[ALSA] oxygen: add I2C support

Add a function to write I2C registers.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/oxygen/oxygen.h

@@ -146,6 +146,7 @@ void oxygen_write_ac97_masked(struct oxygen *chip, unsigned int codec,
 			      unsigned int index, u16 data, u16 mask);
 
 void oxygen_write_spi(struct oxygen *chip, u8 control, unsigned int data);
+void oxygen_write_i2c(struct oxygen *chip, u8 device, u8 map, u8 data);
 
 static inline void oxygen_set_bits8(struct oxygen *chip,
 				    unsigned int reg, u8 value)

sound/pci/oxygen/oxygen_io.c

@@ -190,12 +190,31 @@ void oxygen_write_spi(struct oxygen *chip, u8 control, unsigned int data)
 		--count;
 	}
 
-	spin_lock_irq(&chip->reg_lock);
 	oxygen_write8(chip, OXYGEN_SPI_DATA1, data);
 	oxygen_write8(chip, OXYGEN_SPI_DATA2, data >> 8);
 	if (control & OXYGEN_SPI_DATA_LENGTH_3)
 		oxygen_write8(chip, OXYGEN_SPI_DATA3, data >> 16);
 	oxygen_write8(chip, OXYGEN_SPI_CONTROL, control);
-	spin_unlock_irq(&chip->reg_lock);
 }
 EXPORT_SYMBOL(oxygen_write_spi);
+
+void oxygen_write_i2c(struct oxygen *chip, u8 device, u8 map, u8 data)
+{
+	unsigned long timeout;
+
+	/* should not need more than about 300 us */
+	timeout = jiffies + msecs_to_jiffies(1);
+	do {
+		if (!(oxygen_read16(chip, OXYGEN_2WIRE_BUS_STATUS)
+		      & OXYGEN_2WIRE_BUSY))
+			break;
+		udelay(1);
+		cond_resched();
+	} while (time_after_eq(timeout, jiffies));
+
+	oxygen_write8(chip, OXYGEN_2WIRE_MAP, map);
+	oxygen_write8(chip, OXYGEN_2WIRE_DATA, data);
+	oxygen_write8(chip, OXYGEN_2WIRE_CONTROL,
+		      device | OXYGEN_2WIRE_DIR_WRITE);
+}
+EXPORT_SYMBOL(oxygen_write_i2c);