.
+         */
+        const char *error_msg = "bad slave string format, expecting "
+                "ff-dddddddddddd\n";
+
+        if (buf[2] != '-') {
+                dev_err(dev, "%s", error_msg);
+                return -EINVAL;
+        }
+        i = sscanf(buf, "%02x-%012llx", &family, &id);
+        if (i != 2) {
+                dev_err(dev, "%s", error_msg);
+                return -EINVAL;
+        }
+        rn->family = family;
+        rn->id = id;
+
+        rn64_le = cpu_to_le64(*(u64 *)rn);
+        rn->crc = w1_calc_crc8((u8 *)&rn64_le, 7);
+
+#if 0
+        dev_info(dev, "With CRC device is %02x.%012llx.%02x.\n",
+                  rn->family, (unsigned long long)rn->id, rn->crc);
+#endif
+
+        return 0;
+}
+
+/* Searches the slaves in the w1_master and returns a pointer or NULL.
+ * Note: must hold the mutex
+ */
+static struct w1_slave *w1_slave_search_device(struct w1_master *dev,
+        struct w1_reg_num *rn)
+{
+        struct w1_slave *sl;
+        list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
+                if (sl->reg_num.family == rn->family &&
+                                sl->reg_num.id == rn->id &&
+                                sl->reg_num.crc == rn->crc) {
+                        return sl;
+                }
+        }
+        return NULL;
+}
+
+static ssize_t w1_master_attribute_store_add(struct device *dev,
+                                                struct device_attribute *attr,
+                                                const char *buf, size_t count)
+{
+        struct w1_master *md = dev_to_w1_master(dev);
+        struct w1_reg_num rn;
+        struct w1_slave *sl;
+        ssize_t result = count;
+
+        if (w1_atoreg_num(dev, buf, count, &rn))
+                return -EINVAL;
+
+        mutex_lock(&md->mutex);
+        sl = w1_slave_search_device(md, &rn);
+        /* It would be nice to do a targeted search one the one-wire bus
+         * for the new device to see if it is out there or not.  But the
+         * current search doesn't support that.
+         */
+        if (sl) {
+                dev_info(dev, "Device %s already exists\n", sl->name);
+                result = -EINVAL;
+        } else {
+                w1_attach_slave_device(md, &rn);
+        }
+        mutex_unlock(&md->mutex);
+
+        return result;
+}
+
+static ssize_t w1_master_attribute_show_remove(struct device *dev,
+        struct device_attribute *attr, char *buf)
+{
+        int c = PAGE_SIZE;
+        c -= snprintf(buf+PAGE_SIZE - c, c,
+                "write device id xx-xxxxxxxxxxxx to remove slave\n");
+        return PAGE_SIZE - c;
+}
+
+static ssize_t w1_master_attribute_store_remove(struct device *dev,
+                                                struct device_attribute *attr,
+                                                const char *buf, size_t count)
+{
+        struct w1_master *md = dev_to_w1_master(dev);
+        struct w1_reg_num rn;
+        struct w1_slave *sl;
+        ssize_t result = count;
+
+        if (w1_atoreg_num(dev, buf, count, &rn))
+                return -EINVAL;
+
+        mutex_lock(&md->mutex);
+        sl = w1_slave_search_device(md, &rn);
+        if (sl) {
+                w1_slave_detach(sl);
+        } else {
+                dev_info(dev, "Device %02x-%012llx doesn't exists\n", rn.family,
+                        (unsigned long long)rn.id);
+                result = -EINVAL;
+        }
+        mutex_unlock(&md->mutex);
+
+        return result;
+}
+
 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
         struct device_attribute w1_master_attribute_##_name =   \
                 __ATTR(w1_master_##_name, _mode,                \
@@ -402,6 +534,8 @@ 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 W1_MASTER_ATTR_RW(add, S_IRUGO | S_IWUGO);
+static W1_MASTER_ATTR_RW(remove, S_IRUGO | S_IWUGO);
 
 static struct attribute *w1_master_default_attrs[] = {
         &w1_master_attribute_name.attr,
@@ -413,6 +547,8 @@ static struct attribute *w1_master_default_attrs[] = {
         &w1_master_attribute_pointer.attr,
         &w1_master_attribute_search.attr,
         &w1_master_attribute_pullup.attr,
+        &w1_master_attribute_add.attr,
+        &w1_master_attribute_remove.attr,
         NULL
 };