[ALSA] fm801 - Add mute support for FM-only card with FM801 PCI to tuner bridge

This is improvement of the early support of the FM-only cards where the
fm801 chip represents the PCI to tuner bridge.
The tuner initialization isn't included the mute on as well as mute support
via V4L request. Proposed patch should fix this at least for 64-PCR model.

Signed-off-by: Andy Shevchenko <andy@smile.org.ua>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/pci/fm801.c b/sound/pci/fm801.c
index 25c1087..4c300e6 100644
--- a/sound/pci/fm801.c
+++ b/sound/pci/fm801.c
@@ -978,6 +978,27 @@
 	return val;
 }
 
+static void snd_fm801_tea575x_64pcr_mute(struct snd_tea575x *tea,
+					  unsigned int mute)
+{
+	struct fm801 *chip = tea->private_data;
+	unsigned short reg;
+
+	spin_lock_irq(&chip->reg_lock);
+
+	reg = inw(FM801_REG(chip, GPIO_CTRL));
+	if (mute)
+		/* 0xf800 (mute) */
+		reg &= ~FM801_GPIO_GP(TEA_64PCR_WRITE_ENABLE);
+	else
+		/* 0xf802 (unmute) */
+		reg |= FM801_GPIO_GP(TEA_64PCR_WRITE_ENABLE);
+	outw(reg, FM801_REG(chip, GPIO_CTRL));
+	udelay(1);
+
+	spin_unlock_irq(&chip->reg_lock);
+}
+
 static struct snd_tea575x_ops snd_fm801_tea_ops[3] = {
 	{
 		/* 1 = MediaForte 256-PCS */
@@ -993,6 +1014,7 @@
 		/* 3 = MediaForte 64-PCR */
 		.write = snd_fm801_tea575x_64pcr_write,
 		.read = snd_fm801_tea575x_64pcr_read,
+		.mute = snd_fm801_tea575x_64pcr_mute,
 	}
 };
 #endif