ALSA: hdspm: Replace tasklet with work

The tasklet is an old API that should be deprecated, usually can be
converted to another decent API.  In HDSP-MADI driver, a tasklet is
still used for offloading the MIDI I/O handling (optional via mixer
switch).  It can be achieved gracefully with a work queued, too.

This patch replaces the tasklet usage in HDSP-MADI driver with a
simple work.  The conversion is fairly straightforward.  The only
significant difference is that the work initialization is moved to the
right place in snd_hdspm_create() and cancel_work_sync() is always
called in snd_hdspm_free() to assure killing the pending works.

Link: https://lore.kernel.org/r/20200903104131.21097-8-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/rme9652/hdspm.c

@@ -997,7 +997,7 @@ struct hdspm {
 	u32 settings_register;  /* cached value for AIO / RayDat (sync reference, master/slave) */
 
 	struct hdspm_midi midi[4];
-	struct tasklet_struct midi_tasklet;
+	struct work_struct midi_work;
 
 	size_t period_bytes;
 	unsigned char ss_in_channels;
@@ -2169,9 +2169,9 @@ static int snd_hdspm_create_midi(struct snd_card *card,
 }
 
 
-static void hdspm_midi_tasklet(struct tasklet_struct *t)
+static void hdspm_midi_work(struct work_struct *work)
 {
-	struct hdspm *hdspm = from_tasklet(hdspm, t, midi_tasklet);
+	struct hdspm *hdspm = container_of(work, struct hdspm, midi_work);
 	int i = 0;
 
 	while (i < hdspm->midiPorts) {
@@ -5449,7 +5449,7 @@ static irqreturn_t snd_hdspm_interrupt(int irq, void *dev_id)
 		}
 
 		if (schedule)
-			tasklet_hi_schedule(&hdspm->midi_tasklet);
+			queue_work(system_highpri_wq, &hdspm->midi_work);
 	}
 
 	return IRQ_HANDLED;
@@ -6538,6 +6538,7 @@ static int snd_hdspm_create(struct snd_card *card,
 	hdspm->card = card;
 
 	spin_lock_init(&hdspm->lock);
+	INIT_WORK(&hdspm->midi_work, hdspm_midi_work);
 
 	pci_read_config_word(hdspm->pci,
 			PCI_CLASS_REVISION, &hdspm->firmware_rev);
@@ -6836,9 +6837,6 @@ static int snd_hdspm_create(struct snd_card *card,
 
 	}
 
-	tasklet_setup(&hdspm->midi_tasklet, hdspm_midi_tasklet);
-
-
 	if (hdspm->io_type != MADIface) {
 		hdspm->serial = (hdspm_read(hdspm,
 				HDSPM_midiStatusIn0)>>8) & 0xFFFFFF;
@@ -6873,6 +6871,7 @@ static int snd_hdspm_free(struct hdspm * hdspm)
 {
 
 	if (hdspm->port) {
+		cancel_work_sync(&hdspm->midi_work);
 
 		/* stop th audio, and cancel all interrupts */
 		hdspm->control_register &=