--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2025 Šerif Rami <ramiserifpersia@gmail.com>
+/*
+ * ALSA Driver for TASCAM US-144MKII Audio Interface
+ */
+
+#include "us144mkii.h"
+
+MODULE_AUTHOR("Šerif Rami <ramiserifpersia@gmail.com>");
+MODULE_DESCRIPTION("ALSA Driver for TASCAM US-144MKII");
+MODULE_LICENSE("GPL");
+
+/**
+ * @brief Module parameters for ALSA card instantiation.
+ *
+ * These parameters allow users to configure how the ALSA sound card
+ * for the TASCAM US-144MKII is instantiated.
+ *
+ * @param index: Array of integers specifying the ALSA card index for each
+ * device. Defaults to -1 (automatic).
+ * @param id: Array of strings specifying the ALSA card ID for each device.
+ * Defaults to "US144MKII".
+ * @param enable: Array of booleans to enable or disable each device.
+ * Defaults to {1, 0, ..., 0} (first device enabled).
+ * @param dev_idx: Internal counter for probed TASCAM devices.
+ */
+static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
+static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
+static bool enable[SNDRV_CARDS] = { 1, [1 ...(SNDRV_CARDS - 1)] = 0 };
+static int dev_idx;
+
+static int tascam_probe(struct usb_interface *intf,
+ const struct usb_device_id *usb_id);
+static void tascam_disconnect(struct usb_interface *intf);
+static int tascam_suspend(struct usb_interface *intf, pm_message_t message);
+static int tascam_resume(struct usb_interface *intf);
+
+/**
+ * tascam_card_private_free() - Frees private data for the sound card.
+ * card.
+ * @card: Pointer to the ALSA sound card instance.
+ *
+ * This function is called when the sound card is being freed. It releases
+ * the reference to the USB device.
+ */
+static void tascam_card_private_free(struct snd_card *card)
+{
+ struct tascam_card *tascam = card->private_data;
+
+ if (tascam && tascam->dev) {
+ usb_put_dev(tascam->dev);
+ tascam->dev = NULL;
+ }
+}
+
+/**
+ * tascam_probe() - Probes for the TASCAM US-144MKII device.
+ * @intf: The USB interface being probed.
+ * @usb_id: The USB device ID.
+ *
+ * This function is the entry point for the USB driver on device match.
+ * is found. It performs initial device setup, including:
+ * - Checking for the second interface (MIDI) and associating it.
+ * - Performing a vendor-specific handshake with the device.
+ * - Setting alternate settings for USB interfaces.
+ * - Creating and registering the ALSA sound card.
+ *
+ * Return: 0 on success, or a negative error code on failure.
+ */
+static int tascam_probe(struct usb_interface *intf,
+ const struct usb_device_id *usb_id)
+{
+ struct usb_device *dev = interface_to_usbdev(intf);
+ struct snd_card *card;
+ struct tascam_card *tascam;
+ int err;
+ char *handshake_buf __free(kfree) = NULL;
+
+ if (dev->speed != USB_SPEED_HIGH)
+ dev_info(
+ &dev->dev,
+ "Device is connected to a USB 1.1 port, this is not supported.\n");
+
+ /* The device has two interfaces; we drive both from this driver. */
+ if (intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+ tascam = usb_get_intfdata(usb_ifnum_to_if(dev, 0));
+ if (tascam) {
+ usb_set_intfdata(intf, tascam);
+ tascam->iface1 = intf;
+ }
+ return 0; /* Let the core handle this interface */
+ }
+
+ if (dev_idx >= SNDRV_CARDS) {
+ dev_err(&dev->dev, "Too many TASCAM devices present");
+ return -ENODEV;
+ }
+
+ if (!enable[dev_idx]) {
+ dev_info(&dev->dev, "TASCAM US-144MKII device disabled");
+ return -ENOENT;
+ }
+
+ handshake_buf = kmalloc(1, GFP_KERNEL);
+ if (!handshake_buf)
+ return -ENOMEM;
+
+ /* Perform vendor-specific handshake */
+ err = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+ VENDOR_REQ_MODE_CONTROL, RT_D2H_VENDOR_DEV,
+ MODE_VAL_HANDSHAKE_READ, 0x0000, handshake_buf, 1,
