[ALSA] snd-emu10k1: Removes some distortion from Audigy 2 ZS Notebook.

Modules: EMU10K1/EMU10K2 driver

Description:
Part way to fix ALSA bug#927
Add support for the SPI interface on the CA0108 chip.
This is used to control the registers on the DAC.
Headphone output tested.
Other outputs and Capture not tested yet.
Note: The red LED does not come on, but sound is still OK.

Signed-off-by: James Courtier-Dutton <James@superbug.co.uk>

1 files changed, 36 insertions, 0 deletions

diff --git a/sound/pci/emu10k1/io.c b/sound/pci/emu10k1/io.c
index 5d116dd7403b..7d0cb9db4280 100644
--- a/sound/pci/emu10k1/io.c
+++ b/sound/pci/emu10k1/io.c
@@ -29,6 +29,7 @@
 #include <linux/time.h>
 #include <sound/core.h>
 #include <sound/emu10k1.h>
+#include <linux/delay.h>
 
 unsigned int snd_emu10k1_ptr_read(struct snd_emu10k1 * emu, unsigned int reg, unsigned int chn)
 {
@@ -123,6 +124,41 @@ void snd_emu10k1_ptr20_write(struct snd_emu10k1 *emu,
 	spin_unlock_irqrestore(&emu->emu_lock, flags);
 }
 
+int snd_emu10k1_spi_write(struct snd_emu10k1 * emu,
+				   unsigned int data)
+{
+	unsigned int reset, set;
+	unsigned int reg, tmp;
+	int n, result;
+	if (emu->card_capabilities->ca0108_chip) {
+		reg=0x3c; /* PTR20, reg 0x3c */
+	} else {
+		return 1;  /* For other cards types the SPI register is currently unknown. */
+	}
+	if (data > 0xffff) return 1; /* Only 16bit values allowed */
+
+	tmp = snd_emu10k1_ptr20_read(emu, reg, 0);
+       	reset = (tmp & ~0x3ffff) | 0x20000; /* Set xxx20000 */
+	set = reset | 0x10000; /* Set xxx1xxxx */
+	snd_emu10k1_ptr20_write(emu, reg, 0, reset | data);
+	tmp = snd_emu10k1_ptr20_read(emu, reg, 0); /* write post */
+	snd_emu10k1_ptr20_write(emu, reg, 0, set | data);
+	result = 1;
+	/* Wait for status bit to return to 0 */
+	for (n=0;n<100;n++) {
+		udelay(10);
+		tmp = snd_emu10k1_ptr20_read(emu, reg, 0);
+		if (!(tmp & 0x10000)) {
+			result=0;
+			break;
+		}
+	}
+	if (result) return 1; /* Timed out */
+	snd_emu10k1_ptr20_write(emu, reg, 0, reset | data);
+	tmp = snd_emu10k1_ptr20_read(emu, reg, 0); /* Write post */
+	return 0;
+}
+
 void snd_emu10k1_intr_enable(struct snd_emu10k1 *emu, unsigned int intrenb)
 {
 	unsigned long flags;