+
+/*
+ * Creates hid/cid(s) string needed for modalias and uevent
+ * e.g. on a device with hid:IBM0001 and cid:ACPI0001 you get:
+ * char *modalias: "acpi:IBM0001:ACPI0001"
+*/
+int create_modalias(struct acpi_device *acpi_dev, char *modalias, int size){
+
+ int len;
+
+ if (!acpi_dev->flags.hardware_id)
+ return -ENODEV;
+
+ len = snprintf(modalias, size, "acpi:%s:",
+ acpi_dev->pnp.hardware_id);
+ if (len < 0 || len >= size)
+ return -EINVAL;
+ size -= len;
+
+ if (acpi_dev->flags.compatible_ids) {
+ struct acpi_compatible_id_list *cid_list;
+ int i;
+ int count;
+
+ cid_list = acpi_dev->pnp.cid_list;
+ for (i = 0; i < cid_list->count; i++) {
+ count = snprintf(&modalias[len], size, "%s:",
+ cid_list->id[i].value);
+ if (count < 0 || count >= size) {
+ printk(KERN_ERR "acpi: %s cid[%i] exceeds event buffer size",
+ acpi_dev->pnp.device_name, i);
+ break;
+ }
+ len += count;
+ size -= count;
+ }
+ }
+
+ modalias[len] = '\0';
+ return len;
+}
+
+static ssize_t
+acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, char *buf) {
+ struct acpi_device *acpi_dev = to_acpi_device(dev);
+ int len;
+
+ /* Device has no HID and no CID or string is >1024 */
+ len = create_modalias(acpi_dev, buf, 1024);
+ if (len <= 0)
+ return 0;
+ buf[len++] = '\n';
+ return len;
+}
+static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
+