ALSA: ac97: add AC97 STMicroelectronics' codecs

Add the STMicroelectronics ST7597 codec and an unknown codec
from the same manufacturer found on the Creative SB 128 card (CT4810).
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/pci/ac97/ac97_codec.c

@@ -83,6 +83,7 @@ static const struct ac97_codec_id snd_ac97_codec_id_vendors[] = {
 { 0x4e534300, 0xffffff00, "National Semiconductor", NULL, NULL },
 { 0x50534300, 0xffffff00, "Philips",		NULL,	NULL },
 { 0x53494c00, 0xffffff00, "Silicon Laboratory",	NULL,	NULL },
+{ 0x53544d00, 0xffffff00, "STMicroelectronics",	NULL,	NULL },
 { 0x54524100, 0xffffff00, "TriTech",		NULL,	NULL },
 { 0x54584e00, 0xffffff00, "Texas Instruments",	NULL,	NULL },
 { 0x56494100, 0xffffff00, "VIA Technologies",   NULL,	NULL },
@@ -161,6 +162,7 @@ static const struct ac97_codec_id snd_ac97_codec_ids[] = {
 { 0x4e534350, 0xffffffff, "LM4550",		patch_lm4550,  	NULL }, // volume wrap fix 
 { 0x50534304, 0xffffffff, "UCB1400",		patch_ucb1400,	NULL },
 { 0x53494c20, 0xffffffe0, "Si3036,8",		mpatch_si3036,	mpatch_si3036, AC97_MODEM_PATCH },
+{ 0x53544d02, 0xffffffff, "ST7597",		NULL,		NULL },
 { 0x54524102, 0xffffffff, "TR28022",		NULL,		NULL },
 { 0x54524103, 0xffffffff, "TR28023",		NULL,		NULL },
 { 0x54524106, 0xffffffff, "TR28026",		NULL,		NULL },
@@ -213,6 +215,14 @@ static int snd_ac97_valid_reg(struct snd_ac97 *ac97, unsigned short reg)
 {
 	/* filter some registers for buggy codecs */
 	switch (ac97->id) {
+	case AC97_ID_ST_AC97_ID4:
+		if (reg == 0x08)
+			return 0;
+		/* fall through */
+	case AC97_ID_ST7597:
+		if (reg == 0x22 || reg == 0x7a)
+			return 1;
+		/* fall through */
 	case AC97_ID_AK4540:
 	case AC97_ID_AK4542:
 		if (reg <= 0x1c || reg == 0x20 || reg == 0x26 || reg >= 0x7c)

sound/pci/ac97/ac97_id.h

@@ -62,3 +62,5 @@
 #define AC97_ID_CM9761_78	0x434d4978
 #define AC97_ID_CM9761_82	0x434d4982
 #define AC97_ID_CM9761_83	0x434d4983
+#define AC97_ID_ST7597		0x53544d02
+#define AC97_ID_ST_AC97_ID4	0x53544d04