+ USB_CTRL_TIMEOUT_MS);
+ if (err < 0) {
+ dev_err(&dev->dev, "Handshake read failed with %d\n", err);
+ return err;
+ }
+
+ if (handshake_buf[0] != 0x12 && handshake_buf[0] != 0x16 &&
+ handshake_buf[0] != 0x30) {
+ dev_err(&dev->dev, "Unexpected handshake value: 0x%x\n",
+ handshake_buf[0]);
+ return -ENODEV;
+ }
+
+ /* Set alternate settings to enable audio/MIDI endpoints */
+ err = usb_set_interface(dev, 0, 1);
+ if (err < 0) {
+ dev_err(&dev->dev,
+ "Failed to set alt setting 1 on interface 0: %d\n",
+ err);
+ return err;
+ }
+
+ err = usb_set_interface(dev, 1, 1);
+ if (err < 0) {
+ dev_err(&dev->dev,
+ "Failed to set alt setting 1 on interface 1: %d\n",
+ err);
+ return err;
+ }
+
+ err = snd_card_new(&dev->dev, index[dev_idx], id[dev_idx], THIS_MODULE,
+ sizeof(struct tascam_card), &card);
+ if (err < 0) {
+ dev_err(&dev->dev, "Failed to create sound card instance\n");
+ return err;
+ }
+
+ tascam = card->private_data;
+ card->private_free = tascam_card_private_free;
+ tascam->dev = usb_get_dev(dev);
+ tascam->card = card;
+ tascam->iface0 = intf;
+ tascam->digital_out_source = 1;
+ tascam->capture_34_source = 1;
+
+ strscpy(card->driver, DRIVER_NAME, sizeof(card->driver));
+ if (dev->descriptor.idProduct == USB_PID_TASCAM_US144) {
+ strscpy(card->shortname, "TASCAM US-144",
+ sizeof(card->shortname));
+ } else if (dev->descriptor.idProduct == USB_PID_TASCAM_US144MKII) {
+ strscpy(card->shortname, "TASCAM US-144MKII",
+ sizeof(card->shortname));
+ } else {
+ strscpy(card->shortname, "TASCAM Unknown",
+ sizeof(card->shortname));
+ }
+ snprintf(card->longname, sizeof(card->longname), "%s (%04x:%04x) at %s",
+ card->shortname, USB_VID_TASCAM, dev->descriptor.idProduct,
+ dev_name(&dev->dev));
+
+ err = snd_card_register(card);
+ if (err < 0)
+ goto free_card;
+
+ usb_set_intfdata(intf, tascam);
+
+ dev_idx++;
+ return 0;
+
+free_card:
+ snd_card_free(card);
+ return err;
+}
+
+/**
+ * tascam_disconnect() - Disconnects the TASCAM US-144MKII device.
+ * @intf: The USB interface being disconnected.
+ *
+ * This function is called when the device is disconnected from the system.
+ * It cleans up all allocated resources by freeing the sound card.
+ */
+static void tascam_disconnect(struct usb_interface *intf)
+{
+ struct tascam_card *tascam = usb_get_intfdata(intf);
+
+ if (!tascam)
+ return;
+
+ if (intf->cur_altsetting->desc.bInterfaceNumber == 0) {
+ snd_card_disconnect(tascam->card);
+ snd_card_free(tascam->card);
+ dev_idx--;
+ }
+}
+
+/**
+ * tascam_suspend() - Handles device suspension.
+ * @intf: The USB interface being suspended.
+ * @message: Power management message.
+ *
+ * This function is a stub for handling device suspension.
+ *
+ * Return: 0 on success.
+ */
+static int tascam_suspend(struct usb_interface *intf, pm_message_t message)
+{
+ return 0;
+}
+
+/**
+ * tascam_resume() - Handles device resumption from suspend.
+ * @intf: The USB interface being resumed.
+ *
+ * This function is a stub for handling device resumption.
+ *
+ * Return: 0 on success.
+ */
+static int tascam_resume(struct usb_interface *intf)
+{
+ return 0;
+}
+
+static const struct usb_device_id tascam_usb_ids[] = {
+ { USB_DEVICE(USB_VID_TASCAM, USB_PID_TASCAM_US144) },
+ { USB_DEVICE(USB_VID_TASCAM, USB_PID_TASCAM_US144MKII) },
+ { /* Terminating entry */ }
+};
+MODULE_DEVICE_TABLE(usb, tascam_usb_ids);
+
+static struct usb_driver tascam_alsa_driver = {
+ .name = DRIVER_NAME,
+ .probe = tascam_probe,
+ .disconnect = tascam_disconnect,
+ .suspend = tascam_suspend,
+ .resume = tascam_resume,
+ .id_table = tascam_usb_ids,
+};
+
+module_usb_driver(tascam_alsa_driver);
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