+/*
+ * Let users instantiate I2C devices through sysfs. This can be used when
+ * platform initialization code doesn't contain the proper data for
+ * whatever reason. Also useful for drivers that do device detection and
+ * detection fails, either because the device uses an unexpected address,
+ * or this is a compatible device with different ID register values.
+ *
+ * Parameter checking may look overzealous, but we really don't want
+ * the user to provide incorrect parameters.
+ */
+static ssize_t
+i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct i2c_adapter *adap = to_i2c_adapter(dev);
+ struct i2c_board_info info;
+ struct i2c_client *client;
+ char *blank, end;
+ int res;
+
+ dev_warn(dev, "The new_device interface is still experimental "
+ "and may change in a near future\n");
+ memset(&info, 0, sizeof(struct i2c_board_info));
+
+ blank = strchr(buf, ' ');
+ if (!blank) {
+ dev_err(dev, "%s: Missing parameters\n", "new_device");
+ return -EINVAL;
+ }
+ if (blank - buf > I2C_NAME_SIZE - 1) {
+ dev_err(dev, "%s: Invalid device name\n", "new_device");
+ return -EINVAL;
+ }
+ memcpy(info.type, buf, blank - buf);
+
+ /* Parse remaining parameters, reject extra parameters */
+ res = sscanf(++blank, "%hi%c", &info.addr, &end);
+ if (res < 1) {
+ dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
+ return -EINVAL;
+ }
+ if (res > 1 && end != '\n') {
+ dev_err(dev, "%s: Extra parameters\n", "new_device");
+ return -EINVAL;
+ }
+
+ if (info.addr < 0x03 || info.addr > 0x77) {
+ dev_err(dev, "%s: Invalid I2C address 0x%hx\n", "new_device",
+ info.addr);
+ return -EINVAL;
+ }
+
+ client = i2c_new_device(adap, &info);
+ if (!client)
+ return -EEXIST;
+
+ /* Keep track of the added device */
+ mutex_lock(&core_lock);
+ list_add_tail(&client->detected, &userspace_devices);
+ mutex_unlock(&core_lock);
+ dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
+ info.type, info.addr);
+
+ return count;
+}
+
+/*
+ * And of course let the users delete the devices they instantiated, if
+ * they got it wrong. This interface can only be used to delete devices
+ * instantiated by i2c_sysfs_new_device above. This guarantees that we
+ * don't delete devices to which some kernel code still has references.
+ *
+ * Parameter checking may look overzealous, but we really don't want
+ * the user to delete the wrong device.
+ */