V4L/DVB (9648): em28xx: get audio config from em28xx register

Make use of the em28xx chip configuration register to determine whether
we have AC97 audio, I2S audio, or no audio support at all.

Thanks for Ray Lu from Empia for providing the em2860/em2880 datasheet.
Signed-off-by: Devin Heitmueller <devin.heitmueller@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-reg.h

@@ -17,6 +17,16 @@
 
 /* em28xx registers */
 
+#define EM28XX_R00_CHIPCFG	0x00
+
+/* em28xx Chip Configuration 0x00 */
+#define EM28XX_CHIPCFG_VENDOR_AUDIO		0x80
+#define EM28XX_CHIPCFG_I2S_VOLUME_CAPABLE	0x40
+#define EM28XX_CHIPCFG_I2S_3_SAMPRATES		0x30
+#define EM28XX_CHIPCFG_I2S_5_SAMPRATES		0x20
+#define EM28XX_CHIPCFG_AC97			0x10
+#define EM28XX_CHIPCFG_AUDIOMASK		0x30
+
 	/* GPIO/GPO registers */
 #define EM2880_R04_GPO	0x04    /* em2880-em2883 only */
 #define EM28XX_R08_GPIO	0x08	/* em2820 or upper */

drivers/media/video/em28xx/em28xx-video.c

@@ -1933,16 +1933,49 @@ static struct video_device *em28xx_vdev_init(struct em28xx *dev,
 
 int em28xx_supports_audio_extension(struct em28xx *dev)
 {
+	int rc;
+
 	/* The chip dictates whether we support the Empia analog audio
 	   extension */
 	switch (dev->chip_id) {
 	case CHIP_ID_EM2874:
-		/* Either a digital-only device or provides AC97 audio */
+		/* Digital only device - no analog support */
+		dev->audio_mode = EM28XX_NO_AUDIO;
 		return 0;
+	case CHIP_ID_EM2860:
 	case CHIP_ID_EM2883:
 	default:
+		/* See how this device is configured */
+		rc = em28xx_read_reg(dev, EM28XX_R00_CHIPCFG);
+		if (rc & EM28XX_CHIPCFG_VENDOR_AUDIO) {
+			switch(rc & EM28XX_CHIPCFG_AUDIOMASK) {
+			case EM28XX_CHIPCFG_AC97:
+				em28xx_info("AC97 audio (5 sample rates)\n");
+				dev->audio_mode = EM28XX_AC97;
+				break;
+			case EM28XX_CHIPCFG_I2S_3_SAMPRATES:
+				em28xx_info("I2S Audio (3 sample rates)\n");
+				dev->audio_mode = EM28XX_I2S_3_SAMPLE_RATES;
+				break;
+			case EM28XX_CHIPCFG_I2S_5_SAMPRATES:
+				em28xx_info("I2S Audio (5 sample rates)\n");
+				dev->audio_mode = EM28XX_I2S_5_SAMPLE_RATES;
+				break;
+			default:
+				em28xx_info("No audio support detected\n");
+				dev->audio_mode = EM28XX_NO_AUDIO;
+				return 0;
+			}
+		} else {
+			em28xx_info("USB Audio class device\n");
+			return 0;
+		}
+		/* The em28xx audio extension needs to be loaded */
 		return 1;
 	}
+
+	/* We should never reach this point */
+	return 0;
 }
 
 static int register_analog_devices(struct em28xx *dev)

drivers/media/video/em28xx/em28xx.h

@@ -256,6 +256,13 @@ enum enum28xx_itype {
 	EM28XX_RADIO,
 };
 
+enum em28xx_audio_mode {
+	EM28XX_NO_AUDIO,
+	EM28XX_I2S_3_SAMPLE_RATES,
+	EM28XX_I2S_5_SAMPLE_RATES,
+	EM28XX_AC97,
+};
+
 enum em28xx_amux {
 	EM28XX_AMUX_VIDEO,
 	EM28XX_AMUX_LINE_IN,
@@ -403,6 +410,7 @@ struct em28xx {
 	u32 i2s_speed;		/* I2S speed for audio digital stream */
 
 	enum em28xx_decoder decoder;
+	enum em28xx_audio_mode audio_mode;
 
 	int tuner_type;		/* type of the tuner */
 	int tuner_addr;		/* tuner address */